FNZ 41 - Coccidae (Insecta: Hemiptera: Coccoidea) - Introduction
Hodgson, CJ; Henderson, RC 2000. Coccidae (Insecta: Hemiptera: Coccoidea). Fauna of New Zealand 41, 264 pages.
( ISSN 0111-5383 (print), ; no. 41. ISBN 0-478-09335-7 (print) ). Published 23 Feb 2000
The earliest record of a soft scale insect from New Zealand is from Cook's First Voyage, 1768-71. During this voyage, the botanists Banks and Solander collected much herbarium material, and parts of that collection have been deposited in various museums, including the United States National Museum of Natural History (USNM). At some stage, a single adult female soft scale, along with the piece of leaf beneath it, was cut out from a herbarium specimen and preserved dry in the USNM (accession number 1276401); this is labelled Ctenochiton on Coprosma ace-rosa. There is some doubt about the accuracy of the plant host record, as C. acerosa has very narrow leaves, far narrower than the breadth of a fully mature female Ctenochiton! It is uncertain whether the specimen is Ctenochiton paraviridis n. sp. or Ctenochiton viridis Maskell; the latter has been recorded from Coprosma whereas C. paraviridis has not, but without slide mounting and therefore altering a unique sample, the benefit of the doubt concludes that it is possibly C. viridis.
New Zealand Coccoidea were first studied between 1879 and 1898 by W.M. Maskell, recognised then as one of the World's leading authorities on scale insects. He described about 300 species of Sternorrhyncha from around the world, including many scale insects from New Zealand. Maskell's interest in the then new science of microscopy meant that he was well ahead of his contemporaries in describing species from slide-mounted specimens. Although they were unstained and had other deficiencies, these slides can still be used today. Maskell also kept dried material both of the specimens he collected and of those he was sent. However, these cannot always be considered to be syntype material as he tended to put material collected on different days or from different localities in the same box if he thought they were the same species (see Deitz & Tocker, 1980). Maskell was before his time in recognising that stages other than the adult female might be important in the taxonomy of coccoids and his dry material collection can be useful as it often contains nymphs and males.
Since Maskell's time, there have been a number of other studies on New Zealand Coccoidea. The ten families of Coccoidea now known from New Zealand are as follows: Asterolecaniidae: Maskell's species were re-described by Morrison & Morrison (1927) and the World fauna was revised by Russell (1941); Cerococcidae: 3 species; 2 redescribed by Lambdin & Kosztarab (1976, 1977) and 1 new species (Lambdin, 1998); Coccidae: Morrison & Morrison (1922) and Hodgson (1994a) redescribed the type species of Maskell's three New Zealand genera; Hodgson & Henderson (1998) described a new genus and 2 new species; Diaspididae: some species of the tribe Leucaspidinae by Britten (1937) and de Boer & Valentine (1977); an unpublished field study of the same taxon by Emms (1985); Eriococcidae: a complete revision by Hoy (1962) and more recently a revision of the genus Eriochiton by Hodgson (1994b) and Hodgson & Henderson (1996); Halimococcidae: a Colobopyga species described by Deitz (1979); Margarodidae: completely revised by Morales (1991); earlier papers covering aspects of this family are Brittin (1935), Dumbleton (1967), Morrison & Morrison's (1923) redescription of Maskell's species, and Morrison's (1928) world monograph; Ortheziidae: comments by Green (1929); Phenacoleachiidae: Beardsley (1964); and Pseudococcidae: completely revised by Cox (1987) with an earlier paper by Williams & de Boer (1973).
Thus, the soft scales or Coccidae have not received much attention this century since Maskell described 17 species of indigenous soft scales in three genera (Ctenochiton, Inglisia, and Lecanochiton) over a period of about 20 years, his last paper published in 1898. Exactly 100 years later Hodgson and Henderson (1998) described a fourth genus, Pounamococcus, containing two new species.
This volume provides a complete revision of the adult females currently known, adding descriptions of seven new genera — Aphenochiton, Crystallotesta, Epelidochiton, Kalasiris, Plumichiton, Poropeza, and Umbonichiton — and 25 new species, bringing the total to 11 indigenous genera and 43 species in New Zealand, although it is clear that there are still further species awaiting description. In addition, 14 adventive species are illustrated and briefly described.
None of the species currently included in Ctenochiton and Inglisia described from outside New Zealand are here considered to be congeneric. Thus Inglisia becomes monotypic (I. patella Maskell) with the four other New Zealand species originally placed in Inglisia transferred to either Aphenochiton n. gen. — A. inconspicuus (Maskell) — or Crystallotesta n. gen. — C. fagi (Maskell), C. leptospermi (Maskell), and C. ornata (Maskell). The genus Ctenochiton now includes only C.viridis Maskell and three new species — C. chelyon, C. paraviridis, and C. toru. Ctenochiton depressus Maskell and C. perforatus Maskell are transferred to Kalasiris n. gen.; C. elaeocarpi Maskell and C. flavus Maskell to Plumichiton n. gen.; C. dacrydii Maskell to Poropeza n. gen.; C. fuscus to Crystallotesta n. gen.; C. hymenantherae Maskell to Umbonichiton n. gen.; and C. piperis Maskell to Epelidochiton n. gen. Ctenochiton elongatus Maskell is designated a nomen dubium for reasons explained in full on page 184. The genus Lecanochiton retains its original two species L. metrosideri Maskell and L. minor Maskell. In addition, Lecanium (Eulecanium) spinosum Brittin is synonymised with Parthenolecanium persicae (Fabricius).
The known adult males and immature stages will be described in future volumes.
The Classification of the Lecanoid Coccoidea. The use of cladistic analyses to determine possible relationships within the Coccoidea have been relatively few: Miller, 1984 (many taxa of the Coccoidea, based on a range of characters); Miller and Miller, 1993a, 1993b (affiliations of Puto and Eriokermes); Foldi, 1995 (affiliations of Limacoccus); Miller and Williams, 1995 (affiliations of the Micrococcidae); Qin and Gullan, 1995 (relationships within the Ceroplastinae); Hodgson and Henderson, 1996 (affiliations of Eriochiton); Miller & Hodgson, 1997 (relationships within the lecanoid coccids), and Foldi, 1997 (many taxa, considered from the viewpoint of the evolution of their feeding sites and protective structures). In addition, several non-cladistic phylogenies have been suggested, i.e.. Borchsenius, 1958 (based mainly on adult female characters); Boratyski & Davies, 1971 (based on adult male characters); Koteja, 1974b (based on the structure of the adult female mouthparts); Miller & Kosztarab, 1979 (a version of Boratyski & Davies (1971) modified on the basis of more recent descriptions of males); Danzig, 1986 (using the morphology of the adult female, adult male, and crawler and also life history characters); and Koteja (reviewers' remarks in Kosztarab & Kozár, 1988).
Few classifications have been suggested for the family Coccidae, the most recent being that of Tang et al. (1990), Tang (1991) and Hodgson (1994a). The two papers by Tang proposed a rather complex classification based entirely on female characters but most of the generic groupings were very different from those suggested by the studies of males (Giliomee, 1967). Hodgson (1994a) introduced a classification based on the relationships suggested by the morphology of both adult males and females. He divided the Coccidae into 10 subfamilies, with the Coccinae divided into four tribes, although he considered that the status of these groupings needed further study. This classification was the basis of a cladistic study done by Miller & Hodgson (1997), the results of which are shown in Fig. 1. The New Zealand coccid fauna with a glassy test (those related to Ctenochiton) are here believed to be close to the glassy scales (Cardiococcinae); the placement of genera such as Pounamococcus is uncertain but they appear to be close to the Paralecaniini. It is interesting to note that in all the cladograms of Miller & Hodgson (1997) the Cardiococcinae and Paralecaniini were sister taxa. A detailed phylogenetic analysis will be undertaken once the description of all stages, i.e., including the adult males and immatures, has been completed.
Biology and life cycle. Male and female coccoids go through very different post-embryonic development. The females are considered to be neotenic and reach the non-winged adult stage after two or three moults. The changes that take place at each moult are relatively small and the metamorphosis is of the heterometabolous-paurametabolous type (Fig. 2, p. 21). On the other hand, the development of the male resembles that of a holometabolous type, producing a fully-winged adult stage, quite different from that of the female. The 1st-instar stage or crawler of both males and females usually are indistinguishable. This is the main dispersal stage (Greathead, 1997) and is a feeding stage. The 2nd instar is also a feeding stage for both sexes but the nymphs are usually easily separable because they are sexually dimorphic, those of the male secreting a more elongate glassy test under which all further development takes place. In the male, the 2nd-instar nymph then moults three times giving rise to the non-feeding, sessile prepupal and pupal stages and finally the winged, non-feeding adult male. These moults take place beneath the protective glassy test secreted by the 2nd-instar male nymphs. The adult males of indigenous species emerge backwards from beneath their test, wingtips first, by means of the upwardly flexing plate on the posterior end of the test.
The crawler disperses to locate a suitable feeding site, which may be on the same plant as the natal mother or elsewhere. The test covering a neonate crawler is composed of soft wax that is less protective than that secreted once feeding has started. Crawler mortality is high as many do not find a suitable food source before succumbing to environmental factors, such as high rainfall, desiccation by wind or high temperatures, overcrowding on the natal leaf, and losses through wind dispersal. Surviving nymphs apparently often move away from the first settlement site and disperse further. Male nymphs can move to non-specific host plants once they have ceased feeding (or, perhaps, in the late feeding stages before becoming completely sessile), settle and secrete the wax which fixes the test firmly to the substrate, and then begin metamorphosis. This ability to settle on other plants makes determining the relationships of an adult male to a particular female difficult; thus, plant species on which only male stages are known are not here considered to be true host plants, as the female stages appear to have a more restricted host range.
In the female, subsequent nymphal instars change little other than in size, and the only safe way to be sure that you are looking at an adult is to locate the pregenital disc-pores or the vulva (more difficult). Usually on adult females, other pores such as the dorsal macropores are obvious and the ventral tubular ducts, when present, are more numerous than on younger instars. When most female stages are available, the difference in size of the anal plates and/or the clypeolabral shield makes instar identification reasonably easy (see key to stages, p. 21).
The female life cycle may have either two or three moults after the 1st-instar. Most indigenous species have three nymphal stages before the last moult; the third nymphal stage is sometimes very brief and so it is possible that a third instar is more widespread than records suggest.
With few exceptions, New Zealand native plants are predominantly evergreen (e.g., Wardle 1991, p. 39) and there are few records of coccids from the deciduous native trees. Amongst the evergreens recorded as hosts for scale insects in New Zealand are Hedycarya arborea, Griselinia spp., Mida salicifolia, Myrsine australis, Pseudopanax spp., and Schefflera digitata. The leaves of these lowland broadleaf trees may not senesce for several years, although individual leaves may be shed at any time of the year. Thus, a scale insect species with an annual life cycle can reliably overwinter on the previous summer's (old) leaves. In some univoltine species, e.g., Ctenochiton paraviridis and C. viridis, it is the 2nd-instar nymphs that overwinter; in this case, the female nymphs migrate in the spring from the old leaves and resettle on the new, fast growing shoots, where the rising sap supplies nutrients for rapid growth to maturity. Other univoltine species overwinter as the immature adult female on the leaves (e.g., Aphenochiton subtilis) or on the stems (e.g., Plumichiton pollicinus), whilst others, such as Aphenochiton pubens, are mature and reproduce on leaves from late winter. Sessile male nymphs remain on the old leaves and adult males emerge from there.
In the male, the crawler and the 2nd-instar nymphs are the only feeding stages. The test is usually glued to the plant surface, apparently by waxes secreted from a submarginal band of tubular ducts, the presence of which can separate most 2nd-instar males from 2nd-instar females. In all known male New Zealand 2nd-instar nymphs, there are also two groups of tubular ducts on the dorsum on about the 4th abdominal segment. These ducts secrete a type of wax that appears to act as the hinge for the posterior test plate, so that it can be raised during the emergence of the adult males. The 2nd-instar males moult into an elongate prepupal stage that shows the first signs of wing-buds, dorsal and ventral eyes, and a penial sheath; they lack functional mouthparts. The pupa is similar but the legs and wing-buds are better developed and the penial sheath is longer. The adult male remains beneath the male test for several days until fully developed and the long wax caudal filaments have been secreted (not present in all species), when it emerges backwards, and then actively flies looking for females. As it has no functional mouthparts, its life is rather short, usually only a few days. It is likely that some species of soft scale lack males completely and are therefore parthenogenetic; for example, those of Poropeza, where the adult females are hidden beneath the bark of the host trees.
The adult females of all soft scales have functional mouthparts and feed on sap from the phloem. Before the development of their ovaries, young adult females are only about the size of the last nymphal stage (Fig. 121 under Lecanochiton). They then undergo a very consid-erable increase in size, generally at least two to three times their post-moult size, although this may be as much as ten times for species of Ctenochiton and Poropeza. Once this swelling period is complete, the females are ready to reproduce. In many species (such as those in the genus Lecanochiton), the venter develops a distinct concavity to form a brood chamber. In species of Lecanochiton, the vulva is towards the middle of the abdomen, so that the eggs can be deposited directly into the chamber. In some of the other New Zealand species, such as those in the genera Kalasiris and Pounamococcus, the posterior half of the glassy test is used as the brood chamber, the adult female shrinking into the anterior half of the test as she oviposits; in these species the vulva is close to the anogenital fold at the posterior end of the abdomen. Quite a lot of species appear to contain fully developed nymphs and, therefore, are either viviparous or ovoviviparous (see Tremblay, 1997).
In the adventive Pulvinaria species, the ventral tubular ducts, of which there are three or four types, secrete a long white ovisac from beneath the venter (Figs C84, C85, C87). The eggs are then laid within this.
Distribution and host-plant associations. Fourteen cosmopolitan species of soft scale insects are established in New Zealand. Most of these adventive soft scales can be found in citrus orchards as well as on other host plants. The species found on citrus include the three Ceroplastes species in New Zealand — C. ceriferus (Fabricius), C. destructor Newstead, and C. sinensis Del Guercio — which are restricted to the warmer areas, generally from Northland to Gisborne, and two species of Coccus, two species of Saissetia, and one Parasaissetia species. The species not recorded from citrus are Parthenolecanium corni (Bouché) and the four Pulvinaria species recorded in New Zealand: P. floccifera (Westwood), P. hydrangeae Steinweden, P. mesembryanthemi (Vallot), and P. vitis (Linnaeus).
In New Zealand, the most common and widespread of the adventive soft scales is Coccus hesperidum Linnaeus; it has been found on the Kermadec Islands to the north and Chatham Islands to the south-east, as well as throughout most of the North and South Islands. C. hesperidum is mainly a pest of ornamentals, both outdoors and indoors, and it also occurs in nearly all types of fruit orchards — records are from a total of 35 exotic plant species and from 22 species of native plants. Both of the Saissetia species in New Zealand are also common and widespread; S. oleae (Olivier) is recorded from 21 exotic and 23 native plant species while S. coffeae (Walker) is recorded from 18 exotic and 14 native plant species.
Altogether 6 species of adventive soft scales have been found on indigenous native plants as well as exotic plants, although only two, C. hesperidum and S. coffeae, have been recorded from within native forests; the other four species, Ceroplastes sinensis, Coccus longulus (Douglas), Saissetia oleae, and Parthenolecanium corni were either recorded from garden natives, at forest margins that had been disturbed by human influence, or open natural ecosystems, e.g., on mangroves and bracken. A seventh species, Pulvinaria mesembryanthemi, is found on ice plants that may be considered native but not indigenous. The other 7 species have not been recorded from native plants and are generally of minor significance on exotic plants.
In regard to distribution, all endemic species currently known from New Zealand belong to genera that are here considered to be entirely endemic. Even the genera Ctenochiton and Inglisia (which contain species des-cribed from elsewhere) are considered here to be endemic, so that the non-New Zealand species will need to be reassigned to other genera. This applies even to the Australian species, which might have been expected to be closely related. This strong endemism is also emphasised by the host plants of the New Zealand soft scale fauna, as almost no endemic coccids have been recorded from the many introduced plant species (even in the case of the one exception, the collector noted that it was close to its normal host). As some of the endemic species appear to be fairly polyphagous, this is surprising.
There appears to be no distinct pattern of relationships among the endemic soft scale species and their associated host plant species. The degree of polyphagy ranges from the high of Ctenochiton paraviridis n.sp., Epelidochiton piperis (Maskell), and Plumichiton flavus (Maskell) with 15, 16, and 15 host plant species respectively (in 12-14 plant genera and 11-13 plant families) to lows of 2 or 3 host plant species (e.g., Aphenochiton pronus n.sp. and Plumichiton diadema n.sp.). Another polyphagous species is Kalasiris perforata (Maskell) with 18 host plant species including 6 Coprosma and 6 Pittosporum species. Of the 17 endemic coccid species that have between 4 and 18 associated species of plant hosts, (in 4 to 14 plant genera), Poropeza dacrydii (Maskell) is the only one restricted to a single plant family, the Podocarpaceae (see Appendix B).
The number of endemic soft scale species recorded from particular host-plant species is equally diverse, and in this case Hedycarya arborea is by far the most favoured of the host plants, with 11 endemic coccid species in 9 genera (and no adventive coccid species) recorded from it. Coprosma spp., Pittosporum spp., and Podocarpus totara have respectively 9, 7, and 6 coccid endemics recorded from them (see Appendix A).
Amongst some endemic soft scale genera that have become associated with closely related or single plant genera, the most obvious are Lecanochiton, restricted to the plant genus Metrosideros, and the adult females of Poropeza, restricted to closely related genera in Podocarpaceae. A group of three species Crystallotesta leptospermi (Maskell), C. ornatella n.sp., and Plumichiton pollicinus n.sp. are in effect monophagous on the closely related Kunzea ericoides and Leptospermum scoparium. Other monophage examples for which there are fairly extensive records are Crystallotesta fagi (Maskell) and Crystallotesta neofagi n.sp. recorded from Nothofagus; Aphenochiton kamahi n.sp. from Weinmannia; Plumichiton nikau n.sp. from Rhopalostylis sapida, and Pounamococcus cuneatus Henderson & Hodgson from ferns (Blechnum fraseri in particular).
Some distribution patterns for endemic soft scales can appear disjunct, e.g., Aphenochiton subtilis n.sp with localities recorded from the Three Kings Islands and the northern half of the North Island, then Fiordland and Southland ( map 9), and Kalasiris depressa (Maskell) also with widely separated recorded localities from Northland to Fiordland (map 22). The seemingly haphazard nature of plant associations with insects in New Zealand was noted by Dugdale (1975), and may have evolved over the past millions of years in response to the sometimes violent reversals in both the climate and the shape and extent of the landmass since the Cretaceous. In reality, man has probably induced many of the relic populations of scale insects over the last approximate 150 years, with the huge loss in indigenous forest cover when much of New Zealand was cleared for farming by European settlers (see Miller, 1925, for maps showing total area of indigenous forest in 1840 and in 1924). Thus, the survival of remnant forest patches may have a greater bearing on the modern distribution of indigenous soft scales than past geologic or tectonic events.
Some of the plant-host genera on which the endemic soft scales are known have a much wider geographic distribution. For instance, Dracophyllum is also known from Australia and New Caledonia; Leptospermum is known from Australia, Malaya, and New Caledonia; Nothofagus is known from Australia, New Caledonia, New Guinea, and temperate South America, and yet the New Zealand coccid genera, as understood in this revision, have not been found in these countries. There are a few records in the literature of indigenous species elsewhere in the world but these are here considered to be misidentifications (see under Ctenochiton elongatus, Kalasiris perforata, and Plumichiton flavus).
Like many other New Zealand Sternorrhyncha (Morales, 1991), the adult females of both species of Poropeza are cryptozoic, living hidden beneath the bark of their host trees, and may have an unusual life cycle associated with this habit, with the immature stages feeding on other plants (see under Poropeza) and probably reproducing parthenogenetically. Other species, despite living on the leaf, are extremely well camouflaged. Thus, most Aphenochiton species are very flat and are either a very similar green to that of the leaf or are more or less transparent — the light reflected off the glassy test being the main clue to their presence (Figs C32-C36).
Most leaf-living species are found on the lower leaf surface, but Lecanochiton scutellaris, Plumichiton diadema, P. pollicinus, P. punctatus, and Pounamococcus tubulus all settle on the upper surface. With regard to Pounamococcus tubulus, we have postulated (Hodgson & Henderson, 1998) that this is a mechanism for remaining clean of sooty mould and debris in an area of very high rainfall. In these areas, the lower leaf surfaces of the host plants of P. tubulus acquire a thick burden of other invertebrates, lichens, fungi, and detritus that could smother this insect, while the upper surfaces are maintained clean and shiny by the almost daily washing, which also removes the honeydew. The former four species inhabit less extreme climates and are either heavily sclerotised (L. scutellaris), or have very thick tests (the Plumichiton species).
Parasites and predators. Birds have been observed feeding on soft scales in the native forest, e.g., the kokako (Callaeas cinerea) was recorded feeding on the large Ctenochiton species known as 'sixpenny scales' (Leathwick et al., 1983). Hudson (1891) noted an instance of control of Coccus hesperidum (as Lecanium hispidum) by a species of Rhizobius (Coccinellidae) and Koebele (1893) mentioned the coccinellid beetle Harmonia antipida (White, 1846) as a predator of Ctenochiton viridis. Predatory mites and Cecidomyiidae have not been recorded feeding on indigenous soft scale species, however, the following have been recorded attacking the introduced Ceroplastes destructor: the mite Tyrophagus perniciosus, which is thought to prey on the eggs (Lo, 1995); the steel-blue ladybird (Halmus (=Orcus) chalybeus) which is considered to be a useful biocontrol agent in citrus orchards in Northland (Lo et al., 1992; Lo & Blank, 1992) and a cecidomyiid belonging to the genus Trisopsis (Crosby, 1986). Indigenous species are commonly attacked by entomogenous fungi; indeed, Hosking & Kershaw (1985, p. 208) noted that "the collapse of the epidemic [of Crystallotesta fagi] appeared to be caused by an entomogenous fungus, probably Hypocrella duplex". Three species of parasitic fungi are currently known (see list below) but there are probably more species still to be identified that attack coccids in New Zealand. The list of hymenopterous parasites so far identified (see Appendix C; Valentine & Walker, 1991) is also probably very incomplete and again many more species remain to be discovered. Most instances of parasitism are observed by the round exit hole in tests, and thus parasitoids are seldom reared through for identification. The number of parasitoids emerging from a scale appears to be partly related to the size of the scale, with many larvae contained in large-bodied soft scales such as Ctenochiton paraviridis (Fig. C56) and with only 1-2 from small scales, such as male nymphs. As a defence against parasitism, coccids are often able to encapsulate the invading parasitoid eggs, thus preventing their development (see Blumberg, 1997); in mounted specimens, examples of encapsulation are frequently seen as brown, stalked oval bodies, usually near the margin.
- "Brown blobs": Aegerita webberi H.S. Fawc. (Fig. C69): particularly infesting Ctenochiton paraviridis, probably during the early nymphal stages; when completely infested, there is no remaining evidence of the scale insect (see Myers (1928)).
- "Orange puffs": Hypocrella duplex (Berk.) Petch (Fig. C70): bright orange. Commonly infesting Aphenochiton kamahi, Plumichiton flavus, and P. nikau. In early infest-ations, the scale insect's shape and patterns are visible; in older infestations, the insects become puffed up, either at one end or all over, with a softer, yellow centre on top, sometimes exuding a ribbon-like part.
- "White fungus": Verticillium lecanii (Zimm.) Viégas (Fig. C71): commonly seen on adult female coccids, particularly C. paraviridis, where body outlines remain visible. Note: Verticillium has a looser texture than the other two fungal species -- the mycelium strands have whorls of small branches with spores on their tips, which shine under the light of a binocular microscope.
Parasitoids. All the adventive coccid species are parasitised by non-native hymenopterous parasitoids, and only one of these parasitoid species has also been recorded from an indigenous soft scale, namely Euxanthellus philippiae (Hymenoptera: Aphelinidae) from Kalasiris perforata (as Ctenochiton perforatus). Otherwise the parasitoids recorded from indigenous species are all endemic hymenopterous species. A full list is given in Appendix C.
See Hill (1989) and Morales (1989) for discussion of parasitoids introduced to New Zealand for biological control of Coccus hesperidum and Saissetia oleae.
It seems that none of the indigenous soft scales are economically important. They produce much less honeydew than the Margarodidae and are, therefore, less important both in terms of providing honeydew as a food source (that from Margarodidae supports not only native birds, geckos, and insects but also honey bees and the recently adventive European wasps) and as a substrate for sooty moulds. Crystallotesta [as Inglisia] fagi was blamed for the death of red beech trees (Nothofagus fusca) in an outbreak in the Maruia Valley, South Island, between 1976 and 1978 but there is little direct evidence, and Hosking & Kershaw (1985) considered that the trees had been stressed by several years of drought and that this could have accounted for the higher scale populations. Hoy (1958) studied the scale insects on rata (Metrosideros) and kamahi (Weinmannia) in an attempt to find the causes of reported large areas of die-back in these forest trees. As well as species belonging to other scale insect families, he found Lecanochiton metrosideri and L. minor on rata, and Plumichiton [as Ctenochiton] flavus on kamahi; he concluded that there was no indication that these coccids occurred in high enough numbers to have an adverse effect. It is relatively unlikely that any of the indigenous species will become an economic pest as they appear to be well adapted to their hosts, on which it is likely that they evolved. As they do not appear readily to accept any of the introduced plants, including all current commercial crops, it is also unlikely that they will move onto these plants. For the same reasons, it would appear that they do not have great potential as pests outside New Zealand, other than on closely related host species or genera.
However, a number of other coccids were known from New Zealand from about the time of Maskell. As these are all geographically widespread, cosmopolitan species, it is assumed that all are adventive (i.e., have been accidentally introduced from outside), and it is likely that most of them came with plants introduced by the early European settlers. Fourteen species have been definitely recorded plus two others that were apparently misidentified and, as there are no voucher specimens available, their possible earlier presence cannot be confirmed. The species that are currently of some importance are: Ceroplastes destructor and, to a lesser extent C. sinensis, both of which are serious pests of citrus in both of the major citrus orchard areas of Kerikeri (Northland) and Gisborne (D. Steven pers.comm.); C. sinensis also is a pest on feijoa (Feijoa sellowiana). Coccus hesperidum is a serious pest on ornamental plants, shrubs and ferns, both those grown indoors and outdoors, and can cause death when the infestations are heavy (D. Steven, pers. comm.); C. hesperidum also is found in low density populations on a wide range of introduced perennials, shrubs, and trees including Pinus radiata and Prunus spp., and has been recorded on about 20 indigenous plant species as well as on subtropical crops such as citrus, avocado (Persea americana), and tamarillo (Cyphomandra betacea). Parthenolecanium corni occurs at low levels in Central Otago stonefruit orchards, especially unsprayed orchards, and in particular on apricots (Prunus armeniaca) and plums (Prunus spp.) (G. McLaren, pers. comm.). Pulvinaria floccifera has been recorded on an experimental tea (Camellia sinensis) crop in Nelson, as well as on ornamental camellias. Pulvinaria vitis occurs in sporadic outbreaks on apricots in Central Otago orchards, records being clustered around 1951-52, 1984-85, and (at present) in 1998-1999. Pulvinaria vitis has also been recorded on grapevines (Vitis vinifera) and, although not a serious pest by itself, has been shown to transmit viruses associated with grapevine leafroll closterovirus disease (Belli et al., 1994). Other coccids recorded in low numbers on grapevines are Coccus hesperidum, Parthenolecanium corni, P. persicae, Saissetia coffeae, and S. oleae. Saissetia coffeae is a minor pest of indoor plants and outdoor ornamental shrubs in the warmer north (e.g., Auckland) but has also been found in remnant native forest on indigenous plants including ferns; S. oleae is a pest of citrus in the Gisborne orchard area (D. Steven, pers. comm.); both Saissetia species have been found on indigenous trees in native bush margins near human habitation. Soft scales are seldom found on kiwifruit (Actinidia deliciosa), although Ceroplastes destructor, Coccus hesperidum, and Saissetia oleae, each a primary association, are recorded in the Plant Pest Information Network (PPIN) Database.
COLLECTING AND MOUNTING METHODS
While many species of soft scale insects cannot be identified by looking at either their general live appearance, their host plant, or their infestation site, this is not quite so true of most of the indigenous New Zealand coccids and it is hoped that the accompanying colour plates will help identify many of these species. However, the identity of even these and the majority of other species is best determined or checked by microscopic study of carefully processed, slide-mounted specimens.
Finding and collection. Soft scales may occur on any part of their host plants, from the roots to the fruit, but most often they are found on stems and the undersides of leaves. In other parts of the world, a collector may increase his chances of success by looking for intense ant activity, honeydew droplets, and/or sooty mould. In New Zealand, the only known association between an ant species and a coccid is that of the ant Prolasius advena with Poropeza dacrydii when the latter is under the bark of podocarp trees. While sooty mould can be an excellent indicator, again this is often less helpful than in other parts of the world due to the presence of large numbers of other honeydew producers, particularly margarodids and eriococcids.
Once found, the specimens need to be collected and stored either in 70-95% ethanol or as dried specimens. However, the latter method requires continuous dry storage thereafter, with careful protection from such 'museum pests' as dermestid beetles. All stages of the scale insect should be collected if possible, including the tests of 2nd-instar males and, if only a limited range of stages are available at first collection, it is worth revisiting the host plant at other times of the year to complete the range of stages, thus also gathering life-cycle data. It is important to identify the plant host and record the locality, date, and collector accurately.
Preservation and slide preparation. The following method has been used for the last few years for mounting the New Zealand coccids. If using dried specimens, first soak in 75% ethanol for 1-24 hours to soften. If mounting Ceroplastinae, it is advisable to first remove the thick wax test, by gently breaking it off and/or by soaking in the dewaxing solution (see 8 below).
- Remove one or more specimens from the ethanol preservative and place in a small flat dish. Under the binocular microscope, make a small cut or slit in the side of the abdomen, avoiding damage to the legs. [Note: if separating the body into dorsum and venter for any reason, this is best done at this stage.]
- Transfer the specimens to a heat resistant glass tube (small test tube) which has about 1cm depth of 95% ethanol; put a bung of cotton wool in the top and place the tube in a water bath (at about 90-95°C) and heat for 2 minutes.
- Remove from heat and carefully tip the contents of the tube into a clean small dish; transfer the specimens to another small test tube with about 1cm depth of 10% KOH. Return to the water bath and heat for about 3-7 minutes, or until the specimens appear to be mostly cleared or until the body contents appear liquid (avoid boiling or overclearing at this stage).
- Remove from heat, allow to cool slightly (to avoid the hot fumes of KOH affecting one's eyes when working at the microscope) and again tip contents into a small dish, such as a 5 cm petri-dish, to allow easy manipulation with bent pins or other flattened tools; gently pump and tease out the remaining body contents, including any eggs and/or unborn nymphs (sometimes it can be useful to have one specimen with unborn nymphs remaining inside, for confirmation of ovoviviparity or viviparity). [Note (i): the above maceration method is extremely difficult for very small specimens such as crawlers as they are easily lost after becoming transparent with heating in KOH. This method can still be used if there are many specimens as some will undoubtedly be retained but, alternatively, it may be best to macerate them in 10% KOH at room temperature for about 24 h instead. Note (ii): heavily sclerotised specimens may need extended maceration time; the limits for hot KOH may be <15 minutes, alternatively leave in KOH at room temperature for <several days. Note(iii): all the next stages of the method are in covered staining wells.]
- Transfer to distilled water in a staining well for about 5-10 minutes. [Alternative staining method: if using acid fuchsin stain, add 1-2 drops of acetic-acid-alcohol, leave for a few minutes, then add 1-2 drops of stain (to the water etc.), leave for about 30 minutes or longer until the specimens are a good bright pink colour, then continue at point 6.]
- Preferred staining method: transfer to McKenzie's stain in Essig's Solution (see below) from the distilled water (if NOT using acid fuchsin stain); leave for 30-60 minutes, either in a warming oven at 40°C or under a warm lamp (e.g., a 60 watt light bulb) on the lab bench. [Note: the McKenzie's stain in Essig's Solution may be re-used many times (so long as you ensure that you remove all specimens each time!)]
- Transfer specimens to a clean staining well with 75% ethanol, leave for about 5 minutes. If the specimen(s) are large and very full of stain, repeat this step to wash out excess stain.
- Transfer as above to 95% ethanol, leave for about 5 minutes (= dehydration).
- Transfer as above to a de-waxing mixture, made up fresh thus: mix (1:1) about 0.5 ml xylene and 0.5 ml absolute isopropanol (2-Propanol) (or, if isopropanol unavailable, 95-100% ethanol will do instead), leave for 2-10 minutes to clear any remaining wax; check under the microscope that all wax is gone and, if not, repeat this step, or gently knock off any waxy pieces adhering to the outer body with a pin.
- Transfer as above to absolute isopropanol or absolute ethanol; leave for 10 minutes minimum (= washing and final dehydration). Repeat this step if specimens large.
- Transfer as above to 1-3 drops of clove oil; leave for from 2 minutes up to 2 days (longer than this, the specimens may become brittle).
- Slide mounting: take a clean glass slide and put a small drop of clove oil in the centre; transfer a specimen from the staining well of clove oil to the drop of oil on the slide; under the microscope arrange the specimen so that it is spread out straight; then, with a small piece of paper tissue, very carefully blot away the excess clove oil from the specimen, gently touching the sides only.
Add a very small drop of Canada balsam beside the specimen on the slide, just enough to cover the specimen with a thin film and then, with a pin, gently move the balsam over the specimen; this sticks it in place on the slide; it is very useful to do this when mounting a series of crawlers or nymphs in a row on one slide, as they should not move from their position after the coverslip is applied (see next step); write a code label or number on the slide and leave to set for a few minutes.
- Add a large drop of Canada balsam by gently dropping on top of the specimen; with forceps, carefully place a clean cover slip on it, by lowering at one edge first; there should be enough Canada balsam to infill under the coverslip without unduly flattening the specimen, so that the dorsal and ventral surfaces are clearly separated; a generous amount of Canada balsam at this stage is particularly important for mounting adult males.
- Store the slide flat in a drying oven at about 40°C for 2 weeks, or at room temperature for 6 weeks. The slide must be fully dried before storing on its side, but it may be taken out of the oven earlier if stored flat.
- Add a printed label to each slide with full collection details. At NZAC, we use typed labels printed on a laser printer. The labels are cured on the sheet after printing, to anneal the flakes of ink, by heating in a small oven at 150-160°C for 1 minute.
1. Acetic-acid-alcohol:ethanol, 95% — 50ml
distilled water — 45ml
glacial acetic acid — 20ml
2. McKenzie's Stain:
equal parts of acid fuchsin, erythrosin, and lignin pink, each made up into a 2% aqueous solution.
3. Essig's Solution (Essig's Aphid Fluid):lactic acid (reagent grade 85%) — 20 parts
phenol (liquified) — 2 parts
glacial acetic acid — 4 parts
water, distilled — 1 part
Heat at 56-60°C for 30-60 minutes. Store in a brown bottle.
The suggested stock staining solution is made up of 30 ml Essig's Solution with 60 drops of Mckenzie's stain added; this has a shelf life of several years under normal storage conditions.
Important. The slide-numbering system for Coccoidea operating in NZAC before 1992 used the Julian calendar to select the (accession) number, which represented the day on which the slide(s) were made, e.g.,10 April 1990 would be the 100th day of the year. If two or more unrelated samples were mounted that day, each sample was given a unique lower case letter, e.g., three slides of a mealybug sample might be all numbered #90-100a, and four slides of another sample from a different locality mounted the same day would be all #90-100b, and so on. A sample is defined as a unique collection of material in terms of species, host plant, locality, date, and collector. Thus, the number on the slide referred to the date on which the slides were made, and the lower case letter referred to the sample or collection data. A difficulty with this system compared with the system used now is highlighted by two slides of Poropeza cologabata n. sp. numbered #83-326c, but having no collection data, whereas a slide of Poropeza dacrydii (Maskell) is numbered #83-326f and has collection data from Fiordland. The assumption of shared collection data cannot be made about these slides, or other slides with the same accession number but with different lower case letters, if they were mounted at NZAC before 1992.
However, since 1992 the (accession) numbering system has been changed and slides with the same accession number, but with different lower case letters, are all from the same sample. The numbering now relates to the order in which samples are slide-mounted: the assigned number consists of a prefix with the year's last two digits (as before), followed by the sample number — simply in a running order starting with 001 at the beginning of any year, the next sample handled would be 002 and so on, regardless of the actual date collected. Thus, the first sample for 1998 was #98-001a-c (three slides were made) and a later sample was #98-021 (the twenty-first coccoid sample for 1998 and only one slide was made). The change was necessary to allow for databasing of records, with different instars or adult male/females mounted on separate slides each requiring a unique code number, and also because much more material has been mounted since 1992.
BMNH The Natural History Museum, London, U.K.
CMNZ Canterbury Museum, Christchurch, N.Z.
FRNZ Forest Research, Rotorua, N.Z.
NZAC New Zealand Arthropod Collection, Auckland, N.Z.; [note: NZAC should be assumed where no depository is mentioned].
USNM United States National Museum of Natural History, Smithsonian Institution, Washington D.C., U.S.A.
Material studied. The data given under each species are those on the slide label, categorised under the area codes of Crosby et al. (1998), and arranged approximately from north to south in the New Zealand subregion. After the collection data, the depository is given if different from NZAC, followed by the number of slides and specimens studied, including their life stages, thus: "6/3 && ad, 2 & 3rd, 1 % 2nd" indicates six slides with 3 adult females, two female 3rd-instars, and one male 2nd-instar.
Abbreviations used in collection data
asl — above sea level
cnr — corner
DSIR — Department of Scientific and Industrial Research
FP — Forest Park
FRI — Forest Research Institute
I — Island; Is -- Islands
imm. — immature
km — kilometre(s)
L — Lake
lvs — leaves
m — metre(s)
Mt — Mount, Mountain
no./nos — number(s)
nr — near
NZFS — New Zealand Forest Service
Pt — Point
R — River
Ra — Range
Rd — Road
Res — Reserve
SF — State Forest
Stm — Stream
Stn — Station
Tk, tk — Track, track
V — Valley
Collectors. RCH = R.C. Henderson; W.M.M. = W.M. Maskell (all other collectors not abbreviated).
Illustrations. Text Fig. 1 is a cladogram from a cladistic study of coccid families. Fig. 2 shows the life stages of a typical indigenous coccid. Figs 3-7 are labelled for convenience, with Fig. 3 showing the structures most commonly noted on the indigenous species, whereas Fig. 4 also includes structures found only on some adventive species. Figs 5-7 show each of the main structures in more detail. The size of many structures are given in the text; details of how they were measured are shown in Fig. 7. Figs M8-M31 are Scanning Electron Micrographs showing detail of various structures. Figs C32-C95 are 64 colour photographs of females of most of the species described or discussed. Figs 96-155 are presented in the usual way for Coccoidea, with a central 'map' of the insect, the left half representing the dorsum and the right the venter, with the approximate number and position of most structures indicated by symbols in the body of the map. This central map is surrounded by vignettes showing some of the important features, enlarged as seen under phase-contrast. Phase-contrast emphasises differences in the degree of sclerotisation of a given structure and the appearance of the latter may be different using normal direct light (and even more so under the electron microscope!).
Geographic distribution maps for each indigenous species were prepared by plotting the latitude and longitude point for each collection site.