Landcare Research - Manaaki Whenua

Landcare-Research -Manaaki Whenua

FNZ 11 - Pseudococcidae (Insecta: Hemiptera) - Introduction

Cox, JM 1987. Pseudococcidae (Insecta: Hemiptera). Fauna of New Zealand 11, 232 pages.
( ISSN 0111-5383 (print), ; no. 11. ISBN 0-477-06791-3 (print), ). Published 07 Apr 1987


Mealybugs are one of the eight families of Coccoidea represented in New Zealand. Prior to this account 46 species were known from New Zealand. About half of these were identifiable from descriptions scattered through the world literature, and the remainder were known only from inadequate original descriptions. Most of the 116 species now known from New Zealand are indigenous; about five are probably of Australian origin, and nine are more or less cosmopolitan. Despite the large number of species recorded here, the ease with which new species are discovered and the number of species known only from single collections suggest that less than half of the species actually occurring in this country have been dealt with here. Nevertheless, this work should enable species discovered in future to be placed with their close relatives.

Mealybugs are small (1 - 5 mm in length), plant- feeding insects. A generalised mealybug life cycle is shown in Figure 1. The soft-bodied, wax-covered, wingless females (Figure 2) usually live in secluded positions; the males (Figure 3) are tiny and winged. Identification is based on the female, as this is most readily encountered and is associated with the host plant. Most species produce males, but these are still largely unstudied. Although the females of a few species can be identified with some degree of certainty while alive, positive identifications require their preparation on glass slides for microscopic examination. Identification of species is based largely on the form and distribution of the different types of wax-producing ducts and pores on the integument.

Two major problems arise in the taxonomic study of mealybugs. First there is the question of how to recognise species. The temperatures at which females develop can greatly alter the expression of the very characters by which they are identified (Cox 1983), and differences in host plant may have a similar effect in species with a narrow host range. Some species complexes may be resolved only by experimental rearing and host-transfer work, and some areas where such work would be beneficial, such as with Paracoccus glaucus, are pointed out in the text.

Second, there is the problem of surmising the relationships between the species in order to establish genera. Mealybug species have tended to specialise by reduction of features, and species living in similar habitats tend to look similar. For example, females of the grass-feeding species Balanococcus botulus, Choriococcus oreophilus, and Pseudococcus zelandicus all have elongate body outlines and small, round circuli, although the close relatives of the latter two species are not grass-feeders and are oval in outline, with large, quadrate circuli. Consequently, species that appear similar in different parts of the world may not, in fact, be closely related, and to place them in the same genus would be to suggest some quite spurious zoogeographical links. Therefore I have erected new genera in some instances where similar-looking species in existing genera do occur overseas, in order to avoid confusing biogeographers working solely from the literature. Future work on adult males may help to indicate valid higher taxa.

During this study several individual, often poorly prepared specimens were examined that probably represent undescribed species. It would be undesirable to describe new species on the basis of such specimens, and so these have been briefly mentioned under Remarks for the species to which they would be referred by the key.

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