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EGG, LARVA, AND PUPA OF LEXIPHANES SAPONATUS (COLEOPTERA: CHRYSOMELIDAE: CRYPTOCEPHALINAE)

Published online by Cambridge University Press:  31 May 2012

Laurent LeSage
Affiliation:
Biosystematics Research Institute, Agriculture Canada, Ottawa K1A 0C6

Abstract

The immature stages of Lexiphanes saponatus (Fabricius) are the first members of Nearctic Cryptocephalinae to be described as well as to be studied. The egg is coated with oblique ornamentations as in other Cryptocephalinae. The larva shows several resemblances with that of the Palearctic genus Suffrianus from which it is distinguished mainly by its large papillate frontal setae. The pupa resembles in general those of Chlamisinae but bears very distinctive projections on the seventh and ninth abdominal segments. The life cycle of L. saponatus is also very interesting. Unlike most other cryptocephaline larvae which live in the leaf litter and are unable to climb on plants, the larva of L. saponatus moves easily on its host plant (Cassandra calyculata) and mimics perfectly the plant buds, becoming almost invisible to the human eye. Although me information is incomplete, it is evident that L. saponatus overwinters in the larval stage, in the first or second instar. It is not known if the larva completes its development during the following warm season or overwinters twice as in other Cryptocephalinae.

Résumé

Les différents stades biologiques de Lexiphanes saponatus (Fabricius) sont décrits pour la première fois et constituent aussi les premiers représentants nord-américains de la sous-famille des Cryptocephalinae à être étudiés. L'oeuf est orné d'un motif oblique comme chez les autres membres de cette sous-famille. La larve montre beaucoup d'affinités avec la larve du genre paléarctique Suffrianus et s'en distingue surtout par ses grosses soies frontales papilleuses. La nymphe ressemble en général à celles des Chlamisinae mais possède des protubérances sur les septième et neuvième segments abdominaux tout à fait caractéristiques. Contrairement aux autres larves de Cryptocephalinae qui vivent dans la litière et ne peuvent grimper aux plantes, celle de L. saponatus se meut sans problème sur la plante-hôte (Cassandra calyculata) et imite à la perfection ses bourgeons la rendant à peu près invisible même pour l'oeil averti. Il est certain que L. saponatus hiberne à l'état larvaire, au premier ou au deuxième stade mais on ne sait pas si la larve se transforme en adulte dès la saison chaude suivante ou si elle hiberne une seconde fois, comme cela se produit chez d'autres espèces de Cryptocephalinae.

Type
Articles
Copyright
Copyright © Entomological Society of Canada 1984

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