The Ontogeny of Blister Beetles (Coleoptera, Meloidae) I. A Study of Three Species of the Genus Pyrota

Abstract

Postembryonic ontogeny in the Meloidae is described briefly and a nomenclature of larval phases is proposed. Pyrota mutata Gemminger, P. niyrovittata (Haag-Rutenberg), and P. palpalis Champion were reared to the coarctate phase or beyond on a diet of honey bee provisions and larvae. First-instar Pyrota larvae can develop on pollen mixed with water or honey, but the duration of the instar is decreased by the addition of a bee larva to the diet. The first grub phase consists of 4 instars; larvae in this phase attack bee larvae readily but do not require them for growth. Larvae of P. nigrovittata and P. palpalis reached the coarctate phase in means of 38 and 32 days, respectively, at 27°C; those of P. mutata did so in a mean of 20 days, at a slightly higher temperature. All coarctate larvae of P. mutata and P. nigrovittata diapaused. The ontogeny of P. palpalis was extremely variable beyond the first grub phase. Five of 13 coarctates of this species failed to diapause; 1 larva developed directly to the pupal stage from the coarctate phase; 5 spent 2 instars in the coarctate phase; and 1 of those that reached the second grub phase subsequently reverted to the coarctate before continuing development. In addition, nearly all coarctate larvae of P. palpalis retained first grub anatomical characteristics to a greater or lesser extent. Larvae of P. palpalis (the only species reared to the adult stage) that diapaused in the coarctate phase required a mean of 212 days for complete development (excluding a period of refrigeration during diapause) ; a nondiapausing larva completed development in 57 days. Anatomical changes during ontogeny are extensive and in some cases profound. Interspecific differences in larval anatomy are relatively slight and vary in nature with the phases.