Fecundity of Larra bicolor (Hymenoptera: Crabronidae) and its Implications in Parasitoid: Host Interaction with Mole Crickets (Orthoptera: Gryllotalpidae: Scapteriscus)

S. L. Portman, J. H. Frank, R. McSorley, N. C. Leppla


Larra bicolor F. (Hymenoptera: Crabronidae) is a specialist parasitoid of Scapteriscus (Orthoptera: Gryllotalpidae) mole crickets, attacking adults and medium to large nymphs. Reproductive systems were dissected from 10 female wasps collected in northern Florida. Each had 2 ovaries, each with 3 ovarioles. The maximal number of mature eggs (10) plus developing oocytes (83) was 93. Female wasps deposit an egg on the venter of the host's thorax, and the wasp larva develops as an ectoparasitoid. Twenty newly-emerged female wasps housed in small cages with at least 1 male and with 7 potential hosts replaced daily deposited a mean 2.44 eggs (range 0–10) per day for a total lifetime production averaging 56 eggs (range 17–91) during a lifespan averaging 23.5 d (range 8–40). Assuming 3 wasp generations with fecundity as shown to 1 host generation, per year, the wasp should easily be able to outreproduce its host mole crickets. A few of the hosts became superparasitized with 2 or even 3 eggs, but at most 1 larva of L. bicolor developed successfully on each host, so superparasitism is a disadvantage; its incidence in the laboratory (<2%) and field (3%) was low.

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