Parasitoids For Classical Biological Control Of Tineola Bisselliella (Lepidoptera Tineidae)

Abstract:
Two species of parasitoid wasps, Apanteles carpatus (Hymenoptera Braconidae) and Baryscapus tineivorus (Hymenoptera Eulophidae), are known to successfully parasitize larvae of tineid moths. We have evaluated each species potential impact on suppressing the pest Tineola bisselliella (Lepidoptera Tineidae). Both parasitoids have shown high potential for biological control of webbing clothes moth larvae when tested on different host instars in the laboratory and field. Preferences for parasitizing older and larger host larval instars for egg largely overlap in both species. Apanteles carpatus is a solitary koinobiont and parthenogen, while B. tineivorus is a gregarious koinobiont, with a sex ratio of approximately 1:5 (male:female). Solitary reproduction in A. carpatus markedly suppressed the pest population early on but lagged large numbers of progeny in the F1-generation. Gregarious reproduction resulted in a faster build-up of the F1-generation but lagged the immediate control effect. Combining the release of both parasitoid species for pest control seemed to be the logical conclusion. We tested the reproductive success of both species when experimentally forced into intensive intraguild competition. For this, parasitoids had either to compete simultaneously or slightly time shifted on the same preferred host resource. Reproductive success of A. carpatus was not significantly influenced by the presence of B. tineivorus. B. tineivorus reproductive output was significantly reduced in the presence of A. carpatus. Overall suppression of host development was not significantly enhanced with both parasitoid species co-occurring when compared to their exclusive access to hosts. B. tineivorus does not significantly improve the control of webbing clothes moth hosts when occurring together with and having to compete against A. carpatus, at least in restricted laboratory conditions. Results show that B. tineivorus should be released with a temporal advantage of at least several days. For inundative release, reproduction strategies and even competition between parasitoids is negligible, and a deferred release strategy would not be required.