SummaryThe egg parasitoid, Telenomus podisi, was shown to recognize its host, Euschistus heros, through both chemical and physical cues. These were determined in short‐range bioassays. The cues comprised fertile and infertile host eggs, egg extracts, crude extracts of adult males and females and successive dilutions of the synthetic racemic mixture of methyl 2,6,10‐trimethyltridecanoate, a male‐produced pheromone of E. heros.Some of the treatments used induced a selection process in T. podisi, through host recognition behaviour, indicating a consistent response of this species to E. heros. The possibility that some of these compounds could be exploited as long‐range kairomones, by T. podisi, is discussed.Using GC analysis, an unidentified compound (Rt 24.8 min), possibly from the egg adhesive material, was detected from E. heros egg extracts. Its retention time compared to the methyl 2,6,10‐trimethyltridecanoate showed a lower volatility, suggesting that the egg adhesive may act as a short‐range kairomone.Physical cues appeared to be an important component in the host selection process by T. podisi. The parasitoid discriminated infertile eggs which are differently shaped and smaller than fertile eggs.

No abstract

No abstract

Oviposition habitat choices of species with aquatic larvae is expected to be influenced by both offspring risk of mortality due to predation, and offspring growth potential. Aquatic predators may indirectly influence growth potential for prey by reducing prey density and, for filter feeding prey, by increasing bacterial food for prey via added organic matter (feces, partially eaten victims), creating the potential for interactive effects on oviposition choices. We tested the hypothesis that the mosquito Aedes aegypti preferentially oviposit in habitats with predatory Toxorhynchites larvae because of indirect effects of predation on chemical cues indicating bacterial abundance. We predicted that A. aegypti would avoid oviposition in sites with Toxorhynchites, but prefer to oviposit where bacterial food for larvae is abundant, and that predation by Toxorhynchites would increase bacterial abundances. Gravid A. aegypti were offered paired oviposition sites representing choices among: predator presence; the act of predation; conspecific density; dead conspecific larvae; and bacterial activity. Aedes aegypti preferentially oviposited in sites with T. theobaldi predation, and with killed conspecific larvae, but failed to detect preferences for other treatments. The antibiotic Tetracycline eliminated the strongest oviposition preference. Both predation by Toxorhynchites and killed larvae increased bacterial abundances, suggesting that oviposition attraction is cued by bacteria. Our results show the potential for indirect effects, like trophic cascades, to influence oviposition choices and community composition in aquatic systems. Our results suggest that predators like Toxorhynchites may be doubly beneficial as biocontrol agents because of the attraction of ovipositing mosquitoes to bacterial by-products of Toxorhynchites feeding.

RESUMO.Desenvolvimento de uma alternativa de controle para o bicho-furão-dos-citros, Ecdytolopha aurantiana (Lepidoptera, Tortricidae): da pesquisa básica ao produtor. São descritas todas as etapas da pesquisa, desenvolvidas de 1995 a 2000, para a síntese do feromônio sexual de Ecdytolopha aurantiana (Lima, 1927), visando ao monitoramento desta praga que causa perdas da ordem de 50 milhões de dólares ao ano à citricultura paulista. As pesquisas básicas são apresentadas, incluindo o desenvolvimento de uma dieta artificial para o inseto, estudo de suas exigências térmicas e hídricas, estudos comportamentais, síntese da substância atraente para o macho desde a formulação até a distribuição do feromônio ao agricultor, e a sua comercialização. Trata-se de um caso de sucesso, a um custo de 50 mil dólares, com pesquisas inter-e multidisciplinares e que pode ser adotado para outros insetos-praga do país. PALAVRAS-CHAVE.Biologia; citros; controle biológico; feromônio sexual; manejo integrado de pragas.ABSTRACT. All research steps, developed from 1995 to 2000, to synthesize the sex pheromone of Ecdytolopha aurantiana (Lima, 1927) are described, in order to monitoring this pest that causes losses in the order of 50 million dollars per year to citriculture in the State of São Paulo. The basic researches conducted are described, including the development of an artificial diet for the insect, the study of its temperature and humidity requirements, behavioral studies, and synthesis of the male-attracting substance up to the formulation and distribution of the pheromone to the grower, by means of its commercialization. It is a case of success, at a cost of 50 thousand dollars, involving inter-and multidisciplinary researches, which can be adopted to other insect pests in the country.