Sensory response of the egg parasitoid Telenomus podisi to stimuli from the bug Euschistus heros

Abstract

-The objective of this work was to study the foraging behavior of Telenomus podisi Ashmead (Hymenoptera: Scelionidae) in the presence of stimuli from its host, Euschistus heros (Heteroptera: Pentatomidae). The stimuli selected were: egg mass; virgin males and females; volatile extracts of sexually mature males and females; components of male sex pheromone; a component of the alarm pheromone, hexane and an empty cage as control. In a closed arena, the parasitoids were given the choice between single and combined stimuli presented to them simultaneously. To find the host egg, T. podisi primarily uses the sensory cues released from the male insects. The orientation toward odors of male chemical extract indicates that a source of kairomone was detected. Gas chromatographic analyses of this substance showed peak of methyl 2,6,10-trimethyltridecanoate, the main component of male sexual pheromone. The sensory response to methyl 2,6,10-trimethyltridecanoate confirms that this compound may act as a kairomone to find host eggs. Females and egg mass stimuli were weakly attractive to the parasitoid.Index terms: forage behavior, sex pheromone, olfactory response, combination of stimuli. Resposta sensorial do parasitóide de ovos Telenomus podisi a estímulos provenientes do percevejo Euschistus herosResumo -O objetivo deste trabalho foi estudar o comportamento de busca de Telenomus podisi Ashmead (Hymenoptera: Scelionidae), em presença de estímulos provenientes do hospedeiro Euschitus heros (Heteroptera: Pentatomidae). As fontes de estímulos utilizadas foram: massas de ovos, machos e fêmeas virgens, extratos químicos de machos e fêmeas sexualmente maduros, componentes sintéticos do feromônio sexual do macho de E. heros, um composto sintético do feromônio de alarme, hexano e uma gaiola vazia como controle. Os testes foram conduzidos em arenas, onde foi dada a oportunidade para os parasitóides escolherem entre estímulos isolados e estímulos combinados. Para encontrar o hospedeiro, T. podisi utiliza principalmente estímulos olfativos emitidos pelos machos. As respostas sensoriais aos odores liberados pelos extratos químicos do macho indicam que uma fonte de cairomônio foi detectada. Análises cromatográficas mostraram picos do composto metil 2,6,10-trimetiltridecanoato, principal componente do feromônio sexual do macho de E. heros. As respostas olfativas a metil 2,6,10-trimetiltridecanoato confirmam que este composto pode agir como cairomônio para encontrar o hospedeiro. Estímulos provenientes das fêmeas virgens e de massas de ovos foram pouco atrativos ao parasitóide.Termos para indexação: comportamento de busca, feromônio sexual, resposta olfativa, combinação de estímulos.

Egg parasitoid wasps as natural enemies of the neotropical stink bug Dichelops melacanthus

“…podisi (Moraes et al, 2005(Moraes et al, , 2008. In addition, there is also some evidence that these parasitoids may selectively respond to semiochemicals from stink bugs (Borges et al, 2003;Conti et al, 2004;Salerno et al, 2006;Silva et al, 2006;Laumann et al, 2009) or substrate-borne vibratory signals used in the stink bug sexual communication (Laumann et al, 2007 complexes in tri-trophic interactions, as well as other relevant biological and ecological aspects need to be established.…”

Insecticidal activity of essential oil of Prangos ferulacea (Umbelliferae) against Ephestia kuehniella (Lepidoptera: Pyralidae) and Trichogramma embryophagum (Hymenoptera: Trichogrammatidae)

“…In this study, the larvae of E. kuehniella were tolerant to the fumigant toxicity of P. ferulacea fruit essential oils compared to the adults (LC 99 : 538.755 µL L -1 air and 1.099 µL L -1 air, respectively). In biological control programs, the parasitoid species Trichogramma is used widely against the eggs of Lepidoptera (Silva et al 2006) in particular. Egg parasitoids of this genus are more sensitive against chemical insecticides.…”

Semiochemicals from plants and insects on the foraging behavior of Platygastridae egg parasitoids

“…Several arena bioassays have been carried out using single and/or simultaneous stimuli, such as egg masses; live virgin E. heros males and females; volatile extracts of sexually mature E. heros males and females; 2,6,10-methyl-trimethyltridecanoate, a component of the E. heros sex pheromone; (E)-2-hexenal, a component of the E. heros metathoracic gland; and hexane or air as a control. In these assays, T. podisi females responded to the E. heros male extracts, to 2,6,10-methyl-trimethyltridecanoate, and to (E)-2-hexenal, showing that they use chemical cues from E. heros to find their host egg masses (Borges & Aldrich, 1992;Silva et al, 2006). Trissolcus basalis responds positively to 4-oxo-(E)-2-hexenal and (E)-2-decenal, two major components present in N. viridula glandular secretion, whereas T. podisi is attracted to crude gland extracts of the preferred host, E. heros, and has its walking pattern altered when stimulated with 4-oxo-(E)-2-hexenal (Silva et al, 2006).…”