Parasitismo e superparasitismo de Trichogramma pretiosum Riley(Hymenoptera: Trichogrammatidae) em ovos de Sitotroga cerealella(Oliver) (Lepidoptera: Gelechiidae)

Abstract

-The parasitoid Trichogramma has been used worldwide as biological control agent due to its wide geographic distribution, high specialization and effi cacy against many lepidopteran pests. Biological and behavioral traits of Trichogramma pretiosum Riley parasitizing Sitotroga cerealella (Oliver) eggs were studied aiming to a better understanding of the results from parasitism and superparasitism. The variables investigated were: host acceptance and contact time by T. pretiosum on parasitized host, percentage of parasitoid emergence, number of deformed individuals produced, egg-adult period, sex ratio, offspring female body size and longevity, and number of S. cerealella eggs parasitized/female. Parasitism rejection was observed on parasitized host eggs after 24, 72 and 120h of parasitism. The rejection was higher for eggs parasitized after 72h and 120h of parasitism as compared to the eggs after 24h of parasitism. T. pretiosum contact time on eggs after 24h of parasitism was greater than on 72 and 120h. The offspring produced from hosts from which a single parasitoid emerged were larger, exhibited no deformities and greater capacity of parasitism, different from those produced from eggs where two parasitoids emerged. Offspring longevity, however, was similar for females emerged from hosts from which one or two adults emerged. In conclusion, T. pretiosum was able to recognize previously parasitized eggs and the superparasitism reduced the parasitoid.reproductive success.KEY WORDS: Biological control, egg parasitoid, host compatibility RESUMO -Parasitóides Trichogramma vêm sendo utilizados em todo o mundo como agentes de controle biológico devido à sua ampla distribuição geográfi ca, alta especialização e efi ciência no controle de muitas espécies-praga de lepidópteros. Para o entendimento dos resultados do parasitismo e superparasitismo de Trichogramma pretiosum Riley, estudaram-se os aspectos comportamentais e biológicos desse parasitóide sobre ovos de Sitotroga cerealella (Oliver). As variáveis investigadas foram: aceitação hospedeira e tempo de contato de T. pretiosum com o hospedeiro parasitado, porcentagem de emergência, porcentagem de indivíduos deformados, duração ovo-adulto, razão sexual, tamanho e longevidade de T. pretiosum e número de ovos de S. cerealella parasitados por fêmea descendente. Observou-se rejeição de parasitismo em ovos de S. cerealella previamente parasitados com 24, 72 e 120h de idade. A rejeição foi superior para ovos com 72h e 120h após o parasitismo em comparação com aqueles com 24h. Ovos previamente parasitados com 24h apresentaram maior tempo de contato por T. pretiosum comparados aos de 72h e 120h. Os descendentes oriundos de hospedeiros dos quais apenas um parasitóide se desenvolveu apresentaram-se todos maiores, sem deformidades e com maior capacidade de parasitismo, ao contrário dos indivíduos descendentes de hospedeiros em que dois parasitóides se desenvolveram. Entretanto, a longevidade de fêmeas descendentes não diferiu entre parasitóides oriundos de hospedeiros em ...

Reproductive biology of Palmistichus elaeisis (Hymenoptera: Eulophidae) with alternative and natural hosts

“…This is important, because the body size in many parasitoids is positively correlated with important functional traits including mating, fecundity, reproductive longevity, emergence of progeny and sex ratio (SAGARRA et al 2001, MOREIRA et al 2009). …”

Occurrence of Trichograma Parasitoids in Eggs of Soybean Lepidopteran Pests in Mato Grosso, Brazil

“…According to Moreira et al (2009), in Brazil, T. pretiosum is the most frequently occuring parasitoid and is associated with various hosts in different cultures, such as Tuta absoluta (Meyrick, 1917) in tomato (Pratissoli et al, 2005), Spodoptera frugiperda (Smith, 1797) (Bessera & Parra, 2003) and H. zea (Pratissoli & Oliveira, 1999) in maize, Plutella xylostella (Linnaeus, 1758) in cabbage (Pereira et al, 2004;Zago et al, 2010), Heliothis virescens (Fabricius, 1781) in cotton (Zucchi et al, 1989), A. gemmatalis and Chrysodeixis (= Pseudoplusia) includens (Walker, 1858) in soybean (Bueno et al, 2009). …”

“…Egg parasitoids of the genus Trichogramma (Hymenoptera: Trichogrammatidae) are important because they parasitize eggs of Lepidoptera, Hemiptera and Coleoptera that attack various crops (Parra & Zucchi, 2004) and, for this reason, are used in biological control programs worldwide (Beserra & Parra, 2004). Currently, there are 190 known species of Trichogramma, and 38 of these occur in South America, 28 of which have been recorded in Brazil (Moreira et al, 2009). Despite the importance of soybean production in the state of Mato Grosso, no research has been carried out in the state regarding the occurrence of egg parasitoids, although their effectiveness has been proven by previous research (Foerster & Avanci, 1999;Foerster & Butnariu, 2004).…”

<b>Age and density of eggs of <i>Helicoverpa armigera</i> influence on <i>Trichogramma</i> pretiosum parasitism

“…These results indicate a larger amount of nutrients in the egg, capable of supporting the development of more than one parasitoid. However, when more than one parasitoid develops in the same egg, there may be competition for food resulting in smaller individuals and lower nutritional quality, reflected in the reduction of the number of parasitized eggs per female (Moreira, Santos, Beserra, Torres, & Almeida, 2009).…”

“…Therefore, there is a successive shortening of parasitism behavior, connected to the learning of the female when parasitized the first egg (Moreira, Santos, Beserra, Torres, & Almeida, 2009). However, the learning of females in relation to the number of parasitized eggs depends on the physicochemical characteristics of the host's egg, since they exhibit a seeking behavior characterized by chemical signals (Colazza, Peri, Salerno, & Conti, 2010).…”