Efeito da estocagem em baixa temperatura na capacidade reprodutiva e longevidade de Trissolcus basalis (Wollaston) e Telenomus podisi Ashmead (Hymenoptera: Scelionidae)

Abstract

-Female longevity and fecundity of Trissolcus basalis (Wollaston) and Telenomus podisiAshmead were evaluated at 25ºC after storage periods ranging from one to 140 days at 15ºC, in intervals of 10 days. The oviposition capacity of both parasitoids was also evaluated at 15ºC, following preovipositional periods ranging from one to 60 days, also at 10-day intervals. Females of both species survived for more than five months when stored at 15ºC, however fecundity was significantly reduced by the exposure to the low temperature. Despite the reduction in fecundity, both species were able to parasitize host eggs at 25ºC after spending 140 days at 15ºC. Although parasitism was observed at 15ºC, only 3.1% and 0.2% of the exposed eggs were parasitized by T. basalis and T. podisi, respectively. The proportion of males was significantly increased in the progeny of T. basalis females, maintained at 15ºC, for any of the storage periods investigated. Similar results were obtained for T. podisi stored at 15ºC up to 50 days; however the females of this species, maintained at the lower temperature for longer periods, either laid no eggs or produced progenies with sex-ratio similar to the control insects, kept at 25ºC. The presence of females in the offspring of both parasitoid species indicate that mating occurred at the lower temperature. The increased longevity and reduced fecundity of T. basalis and T. podisi obtained when the adults were stored at 15ºC, show that both species hibernate, and this arrestment can be useful as a tool for mass production and storage of T. basalis and T. podisi during autumn and winter.KEY WORDS: Insecta, Pentatomidae, egg parasitoids, biological control, hibernation.RESUMO -A longevidade e a fecundidade de fêmeas de Trissolcus basalis (Wollaston) e Telenomus podisi Ashmead foram avaliadas a 25ºC após permanecerem a 15ºC por períodos variando de um a 140 dias, a intervalos de 10 dias. A capacidade de oviposição dos dois parasitóides também foi avaliada a 15ºC, após períodos de pré-oviposição entre um e 60 dias, igualmente em intervalos de 10 dias. Fêmeas das duas espécies sobreviveram por mais de cinco meses a 15ºC, porém sua fecundidade foi significativamente reduzida. Entretanto, ambas as espécies foram capazes de parasitar ovos dos respectivos hospedeiros a 25ºC após permanecerem por 140 dias a 15ºC. Apesar de ter ocorrido parasitismo a 15ºC, apenas 3,1% e 0,2% dos ovos ofertados foram parasitados por T. basalis e T. podisi, respectivamente. A proporção de machos aumentou significativamente na progênie produzida por fêmeas de T. basalis mantidas a 15ºC, em qualquer dos períodos de estocagem avaliados. Resultados semelhantes foram obtidos para T. podisi mantidos a 15ºC por até 50 dias; períodos de estocagem mais longos resultaram ou na ausência de parasitismo, ou em razões sexuais semelhantes à da testemunha, mantida a 25ºC. Todavia, a presença de fêmeas na descendência dos parasitóides mantidos a 15ºC indica a ocorrência de cópula na baixa temperatura. A elevada longevidade e a reduzida ...

Emergence, longevity and fecundity of Trissolcus basalis and Telenomus podisi after cold storage in the pupal stage

“…Adults of T. basalis emerging at 15ºC were small, inactive and survived less than one day (Orr et al, 1985). Foerster & Nakama (2002) found that the mean longevity of T. basalis and T. podisi transferred from 25ºC to 15ºC one day before the predicted date for emergence was of about five months; this value is lower than the results obtained in this work. Longevity of T. basalis and T. podisi at 15ºC was also higher than that of other Scelionidae species such as Ceratobaeus masneri Austin (Austin, 1984) and Trissolcus oenone (Dodd) (James & Warren, 1991).…”

“…Progeny sex ratio ranged from 0.87 to 0.92 for T. basalis, and from 0.34 to 0.69 for T. podisi and was Flanders (1938) states that this impact is due to the fact that the reproductive organs are the ones most likely to be affected by the low temperature. Foerster & Nakama (2002) found that T. basalis and T. podisi kept for 20 days at 15ºC had their fecundity reduced by more than 80% and 95%, respectively, and as reported for T. remus, parasitoids maintained at 5ºC for three days had a significant reduction in fecundity (Gautam, 1986).…”

“…Storage of Trissolcus basalis (Wollaston) and Telenomus podisi Ashmead eggs and larvae was unsuitable for parasitoid emergence. However, adults of T. basalis and T. podisi that emerged at 15ºC when pupae were stored one day before the predicted date for emergence survived for about five months at the low temperature (Foerster & Nakama, 2002).…”

Cold tolerance of Trissolcus japonicus and T. cultratus, potential biological control agents of Halyomorpha halys, the brown marmorated stink bug

“…Furthermore, related parasitoids are known to overwinter as adults (Fathi et al, 2011;Foerster and Nakama, 2002;James, 1988;Ryan et al, 1981) and under bark (Fathi et al, 2011). No information exists on subzero temperature limits for T. japonicus and T. cultratus, nor the extent of cold tolerance variation among populations of each species.…”

Caracterização fitoquímica e avaliação do potencial acaricida e inseticida do óleo essencial de Hymeneae courbaril L. var. courbaril sobre o ácaro-rajado e o gorgulho do milho

“…Estudos sobre os efeitos letais dos óleos essenciais são de grande relevância nos programas de controle de pragas, pois as concentrações podem influenciar de modo positivo ou negativo o desempenho das espécies nos agroecossistemas, como por exemplo, no comportamento sexual alimentar, crescimento populacional, reprodução e longevidade (Foerster & Nakama, 2002).…”