Temperature and Exposure Time in Cold Storage Reshape Parasitic Performance of Habrobracon hebetor (Hymenoptera: Braconidae)

Abstract

Cold storage can extend shelf life of parasitoids for use in biocontrol. However, cold storage may have negative impacts on life history traits of the parasitoids and, therefore, on their performance as biocontrol agents. Here, we examine the effect of cold storage on life history traits of Habrobracon hebetor (Say) (Hymenoptera: Braconidae), a parasitoid of several economic lepidopteran pests. Newly emerged wasps were stored at three constant temperatures (3°C, 5°C, 7°C) for up to 4 wk. Both temperature and exposure time significantly affected longevity, parasitism, fecundity, and sex ratio. Significant reduction in longevity was observed at 3°C and 7°C, whereas longevity of wasps stored at 5°C remained stable up to the second week and then gradually decreased in Weeks 3 and 4. Parasitism rate also significantly decreased after cold storage at 3°C, 5°C, and 7°C (ranked from high to low). Fecundity decreased at T 3°C and T 5°C but this trait was not affected by storage at T 7°C. A significant shift in male production was observed at T 5°C in Week 3, but in Week 4, the only treatment with male biased reproduction was T 3°C. These results show that the effect of temperature and exposure time in cold storage is trait dependent. Overall, storage at 5°C for a period of 3 wk least impacted most life-history traits of H. hebetor wasps.

Habrobracon hebetor and Pteromalus cerealellae as Tools in Post-Harvest Integrated Pest Management

“…Foraging behavior and reproductive performance of H. hebetor are affected by temperature inside storage facilities [68,69,70]. Egg production by the Braconid ectoparasitoid has been shown to increase with temperature and maximum fecundity occurred at 25 °C [68], while egg laying capacity was observed to decline at cold temperatures of 3 and 5 °C [71,72,73]. In addition, cooler storage temperatures have the potential to decrease parasitism, resulting in a decrease in host mortality [72].…”

“…Egg production by the Braconid ectoparasitoid has been shown to increase with temperature and maximum fecundity occurred at 25 °C [68], while egg laying capacity was observed to decline at cold temperatures of 3 and 5 °C [71,72,73]. In addition, cooler storage temperatures have the potential to decrease parasitism, resulting in a decrease in host mortality [72]. Though the developmental time of immature stages of H. hebetor have been shown to decrease with increases in temperature [72], the lower threshold observed for development was between 11–12 °C [74].…”

“…In addition, cooler storage temperatures have the potential to decrease parasitism, resulting in a decrease in host mortality [72]. Though the developmental time of immature stages of H. hebetor have been shown to decrease with increases in temperature [72], the lower threshold observed for development was between 11–12 °C [74]. The larval stages of H. hebetor are very sensitive to temperature.…”

“…The sex ratio of H. hebetor is affected by temperature and exposure time [69]. For instance, the sex ratio of H. hebetor offspring skewed towards males when parents were kept at 3 or 5 °C for 4 or 3 weeks, respectively [72].…”

Potencial do ectoparasitoide >i<Habrobracon hebetor>/i< Say, 1857 (Hymenoptera: Braconidae) para controle biológico de treze espécies de lepidópteros-praga

“…Isso é importante, pois um dos fatores que determinam a viabilidade de se produzir e comercializar um inimigo natural é o tempo que os inimigos naturais permanecem viáveis para serem utilizados. Seyahooei et al (2018) concluíram que fêmeas podem viver por até três semanas a 5ºC, sem comprometer seus parâmetros biológicos e Chen et al (2013) observaram que as fêmeas do parasitoide permanecem em diapausa por oito semanas à 5ºC. As fêmeas que sofreram diapausa, produziram mais descendentes, em relação às fêmeas que não sofreram diapausa.…”