Cold stored ectoparasitoid of Cydia fruit moths released under different temperature regimes

Abstract

Cold storage of parasitoids to be used in biological control programs is desirable but risky for the performance of the stored parental generation as well as for its offspring. We studied the performance of cold stored and unstored parasitoids after release at different temperature regimes in the laboratory at the level of two subsequent generations in Hyssopus pallidus (Askew) (Hymenoptera: Eulophidae). This gregarious ectoparasitoid is a candidate biocontrol agent of Cydia pomonella L. (Lepidoptera: Tortricidae) and Cydia molesta (Busck) (Lepidoptera: Tortricidae) larvae, two fruit pests of high economic significance in apple cultivation. Cold storage for 14 days at 4°C imposed to the pupal stage of the parasitoid did not reduce the parasitism capacity of the parental generation, nor did it alter the female biased sex ratio of the progeny. Remarkably, this short-term storage of the parental generation exhibited a significant and consistently positive effect on offspring weight throughout all ambient temperature regimes, resulting in an increased offspring weight. Furthermore, offspring number was only reduced after release at low ambient temperatures, but not at 25°C and 30°C. Irrespective of whether the parasitoids originated from the stored or unstored group, highest parasitism rate was achieved at temperatures above 20°C. In conclusion, this candidate biocontrol agent can be cold stored for short periods without any measurable quality loss after release at most except at low ambient temperatures. Our findings suggest that H. pallidus is a thermophilous parasitoid that will perform best when applied at warm ambient temperatures in fruit orchards.

Changes in the bacterial communities of Harmonia axyridis (Coleoptera: Coccinellidae) in response to long-term cold storage and progressive loss of egg viability in cold-stored beetles

“…However, our study revealed that cold-stored beetles exhibited a significant decline in the three-day average egg hatch rates, which reached nearly zero on days 17–19. Furthermore, we observed that eggs produced by F1 offspring of cold-stored beetles displayed severely reduced hatchability from the onset of oviposition, indicating transgenerational effects ( Hackermann et al, 2008 ). The extent to which the marked increase in unclassified_f_Enterobacteriaceae within the female reproductive tract of cold-stored H. axyridis adults is associated with their poor reproductive performance remains unclear.…”

Influence of larval rearing temperature on the quality of cold‐stored Oomyzus sokolowskii Kurdjumov (Hymenoptera: Eulophidae)

“…; Häckermann et al. ; Colinet and Boivin ). For example, storage of the pupae of Telenomus busseolae (Gahan) (Hymenoptera: Scelionidae) in the eggs of Sesamia nonagrioides (Lefebvre) (Lepidoptera: Noctuidae) at 4°C (60 ± 5% RH) for 1 week had a significant adverse effect on adult emergence, and for 2 weeks, percentage parasitism of host eggs by emerged females was significantly reduced (Bayram et al.…”

“…Storage of natural enemies, particularly parasitoids, at suboptimal temperatures can be valuable for increasing their shelf-life, but entails risks of compromised performance of both the stored parental generation and their offspring (Okine et al 1996;H€ ackermann et al 2008;Colinet and Boivin 2011). For example, storage of the pupae of Telenomus busseolae (Gahan) (Hymenoptera: Scelionidae) in the eggs of Sesamia nonagrioides (Lefebvre) (Lepidoptera: Noctuidae) at 4°C (60 AE 5% RH) for 1 week had a significant adverse effect on adult emergence, and for 2 weeks, percentage parasitism of host eggs by emerged females was significantly reduced (Bayram et al 2005).…”

Lethal and Sublethal Effects of Long-term Cold Storage on Indoor-reared Harmonia Axyridis Adults

“…For the mymarid wasp, Gonatocerus ashmeadi Girault (Hymenoptera: Mymaridae), cold storage of immature wasps for 40 days even caused 44% female sterility, and tremendous parasitism and fecundity reduction of 70% and 73%, respectively 8 . Moreover, studies showed that some sublethal effects can even be passed to their offsprings, called "transgenerational effects" 9 . For G. ashmeadi, when cold storage of the adult parents was more than 20 d, delayed development, decreased fecundity, reduced longevity, and increased male production were observed in F1 generation 10 .…”