Abstract
The green lacewing, Chrysopa pallens Wesmael, is one of the most beneficial and prolific insects found in many horticultural and agricultural cropping system. Here, the effects of low temperature storage on quality of C. pallens were investigated by storing cocoons at 10 °C for different days. Results revealed, after removal from cold storage, emergence rate declined gradually as storage duration increased. After storage of 20 days, the emergence rate in cold-stored group is about 62.8% of that in unstored group. After eclosion, lifetime fecundity, preemergence period, oviposition period and longevity of adults in cold-stored group showed curves similar to emergence rate. However, preoviposition period and egg hatchability were not significantly affected by cold. After being stored for 20 days, the total fecundity of females emerging from cold-stored cocoons was about 64.5% of that of females emerging from unstored cocoons. Six days post emergence, females in cold-stored group showed apparent arrest of ovarian development and significant reductions of protease, lipase and trehalase activities when compared to unstored controls. When bovine insulin was exogenously used, the females emerging from cold-stored cocoons dramatically restored ovarian development and reproductive capacity. These results suggested that C. pallens pupae are suitable for cold storage and insulin hormone can be used as reproduction stimuli in this predatory species after cold storage.
Highlights
The green lacewing, Chrysopa pallens Wesmael, is one of the most effective natural predators and has distribution in most agricultural areas of the world[1,2]
After application of bovine insulin, ovarian scale and reproductive output were dramatically restored. These results suggested that cold storage was a useful technique for improving flexibility and efficiency in mass production of C. pallens and insulin hormone could be applied as reproduction stimuli after chilling treatment
When prepupae diapause was triggered in the green lacewing C. pallens, the prepupae stage was extended from 6.4 days to 49–82 days, depending on photoperiod and tempterature[39]
Summary
The green lacewing, Chrysopa pallens Wesmael, is one of the most effective natural predators and has distribution in most agricultural areas of the world[1,2]. Many studies revealed that most parasitoids can endure short-period cold storage with minimal impairment in fitness and viability[19,20,21,22,23,24]. In these studies, important biological characteristics, including survival, longevity, fecundity and behavior, were evaluated[17,25,26,27,28,29]. Application of bovine insulin promoted ovarian development and elevated reproductive output in lacewing female adults kept at rearing conditions[34], implying the application prospect of insulin hormone in production of natural enemies insects
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