Effect of cold storage on survival, reproduction and development of adults and eggs of Franklinothrips vespiformis (Crawford)

Cold storage effects on both female adults and eggs of the predatory thrips Franklinothrips vespiformis (Crawford) (Thysanoptera: Aeolothripidae) were investigated. The effect of low temperatures (5.5, 7.0, 8.5, 10.0 and 12.5 °C) on survival of F. vespiformis adults was firstly recorded. Survival times were significantly reduced at the lower temperatures tested, whereas storage at 10.0 and 12.5 °C provided the longest survival. Life-history consequences of exposing adults to moderately low temperatures were examined in terms of pre-oviposition period, oviposition rate, egg viability and survival after storage. Adults stored at 7.0 °C showed longer pre-oviposition period and shorter longevity than unstored females but other reproductive attributes were not significantly affected by storage regime. Low temperature and storage period affected egg viability and subsequent development of pre-imaginal stages. No eggs hatched after a 20-day period of storage at 5.5 and 7.0 °C, whereas eggs stored at 12.5 °C hatched significantly faster than ones stored at 10.0 °C and unstored eggs. Increasing the egg storage period from 10 to 20 and 30 days decreased the oviposition rate of adults and egg viability. An essential component in the successful mass rearing and distribution of these predators is the development of a reliable storage schedule of eggs and adults. Long-term storage was unsatisfactory, however their short-term storage (3.5 weeks at 10.0 and 12.5 °C for adults and 4–5 weeks at 12.5 °C for eggs) gave satisfactory results, which suggest the efficacy of such storage during the mass production of the biocontrol agent.