Effect of cold storage on the performance of Telenomus busseolae Gahan (Hymenoptera:Scelionidae), an egg parasitoid of Sesamia nonagrioides (Lefebvre) (Lepidoptera:Noctuidae)

Cold storage of both pupae and adults of Telenomus busseolae Gahan (Hymenoptera: Scelionidae) was investigated. Firstly, the effect of storage at three temperatures (4, 8, 12 +/- 1 degrees C), for seven time durations (1, 2, 4, 6, 8, 10, and 12 weeks) and four preimaginal ages of T busseolae pupae (9, 11, 13, and 15 day old parasitized eggs) in the eggs of Sesamia nonagrioides (Lefebvre) (Lepidoptera: Noctuidae) was studied. Laboratory performance of emerged parasitoids was measured and compared to that of the unstored (control) parasitoids. Storage had a significant adverse effect on mean adult emergence. T busseolae could be stored for 4 weeks at 4 and 8 +/- 1 degrees C but only 2 weeks storage was possible at 12 +/- 1 degrees C. Furthermore, mean percentage parasitism of host eggs by emerged parasitoids was reduced and F1 progeny sex ratio of the parasitoid became more male biased with increasing length of storage treatment. There was no effect of cold storage on the mean adult emergence of F1 progeny. Secondly, storage of adult T busseolae was investigated at two temperatures (8 and 12 +/- 1 degrees C) and six different storage times (1, 2, 4, 8, 12, and 16 weeks). Percent survival was reduced with longer storage times. Even though parasitoids survived for 12 weeks at both 8 and 12 degrees C temperatures, storage times influenced percent parasitism. Parasitoids stored for 8 weeks or longer parasitized fewer eggs than parasitoids stored for shorter times. Neither percent emergence nor sex ratio of F1 progeny was affected by storage temperatures and storage times. The current study suggests that T busseolae adults were successfully stored up to 12 weeks although some reduction in percent parasitism occurred at both temperatures. The ideal storage temperature for T busseolae adults was 12 +/- 1 degrees C. Results are discussed in relation to potential mass production and release of T busseolae for biological control of S. nonagrioides. (c) 2005 Elsevier Inc. All rights reserved.