Abstract: Sugar diets can prolong longevity of synovigenic parasitoids. To understand the differences in the nutritional function of naturally occurring sugars to synovigenic parasitoids, the longevity and oogenesis of Diglyphus isaea (Walker), a predominant parasitoid of Liriomyza leafminer provided respectively with glucose, fructose, sucrose, trehalose and melezitose, were compared in this experiment. The results showed that the longevity of female wasps feeding on sugars was prolonged significantly (P<0.0001). Longevity of wasps feeding on fructose was significantly longer than that feeding on glucose, sucrose, trehalose and melezitose, respectively (P<0.0001). However, no differences were observed in the longevity of wasps feeding on glucose, sucrose and trehalose (P>0.4234), which was, however, significantly longer than that feeding on melezitose (P<0.0001). The longevity was positively related with body size when female wasps fed on different sugars. Newly emerged females did not bear the third grade eggs (mature eggs) in their ovaries. When water was available, the number of the third grade eggs reached the maximum at 24 h after eclosion, while all of the third grade eggs were reabsorbed at 48 h. When the parasitoids fed on the five kinds of sugars, the number of the third grade eggs and the total number of eggs including immature and mature eggs significantly increased and then declined gradually. Meanwhile, the peak time of the total number of eggs varied among the different treatments, but the maximums of both the third grade eggs and total eggs had no significant differences among female wasps feeding on different sugars (P>0.05). The results provide a basis for mass-rearing indoors and mass-releasing in fields of the parasitoid D. isaea.

Key words: Synovigenic parasitoid, Diglyphus isaea, sugar, longevity, oogenesis