Abstract: Acridine orange is a dye that can be used to label insect. In this paper, the effect of acridine orange on longevity, fecundity and development of Trichogramma ostrinieae offspring were investigated by feeding the wasps with different concentrations of the dye. The results indicated that feeding the dye prolonged the wasp's longevity. Longevity of females fed 5 mg/L solution of the dye was 5.7 d, significantly longer than 4.8 d in the control. Male wasps fed 20 mg/L solution lived the longest (5.5 d) among three treatments and the control. Fecundities within 6 h were 29.9 and 30.1, respectively, for those fed 5 mg/L and 10 mg/L acridine orange solutions, which were marginally lower than that in the control (34.9) and that (35.1) of wasps fed on 20 mg/L solution. Negative effects of acridine orange were found on parasitism, wasp emergence rate and number of wasp offspring. Parasitism of Corcyra cephalonica eggs was significantly lower in wasps fed 10 mg/L solution (73.67%) than in the control (87.83%). Offspring emergence rate was significantly lower in wasps fed 5 mg/L solution (96.46%) than in the control (99.50%). Number of offspring of wasps fed 5 mg/L and 10 mg/L were (17.1±0.8) and (17.1±1.2), respectively, both significantly lower than that in the control (21.4±0.7). The fluorescence in wasps could be monitored under epifluorescence 24 h after feeding on acridine orange solution. However, because of self-fluorescence in T. ostriniae, it was impossible to distinguish all the unfed wasps from those labeled with acridine orange. So, when the effects of feeding acridine orange on longevity, fecundity and parasitism ability of T. ostriniae and the label efficiency of the dye were considered together, acridine orange could be used as marker to label Trichogramma wasps after being modified or changing physicochemical conditions to eliminate the effects of self-fluorescence of organism.

Key words: longevity, parasitism rate, emergence rate, female proportion, fluorescence, label