Influence of gamma-irradiation on flight ability and dispersal of Conopomorpha sinensis (Lepidoptera: Gracillariidae)

Assessment of quality of male insects has been done primarily in area-wide integrated pest management (AW-IPM) programs that have a sterile insect technique (SIT) component. Routine monitoring of sterile male quality needs to be carried out both in the mass-rearing facility and in the field. Simple bioassays, which can be conducted in the laboratory or under semi-field conditions, would be potential surrogates for laborious field tests that are usually very costly. In the laboratory, a flight mill system was used to assess the quality of males of the litchi stem-end borer, Conopomorpha sinensis (Lepidoptera: Gracillariidae), in terms of flight distance, flight duration and speed. Flight distance, duration, mean speed and greatest speed of non-irradiated adult males were 13,926 m, 29,365 s, 0.42 m/s, and 1.01 m/s, respectively, during a 24 h period. Although the values of these parameters of non-irradiated males were greater than corresponding values for moths irradiated with 150 and 200 Gy, there were no significant differences between the various treatments and the non-irradiated control group. These data suggest that irradiation with 150 and 200 Gy did not significantly affect the flight ability of male litchi stem-end borers. This study also included 2 field release and recapture experiments. The data of the field experiments indicated that recapture rates, dispersal distances, and dispersal directions of the 150 and 200 Gy irradiated males were not significantly different from those of non-irradiated males. These data indicate that the ability of litchi stem-end borer males irradiated with doses of 150 and 200 Gy to disperse in the field was not impaired in comparison with non-irradiated males.