Irritant and repellent behaviors of sterile male Aedes aegypti (L.) (Diptera: Culicidae) mosquitoes are crucial in the development of disease control strategies applying sterile insect technique.

The mosquito Aedes aegypti, known to transmit important arboviral diseases, including dengue, chikungunya, Zika and yellow fever. Given the importance of this disease vector, a number of control programs have been proposed involving the use of the sterile insect technique (SIT). However, the success of this technique hinges on having a good understanding of the biology and behavior of the male mosquito. Behavioral responses of Ae. aegypti male populations developed for SIT technology were tested under laboratory conditions against chemical and natural irritants and repellents using an excito-repellency (ER) chamber. The results showed that there were no significant behavioral escape responses in any of the radiation-sterilized male Ae. aegypti test populations when exposed to citronella, DEET, transfluthrin, and deltamethrin, suggesting that SIT did not suppress the expected irritancy and repellency (avoidance) behaviors. The type of information reported in the current study is vital in defining the effects of SIT on vector behavior and understanding how such behavior may influence the success of SIT technology with regard to other vector control interventions.

Low-Dose Irradiation With Modified Atmosphere Packaging for Mango Against the Oriental Fruit Fly (Diptera: Tephritidae).

Irradiation is used to disinfest the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) and other pests on mango fruits before export from Thailand to foreign markets. Modified atmosphere packaging (MAP) used during export of mangoes creates a low-oxygen environment that may reduce the efficacy of quarantine irradiation treatment against B. dorsalis. 'Nam Dok Mai' mangoes infested with third-instar larvae of B. dorsalis, wrapped with three different kinds of MAP bags (CF1, FF5, and H34M) or no MAP, were treated with gamma radiation at 0 (control), 30, 60, 90, 120, and 150 Gy. The average O2 and CO2 concentrations in MAP bags with mangos were 7.2 and 8.7% in the H34M bag, 8.6 and 21.2% in the CF1 bag, and 9.6 and 26.7% in the FF5 bag, respectively. The use of MAP on infested mangoes significantly increased mortality of B. dorsalis under irradiation treatment. The estimated lethal doses to cause 99% mortality (LD99) for no MAP and MAP (CF1, FF5, and H34M bags) treatments were 58.1, 41.6, 43.8, and 47.4 Gy, respectively. Therefore, MAP acted as an additional stressor rather than providing radioprotection in irradiated B. dorsalis. Large-scale confirmatory testing of 35,000 B. dorsalis larvae treated at a radiation dose of 150 Gy in mangoes with H34M MAP bags produced no survivors to the adult stage. Commercial use of MAP producing the O2 levels that we observed for mangos in this study will not reduce the efficacy of the approved 150 Gy quarantine irradiation treatment for B. dorsalis.