Radiation-induced sterility for pupal and adult stages of the malaria mosquito <it>Anopheles arabiensis</it>

• Main Authors: Knols Bart GJ, Parker Andrew G, Helinski Michelle EH
• Format: Article
• Language: English
• Published: BMC 2006-05-01
• Series: Malaria Journal
• Online Access: http://www.malariajournal.com/content/5/1/41

<p>Abstract</p> <p>Background</p> <p>In the context of the Sterile Insect Technique (SIT), radiation-induced sterility in the malaria mosquito <it>Anopheles arabiensis </it>Patton (Diptera: Culicidae) was studied. Male mosquitoes were exposed to gamma rays in the pupal or adult stage and dose-sterility curves were determined.</p> <p>Methods</p> <p>Pupae were irradiated shortly before emergence (at 22–26 hrs of age), and adults <24 hrs post emergence. Doses tested ranged between 0 and 100 Gy. The effects of irradiation on adult emergence, male survival, induced sterility and insemination capability were evaluated. Emergence and insemination data were analysed using independent t-tests against the control. Correlation analyses were performed for insemination rate and dose and insemination and fecundity. Male survival was analysed using Kaplan-Meier survival analyses. Finally, the calculated residual fertility values were inverse-normal transformed and linear regression analyses performed.</p> <p>Results</p> <p>Irradiation of pupae, for all doses tested, had no effect on adult emergence. Survival curves of males irradiated as pupae or adults were similar or even slightly higher than non-irradiated males. Overall, adults appeared to be slightly more susceptible to irradiation, although no significant differences for individual doses were observed. In the pupal stage, a significant negative correlation was found between insemination and dose, but the correlation-coefficient was associated with less than 25% of the total variation. A review of the literature indicated that <it>An. arabiensis </it>is more radiation resistant than other anopheline mosquitoes.</p> <p>Conclusion</p> <p>The optimal dose for male insects to be released in an SIT programme depends on their level of sterility and competitiveness. The use of semi-sterilizing doses to produce more competitive insects is discussed. The most convenient developmental stage for mosquito irradiation on a mass-scale are pupae, but pupal irradiation resulted in a lower insemination rate at the highest dose compared to adult irradiation. On the basis of this study, a suitable dose range that includes semi-sterilizing doses is identified to initiate competitiveness experiments for males irradiated at both developmental stages.</p>