Submitted to: Entomologia Experimentalis et Applicata
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/8/2009
Publication Date: 4/1/2009
Citation: Segura, D.F., Caceres, C., Vera, T., Wornoayporn, V., Islam, A., Teal, P.E., Cladera, J.L., Hendrichs, J., Robinson, A.S. 2009. Enhancing mating performance after juvenile hormone treatment in Anastrepha fraterculus (Diptera:Tephritidae): a differential response in males and females acts as a physiological sexing system. Entomologia Experimentalis et Applicata. 131:75-84. Interpretive Summary: One way to control this pest is the sterile insect technique (SIT). Control is achieved in SIT by mass release of sterile males who mate with wild females. Wild females that mate with sterile males do not produce viable eggs which, over time, results in population decline and eradication. One of the more significant costs associated with SIT protocols for Tephritid flies is the need to hold mass reared adult flies for as many as 7 days, or more, days prior to release because males require time to become sexually mature. Scientists at the Instituto de Genética “E. A. Favret”- Instituto Nacional de Tecnología Agropecuaria, Buenos Aires, Argentina, Joint FAO/IAEA Programme of Nuclear Techniques in Food and Agriculture, Entomology Unit, Seibersdorf, Austria, Estación Experimental Agroindustrial Obispo Colombres, S. M. de Tucumán, Argentina and the Center for Medical Agricultural and Veterinary Entomology, USDA-ARS, Gainesville Florida, have been studying how hormone therapy can improve SIT. They have discovered that addition of the hormone mimic, methoprene, accelerates reproductive development in males of the South American Fruitfly. The scientists are now developing methods to incorporate this technologies into mass rearing of sterile flies to improve efficacy of SIT.
Technical Abstract: Methoprene treatment can reduce the time required for sexual maturation in Anastrepha fraterculus (Diptera: Tephritidae) (Wiedemann) males under laboratory conditions, supporting its use as a treatment for sterile males within the context of the Sterile Insect Technique (SIT). Here we evaluated sexual behaviour, mating competitiveness of methoprene-treated males, and female readiness to mate after methoprene-treatment under field cage conditions. The study involved two strains of A. fraterculus from Argentina and Peru, which show several polymorphisms in relation to its sexual behaviour. We analyzed also whether methoprene treatment affected male and/or female behaviour in the same way in these two strains. Methoprene-treated males were equally competitive with untreated mature males, and became sexually competitive six days after emergence (3-4 days earlier than untreated males). By contrast, methoprene did not induce sexual maturation in females or, at least, it did not induce a higher rate of mating in 7 day-old females. These results were observed both for the Argentina and the Peru strains. Altogether, our results indicate that methoprene treatment produces sexually competitive males under field cage conditions. In the absence of a genetic sexing system, and when sterile males and females of A. fraterculus are released simultaneously, the fact that females do not respond as males to the methoprene treatment acts as a physiological sexing effect. Therefore, in the presence of mainly sexually immature sterile females, released sexually-mature sterile males would have to disperse in search of wild fertile females, thereby greatly reducing matings among the released sterile insects and thus enhancing SIT efficiency.