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Submitted to: Journal of Entomological Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 5/23/2004 Publication Date: 1/1/2005 Citation: Villavaso, E.J. 2005. Effects of irradiation on reproduction in tarnished plant bug, lygus lineolaris (heteroptera: miridae) and f1 progeny.. Journal of Entomological Science. Interpretive Summary: Tarnished plant bugs (TPB)and their western cousins caused a reduction of nearly 200,000 bales of U. S. cotton in 2002. Midsouth TPB overwinter and reproduce in the spring on plants near cotton fields. When these plants begin to die in the spring, TPB abandon them for more suitable hosts, like newly squaring cotton. If lab-reared TPB could be made sexually sterile by irradiation, they could be released into the winter plant habitat. There they could mate with members of the native population, thus reducing egg hatch and the number of subsequent offspring. Even better, the few offspring produced will be more sterile than their irradiated parents. These offspring will "grow up" beside the native population and be right there in adulthood to consort with the natives and further suppress their populations. This biologically sound and environmentally safe method of suppressing TPB populations will take place on the winter hosts so the sterile bugs will not cause harm to the crop. Our research showed that reductions in egg-to-adult development of 100% can be achieved with high dosages of radiation. Lower dosages produce less initial sterility, but the offspring are much more sterile than their parents. High dosages tend to take a higher toll on TPB vigor, so treating the bugs with lower dosages may make them more competitive and thus more likely to produce offspring in the field that will be more sterile and more competitive than their irradiated parents. Technical Abstract: Tarnished plant bugs, Lygus lineolaris (Palisot de Beauvois) were administered dosages of 0, 5, 10, 15, 20, and 40 krad (10 krad = 100 Gy) of gamma-radiation from a 137Cs source. Reductions in egg hatch and egg-to-adult development in both irradiated parents and their F1 progeny were proportional to dosage received. Egg hatch averaged 58.9% in untreated parents and fell to 35.5% and 4.6% when males were treated with 15 and 40 krad, respectively. Egg-to-adult development was more severely curtailed than egg hatch, with untreated groups averaging 36.0% development compared with 6.8% at 15 krad and 0% at 40 krad. F1 progeny produced greater reductions in egg hatch and egg-to-adult development than their treated parents. Eggs from untreated females mated with F1 male progeny averaged 58.9% for the untreated control compared with 18.5% and 0.9% for the 10 and 20 krad groups, respectively. Egg-to-adult development in those groups averaged 38.4, 5.4, and 0.1%, respectively. Females were more susceptible to the effects of irradiation than males. Hatch of eggs from F1 female progeny mated to untreated males averaged 61.8, 21.0, 3.7, and 0% for dosages of 0, 5, 10, and 20 krad, respectively, and egg-to-adult development averaged 39.4, 5.5, 0.1, and 0% for those treatments, respectively. Mortality in the 5 and 10 krad groups was similar to the untreated control, but fell abruptly at 15 to 20 krad and again at 40 krad. |
