Mortality of Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) by gamma irradiation

Abstract

The western flower thrips, Frankliniella occidentalis (Pergande), is a good working model for studies of irradiation as a quarantine treatment on agricultural products against this insect group. A study was conducted to evaluate the mortality of this species, resulting from different dosages of gamma irradiation. . Field populations were collected and exposed to 0.5, 1.0, and 1.5 kGy in a 60-Cobalt irradiator. In a first experiment, 645 adult F. occidentalis per treatment were used. Adult mortality reached 35% to 67% after 1 h exposure, significantly higher than the control. In a second experiment with the same dosages and storage at 5-6°C, evaluations were done at days 8 and 14 on at least 200 adults. Mortality increased significantly with the dosage of irradiation over time, and reached 95% with the higher dosage. In general, there were no differences between 8 and 14 days under cold storage for a given dosage. From a quarantine point of view, it is suggested to evaluate the combined effect of higher irradiation dosages and colder storage, as well as the effects of the treatments on fertility and fecundity of thrips. © 2007 Instituto de Investigaciones Agropecuarias, INIA.