Immediate and delayed effects of short exposures to phosphine on adults and larvae of the khapra beetle, Trogoderma granarium. (January 2021)

• Record Type: Journal Article
• Authors: Gourgouta, Marina; Agrafioti, Paraskevi; Athanassiou, Christos G.
• Is Part Of: Journal of stored products research. Volume 90(2021)
• Publication Date: 2021-01
• Subjects: Quarantine pest -- Khapra beetle -- Short exposures -- Diagnostic test -- Immobilization -- Phosphine -- Tolerance; Food -- Storage -- Periodicals; Farm produce -- Storage -- Diseases and injuries -- Periodicals; Entomology -- Periodicals; Food Contamination -- Periodicals; Food Preservation -- Periodicals; Insect Control -- Periodicals; Aliments -- Entreposage -- Périodiques; Produits agricoles -- Entreposage -- Maladies et dommages -- Périodiques; Electronic journals; 631.568
• DOI: 10.1016/j.jspr.2020.101737
• Languages: English
• ISSNs: 0022-474X

Abstract

Abstract: Adults and larvae of the khapra beetle, Trogoderma granarium Everts were exposed to 3000 ppm of phosphine through the Phosphine Tolerance Test. In a first series of bioassays, observations were taken every 2 min and the exposed individuals were classified either as walking normally or as being immobilized (knocked down), i.e., not walking normally. In the second series of bioassays all individuals were exposed for 90 min to phosphine. For both bioassays delayed mortality was noted after a 7 and 14-day post exposure interval. Larvae were found to be more tolerant than adults, as the time required for the individuals to be immobilized was up to 20 min, which was almost twice as long as the time required for the immobilization of the adults. There were high levels of adult mortality 7 days later, and complete (100%) mortality 14 days after the exposure. In contrast, larval mortality was low, for both post-exposures. Adults were 100% immobilized after the termination of the 90-min exposure interval at 3000 ppm of phosphine, while the percentage of the active larvae was extremely low. Regarding the 7 days post exposure interval the percentage of larval immobilization was higher than that of adults, but this was reversed seven days later. Interestingly, development of the larvae was delayed compared to the control, after the 90 min exposure, in contrast to 20 min exposure which did not cause any delayed effect. Our work provides some first data for the evaluation of the influence of short exposures to phosphine on adults and larvae of T. granarium, which may be very useful in creating an effective initial quantification plan for the control of this species. Highlights: Trogoderma granarium was exposed to 3000 ppm of phosphine through the Phosphine Tolerance Test. Mortality was recorded during the exposure period, for both exposure intervals (20 and 90 min). Delayed mortality was noted after a 7 and 14-day post exposure period. Larvae were found to be more tolerant than adults. High levels of adult mortality were achieved 7 days later and 100% mortality 14 days after the exposure.