Insecticide resistance and control failure likelihood among populations of the boll weevil (<i>Anthonomus grandis</i>) from Mato Grosso (Brazil)

Abstract

The cotton producers from southern Mato Grosso are currently experiencing control failure with the use of the use of insecticides against the cotton boll weevil Anthonomus grandis Boheman, the main pest species of this commodity. Therefore, the present study was designed to survey insecticide resistance and the associated likelihood of control failure among boll weevil populations in the region. Ten insect populations were sampled during the 2016/2017 season and subjected to time-mortality (contact) bioassays in glass vials impregnated with dried insecticide residues at their respective label rates. The three insecticides most frequently used in the region were surveyed: the organophosphate malathion and the pyrethroids beta-cyfluthrin and zeta-cypermethrin. The survival curves showed estimates of the respective median survival time (LT50) for each combination of insecticide and insect copulation. However, there were no significant differences in susceptibility among populations. The estimates of control failure likelihood for each compound at their respective label rates also indicated negligible risk of control failure with their use. These findings are consistent with time-mortality results indicating the lack of insecticide resistant populations at the surveyed sampling sites, suggesting that the reported field control failures result from other causes such as problems with insecticide application.

Laboratory Selection and Assessment of Resistance Risk in Drosophila suzukii (Diptera: Drosophilidae) to Spinosad and Malathion

“…In contrast, D. suzukii susceptibility to malathion was unaffected in a laboratory colony in British Columbia, Canada even after several generations of continuous exposure to malathion [ 15 ]. However, once developed, the ecological backlash of insecticide resistance can be costly due to the potential for control failures [ 16 , 17 , 18 , 19 , 20 , 21 , 22 ]. Armes et al [ 16 ] reported huge control failures in India’s cotton belt due to Helicoverpa armigera resistance to insecticides.…”

Physiological changes throughout an insect ear due to age and noise - A longitudinal study

“…At 10 days post their last moult, the locusts’ wings were clipped and they entered the experimental pipeline. The desert locust follows the same type III (exponential) survival curve ( Demetrius, 1978 ) as other insects (Boll Weevil, Oliveira-Marra et al., 2019 ; mosquito, Vézilier et al., 2012 ), where a period of low mortality is followed by a steep exponential decline in survival. Approximately 50% of locusts were dead at 12 days post first noise exposure or mock noise exposure (for control group) and there was no stark difference, in survival, between noise-exposed and control locusts.…”

Field‐evolved resistance to beta‐cyfluthrin in the boll weevil: Detection and characterization

“…No significant variation was found in the Brazilian survey to the field rates of commercial formulations in terms of lethal times, and the study showed only short variation in time to obtain expected mortality across locations with the same tested insecticide. Therefore, the authors concluded that control failures were likely related to operational factors rather than insecticide resistance 24 . However, there are reports of low efficacy of some pyrethroids, in both laboratory and field tests 19 and the mortality rate of boll weevils after treatment has declined over recent years 25 .…”