EVALUATION OF THE SUSCEPTIBILITY OF THE BOLL WEEVIL (Anthonomus grandis, BOHEMAN) TO MALATHION IN THE LAGUNA REGION

Abstract

Background. Resistance to an insecticide is what determines its effectiveness and the lack of information limits effectiveness in the control of the boll weevil in cotton crops. Objective. The objective of the study was to determine the susceptibility of the boll weevil (Anthonomus grandis Boheman) to malathion in the Laguna, Mexico. Currently, this pest is considered as the one with the highest economical impact on cotton cultivation in the region. Methodology. Three bioassays were carried out, one in the state of Coahuila in the 2017 agricultural season and in the 2018 and 2019 seasons in the states of Coahuila and Durango. Boll weevils reared in the laboratory, as well as those collected in the field were used to obtain DL50 and DL95. The mortality data was analyzed using the Probit analysis. Results. The mean lethal dose after 48 hours in the three agricultural cycles fluctuated between 0.19 and 0.39 µg/µl for adults raised in the laboratory and the data observed for adults collected in the field was between 0.37 and 0.44 µg/µl. Implications. Periodic bioassays are suggested to detect populations resistant to malathion. Conclusion. It was determined that the boll weevil populations in the Laguna Region were susceptible to malathion, since the mean lethal dosage for the 3 agricultural seasons was < 1 µg/µl.