Susceptibility to acaricides in Oligonychus perseae from avocado orchards in Nayarit, Mexico

Abstract

The present investigation was carried out in the Autonomous University of Nayarit with the aim of determining the relative resistance (RR at level of LC50 and LC95) of Oligonychus perseae from Hass avocado orchards to acaricides in comparison to a susceptible population. Mite populations were obtained from three sample sites of commercial Hass avocado plantations: one from the municipality of Xalisco (rural areas) and two from the municipality of Tepic (El Ahuacate and San Cayetano), Mexico; a mite population collected from the Agriculture School was taken as susceptibility reference. Fenpropathrin, abamectin and dimethoate were used as acaricides in serial dilutions from 1000 to 0.1 ppm and a control of distillated water. Mortality was determined at 24 hours. Obtained data were analyzed using Probit, through the Polo Plus program to obtain LC50 and LC95 values, which were compared between assayed populations to determine resistance levels. O. perseae mite populations from Xalisco, El Ahuacate and San Cayetano did not present resistance at level at LC50 and LC95 from the three tested acaricides. For fenpropathrin, in the three populations, RR50 and RR95 values ranged from 1.1 to 1.2x, and from 1.6 to 2.0x, respectively. For abamectin, RR50 and RR95 values varied from 0.6 to 1.1x and 0.2 to 0.8x, respectively. Finally, in the case of dimethoate, RR50 and RR95 values fluctuated from 0.6 to 1.1x and 0.4 to 3.6x, respectively.