Summary: | 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.
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