Pesticidi i Fitomedicina (Jan 2007)
Determination of Resistance Levels of Myzus persicae (Sulzer) by Biochemical Methods
Abstract
Peach/potato aphid Myzus persicae (Sulzer) has developed three mechanisms of resistance: overproduction of one or two closely related carboxylesterases (E4 and FE4), production of modified acetylcholinesterase (MACE and knockdown resistance). Biochemicaldiagnostic methods can be used to identify levels of carboxylesterase production and sensitivity of modified acetylcholinesterase and, based on the values acquired we can classify aphids into one of the resistance cathegories. We used two tests: the total esterase activitytest and test for checking sensitivity of acetylcholinesterase (MACE). Myzus periscae persicae from peach and Myzus persicae nicotianae from tobacco were tested. The total esterase activity test showed that 65% of the aphids tested were moderately resistant and 35% were highly resistant. Resistance based on the production of modified acetylcholinesterase is less represented because 80% of the aphids tested were susceptible to pirimicarb, which was used in the experiment. Also, both tests showed that aphids from tobacco were more susceptible than aphids from peach.
