Resistance Affects the Field Performance of Insecticides Used for Control of Choristoneura rosaceana in Michigan Apples and Cherries

Abstract

Field-based residual bioassays and residue analysis were conducted to assess the field performance and toxicity longevity of different insecticides that had previously been associated with resistance of Choristoneura rosaceana populations collected from apple and cherry orchards. In this study, 12–24 h-old larvae of apple and cherry populations were exposed to apple and cherry leaf samples, respectively, at post-application intervals and a susceptible population served as a reference of each. In the apple and cherry trials, the order of residual longevity of insecticides that effectively controlled the tested populations was as follows: bifenthrin and spinetoram (apple: 14, cherry 21-d post-application), phosmet (apple: 7, cherry 14-d post-application), chlorantraniliprole (apple: 7-d post-application), and indoxacarb and emamectin benzoate (apple: 1, cherry 7-d post-application). Compared to the susceptible population, the resistant populations resulted in a measurable loss of field performance, or “practical resistance”, for the insecticides emamectin benzoate (at 7-d post-application), chlorantraniliprole (at 21-d post-application), and indoxacarb (at all post-application intervals) in the apple trials, while in cherry trial just indoxacarb at 7-d post-application showed a reduced efficacy. In terms of long-lasting residues, only chlorantraniliprole and indoxacarb maintained measurable leaf residues over all post-application intervals while the leaf residues of the other compounds had largely degraded within the first 7 days. These findings can help fruit growers make adjustments to their spray/re-application intervals and optimally utilize important chemical tools in their integrated pest management programs.

Change‐point analysis of lambda‐cyhalothrin efficacy against soybean aphid (Aphis glycines Matsumura): identifying practical resistance from field efficacy trials

“…15 Potential differences in efficacy of insecticides under laboratory and field conditions have been documented elsewhere. [16][17][18][19] Practical resistance is defined as "field-evolved resistance that reduces pesticide efficacy and has practical consequences for pest control". 20 More specifically, the Insecticide Resistance Action Committee's definition of resistance specifies "the repeated failure of a product to achieve the expected level of control when used according to the label recommendation for that pest species."…”

“…It is important to note that such documentation of resistance in the laboratory does not always equate to a reduction in the field efficacy of insecticide applications against the pest 15 . Potential differences in efficacy of insecticides under laboratory and field conditions have been documented elsewhere 16–19 . Practical resistance is defined as “field‐evolved resistance that reduces pesticide efficacy and has practical consequences for pest control” 20 .…”