Biorational Management of Pecan Nut Casebearer, Acrobasis nuxvorella Neuzing1, and its Effect on Associated Parasitoids

Abstract

Biorational methods (Trichogramma, methoxyfenozide, and spinetoram), conventional control (chlorpyrifos ethyl), and no control were used against pecan nut casebearer, Acrobasis nuxvorella Neuzing, in pecan (Carya illinoinensis (Wangenh) K. Koch), orchards in the Comarca Lagunera region of Coahuila and Durango, Mexico, during the 2016 and 2017 growing seasons. Effects of different management strategies were evaluated on the abundance of A. nuxvorella and damage caused to nuts, as well as abundance, diversity, and rate of parasitism. From April through June both seasons, sexual pheromone traps were used to monitor A. nuxvorella. A sample of 310 panicles from 31 randomly selected trees (10 per tree) was taken to estimate damage by first (May) and second (July) generations of A. nuxvorella each year. The effect of management type on moth abundance and percentage of damage to panicles were analyzed. In 2016 and 2017, management type significantly affected moth abundance. With contrast tests in 2016, significant differences in damage were detected only in the second generation between orchards treated with methoxyfenozide and those treated with spinetoram. In 2017, all management types were statistically similar. In general, spinetoram was most effective in controlling the borer. Parasitism in 2016 was 7.7% for the check and 2.7% in larvae with spinetoram. In 2017, 6.6% of larvae of the check were parasitized, and 2.0% of larvae in the orchard where Trichogramma and methoxyfenozide were used. The most abundant parasitoids were Apanteles epinotiae Viereck (45.4%) and Goniozus nephantidis Muesebeck (31.8%). Parasitoid Macrocentrus instabilis Muesebeck was a new record for the State of Durango, Mexico.