The control of Epicometis hirta Poda in apple orchards with azadirachtin

Abstract

Epicometis hirta damages flowers and flower buds of stone fruits. The chemical control of this pest is not recommended because it is usually applied in the flowering period, when bees and other pollinators are present and can cause uncontrolled mortality for such important species. This experiment aimed to assess the efficacy of the biological (azadirachtin) and chemical (tau-fluvalinate) insecticides on E. hirta in apples. Before the application, the active ingredients’ content was determined and their physical and chemical properties were tested in accordance with the recommendations of FAO and WHO. The experiments were carried out during 2015 in Vojvodina province, Serbia (localities Čelarevo and Kovilj) in apple orchards, using standard OEPP methods and a modified method in accordance with the pest biology and apple phenofaze. Insecticides’ amounts were calculated for the amount of active ingredient L-1, then applied as follows, azadirachtin (10 g a.i. L-1) was applied at 0.3% concentration and tau-fluvalinate (240 g a.i. L-1) in an amount of 0.3 L ha-1. Three assessments were made, after one, three and seven days of the treatment, by counting the number of the dead + paralyzed beetles and determining the damage on apple flowers. The results were presented as an efficacy percentage (%). Also a laboratory test was carried out. In Čelarevo the efficacy of azadirachtin was very low (9.5 to 12.5%) while tau-fluvalinate ranged from 5.0 to 100%. In Kovilj the efficacy of azadirachtin, depended on the time of evaluation, and ranged from 37.5 to 68.6%, and tau-fluvalinate ranged from 73.3 to 100%. At both localities, flowers were completely damaged in the control, while the damage was less in treatments with insecticides. In laboratory conditions low mortality was registered after 24 and 48 h of exposure and only after 72 h the mortality ranged from 42.5 to 51.0%, depending on the insecticide. The flower damage was not as severe when compared to the control where the entire flowers were eaten. We can conclude that the biological insecticide azadirachtin exhibited mainly repellent and partially insecticidal effects on E. hirta in apple orchards.