Chemical control of Diatraea saccharalis Fabricius, 1794 (Lepidoptera: Crambidae) in rice cultivation (Oryza sativa L.), and its effect on some biological controllers

Diatraea saccharalis is a polyphagous and stem borer pest feeding on rice crops in Colombia. Its larvae damage the stem between the tillering and flowering stages of the crop, causing production losses of up to 63%. The study aims to evaluate the efficacy, residuality, and phytotoxicity of five formulations (plinazolin, emamectina benzoate, thiamethoxam, chlorantraniliprole, and cyantraniliprole) in different concentrations to control the larvae and determine their effect on beneficial organisms in the rice agroecosystem. This study was conducted under shade house and laboratory conditions at the National University of Colombia (Palmira campus). Rice plants at 30 and 50 days of age were used and infested with II instar larvae of D. saccharalis before and after the spray of treatments to evaluate prophylactic and curative effects. The effects of the best pesticide candidates on adults of the parasitoid Lydella minense and the predator Chrysoperla carnea were assessed. Prophylactic applications, of all treatments, were more effective in controlling the D. saccharalis larvae than curative applications. No phytotoxic effects were observed on the treated rice plants. The treatment of plinazolin + emamectin benzoate (150ml/ha) showed the best efficacy in controlling D. saccharalis larvae; with an effectiveness of 75 - 100% in preventing the symptom of heart rot in the plants and with residual effect up to 14 days after spraying. Under this treatment, beneficial insects were killed between 24 and 48 hours after spray (100% mortality), providing an opportunity for them to perform their predation and parasitism work in the rice cultivation agroecosystem.