Toxicity and sublethal effects of allyl isothiocyanate to Sitophilus zeamais on population development and walking behavior

Essential oils and their derivatives have been suggested as promising alternatives for the control of insect pests. However, the potential sublethal effects of these substances on insects can contribute to the development of resistance strategies that could compromise its control. This study aimed to evaluate the toxicity of allyl isothiocyanate (AITC) on adults of five populations of Sitophilus zeamais (Coleoptera: Curculionidae). The effects of sublethal doses of AITC on the locomotor behavior and development of the insect population were also evaluated. The AITC toxicity was determined by a bioassay for lethal concentrations, wherein the mortality curves were established using increasing concentrations of AITC ranging from 0.5 to 10.0 mu L L-1. The locomotor behavior was evaluated by distance walked, walking velocity and resting time. In addition, the daily and cumulative emergencies for all populations were evaluated. The LC50 found indicated a uniform susceptibility among the populations studied, without any indication of resistance to the AITC. All populations of S. zeamais had their population growth rates affected by sublethal exposure to AITC, presenting delayed accumulated emergence and a reduction up to 80.9% in the daily emergence. Although differences have been observed in the pattern of walking of the populations, treatment with AITC did not influence their locomotor behavior. The results indicate a lower risk of resistance development in the short term, suggesting that AITC can be a potential alternative for the control of S. zeamais on stored products.