Effectiveness of Insecticides to Control Small and Large Larvae of Helicoverpa armigera (Hübner, 1805) (Lepidoptera: Noctuidae)

Helicoverpa armigera (Hübner, 1805) (Lepidoptera: Noctuidae) is a cosmopolitan pest with wide geographical distribution in Brazil. This pest was officially registered in 2013 on cotton, soybean, corn, and some weeds, although this species may have been present in the country since 2008. The objective of this work was to evaluate the efficiency of eight insecticides (seven chemicals and a biological product) to control small and large H. armigera caterpillars. The experiment was conducted under laboratory conditions (T 22±1 °C; RH 70±10%; 12h photoperiod), with nine treatments (g a.i./ha dose): flubendiamide (72), chlorantraniliprole + lambda-cyhalothrin (30 + 15), chlorfenapyr (288), spinetoran (18), indoxacarb (120), emamectin benzoate (10), metomil (322.5), Bacillus thuringiensis (500), and control (water). A completely randomized design was used with four replications for each size of caterpillars (small and large), and each repetition (plot) consisted of five H. armigera caterpillars fed with bean leaves immersed in the different treatments evaluated. The larval mortality evaluations were performed at one, three, five, and seven days after contact with the treated bean leaves, determining the control efficiency (E%) through the formula of Abbott (1925). All chemical and biological treatments tested caused significant mortality of small and large H. armigera caterpillars, reaching a control percentage of 100% at seven days after treatment, demonstrating the possibility of using the insecticides tested to control this pest under field conditions.