Efeito de formulações comerciais de Azadirachta indica A. Juss incorporadas à dieta artificial, sobre a biologia de Helicoverpa armigera (Hübner, 1808) (Lepidoptera: Noctuidae)

Abstract

In 2013, Helicoverpa armigera (Hübner, 1808) (Lepidoptera: Noctuidae), which was considered to be the A1 quarantine pest, was identified in Brazil causing severe damage to several agricultural crops. Chemical control was the main way to combat it, especially because of the speed of the insect mortality, however, its indiscriminate use led to problems of pest resistance. Currently, the use of alternative sources is recommended in comparison to the existing traditional practices with the integration of control methods in pest management, such as the use of botanical insecticides capable of controlling insect pests with great efficiency, causing mortality and/or interfering with its biology. The objective of this study was to evaluate the effect of commercial products based on neem Azadirachta indica A. Juss on the parameters of H. armigera biology, when incorporated in the artificial diet. The study was conducted in the Entomology Laboratory of the Embrapa Coastal Tablelands, Unit of Research Execution and Development in the municipality of Rio Largo, AL, where the artificial diet was prepared and the products were incorporated to it. The following products were used: Neenmax®, Nim-I-go® and Emulzinim® (neem-based); the insecticide Pirate® (positive control) and distilled water (negative control). Newly hatched H. armigera caterpillars were placed on plastic plates with the artificial diet containing the products and removed after 72 hours to new plates containing diet without the insecticides. Insects were raised until the emergence of adults to form couples. The following biological parameters were evaluated: viability and duration of the immature stages; pupae weight; sex ratio; fecundity, fertility, pre-oviposition period, oviposition period and adult longevity. The experimental design was completely randomized, with five treatments (products and controls) and 10 repetitions. Mean values were submitted to variance analysis and compared by the Tukey‟s test at 5% of significance using the SASM – Agri program. Among neem-based products evaluated, Neenmax® was the most efficient, killing 94% of the caterpillars, and not statistically differing from Pirate® (100%), and 0% of viability of the pupae. The Emulzinim® and Nim-I-go® products caused 36% and 46% of caterpillar mortality, and 86% and 88% of viability in the pupae, respectively, differing from the first two and also from the negative control (0% caterpillar mortality and 100% pupae viability). The Emulzinim® and Nim-I-go® products affected the biological parameters of H. armigera, differing statistically from the negative control, for all the other variables evaluated except for the sex ratio and the pre-oviposition period. All the neem-based products used in this study caused some alteration in the biological development of H. armigera, whereas Neenmax® proved to be efficient in controlling the pest using the recommended dose by the manufacturer.