Action of some insecticides with sterilizing properties on Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae) and its predator Doru luteipes (Scudder, 1876) (Dermaptera: Forficulidae) / Ação de alguns inseticidas com propriedades esterilizantes sobre Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae) e seu predador Doru luteipes (Scudder, 1876) (Dermaptera: Forticulidae)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The fall armyworm, Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae), is an important pest of the maize culture. In the tropical area, it causes severe damages, reducing the income from grains by up to 60%. Its control is normally carried out by the application of conventional insecticides, but this method is not recommended due to the negative aspects of ecological disequilibrium, pest resistance, toxicological and economic factors. The chemosterilization with the modern insecticides that act in the physiology of the insects can be a tool added to the integrated pest management, because the products used have low toxicity when eaten by mammals and their natural enemies. Moreover, this process reduces the amount of insecticides substantially if compared with the conventional system. The objectives of this work were to study the use of some insecticides with sterilizing properties on the adult of S. frugiperda, determining necessary dosage, evaluating the effect of those products in conditions of vegetable house, counting the spermatophores found in the female, determining the distance at which the baits should be placed in the field and evaluating the effect of the products tested on nymphs and adults of D. luteipes, one of the main natural enemies of the fall armyworm. The sterilizers were supplied to the moths through ingestion with a 10% of honey solution. The insecticides used and respective dosages were abamectin (0.45 mL/L water), chlorfluazuron (2.0 mL/L water), flufenoxuron (2.0 mL/L water), lufenuron (0.75 mL/L water), novaluron (2,0 mL/L water) and piryproxyfen (12.0 mL/L water), a control plot was used for comparison. Except for lufenuron, all the insecticides reduced the fecundity of S. frugiperda, and the smallest number of eggs was found in the treatment with flufenoxuron. The viability of the eggs was also affected by the products. The sterilizers shown most effective in reducing egg viability were chlorfluazuron and lufenuron, that caused viability of only 0.24% of the eggs. The individuals' longevity, males and females alike, were affected by all of the products, excepting lufenuron. In the vegetable house, the treatments produced results similar to those found in the laboratory. However, as the parameters were less controlled outside the laboratory, different values were found. The products, except for clorfluazuron, affected the spermatophores nunmber found in the females, suggesting that the substances affected the reproductive system of the moths in the ovogenesis, spermatogenesis, embryogensis or other related process. The products chlorfluazuron, flufenoxuron, lufenuron and novaluron were 100% selective to nymphs of D. luteipes; whereas chlorfluazuron and novaluron only presented 100% of selectivity in adults. It can be concluded that chemosterilization is a viable method to be applied with integrated management of S. frugiperda.

ASSUNTO(S)

inseticidas lagartas seletivity spodoptera frugiperda doru luteipes insecta sterilization milho insetos predadores viability

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