Aspectos bioecológicos de Alabama argilácea Hübner em algodão pulverizado com caulim

Abstract

The cotton is the crop of the greater socio-economic importance to Brazil that is fifth largest producer of this malvaceae. The pests constitute a major factor to reduce cotton yield and the cotton leafworm is the main defoliating pest of tis crop. Chemical control is the main tactic employed by cotton farmers. The use of mineral particles (kaolin) becomes an alternative to replace and/or optimize the control of this pest. The objective of this research was to evaluate the behavior of oviposition of the Alabama argillacea sprayed on cotton plants with kaolin and the interference of particle film in food consumption and life cycle of this insect. The study was conducted in the Insect Biology at Laboratory of Embrapa Cotton and Molecular Pathology. Three experiments were conducted. The first experiment was to determine the oviposition preference and viability of eggs of A. argillacea in cotton plants with the choice and under contained conditions. The experimental design was a randomized block, factorial 2 x 7, represented by cotton tile covering with spray insecticide (F1 = distilled water with kaolin at a dose of 60 g / L and F2 = control, distilled water) and seven plant structures (L1 = bud, L2 = square, L3 = stem, L4 = leaf stem, L5 = the first and second branches of leaves fruitful, L6 = leaves from the third and fourth branches fruitful and L7 = leaves the fifth and sixth branches fruitful). The data obtained in these tests were submitted to analysis of variance and means compared by Tukey test at 5% probability. The second experiment was conducted to determine the leaf consumption of the first instar of cotton leafworm, A. argillacea on cotton leaves with kaolin and without. The experimental design was completely randomized in a factorial 2 x 4, represented by the treated leaves (F1= distilled water with kaolin and F2= distilled water) and four observation periods (P1= 6 h, P2= 12 h, P3= 24 h and P4= 48 h) of the leaf area consumed by cotton leafworm. The data were subjected to analysis of variance and regression. In the third experiment aimed to study the development, survival and reproduction of cotton leafworm with cotton leaves with kaolin and without. The experimental design was completely randomized with two treatments and forty repetitions. Treatments consisted of cotton leaves sprayed with kaolin and with water (control). The data were subjected to analysis of variance at 5% probability. The oviposition of moths of the cotton leafworm is reduced in cotton plants treated with kaolin and egg distribution is affected by kaolin in choice test. The cotton leafworm of the first instar survive fewer in cotton plants treated with kaolin. The neonate cotton leafworm survivors reach the end of larval phase feeding usually with leaves of cotton with kaolin, developing and reproducing similar to cotton leafworm fed on leaves without kaolin.