Paulo Eduardo Degrande

Evaluation of the Boll Weevil Anthonomus grandis Boheman (Coleoptera: Curculionidae) Suppression Program in the State of Goiás, Brazil

The boll weevil Anthonomus grandis Boheman (Coleoptera: Curculionidae) is the most important cotton pest in Brazil. A large-scale field-testing of a Boll Weevil Suppression Program (BWSP) was implemented to assess its technical and operational feasibility for boll weevil suppression in the state of Goiás, Brazil. The pilot plan focused on 3,608xa0ha of cotton during the 2006/2007 and 6,011xa0ha in the 2007/2008 growing seasons; the areas were divided into four inner zones with an outer buffer zone. We analyzed data on boll weevil captures using pheromone traps installed in the BWSP fields, on the detection of the first insect and the first damaged floral bud, greatest damage, and number of insecticide applications. The nonparametric Mann–Whitney U test was used to evaluate the differences between presuppression and suppression years. Fourteen pheromone-baited trapping evaluations were used to compare the weevil populations from 2006/2007 and 2007/2008 growing seasons. The BWSP regime reduced in-season boll weevil captures from 15- to 500-fold compared to presuppression levels in the preceding year. The low capture rates were related to delays in infestation and damage by weevils. The smaller population size measured by trapping and field monitoring reduced the number of required insecticide treatments. The BWSP strategy was efficient in suppressing populations of this pest and is a viable program for cotton production in subtropical and tropical regions, with long-term economic and environmental benefits.

Efeitos da adubação nitrogenada em algodoeiro sobre a biologia de Aphis gossypii Glover (Hemiptera: Aphididae)

The cotton aphid, Aphis gossypii Glove, is one of the pests of cotton crop and its relation with the host seem to depend on the amount of nitrogen available to the plant. The biology of A. gossypii using different cotton nitrogen fertility regimes was studied under greenhouse conditions, in Dourados, MS. A completely randomized design with nine replications in a factorial scheme (2x4x2)+1 was used. Two nitrogen sources (sulphate of ammonium and urea), four doses of nitrogen (50, 100, 150 and 200 kg ha-1), two different times of nitrogen application and one additional treatment without nitrogen were taken as factors. The nymphal phases, the pre-reproductive, reproductive and pos-reproductive periods, longevity, the life cycle and fecundity of the cotton aphid were evaluated. The doses of nitrogen influenced the cotton aphid biology in both sources and times of application, favoring its development and fecundity.

Ataque de lagartas em estilo-estigma e grãos da espiga de diferentes híbridos de milho-Bt

A cultura do milho e atacada por diversas pragas ao longo do seu ciclo e recentemente foi constatada a ocorrencia de Helicoverpa armigera atacando espigas de milho no Brasil. O objetivo do trabalho foi avaliar o ataque de lagartas em estilo-estigma e graos da espiga de diferentes hibridos de milho-Bt. O estudo foi realizado no municipio de Dourados (MS). Avaliaram-se os insetos encontrados nos estilos-estigma presentes em cinco espigas de milho por parcela. Foram realizadas tres avaliacoes dos estilos-estigma e uma quarta avaliacao dos danos nas espigas do milho. Houve diferenca estatistica significativa entre o numero de lagartas de Spodoptera frugiperda encontradas no estilo-estigma dos hibridos estudados. Ocorreu um maior numero de lagartas no hibrido de milho nao-Bt, proximo de 0,5 lagartas/estilo-estigma, seguido do hibrido de milho Cry1Ab, Cry1A.105, Cry2Ab2 e por ultimo o menos infestado, com a proteina VIP3Aa20. O hibrido de milho que expressa a proteina VIP3Aa20 apresentou menor numero de lagartas no estilo-estigma.