FORMULAÇÃO MULTICOMPONENTE PARA MONITORAMENTO DE LEPIDÓPTEROS PRAGA EM ÁREAS DE SOJA NO MATO GROSSO

Introdução: O complexo de lepidópteros-praga da soja, tem afetado diretamente a produção devido aos prejuízos pela destruição direta das vagens, além de reduzir a área fotossintética das plantas, pela desfolha. Com isso, faz-se necessário aplicações sucessivas de inseticidas, que impactam drasticamente o meio ambiente. Desta forma, uma alternativa sustentável para minimizar tais impactos, seria a utilização de feromônio sexual, que são sinais químicos emitidos pelos lepidópteros para o acasalamento. Estes feromônios podem conter compostos comuns atrativos a diferentes mariposas que conseguem ser usados para mais de uma espécie, ajudando assim o monitoramento nas lavouras de soja. Objetivo: Avaliar a eficiência de duas formulações multicomponentes no monitoramento de lepidópteros-praga da cultura da soja. Material e métodos: O experimento foi conduzido em delineamento inteiramente casualizado em uma área de soja no município de Tangará da Serra – MT, onde foram utilizadas armadilhas do tipo delta, de cor branca, para a captura dos adultos. As armadilhas ficaram dispostas a 100m da bordadura, distanciadas uma da outra a 50m. Foram avaliadas duas formulações multicomponentes e como controle utilizou-se hexano. Foram efetuadas cinco repetições e os tratamentos foram distribuídos em armadilhas tipo delta para a captura dos adultos e as avaliações eram realizadas semanalmente. Os dados foram submetidos ao Modelo Linear Generalizado (GLM), analisando a diferença entre os tratamentos pelo teste Tukey. Resultados: Foram coletadas 673 mariposas, com predominância para os noctuideos Spodoptera frugiperda e Chrysodeixis includens e o piralídeo Elasmopalpus lignosellus. A formulação 2 capturou 280 mariposas e diferiu estatisticamente da formulação 1 que coletou 241 e do hexano que teve uma coleta de 152 (p<0,05). Conclusão: As formulações avaliadas foram eficientes no monitoramento lepidópterospraga da soja, sendo uma alternativa promissora para o monitoramento deste complexo na cultura da soja.

Sugarcane Green Harvest Effects on Arthropod Ground Predators and Lesser Cornstalk Borer (Lepidoptera: Pyralidae) Damage

A field trial was conducted to determine the effects of harvest method (green cane harvest versus preharvest burning) and different crop residue removal treatments on the populations of ground-inhabiting arthropod predators and Elasmopalpus lignosellus (Zeller) (Lepidoptera: Pyralidae) in the first ratoon crop. Neither preharvest burning nor percentage crop residue removal after green cane harvest had any significant effect on the numbers of ants (Hymenoptera: Formicidae) (F = 1.00; df = 4; P = 0.412) or spiders (Araneae) (F = 0.08; df = 4; P = 0.921) captured in pitfall traps. In contrast, crop residue levels remaining after green cane harvest significantly impacted E. lignosellus damage to the ratoon crop, with increased damage associated with lower levels of residue. Removal of ≥66% of the crop residue caused a significant (F = 132.68; df = 3; P &lt; 0.001) increase in E. lignosellus damage that would likely reduce sugarcane yield, while 33% of the residue could be removed without increasing damage. Overall, our data indicate that green cane harvesting will not affect arthropod ground predators but may reduce the risk of E. lignosellus damage.

SUSCEPTIBILITY OF Elasmopalpus lignosellus PUPAE TO ENTOMOPATHOGENIC NEMATODES IN MAIZE

Virulence and concentration of entomopathogenic nematodes (NEPs)in Elasmopalpus lignosellus pupae were evaluated. In the laboratory, the virulence of the isolates Heterorhabditis amazonensis MC01, H. amazonensis JPM3, H. amazonensis GL, Steinernema carpocapsae All and Heterorhabditis sp. Nepet 11 was evaluated and, subsequently, H. amazonensis GL was applied at concentrations of 8; 16; 24 and 32 IJ cm-2. The EPNs were applied to Petri dishes containing ten pupae with five replications. Mortality was assessed every 24 hours for three days. In a greenhouse, H. amazonensis GL was tested at concentrations 24, 25, 26 and 27 IJ cm-2. The IJs were applied in pots containing a 20-cm high ‘BM 3061’ maize plant, besides six pupae with four replications. Knowing that the efficiency of EPNss is directly related to the ability to search and penetrate the host, it was found that H. amazonensis GL is highly virulent to E. lignosellus, presenting an LC50 of 6.49 IJ cm-2 after 48 hours, 5.61 IJ cm-2 in 72 hours and LC90 of 39.70 IJ cm-2 in 48 and 27.73 IJ cm-2 in 72 hours under laboratory conditions. In the soil, pupal mortality was lower and a concentration of 25 IJ cm-2 was responsible for the death of 50% of the population, since environmental variability influences the dynamics of IJ infection and insect defense.

Potential of transgenic Bt-maize for management of Elasmopalpus lignosellus

The Lepidoptera insects are responsible for large losses in maize production in Brazil, and stand out those that attack seedlings, such as lesser cornstalk borer, Elasmopalpus lignosellus (Zeller). The objective of this work was to compare the performance of transgenic Bt maize in the control of the E. lignosellus caterpillar in the maize seedlings phase in two trials. In the first trial six treatments were tested: (1) Conventional Non-Bt maize; (2) Conventional Non-Bt maize with insecticide application; (3) transgenic maize expressing the Cry1Ab genes; (4) Cry1F; (5) Cry1A.105 + Cry2Ab2; (6) Cry1A.105 + Cry2Ab2 + Cry1F. The experimental design was randomized blocks, where each treatment was repeated 4 times in plots of 22.5 m2. Ten consecutive plants with third instar larvae of E. lignosellus in the seedling stage were artificially infested. Only the Non-Bt maize (Control) was affected by the E. lignosellus caterpillar, but all the treatments presented tillering, galleries and holes in the stem. In the second assay the genotypes used were seeded on 11/23/2012, and the damages of 3rd instar caterpillars of E. ligosellus (Zeller) were evaluated. The treatments were: (1) Conventional Non-Bt maize (Control); (2) transgenic maize expressing the Cry1F + Cry1A.105 + Cry2Ab2 genes; (3) Cry1A.105 + Cry2Ab2; (4) Vip3Aa20; (5) Vip3Aa20 + Cry1Ab; (6) Cry1F; (7) Cry1Ab + Cry1F. The plots were formed by a line spaced in 0.7 m of 2 m, with 10 plants, with barriers to prevent the exit of artificially infested insects. In the first and second assays, non-Bt maize with or without insecticide application were affected by E. lignosellus caterpillars. However, Bt transgenic maize was not harmed by E. lignosellus caterpillars, except the Vip3Aa20 treatment. Bt transgenic plants were poorly damaged by E. lignosellus in the seedling and leaf stage.