Abundance and diversity of ground‐dwelling arthropods of pest management importance in commercial Bt and non‐Bt cotton fields

Abstract

The modified population dynamics of pests targeted by the Cry1Ac toxin in Bacillus thuringiensis (Bt) transgenic cotton (Bt cotton) and possible reduced insecticide use in these transgenic varieties may exert a variety of effects on ground-dwelling predator communities. A survey of ground-dwelling arthropods was carried out weekly each of 3 years (during the cropping season) in commercial Bt and non-Bt cotton fields. Sixty-five taxa of ground-dwelling arthropods (carabids, cicindelines, staphylinids, dermapterans, heteropterans and araneids) of importance for cotton pest management were recorded in the survey. Species abundance and dynamics across seasons were evaluated with univariate analysis of variance for higher taxa or multivariate principal response curve analysis for the whole community of 65 taxa. Diversity and richness indices and cumulative species curves also were calculated. The analyses demonstrated no differences in the ground-dwelling arthropod communities between cotton types. One araneid species, Pardosa pauxilla, comprised ;80% of all araneids, Labidura riparia comprised ;96% of all dermapterans, Megacephala carolina comprised ;97% of cicindelines and four carabid species (Selenophorus palliatus, Apristus latens, Harpalus gravis and Anisodactylus merula) comprised ;80% of carabid species. M. carolina outnumbered all other collected species in each of the 3 years. When only predatory carabid species were considered, A. merula, Calosoma sayi, Harpalus pennsylvanicus and Stenolophus ochropezus were predominant and numbers trapped were similar between cotton types. The abundance of dermapterans, staphylinids, araneids and heteropterans varied among sample dates and across seasons but did not differ between cotton types. The frequent capture of M. carolina, S. palliatus and P. pauxilla in all fields and seasons in both cottons suggests that these species may be important for monitoring further changes in local communities as result of agricultural practices.

Parasitoides do bicudo Anthonomus grandis e predadores residentes em algodoeiro pulverizado com caulim

“…TORRES, 2006). A abundância média de larvas de Coccinellidae foi similar entre os tratamentos com e sem caulim (Figura 2).…”

Diversity of carabid beetles (Coleoptera: Carabidae) under three different control strategies against European corn borer in maize

“…In most cases, assemblages of epigeal arthropods seemed not to be affected by presence of transgenic Bt maize (Volkmar & Freier 2003;Candolfi et al 2004;Sehnal et al 2004;Habuštová et al 2005Habuštová et al , 2006Pons et al 2005;Eizaguirre et al 2006;Farinos et al 2008;Balog et al 2011; but see Wold et al 2001), and these results were repeated also for Bt cotton and vegetables (Leslie et al 2007;Torres & Ruberson 2007). Indeed, some authors conclude that compared to conventional farming, the use of transgenic plants enhances arthropod biodiversity in crop fields via reduced input of insecticides to the system (Ferry et al 2006;Leslie et al 2007).…”

Parasitoides do bicudo Anthonomus grandis e predadores residentes em algodoeiro pulverizado com caulim

“…Estes grupos de inimigos naturais foram relativamente comuns em ambos os tratamentos em 2011, e menos abundantes em 2010 (Figura 2). Entre as formigas, podemos destacar Solenopsis invicta Buren (Hymenoptera: Formicidae), que é uma espécie frequentemente encontrada associada às colônias de pulgões em algodoeiro (TORRES; RUBERSON, 2006). Esta é citada como predadora de insetos desfolhadores do algodoeiro e do bicudo, mas também sendo uma espécie que interfere com a abundância de outros inimigos naturais, importantes no manejo de pragas do algodoeiro (KAPLAN; EUBANKS, 2002).…”

“…Os principais parasitoides do bicudo são Bracon vulgaris Ashmead (Hymenoptera: Braconidae) e Catolaccus grandis Burks (Hymenoptera: Pteromalidae) (MORALES-RAMOS et al, 1998;RAMALHO et al, 2000), sendo que o primeiro também parasita e se desenvolve em larvas da lagarta rosada. Se comparado às demais pragas da cultura, constata-se que existem poucos inimigos naturais associados ao bicudo (WHITCOMB; BELL, 1964;TORRES, 2006). No entanto, para qualquer método de controle compondo o manejo integrado de pragas preconiza-se que esse seja compatível com os agentes de controle biológico.…”