Fontes Alternativas De Pólen Utilizadas Pelo Bicudo-Do-Algodoeiro Em Duas Regiões Produtoras De Algodão Na Bahia

Abstract

RESUMO -O bicudo-do-algodoeiro (Anthonomus grandis Boheman) (Coleoptera: Curculionidae) é um dos principais fatores limitantes para a expansão da cultura do algodão. Ele apresenta diferentes aspectos biológicos e comportamentais que garantem seu sucesso na exploração do agroecossistema algodoeiro. O objetivo deste trabalho foi identificar os recursos alimentares utilizados pelo bicudo na safra e entressafra de cultivos de algodão localizados nos municípios de Iuiu e Correntina (BA) e em ambientes de Caatinga e Cerrado, contíguos aos algodoais, respectivamente. As coletas dos adultos foram realizadas no período de fevereiro a setembro/2013 por meio de armadilhas com feromônio. As amostras foram processadas para identificação dos tipos polínicos encontrados no aparelho digestivo dos insetos. Os resultados indicaram que a praga explora 22 famílias botâni-cas como fonte de alimento, das quais 16 na Caatinga e 5 no Cerrado. Nos bicudos coletados em algodão foram encontrados 8 gêneros botânicos em Iuiu e 10 em Correntina, sendo apenas três coincidentes aos dois cultivos (Angelonia, Mimosa e Myrcia sp.1). Grãos de Pólen de 26 gêneros de plantas foram identificados para Caatinga e 6 para o Cerrado, ocorrendo três gêneros comuns às duas áreas (Myrcia sp.2, Eucalyptus e Mimosa). O bicudo explora fontes alternativas de alimento nas principais regiões produtoras de algodão da Bahia, com destaque para a Caatinga, que apresenta maior quantidade de famílias e gêneros botânicos utilizados pela praga.Palavras chaves: Anthonomus grandis. Caatinga. Cerrado. Palinologia. Sobrevivência. ALTERNATIVE POLLEN SOURCES FOR BOLL WEEVIL IN TWO COTTON GROWING AREAS OF BAHIA STATEABSTRACT -Cotton boll weevil, Anthonomus grandis Boheman (Coleoptera: Curculionidae), is one of the most limiting factors for cotton crop expansion. It presents different biological and behavioral aspects that ensure its success on this agroecosystem. This research aimed to identify pollen sources used by this insect during harvest and intercrop periods of cotton cultivations in Iuiu and Correntina -BA, Brazil; moreover, evaluating Caatinga and Cerrado neighboring areas. Adult insect samplings were made from February to September of 2013, through pheromone traps. Samples were analyzed to identify the pollen types inside the digestive system of insects. The results indicated that the pest explores 22 botanical families as nourishment source, from which 16 in Caatinga and five in Cerrado. Regarding crop samples, eight genera were found in Iuiu and Correntina, being three found in both areas (Angelonia, Mimosa and Myrcia sp.1). Pollen from 26 genera were identified for Caatinga and six for Cerrado, with three genera in common for both (Myrcia sp.2, Eucalyptus, and Mimosa). The boll weevil uses alternative sources of food within the main cotton growing regions in Bahia State, highlighting the Caatinga with most of the botanical families and genera explored by the pest.

Survival pattern of the boll weevil during cotton fallow in Midwestern Brazil

“…At the end of the crop cycle, the adults search for alternative food sources and shelter in order to survive the fallow period. This mass egress, both during and after the harvesting procedures, has been reported in the state of São Paulo, in the Distrito Federal, and in the state of Bahia by Campanhola et al (1988), Ribeiro et al (2010), and Macêdo et al (2015), respectively, and has been confirmed in monitoring studies using traps baited with pheromone, carried out in cotton-producing areas in the state of Goiás (Lima Jr. et al, 2013).…”

“…However, the physiological reduction in reproduction does not keep boll weevils from moving and searching for food to survive until the cotton fields have been planted again and squares begin to form (Jones et al, 1992;Hardee et al, 1999;Showler & Abrigo, 2007;Ribeiro et al, 2010;Macêdo et al, 2015). In addition, these areas may possibly provide shelter for adult boll weevils to protect themselves against adverse conditions, such as low humidity and high temperatures, both typical of this region in the cotton fallow period.…”

“…A similar behavior has also been observed for boll weevils in the temperate and subtropical regions of North America (Showler, 2003(Showler, , 2006. In the tropics and subtropics, males and females go into reproductive dormancy (Spurgeon & Raulston, 2006;Paula et al, 2013), but remain active throughout the year (Guerra et al, 1982;Macêdo et al, 2015) due to alternative foods that can sustain them in the absence of cotton (Hardee et al, 1999;Ribeiro et al, 2010).…”

“…In the Cerrado and Caatinga biomes in Brazil, Ribeiro et al (2010) and Macêdo et al (2015) observed the movement of boll weevils in areas near cotton fields throughout the growing and fallow periods, even when squares and bolls were available. Ribeiro et al (2010) analyzed the digestive tract of adults captured in areas of uncleared vegetation around these fields and found pollen from more than 20 plant families and from Pteridophyta, as well as fungal spores and algal cysts.…”

“…Ribeiro et al (2010) analyzed the digestive tract of adults captured in areas of uncleared vegetation around these fields and found pollen from more than 20 plant families and from Pteridophyta, as well as fungal spores and algal cysts. In cotton fields, Ribeiro et al (2010) and Macêdo et al (2015) captured boll weevils at low densities even after the plants had been defoliated and harvested, and the crop residues destroyed and incorporated into the soil. Showler (2003) also captured a large number of boll weevils in these fields after the crop was harvested and the residues had been removed, which was attributed to cotton crop residues, including dry and damaged bolls, left on or in the soil.…”