Preferência alimentar do bicudo-do-algodoeiro por frutos de diferentes cultivares e idades

Abstract

Resumo -O objetivo deste trabalho foi avaliar a preferência alimentar de adultos do bicudo-do-algodoeiro, Anthonomus grandis Boheman, 1843 (Coleoptera: Curculionidae), por duas cultivares de algodão (Gossypium hirsutum L.) com frutos de diferentes idades. Foram realizados quatro experimentos em laboratório, avaliando-se o número de orifícios de alimentação. Maçãs de 2, 8 e 12 dias de idade, das cultivares IAC-20 e Reba P288, foram oferecidas aos insetos, confinados em recipientes, com opção de escolha quanto à idade e cultivar (primeiro experimento), sem opção de escolha quanto à idade e cultivar (segundo experimento), sem opção de escolha quanto à cultivar e com opção quanto a idade (terceiro experimento) e sem opção quanto à idade e com opção de escolha quanto à cultivar (quarto experimento). Observou-se preferência por maçãs da cultivar IAC-20 com dois dias de idade, com uma redução de danos de 23,53% e 78,43%, respectivamente, aos oito e aos doze dias de idade.Termos para indexação: Anthonomus grandis, Gossypium hirsutum, pragas de plantas, dano, algodão. Boll weevil feeding preference for fruits of cotton cultivars at different agesAbstract -The objective of this work was to assess the boll weevil, Anthonomus grandis Boheman, 1843 (Coleoptera: Curculionidae) feeding preference for fruits of two cotton cultivars at different ages. The number of feeding holes was assessed in four laboratory experiments. Cotton bolls from cultivars IAC-20 and Reba P288, at the age of 2, 8 and 12 days were offered to the insects, confined in recipients, with (first experiment) and without (second experiment) possibilities of choice both age and cultivar; without possibilities of choice concerning cultivar and with possibilities of choice concerning age (third experiment); without possibility of choice concerning age and with possibility of choice concerning cultivar (fourth experiment). Boll weevil showed preference for the fruits of IAC-20 cultivar. Insect fed more frequently on fruits at the age of two days, with damage reduction of 23.53% and 78.43% on fruits at the age of 8 and 12 days, respectively.

Spatial distribution of adult Anthonomus grandis Boheman (Coleoptera: Curculionidae) and buds with feeding punctures on conventional and Bt cotton

“…The results of this study are similar to those reported by Busoli et al (2004), who observed that individuals of A. grandis prefer feeding on the flower buds located on the upper third of the plant.…”

“…The higher A. grandis population found on Bt crop maybe a result of the lack of inter-specific competition, which is more intense between populations ofarthropods breeding on conventional crops, such as those of the target lepidopteran Alabama argillacea (Hübner, 1818), Heliothis virescens (Fabricius, 1781) and Pectinophora gossypiella (Saunders, 1844) (CATTANEO et al, 2006;ROMEIS et al, 2006). However, this hypothesis needs to be tested more rigorously.…”

“…This weevil has a high reproductive rate and is a very destructive pest (FONSECA et al, 2011;CHOI et al, 2011). Adults of A. grandis use their mouthparts to pierce the flower buds of cotton Gossypium hirsutum (Linnaeus, 1753), making punctures where they feed and oviposit (BUSOLI et al, 2004;BEZERRA;SILVA, 2008); these punctures are here in called feeding punctures and oviposition punctures. Control of this pest is usually done with chemicals that are not always effective.…”

Within plant distribution of Anthonomus grandis (Coleoptera: Curculionidae) feeding and oviposition damages in cotton cultivars

“…cephalosporioides Costa). The growth regulator mepiquat chloride (Pix ® ) was applied 45 DAE as recommended for the crop (0.5 L ha -1 active ingredient), to achieve a plant height between 1.2 and 1.3 m, as recommended for mechanical harvesting (BUSOLI et al, 1994).…”

Characterization of Bacillus thuringiensis isolates toxic to cotton boll weevil (Anthonomus grandis)

“…Cotton boll weevil, Anthonomus grandis Boheman (Coleoptera: Curculionidae), is a signiWcant pest of cotton production in the Americas (Busoli et al, 1994;Gallo et al, 2002). In order to decrease damage and loss of production, this pest has been controlled primarily by the use of chemical agents.…”