Effect of diameter of the cotton squares in the development of boll weevil

Abstract

The objective of this work was to study the effect of diameter of the cotton squares in the corporal mass of adults of boll weevil, Anthonomus grandis Boheman (Coleoptera: Curculionidae). The assay was carried out under field and laboratory conditions, in Jaboticabal, São Paulo State, Brazil. Six samplings obtained from a random harvesting of ten plants of each cultivar (Coodetec 405 and Fibermax 986). The number and diameter of squares were recorded for each plant. Squares with oviposition orifices were kept individually in a recipient and observed daily until adult emergence. The larger the diameter of the squares, the more corporal mass of boll weevil newly emerged adults in both cultivars.Key words: Insecta, Curculionidae, Anthonomus grandis, Gossypium hirsutum. RESUMO EFEITO DO DIÂMETRO DO BOTÃO FLORAL NO DESENVOLVIMENTO DO BICUDO-DO-ALGODOEIROO objetivo deste trabalho foi estudar o efeito do diâmetro dos botões florais de algodoeiro na massa corporal de adultos do bicudo-do-algodoeiro, Anthonomus grandis Boheman (Coleoptera: Curculionidae). O experimento foi realizado em condições de campo e laboratório, em Jaboticabal (SP), Brasil. Foram realizadas seis amostragens, coletando-se ao acaso dez plantas nas cultivares Coodetec 405 e Fibermax 986, avaliando-se o número e o diâmetro de botões florais. Os botões florais com orifícios de oviposição foram individualizados em frascos e observados diariamente para a visualização da emergência dos adultos. Botões florais com maiores diâmetros proporcionam maior massa corporal de adultos de A. grandis recém-emergidos nas duas cultivares.Palavras-chave: Insecta, Curculionidae, Anthonomus grandis, Gossypium hirsutum. laboratory, the number of cotton squares and bolls was counted and their diameters were measured. The squares were carefully examined for A. grandis oviposition orifices.Cotton squares with oviposition orifices were kept individually in photographic film containers (3 cm in diameter, 5 cm high), with a hole in the lid (2 cm in diameter) covered by a quadrangular piece of "voiale". These containers were observed daily, and the newly emerged adults (up to 24 hours) were individually weighed in an electronic precision scale.The numbers of squares and their respective diameters in two cotton cultivars were examined with analyses of variance (ANOVA) using Stat program. The numbers of squares were (x + 0.5) 1/2 transformed before statistical analysis, but results are presented as non transformed means. Where significant F values were obtained, means were separated using Tukey test (á = 0.05).For characterization of the relation between the corporal mass of the adults of boll weevil and the respective diameters of cotton squares in the two cultivars, were carried through an analysis of polynomial regression, determining the curves more adjusted and the respective coefficients of determination (R 2 ). The corporal mass of 39 and 37 adults and the respective diameters of the squares in the Coodetec 405 and Fibermax 986, respectively, were measured. The diam...

Interaction of Anthonomus grandis and cotton genotypes: biological and behavioral responses

“…Similarly, Michelotto et al. () found that cotton squares with larger diameters produced larger boll weevils. Curiously, weevil development time and weight of cotton squares were not correlated in our study.…”

“…This result is consistent with the fact that the boll weevil prefers to lay eggs on squares larger than 6 mm in diameter (Showler, 2005), which contain more nutrients for the developing larvae. Similarly, Michelotto et al (2007) found that cotton squares with larger diameters produced larger boll weevils. Curiously, weevil development time and weight of cotton squares were not correlated in our study.…”

Infestation of Anthonomus grandis grandis (Coleoptera: Curculionidae) contributes to forming shelter structures in cotton plants

“…The accumulation of reserve tissue in weevils is one of these strategies (Brazzel & Newsom, 1959; Paula et al., 2013; Spurgeon et al., 2003). Larger diameter cotton reproductive structures produce heavier and longer lived boll weevils (Greenberg, Sappington, et al., 2004; Michelotto et al., 2007; Paula et al., 2013) due to the greater quantity of resources available for the initial development of this insect. Thus, the longevity and survival of boll weevils may increase when developing inside larger green bolls (future dry bolls) compared to smaller bolls.…”

Trinta anos do bicudo-do-algodoeiro no Brasil

“…O peso médio dos adultos de A. grandis foi 0,01 g e o comprimento de 7,6 mm . Com relação ao peso dos adultos, segundo Michelotto (2005) e Michelotto et al (2007), observou-se uma correlação positiva entre o diâmetro dos botões florais que são ovipositados pelas fêmeas do bicudo e a massa corporal dos adultos emergidos desses botões, ou seja, um maior diâmetro de botão implica num adulto de maior massa corporal. Por isso, a escolha da variedade implica no controle desses insetos, uma vez que as fêmeas procuram os botões maiores para realizar a oviposição, pois esses oferecem alimento suficiente para o desenvolvimento das larvas Michelotto, 2005).…”