Mechanical damage in cotton buds caused by the boll weevil

Abstract

-The boll weevil (Anthonomus grandis Boheman) causes high levels of bud abscission in cotton plants due to feeding or oviposition punctures. It has been reported that abscission is mainly due to enzymes present in the insect's saliva, but mechanical damage could also contribute to square abscission. The objective of this paper was to undertake an analysis of the morphological damages caused by the insect in cotton squares using microscopy. Anthers and ovules are the main target of boll weevil feeding. The process initiates by perforation of young sepal and petal tissues and proceeds with subsequent alimentation on stamen and ovary leading to abscission of floral structures.Index terms: Gossypium hirsutum, Anthonomus grandis, abscission, animal feeding. Danos mecânicos em botões florais de algodão causados pelo bicudo-do-algodoeiroResumo -O bicudo (Anthonomus grandis Boheman) provoca alto porcentual de abscisão de botões florais no algodoeiro causada pelos orifícios de alimentação e oviposição. Embora a abscisão ocorra em virtude principalmente da ação de enzimas presentes na saliva do inseto, o dano mecânico também poderia contribuir para a queda dos frutos. O objetivo desse trabalho foi avaliar danos morfológicos causados pelo inseto nos botões florais com auxílio da microscopia. O principal alvo de alimentação do bicudo são as anteras e os óvulos. Esse processo, preferencialmente iniciado nas sépalas e pétalas mais novas, inclui a perfuração dos tecidos e posterior mastigação dos estames e ovário levando a abscisão da estrutura floral.Termos para indexação: Gossypium hirsutum, Anthonomus grandis, abscisão, alimentação animal.

Stable integration and expression of a cry1Ia gene conferring resistance to fall armyworm and boll weevil in cotton plants

“…The abscission is mainly due to enzymes present in the insect's saliva, but mechanical damage could also contribute to square abscission. 16,35 In Brazil, since the introduction of the boll weevil in 1983, several cotton fields have been destroyed, resulting in serious damage to farmers, especially to those located in the semi-arid north-east region. Adopting a proactive approach, Embrapa Cotton (Embrapa Algodão) has developed several technologies to minimise production losses, including those of early cultivars with a concentrated fruit set and short cycle.…”

Formação de carimãs e sobrevivência do bicudo do algodoeiro em cultivares de algodão

“…Os carimãs podem ser formados pelos danos causados pela alimentação das larvas e adultos do bicudo e oviposição de suas fêmeas nessas estruturas [11], além da alimentação de outros insetos, como o tripes que pode inocular microrganismos causadores de doenças e, por consequência de carimãs [12,13,14]. Dessa forma, reduzir a formação de carimãs em lavouras de algodão pode ser de fundamental importância para minimizar a infestação de bicudos na próxima safra [6,8].…”

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

“…The extensive plantation of monocultures like soy, corn, cotton, canola and other plants, requires a high investment in insecticides owing to their resident pests, especially from the lepidopteran and coleopteran orders. According to Santos et al (2003), about US$ 3-5 billion are spent on pesticides per year, and of that US$ 645 million are spent in cotton plantations.…”

“…Transgenic cotton plants encoding a Bacillus thuringiensis Berliner protein (Bt cotton) have been adopted by farmers in Mexico and the USA to control caterpillar infestations, and this approach has contributed to a decrease in insecticide applications by 50%. In Argentina, this reduction in insecticide use has reached 65% (Santos et al, 2003).…”