Inseticidas botânicos aplicados sobre Aphis gossypii e seu predador Cycloneda sanguinea em algodão-colorido

Abstract

Resumo -O objetivo deste trabalho foi avaliar os efeitos de inseticidas botânicos sobre Aphis gossypii e seu predador Cycloneda sanguinea, em algodão-colorido. Foram avaliados inseticidas botânicos à base de azadiractina, extrato aquoso de sementes de nim e óleo de mamona, nas concentrações de 0 a 2%, de 0 a 2,5% e de 0 a 3%, respectivamente. Os bioensaios, em delineamento inteiramente casualizado, foram realizados em laboratório. A mortalidade do pulgão variou de 64 a 100% para azadiractina; 12 a 92% para extrato aquoso de nim; e 8 a 68% para óleo de mamona. A taxa instantânea de crescimento mostrou-se negativa a partir da concentração 1,25% para azadiractina, 2,25% para extrato aquoso de nim, e 3,0% para óleo de mamona. Todos os inseticidas apresentaram toxicidade para larvas de 1 o instar do predador, com mortalidade de 96,7 a 100% para azadiractina e extrato aquoso de nim, e de 50 a 100% para óleo de mamona. Para o 4 o instar, a mortalidade variou de 87,5 a 100% para azadiractina, 73,3 a 100% para o extrato de nim, e 43,3 a 100% para o óleo de mamona. Os inseticidas testados são promissores para o manejo de A. gossypii, porém mostraram-se pouco seletivos a C. sanguinea.Termos para indexação: Azadirachta indica, azadiractina, crescimento populacional, extrato aquoso de nim, inseticidas naturais, óleo de mamona. Botanical insecticides applied on Aphis gossypii and its predator Cycloneda sanguinea on naturally colored cottonAbstract -The objective of this work was to evaluate the effects of botanical insecticides on Aphis gossypii and its predator Cycloneda sanguinea, in naturally colored cotton. The botanical insecticides based on azadirachtin, aqueous extract of nim seeds, and castor oil were tested at the concentrations from 0 to 2%, 0 to 2.5%, and 0 to 3%, respectively. The bioassays were performed in laboratory conditions, in a completely randomized design. Aphid mortality ranged from: 64 to 100% for azadirachtin; 12 to 92% for nim aqueous extract; and 8 to 68% for castor oil. The instantaneous rate of increase reached negative values starting from concentrations of: 1.25%, for azadirachtin; 2.25%, for nim aqueous extract; and 3.0%, for castor oil emulsion. All insecticides were toxic to the first instar larvae of the predator, with mortality values from 96.7 to 100%, for azadirachtin and nim aqueous extract, and from 50 to 100% for castor oil emulsion. For the 4 th instar larvae, mortalities ranged from 87.5 to 100% for azadirachtin; from 73.3 to 100% for nim aqueous extract; and from 43.3 to 100% for castor oil emulsion. The tested insecticides are promising for A. gossypii management, although they are not selective toward C. sanguinea.

The Sublethal Effects of Insecticides in Insects

“…Aphis gossypii Glover (Hemiptera: Aphididae) exposed to botanical insecticides based on azadirachtin, aqueous extract of neem seeds, and castor oil presented negatives values for the instantaneous rate of increase (r i ) [60]. Negatives r i for A. gossypii population were also observed with the use of the botanical insecticides Compostonat Negatives r i and a decline in the population of Myzus persicae (Sulzer) (Hemiptera: Aphididae) were reported when using the botanical insecticide based on neem oil, NeemAzal T/S ® [62].…”

“…The effect of the neem-based botanical insecticide Azamax ® , the aqueous extract of neem and the emulsifiable oil of Ricinus communis (Euphorbiaceae) demonstrated an adversely affect upon the development of first and fourth instars larvae of the predator Cycloneda sanguinea (Linnaeus, 1763) (Coleoptera: Chrysopidae) [60]. Lethal and sublethal effects on Eriopis connexa (Germar, 1824) (Coleoptera: Chrysopidae) were also observed in laboratory when using neem seeds extract [62].…”

Population growth and within-plant distribution of the striped mealybug Ferrisia virgata (Cockerell) (Hemiptera, Pseudococcidae) on cotton

“…Therefore, it is possible that F. virgata has mechanisms to tolerate or overcome defensive traits of various plants. Probably, the morphophysiological variations between cotton cultivars studied, such as the presence of leaf trichomes (Breda 2011), were not sufficient to cause changes in F. virgata development. Similar results were also found by Fernandes et al (2001) in their study on the population growth of the cotton aphid Aphis gossyppii Glover, 1877 (Hemiptera, Aphididae) in different cotton cultivars.…”

Produtos naturais no manejo agroecológico de pragas e seus inimigos naturais do algodoeiro consorciado com milho, feijão-caupi e gergelim

“…Os inseticidas vegetais podem causar efeitos variados sobre os insetos-praga e inimigos naturais, mas o fato de serem de origem botânica não significa de imediato serem mais seguro ou menos tóxicos (BREDA et al, 2011). São muitas as espécies de artrópodes predadores e parasitóides associados à cultura do algodão e a presença de inimigos naturais é muito importante para estabelecer um equilíbrio ecológico em sistemas agroecológicos e sua preservação e manutenção pode indicar a seletividade de inseticidas vegetais aplicados nas culturas (BARROS et al,2006;SUJII et al,2007;COSTA et al, 2010).…”