Interação entre inseticidas e umidade do solo no controle do pulgão e da mosca-branca em algodoeiro

Abstract

Resumo -O objetivo deste trabalho foi avaliar o controle exercido por tiametoxam e pimetrozine, em aplicação foliar ou ao solo, sobre Bemisia tabaci e Aphis gossypii, em algodoeiro, e determinar a interação entre formas de aplicação e a umidade do solo, em diferentes intervalos após a aplicação. Foram aplicados inseticidas via pulverização ou esguicho ao solo, em plantas de algodoeiro submetidas a três faixas de umidade do solo. Os inseticidas foram testados separadamente, em arranjos fatoriais, com formas de aplicação (tiametoxam), pragas (pimetrozine) e teores de umidade no solo como fatores de variação, com as avaliações repetidas no tempo. Foram realizadas avaliações após 3 horas e aos 3, 6, 12, 24 e 32 dias após a aplicação. Os inseticidas, em pulverização, apresentaram controle superior a 80%, até 6 dias depois da aplicação, para mosca-branca e pulgão. O uso de tiametoxam com esguicho, na menor faixa de umidade, propiciou controle inferior a 60%, no dia da aplicação, superior a 90%, aos 3 e 6 dias, e superior a 80%, aos 12 dias após aplicação. O grau de estresse hídrico em que se encontra a planta é importante para a escolha do inseticida e da modalidade de aplicação mais adequados ao controle das pragas avaliadas.Termos para indexação: Aphis gossypii, Bemisia tabaci, Gossypium hirsutum, método de aplicação, pimetrozine, tiametoxam. Interaction between insecticides and soil moisture in the control of whitefl y and aphid in cottonAbstract -The objective of this work was to evaluate the control, in cotton plants, of Bemisia tabaci and Aphis gossypii by thiamethoxam and pymetrozine, with foliar or soil drench applications, and to determine the interaction between application method and soil humidity, in different intervals after insecticide application. Insecticide application consisted of foliar spray and soil drench, using cotton plants submitted to three levels of soil moisture. The insecticides were tested separately, in factorial arrangements, with application methods (thiamethoxam), pest species (pymetrozine) and soil moisture levels, as treatments, with repeated measures on time. Evaluations were carried out after 3 hours, and at 3, 6, 12, 24, and 32 days after application. Foliar spray of both insecticides provided over 80% control, for both pests, up to 6 days after application. Thiamethoxam applied in soil exhibited control bellow 60%, at the day of application, over 90%, at 3 and 6 days, and over 80%, 12 days after application. Plant water stress levels are important to be considered in selection of most suited insecticides and application methods, for control of the evaluated pests.

Zoophytophagous pentatomids feeding on plants and implications for biological control

“…The predator-rearing method followed the description in Torres et al (2006a, b). Cotton plants used in the experiments were cultivated in pots containing soil and humus (2:1 ratio) and under greenhouse conditions following standard procedures as described in Torres and Silva-Torres (2008).…”

“…Neonicotinoids are versatile insecticides recommended as foliage spray, seed or soil treatment ). The mortality of aphids and whiteflies in cotton foliage treated with neonicotinoid application in soil with proper moisture and temperature can be achieved less than 16 or 24 h after application in potted cotton plants in the laboratory and greenhouse (Nauen et al 1998;Torres and Silva-Torres 2008).…”

Reducing boll weevil populations by clipping terminal buds and removing abscised fruiting bodies

“…Whereas squares used for boll weevil oviposition typically abscise in 5 days (Showler & Cantú, ), some squares and most abscised bolls fall to the ground because of physiological stress related to high temperature, nutrient (especially N) deficiency, and water deficit (Ritchie et al., ). Because rain is relatively scarce or irregular in our semiarid test area (only 403 mm from 1 May to 22 September in 2009), which is less than ideal (580–780 mm) for the growth of cotton (Pereira et al., ; Torres & Silva‐Torres, ). In 2011, 760 mm of rain occurred from 30 May to 30 July, but only 80 mm from August to October, the period of fruit set and boll development.…”

An Electrochemical Sensor Based on Electropolymerization of ß‐Cyclodextrin and Reduced Graphene Oxide on a Glassy Carbon Electrode for Determination of Neonicotinoids

“…During 2007, about 29 % of beekeepers in United State reported CCD in their colonies, with losses of up to 75 percent. Countries such as Japan, China and Brazil also reported problems with the disorder .…”