Efeitos da terra diatomácea sobre Diabrotica speciosa (Germar, 1824) (Coleoptera: Chrysomelidae) em batata inglesa

Abstract

RESUMOA espécie Diabrotica speciosa é um crisomelídeo responsável por causar danos consideráveis à batateira, o que torna indispensável seu controle com inseticidas para minimizar os prejuízos causados à cultura. Assim, objetivou-se, com este trabalho, avaliar os efeitos da terra diatomácea sobre o comportamento alimentar e a mortalidade de D. speciosa em batata inglesa em condições de laboratório. Adotou-se o DIC com três tratamentos e oito repetições, sendo: 1 -testemunha; 2 -TD polvilhada (0,5 g/vaso) e 3 -TD pulverizada a 1%. As batateiras, cv. Emeraude, foram polvilhadas ou pulverizadas com TD, 30 dias após o plantio e, 24 horas após a aplicação, as plantas foram fornecidas aos insetos, sem e com chance de escolha. Houve diferença significativa entre os tratamentos, sendo a menor porcentagem de folíolos com injúrias observada em plantas que receberam a aplicação de TD pulverizada (teste sem chance de escolha) e TD polvilhada ou pulverizada (teste com chance de escolha). Também houve redução do número de injúrias foliares às 24 e às 48 horas (TD polvilhada ou pulverizada) e, às 72 horas, a redução foi observada somente com a aplicação da TD polvilhada. Com relação à ação inseticida da TD, foi verificado seu efeito após 48 horas, tanto via polvilhamento, quanto via pulverização. Assim, a aplicação de TD pode auxiliar no manejo de D. speciosa, contribuindo para conferir proteção às plantas de batata inglesa e aumentar a mortalidade desse inseto-praga.Termos para indexação: Insecta, dióxido de sílica, MIP. ABSTRACTThe species D. speciosa is a chrysomelid responsible for causing considerable damage on potato plant, making its control with insecticides essential to minimize the damage caused to this culture. The objective of this study was to evaluate the effects of diatomaceous earth (DE) on feeding behavior and mortality of D. speciosa in potato under laboratory conditions. A completely randomized design was used with three treatments and eight replicates being: 1 -control; 2 -sprinkled DE (0.5 g/vase) and 3 -1% sprayed DE. The potato plants, cv. Emeraude, were sprinkled or sprayed with DE 30 days after the planting and 24 hours after the application, the plants were supplied to insects, with and without a chance of choice. There was significant difference among treatments with a lower leaflet with injury percentage observed in plants that received the application of powdered DE (tests without chance of choice) and sprinkled or powdered DE (tests without chance of choice). There was also reduction of the number of leaf injuries at 24 and 48 hours (sprinkled or powdered DE) and, at 72 hours, the reduction was only observed with the application of sprinkled DE. Regarding the insecticidal activity of TD, its effect was verified after 48 hours, through sprinkling or spraying. As a result, the application of DE may help in the management of D. speciosa, contributing to provide protection to potato plants and to increase the mortality of this insect pest.

Chemical Characterization and Application of the Essential Oils from Chenopodium ambrosioides and Philodendron bipinnatifidum in the Control of Diabrotica speciosa (Coleoptera: Chrysomelidae)

“…Bioassays with D. speciosa were conducted at the Laboratory of Plant Resistance to Insects, Department of Entomology, UFLA, according to the method described by Assis et al [19], with modifications. The bean plants were grown in pots with a capacity of 3 kg using the C Horizon soil (Latossolo Vermelho Escuro) fertilized with 3 g of NPK fertilizer (8-28-16) per pot, equivalent to 450 kg•ha -1 , as substrate.…”

“…The vessels were distributed randomly on benches inside the climate chamber (temperature equal to 30˚C during the day and 25˚C at night, relative humidity, 70% ± 10% and 12 h of light) and covered with organza fabric supported on two iron rods fixed to the substrate of the vessel, forming a cage of approximately 20 cm diameter and 60 cm high. Ten adults per cage were released after treatment [19]. Seven days after the application of the essential oils, the percentage of leaves with injury and the degree of defoliation were evaluated using the AM-300 portable meter (ADC BioScientific Ltd, England).…”