Repelência e deterrência alimentar de vaquinhas por óleos de nim e cinamomo aplicados em folhas de feijoeiro

This work aimed to evaluate the repellent and deterrent effect of the application of concentrations of neem and chinaberry oil on bean leaves on the leaf beetles Diabrotica speciosa (Germar) and Cerotoma arcuata (Olivier). The concentrations of neem oil tested were 0.625, 1.25, 2.50, 5.00, 10.00 and 20,00 mL, corresponding respectively to 1, 2, 4, 8, 17 and 33 ppm of azadirachtin A and the concentrations of chinaberry oil used were the same used to neem oil, corresponding, however, to 1.875, 3.75, 7.50, 15.00, 30.00 and 60.00 mg mL(-1) of chinaberry extract, respectively. For the free-choice tests, glass containers were used as arenas, whereas for the no-choice tests Petri dishes were used, where in both one insect per treatment was released in the center. Attractiveness was evaluated in predetermined time periods, in addition to the leaf consumption, at the end of the experiment. Neem oil is repellent to D. speciosa and C. arcuata, with more efficient results at the 5.00, 10.00 and 20.00 mL concentrations. All concentrations of neem oil reduce leaf consumption of both insects, except in the no-choice test with D. speciosa, in which only the 10.00 and 20.00 mL concentrations are deterrent. Chinaberry oil provides high repellent activity on both leaf beetle species, and the 10.00 and 20.00 mL concentrations stood out. The 10.00 and 20.00 mL concentrations of chinaberry oil are deterrent to D. speciosa and C. arcuata.

A comparative analysis reveals weak relationships between ecological factors and beta diversity of stream insect metacommunities at two spatial levels

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Subacute toxicity assessment of diflubenzuron, an insect growth regulator, in adult male rats

Difubenzuron (DFB), an insecticide and acaricide insect growth regulator, can be used in agriculture against insect predators and in public health programs, to control insects and vectors, mainly Aedes aegypti larvae. Due to the lack of toxicological assessments of this compound, the objective of the present study was to evaluate the toxicological effects of subacute exposure to the DFB insecticide in adult male rats. Adult male rats were exposed (gavage) to 0, 2, 4, or 8 mg/kg of DFB for 28 days. No clinical signs of toxicity were observed in the DFB-treated animals of the experimental groups. However, there was an increase in serum levels of alanine aminotransferase in the group that received 8 mg/Kg/DFB/day and urea at doses of 4 and 8 mg/Kg/DFB/day, without altering other biochemical or hematological parameters. The subacute exposure to the lowest dose of DFB caused significant decrease in testis weight, daily sperm production, and in number of sperm in the epididymis in relation to the control group. However, no alterations were observed in the sperm morphology, testicular, epididymis, liver and kindney histology, or testosterone levels. These findings unveiled the hazardous effects of DFB on male reproduction after the subacute exposure and special attention should be addressed to the effects of low doses of this pesticide.