Toxicidade de formulações de nim (Azadirachta indica A. Juss.) ao ácaro-rajado e a Euseius alatus De Leon e Phytoseiulus macropilis (Banks) (Acari: Phytoseiidae)

Abstract

The toxicity of selected commercial formulations of neem on Tetranychus urticae Koch (Acari: Tetranychidae) and two predatory mites Euseius alatus De Leon and Phytoseiulus macropilis (Banks) was studied. Topical toxicity was tested with the commercial formulations (Natuneem, Neemseto and Callneem) and extract of neem's seeds at concentration 1%, compared to the standard acaricide abamectin at concentration of 0.3 ml/L and the control treatment (distilled water). Based on the best performance against T. urticae through topical contact, the formulation Neemseto was selected to be evaluated using different concentrations against eggs, and residual and repellent effects on adults of the mites. Egg treatment consisted of dipping eggs into Neemseto dilutions and control treatment for five seconds. In addition, residual and repellent effects of Neemseto for adult mites consisted of using leaf discs dipped into the dilutions for five seconds. The toxicity of Neemseto on eggs and adults was greater for T. urticae compared to the toxicity observed for the predatory mites. Neemseto was repellent for T. urticae and E. alatus when tested at the concentrations of 0.25, 0.50 and 1.0%, and did not affect P. macropilis. Neemseto using all concentrations, while for the predatory mites significant reduction of mite fecundity was only observed at the largest concentrations reduced the fecundity of T. urticae significantly. So Neemseto, among tested neem formulations, performed better against the twospotted spider mite and exhibited relatively low impact against the predatory mites studied.

Azadirachtin on Oligonychus yothersi in yerba mate Ilex paraguariensis

“…Furthermore, many mites were observed in the water surrounding the disk (Table 2). BRITO et al (2006) also observed the repellent effects of azadirachtin (Neemseto ® , 0.25, 0.5 and 1%) against T. urticae, with 96 to 98% repellency. However, these values were observed 3 days after mites were placed on the azadirachtintreated areas.…”

“…Azadirachtin can cause partial or complete egg sterility (SCHMUTTERER, 1990), and no hatching of T. urticae eggs treated with Neemseto ® has been observed, independently of the concentration tested (0.25, 0.5 and 1%) (BRITO et al, 2006). In addition, azadirachtin sprayed on T. urticae eggs decreased hatching by 50 to 70% (SCHLESENER et al, 2013).…”

“…In the present study; however, a higher mortality percentage was obtained using a commercial product in a concentration 75% lower. This can be attributed to the standardized formulation of the commercial product (BRITO et al, 2006;BERNARDI et al, 2012).…”

“…In addition, the use of azadirachtin has a reduced effect on predatory mites being an alternative for conservative biological control (BRITO et al, 2006;BERNARDI et al, 2012).…”

“…However, the composition of neem-based commercial products in Brazil varies according to the origin of plants used in the formulation. For this reason, a standardized product with a high degree of purity is desirable (BRITO et al, 2006;BERNARDI et al, 2013).…”