Compatibilidade de Isaria javanica com diferentes inseticidas e sua influência no controle de Bemisia tabaci na cultura do algodão

Abstract

The combined use of chemical insecticides in association with microbiological agents of insect pest control can increase the efficiency of the control and enable the reduction of active ingredients applied in crops, minimizing risks of environmental contamination and acquiring pest resistance. Among the promising alternatives of microorganisms are entomopathogenic fungi, especially Isaria javanica , which has been showing high control rates of nymphs and whitefly adults (Bemisia tabaci). This study aimed to evaluate the in vitro compatibility of an isolate of I. javanica, identified based on morphology and molecular characterization, with insecticides based on Acetamiprido+Piriproxifen, Diadentiurom, Piriproxifen, Bifetrin+Carbosulfan, Bifetrin, Thiamethoxam+ Cialothrin and Acetamiprido+Bifentrin used to control Bemisia tabaci (whitefly) at the Três Lagoas Production Unit (SCHEFFER and CIA LTDA, Sapezal, MT). The compatibilities were evaluated using the commercial doses recommended by the manufacturers and volume of syrup according to the application flows of terrestrial spray already adopted in the production routine; (PV) 40 L.hec-1, low oily volume (BVO) 8 L.hec-1 and ultra-low flow (UBV) 3 L.hec-1. For this, mycelial growth, production, and germination of spores were evaluated. Insecticides were added when solidification of the culture medium. The isolate of the fungus I. javanica was inoculated and incubated for 7 days, in an air-conditioned chamber at 25±1 ºC, relative humidity 70±10% and photoperiod of 12 hours. For spore germination, the incubation period was 20 hours, under the same conditions mentioned above. The experimental design used was the entirely randomized composite of twelve chemical treatments and one control, with three replications. The biological index was used to establish the toxicological classification of the action of insecticides on the fungus. The results showed that the toxicity of The AI may vary with the application flow, thus Acetamipride+Bifentrin and Acetamiprido+Piriproxifen were classified as toxic for application in ultralow flow, moderately toxic by low oily volume and compatible for terrestrial spraying. On the other hand, the product based on Piriproxifen, Bifetrin and Bibifethra+Carbosulfan inhibited the development of the fungus regardless of the flow used, being classified as toxic, while the insecticides containing Diadentiurom and Thiamethoxan+Cialotrine showed no sign of toxicity, being therefore compatible. Insecticides classified as compatible can be safely used in the integrated management of agricultural pests in applications jointly with the biological agent Isaria javanica.