Atividade de um produto à base de azadiractina e de isolados de Beauveria bassiana visando ao controle do ácaro-vermelho, Oligonychus yothersi

Abstract

Yerba mate (Ilex paraguariensis A. St. -Hil.) is a culture of great economic importance in Southern Brasil and suffers attacks by phytophagous mite Oligonychus yothersi (McGregor, 1914), causing economic damages. The mite attacks the adaxial surface of yerba mate leaves and causes browning and falling of the leaves. The aim of this work was to select the isolates of Beauveria spp. to control O. yothersi in yerba mate leaves and evaluate the Azamax® activity on O. yothersi by systemic irrigation of yerba mate plants. Total mortality of O. yothersi varied between 15 and 92% among the evaluated isolates and confirmed mortality varied between 1 to 80%. The isolates that stood out in total mortality were UNIOESTE 53, 87 and 97, with total mortality above 70%. In biological parameters evaluation, the isolates UNIOESTE 87 and 97 showed higher results than UNIOESTE 53. Related to evaluations of Azamax® , it affected the viability of egg-adult of O. yothersi in 50% in treated group and 63.3% in control group. The average fecundity was significant difference, obtaining the larger values in control group (34.0 days) and the smaller values in treatment group (19.4 days). The highest mortality occurred in the third week of application of the lowest doses, with 62.7% of mortality. There was no significant difference between the tested dosages and the amount of irrigation performed. However, different Azamax® concentrations showed acaricidal action on O. yothersi populations, affecting survival and fecundity. These results indicate that Azamax® has acaricidal activity and potential as an alternative to control of O. yothersi populations when used with systemic irrigation of yerba mate plants, and the fungal isolates UNIOESTE 87 and UNIOESTE 97 are the most indicated for further studies aiming the control of yerba mate red mite.