ABSTRACT

The brown stink bug, Euschistus heros (F.) is one of the most important pests in soybean culture. However, its control has become difficult, due to the ineffectiveness and side effects of commonly used chemical insecticides. Entomopathogenic fungi has potential to be used to control brown stink bugs, with products already registered and marketed in Brazil. However, the natural low susceptibility of the brown stink bug to known isolates has led to the search for new isolates, under laboratory conditions. Thus, the objective of the present study is to select Beauveria bassiana isolates with high virulence against the brown stink bug and characterise their productivity in culture medium. The effect of some fungicides used in soybean crops on some fungi parameters was also evaluated. In addition, the efficiency of the fungi to control stink bugs was evaluated in a greenhouse. Among 24 isolates, Unioeste 76 isolate (B. bassiana lato sensu) was selected due to its higher insecticidal activity (96% insect mortality; 1 × 10⁸ conidia/mL) and productivity in culture medium (5.2 × 10⁹ conidia/g of rice). All fungicides affected the fungal parameters. In the greenhouse, soybean plants were sprayed with fungal suspension (1 × 10⁸ and 1 × 10⁹ conidia/mL) before and after infestation with adult stink bugs. After 14 days, mortality varied from 80 to 90%, respectively for treatment before and after infestation, proving the potential of the fungus. Therefore, field tests should be conducted with the formulated fungus.

摘要

褐色臭虫Euschistus heros (F.) 是大豆养殖中最重要的害虫之一。然而，由于常用化学杀虫剂的无效和副作用，其控制变得困难。昆虫病原真菌具有用于控制褐臭虫的潜力，其产品已在巴西注册和销售。然而，棕色臭虫对已知分离株的天然低敏感性导致在实验室条件下寻找新的分离株。因此，本研究的目的是选择白僵菌分离物对棕色臭虫具有高毒力，并表征了它们在培养基中的生产力。还评估了大豆作物中使用的某些杀菌剂对某些真菌参数的影响。此外，在温室中评估了真菌控制臭虫的效率。在 24 个分离株中，选择 Unioeste 76 分离株 ( B. bassiana lato sensu) 是因为它具有较高的杀虫活性（昆虫死亡率为 96%；1 × 10 ⁸分生孢子/mL）和在培养基中的生产力（5.2 × 10 ⁹分生孢子/g白饭）。所有杀菌剂都会影响真菌参数。在温室中，大豆植株喷洒真菌悬浮液（1 × 10 ⁸和 1 × 10 ⁹分生孢子/毫升）在成年臭虫侵染之前和之后。14 天后，感染前后的死亡率分别为 80% 至 90%，证明了真菌的潜力。因此，应使用配制的真菌进行现场试验。