The Potential of Beauveria against Root Mealybugs Formiccoccus sp. (Homoptera: Pseudococidae) Black Pepper in Dak Lak Province of Vietnam

Abstract

Root mealybugs Formicoccus sp.(Hemiptera: Pseudococcidae) currently emerge as an economically important soil-borne insect pest in the production of black pepper (Piper nigrum L.) in Dak Lak province of Vietnam. Entomopathogenic fungi can be used in agricultural production as feasible safe biocontrol agents and plant growth promoters. This study aimed to isolate, select and identify the local Beauveria sp. strains from the black pepper fields, as well as evaluate the effects of the selected strains on the growth of black pepper. The results showed that the frequency of positive Beauveria sp. soil samples collected from organic black pepper fields was significantly higher than that from conventional black pepper fields. Twenty-one Beauveria sp. strains in black pepper organic fields and four Beauveria sp. strains in black pepper conventional fields were successfully isolated, among them, the Beauveria bassiana BB1 was examined and evaluated for its biocontrol potential against Formicoccus sp. and its ability to promote the growth of black pepper seedlings. In the laboratory experiments, the mortality of both adults and first instar nymph root mealybugs Formicoccus sp. caused by B. bassiana BB1 culminated 100% at 21 days after treatments. In the nethouse, at 6 months after treatment, the efficacy of B. bassiana BB1 against black pepper root mealybugs reached 99.18%. The levels of photosynthetic pigments in the leaves of the black pepper seedlings increased about 2 times compared to the control. Moreover, B. bassiana BB1 strain also remarkably promoted the growth of the black pepper seedlings under the nethouse conditions.