Extracellular enzyme activity of entomopathogenic fungi, Beauveria bassiana and Metarhizium anisopliae and their pathogenicity potential as a bio-control agent against whitefly pests, Bemisia tabaci and Trialeurodes vaporariorum (Hemiptera: Aleyrodidae).

OBJECTIVE: This study was aimed to assess the enzymatic activity and pathogenicity potential of Beauveria bassiana and Metarhizium anisopliae against whiteflies in Ethiopia. RESULTS: The data showed that Beauveria bassiana AAUMB-29, AAUMFB-77, and AAUEB-59 generated the highest chitinase (EI = 3.41), lipase (EI = 4.45), and protease activities (EI = 5.44) respectively. The pathogenicity study of isolates on whitefly nymphs and adults indicated significant variation (P < 0.05) with mortality ranging from 71.67 to 98.33% and 60 to 100% against Bemisia tabaci and Trialeurodes vaporariorum nymphs respectively. The mortality of adults was between 58 and 94.27% against B. tabaci and 59.03 to 95.37% against T.vaporariorum. The result also showed that AAUMB-29, AAUMFB-77, and AAUDM-43 were the most virulent with LC50 values of 2.7 × 104, 5.3 × 104, and 5.4 × 104 conidia/ml against nymphs of B. tabaci, and with LC50 values 6.8 × 104, 8.2 × 104, and 7.2 × 104 conidia/ml against nymphs of T. vaporariorum, respectively. The B. bassiana AAUMB-29, B. bassiana AAUMFB-77, and M. anisopliae AAUDM-43 induced the highest whitefly mortality than other isolates. These isolates can be recommended for further tests under field conditions to fully realize their potential as effective biocontrol agents against whitefly pests in tomato.

Phenotypic, molecular, and virulence characterization of entomopathogenic fungi, Beauveria bassiana (Balsam) Vuillemin, and Metarhizium anisopliae (Metschn.) Sorokin from soil samples of Ethiopia for the development of mycoinsecticide.

Fungal entomopathogens are the most effective biocontrol agents against insect pests in the natural ecosystem. This study was conducted for phenotypic, molecular, and virulence characterization of locally isolated entomopathogenic fungi from soil samples of six localities in Ethiopia. Entomopathogenic fungi were isolated from 120 soil samples with the galleria baiting method. A total of 65 (54.2%) entomopathogenic fungal isolates belongs to Beauveria spp and Metarhizium spp were identified based on cultural and morphological features. All isolates were pre-screened based on germination, vegetative growth rate, and spore production as fungal in-vitro virulence determinates. Isolate AAUKB-11 displayed the peak germination of 99.67% and isolate AAUMFB-77 achieved the highest radial growth rate of 3.43 mm day-1 with the highest sporulation 4.60 × 108spores/ml. The phylogenetic analysis of ITS-rDNA confirmed that 7 isolates were identified as B. bassiana and 5 isolates were categorized into M. anisopliae. Selected B. bassiana and M. anisopliae strains were evaluated for their pathogenicity efficiency against G. mellonella larvae and caused 86.67%-100% mortality. The mortality rates of G. mellonella larvae peaked at 100% with 4(33.33%) isolates from B. bassiana and 2(16.67%) isolates from M. anisopliae after 10 days of treatments. The high virulent isolate, B. bassiana AAUMB-29 displayed the least LT50 value of 2.36 days followed by isolate B. bassiana AAUMFB-77 with LT50 of 2.53 days. Future studies should be needed to focus on the evaluation of high virulent isolates against other potential insect pests to assess their vigorous role as favorable biological control agents.