The invasive ambrosia beetle, Xylosandrus germanus Blandford (Coleoptera: Curculionidae: Scolytinae), is one of the most significant pests in hazelnut orchards in Turkey. Chemical control of the beetle is very difficult, because it spends the majority of its life in the sapwood of host trees. In this study, entomopathogenic fungi (EPF), Metarhizium anisopliae (TR-106 isolate), and Beauveria bassiana (TR-217 isolate) were tested against the female adults of X. germanus under laboratory conditions by two different methods. In the first method, conidial concentrations (1 × 10 6 and 1 × 10 8 conidia ml −1 ) of the fungal isolates were directly applied to the beetles in Petri dishes (2 ml per dish), using a Potter spray tower. In the second method, the same conidial concentrations were applied on a sterile hazelnut branch placed in the Petri dishes, and then, beetles were released in dishes. The Petri dishes were incubated at 25 ± 1°C and 75 ± 5% RH, 16:8-h light:dark photoperiod. Lethal time values (LT 50 and LT 90 ) for the isolates were calculated, using Probit analysis. As a result, LT 50 and LT 90 values of M. anisopliae isolate at 1 × 10 8 conidia ml −1 were 4.43 and 6.01 days, respectively, at the beetle application method and 3.97 and 5.68 days, respectively, at the branch application method. LT 50 and LT 90 values were 6.03 and 10.80 days, respectively, at 1 × 10 8 conidia ml −1 , when B. bassiana was applied directly on the beetles and 5.96 and 11.79 days at the same concentration, when it was applied on the branch application method. M. anisopliae at 1 × 10 8 conidia ml −1 caused 100% mortality rate at the end of the 8th day in the two application methods. The mortality rates when applying 1 × 10 8 conidia ml −1 of B. bassiana recorded 64% and 80% by the end of the 8th day on branch and insect application methods, respectively. The efficiency of 1 × 10 6 conidia ml −1 of the isolates was lower than 1 × 10 8 conidia ml −1 against X. germanus in both application methods. This study showed that the isolates of TR-106 and TR-217 had a significant potential as biological control agents against X. germanus.
The efficacy of the native entomopathogenic fungus, Isaria fumosorosea TR-78-3, was evaluated against females of the bark and ambrosia beetles, Anisandrus dispar Fabricius and Xylosandrus germanus Blandford (Coleoptera: Curculionidae: Scolytinae), under laboratory conditions by two different methods as direct and indirect treatments. In the first method, conidial suspensions (1 × 10 6 and 1 × 10 8 conidia ml −1) of the fungus were directly applied to the beetles in Petri dishes (2 ml per dish), using a Potter spray tower. In the second method, the same conidial suspensions were applied on a sterile hazelnut branch placed in the Petri dishes. The LT 50 and LT 90 values of 1 × 10 8 conidia ml −1 were 4.78 and 5.94/days, for A. dispar in the direct application method, while they were 4.76 and 6.49/days in the branch application method. Similarly, LT 50 and LT 90 values of 1 × 10 8 conidia ml −1 for X. germanus were 4.18 and 5.62/days, and 5.11 and 7.89/days, for the direct and branch application methods, respectively. The efficiency of 1 × 10 6 conidia ml −1 was lower than that of 1 × 10 8 against the beetles in both application methods. This study indicates that I. fumosorosea TR-78-3 had a significant potential as a biological control agent against A. dispar and X. germanus. Further studies are necessary to evaluate the efficacy of the isolate on the pests under field conditions.
The efficacy of the two entomopathogenic fungi, Metarhizium anisopliae (TR 106) and Beauveria bassiana (TR 217), was tested against the adults of the cowpea weevil, Callosobruchus maculatus F. (Coleoptera: Chrysomelidae: Bruchinae) in laboratory. Two concentrations of conidial suspensions (1 × 10 6 and 1 × 10 8 conidia/ml) of M. anisopliae and B. bassiana isolates were directly applied on four pairs of adult beetles in Petri dishes (2 ml/dish) and then incubated at two different climatic regimes; 22±1°C and 26 ± 1°C with 70 ± 5% RH, 16:8 h light-to-dark. Lethal time values (LT 50 and LT 90 ) were calculated using probit analysis. As a result, the LT 50 and LT 90 values of M. anisopliae (1 × 10 8 conidia/ml) were 4.45 and 5.34 days at 26°C and 5.17 and 6.15 days at 22°C, respectively. LT 50 and LT 90 values of B. bassiana (1 × 10 8 conidia/ml) were 4.07 and 5.11 days at 26°C and 4.07 and 5.41 days at 22°C, respectively. LT 50 and LT 90 values of M. anisopliae (1 × 10 6 conidia/ml) were 5.42 and 6.43 days at 26°C and 6.08 and 7.54 days at 22°C, respectively. The LT 50 and LT 90 values of B. bassiana (1 × 10 6 conidia/ml) were 5.67 and 7.15 days at 26°C and 5.47 and 7.50 days at 22°C, respectively. Approximately 100% of mycoses were obtained in all treatments. In general, the effectiveness of these two entomopathogens increased by increasing suspension concentrations and temperature. These results suggest that the two isolates may be very successful in biological control of the C. maculatus and may be alternatives for chemical pest management.
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