Efficacy of native isolates of Metarhizium anisopliae and Beauveria bassiana against the invasive ambrosia beetle, Xylosandrus germanus Blandford (Coleoptera: Curculionidae: Scolytinae)

Abstract

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.

Pathogenicity of some entomopathogenic fungal strains to green peach aphid, Myzus persicae Sulzer (Homoptera: Aphididae)

“…Aphids have developed resistance against commonly used pesticides (Rousselin et al 2017). There are more than 700 fungus and nematode species which attack insect pests (Ak 2019;El Husseini 2019a;Javed et al 2019;Tuncer et al 2019). The commonly used strains having potential for pest management have been categorized into two groups.…”

Recent advances toward the sustainable management of invasive Xylosandrus ambrosia beetles

“…Isolates of B. bassiana (TR-217) and M. anisopliae (TR-106) were sampled from X. germanus cadavers and tested against the pest in the laboratory. Eighty and 100% mortality was obtained following B. bassiana and M. anisopliae topical applications, respectively, both at 1 × 10 8 conidia ml −1 dosages (Tuncer et al 2019). Moreover, another entomopathogenic fungus, Isaria fumosorosea Wize (strain TR-78-3) (Ascomycota: Hypocreales), significantly reduced survival of X. compactus in laboratory trials both after direct application to the beetles and indirect treatment of hazelnut branches (Kushiyev et al 2018).…”

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Selection ofBeauveria bassiana(Hypocreales: Cordycipitaceae) strains to controlXyleborus affinis(Curculionidae: Scolytinae) females

“…Studies have shown that EPF were infective to ambrosia beetles, including Xyleborus volvulus Fabricius (Coleoptera: Curculionidae), X. bispinatus Eichhoff (Coleoptera: Curculionidae), Xylosandrus germanus Brandford (Coleoptera: Curculionidae), Xy. crassiusculus Motschulsky (Coleoptera: Curculionidae) (Castrillo, Griggs & Vandenberg, 2013;Avery et al, 2018;Tuncer et al, 2019).…”