Journal Of Agricultural Science And Technology, cilt.24, sa.2, ss.393-405, 2022 (SCI-Expanded)
Colorado potato beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae)
damages potato, tomato, and eggplant, and is one of the most serious agricultural pests all
over the world. Due to its resistance against chemical insecticides and some biopesticides,
new biocontrol agents compatible with different ecological conditions are needed urgently
for the integrated pest management programs of this pest. For this purpose, we studied
the insecticidal effects of thirteen indigenous microbial isolates including
entomopathogenic bacteria, fungi, and nematodes from our culture collection against L.
decemlineata with screening and dose-response tests under laboratory conditions. Bacillus
thuringiensis strain Xd3 caused 83% and 73% mortality against larvae and adults of the
pest at 109 CFU mL-1 concentration within 10 days, respectively. While fungal isolate
Metarhizium anisopliae Gg-12 yielded 98% mortality with 107 conidia mL-1 concentration
on larvae at 15 days, mortality provided by Gg-12 on adults reached 100% at the same
concentration and period. Steinernema websteri AS1 was determined as the most effective
entomopathogenic nematode with 92% mortality within seven days on larvae. Based on
probit analysis, the LC50 values of B. thuringiensis Xd3 against larvae and adults were
calculated as, respectively, 1.73×106 and 1.69×107 CFU mL-1, and that of M. anisopliae
Gg12 were 1.18×104 and 6.2×103 conidia mL-1, and that of S. websteri AS1 was 117 IJs mL-
1. Considering these results, the biopesticides developed from these isolates can be used
safely and successfully in the pest management control programs of Colorado potato
beetle.