Compatibility of some botanicals and the entomopathogenic fungus, Beauveria bassiana (Bals.), against the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae)

Abstract

Background: The red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), is a serious pest of stored grain commodities worldwide which results in considerable losses to stored wheat, Triticum aestivum (Linn.). Main body: The present laboratory bioassay was carried out to examine the efficiency of the fungus, Beauveria bassiana (Bals.) formulation (Racer TM), and Neem extract (NE), Eucalyptus extract (EE), and Tobacco extract (TE) against 3rd instar larvae of T. castaneum. The fungal formulation was applied at 0.3 × 108, 0.6 × 108, and 0.9 × 108 conidia kg−1 of the crushed wheat grains; as well, it was mixed separately with 5% concentrations of each plant extract under the laboratory conditions of 30 ± 2 °C and 65 ± 5% RH. Mortality rate of the tested larvae was enumerated after regular intervals of times. Mortality of the larvae increased at the highest combined concentrations of the fungal conidial formulation and the plant extracts rather than their single treatments. The highest mortality rate of the larvae (71.32%) was recorded at the highest concentration binary mixture of (Racer TM +NE), whereas relatively the lowest mortality rate (15.54%) was enumerated in the combined treatments of (Racer TM +NE). Furthermore, the highest separate concentration of B. bassiana (0.9 × 108 conidia/ml) persistently resulted in more larval mortality (32.68%) of 3rd instar larvae of T. castaneum than the plant extracts (7.52, 9.89, and 14.61%), respectively. A noticeably greater rate of mycosis and sporulation was counted in the larvae of the insect in separate treatments of B. bassiana than in its combined applications with the plant extracts. The highest mycosis (85.13%) and sporulation (160.12 conidia/ml) was detected in the treatment, where the lowest concentration of B. bassiana (0.3 × 108 conidia/ml) was used, alone. Conclusion: Hence, it was concluded that integrated use of these two bio-pesticides plus the fungus can be helpful in the integrated pest management program of T. castaneum.