Assessment of the potential pathogenicity of Penicillium mallochii conidial suspensions and ethanol extract against almond moth Cadra cautella (Walker) (Lepidoptera: Pyralidae)

Recently, confirmed data on the identification of entomopathogenic fungi belonging to the genera Penicillium, Aspergillus, Fusarium, Beauveria, Cordyceps, Fusarium, Metarhizium, Purpureocillium and Beauveria have been gradually increasing. This study was conducted to evaluate the effect of Penicillium mallochii conidia and ethanol extract to control Cadra cautella. The study was carried out in Turkey, at Balıkesir University (BAUN), Faculty of Science and Literature, Department of Biology, under controlled laboratory conditions of 25 ± 1 °C temperature, 65 ± 5% relative humidity and a photoperiod of 12:12 h L/D. Topical application assays of ethanol extract gave an LD₅₀ of 3.107 mg/mL (95% confidence limits, 1.339–15.421 mg/mL), and conidial suspensions gave an LD₅₀ of 10^8.448 conidia/mL (95% confidence limits, (10^7.638− 10^10.358 conidia/mL). The collected data in the current study compared to the control and a drastic reduction in the total number of eggs were observed more than 70% in all doses by P. mallochii conidial suspensions and over 80% in all doses by ethanol extract. As a result of our study, we found that the strong mortality rates of C. cautella larvae and significant reductions in the number of eggs depended on both the concentration of conidial suspensions and the concentration of the ethanol extract. Also, the cytotoxic effect of crude extracts was also tested on mouse cell lines found to be cytotoxic at higher concentrations than 0.708 mg/mL. Two important findings of the study are presented here for the first time; one of them is that P. mallochii is an entomopathogenic species that does not produce significant mycotoxins such as Aflatoxin B1, B2, G1 and G2, or Ochratoxin A. The second is that P. mallochii is effective on C. cautella larvae. Considering our findings P. mallochii can be recommended as a promising candidate entomopathogen for inclusion in pest control and use of ethanol extracts and conidial suspensions would demonstrate notable level of efficacy in biological control programs. Future research should explore the impacts of P. mallochii on other pest insects and focus on field trials in diverse environments to validate these laboratory findings.