Efficacies of some isolates of Lecanicillium lecanii to control Tribolium castaneum (Col., Tenebrionidae)

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ORIGINAL ARTICLE

Efficacies of some isolates of Lecanicillium lecanii to control Tribolium castaneum (Col., Tenebrionidae) Freshteh Broumandnia1 · Ali Rajabpour1 Received: 10 January 2020 / Accepted: 13 April 2020 © Deutsche Phytomedizinische Gesellschaft 2020

Abstract The entomopathogenic fungi are safe and ecofriendly biocontrol agents which can be applied against stored product pests. In this study, potentials of some Iranian isolates of Lecanicillium lecanii (PAL6, PAL7 and PAL8) and Lecanicillium muscarium to control Tribolium castaneum (AGM5) were investigated under laboratory conditions. For this purpose, the ­LC50 and ­LT50 values of each isolates to adults of the beetle were estimated. Results showed that all of the isolates were virulent to the pest. The estimated L ­ C50 values were ranged from 2.8 × 106 to 6.13 × 1022 (conidia/mL). The lowest and the highest ­LC50 values were estimated for L. lecanii (PAL7) and L. mucarium (isolate AGM5), respectively. The L ­ T50 values varied from 4.99 to 13.65 days. The L ­ T50 values were decreased by increasing conidial concentrations of each isolate. Moreover, at each conidial concentration, the ­LT50 values for L. lecanii isolate PAL8 were significantly lower than other isolates. Totally, among the isolates, L. lecanii isolate PAL7 (at concentration 1­ 07 conidia/mL) is the most promising isolate. The laboratory study is preliminary, and further experiments under field condition are required before any recommendations. Keywords  Enthomopathogen · Stored product pest · Pathogenicity · IPM

Introduction Stored insect pests cause severe quantitative and qualitative damages to various stored products every year. The damage is 5–40% in countries where efficient control strategies have not been done (Hagstrum 2016). Red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), is an important pest of many stored products. The larvae and adults cause quantitative (grain weight loss) and qualitative damages (loss of nutritional, industrial and marketing properties) (Padin et al. 2002). The life cycle of the pest is completed during 20 days, and each female can optimally lay 300–400 eggs (Abdullahi et al. 2019). Fumigations with biocides including phosphine and methyl bromide have been widely used to control the pests in silo and other similar environments (Zettler and Arthur 2000; Salehi et al. 2016). However, fumigant applications have been restricted in many regions of the world due to * Ali Rajabpour [email protected]; [email protected] 1



Department of Plant Protection, Faculty of Agriculture, Agricultural Sciences and Natural Resources University of Khuzestan, Mollasani, Ahvaz, Iran

their side effects on nontarget organisms and pest resistance (Rajabpour et al. 2019). Microbial control can be used as an ecofriendly alternative to the chemicals. Entomopathogenic fungi (EPF) are the most abundant type of the microbial agents (Liu et al. 2009) which can directly penetrate in insect integument, unlike bacteria and viruses which they sho