The Effect of the Iranian Strain of Metarhizium anisopliae Applied Alone and in Combination with Diatomaceous Earth and Kaolin against Plodia interpunctella

The Indian meal moth, Plodia interpunctella Hubner, is an important pest in pistachio stores which causes great damage to this product. Considering the importance of human health and protecting the environment, it is important to reduce the use of pesticides in pest control. One of the non-chemical methods to control this pest is the use of biological control agents such as entomopathogenic fungi combined with mineral and natural materials such as diatomaceous earth and kaolin.

The current study investigated the lethal effect of Metarhizium anisopliae alone and in combination with diatomaceous earth and kaolin at controlled conditions (25±1oC, RH 85±5%, and a photoperiod of 16: 8 h L: D). The dipping test was conducted on the first instar larvae of Plodia interpunctella grown on pistachios of the round variety.

The results showed that the lethal concentration of M. anisopliae (0.5×106 conidia ml-1 ) caused 15, 27, 42, 50, and 55% mortality in the pest population after 24, 48, 72, 96, and 120 hours, respectively. Also, 20, 30, 40, 52, and 60% mortality were observed at LC50= 486.5 mg/kg of diatomaceous earth, respectively. Moreover, kaolin powder at LC50= 900 mg/kg caused 22.5, 32.5, 40, 50 and 60% mortality, respectively. However, the mortality in M. anisopliae treatment in combination with diatomaceous earth and kaolin powder in lethal concentration indicated the additive effect of M. anisopliae.

The results suggested that M. anisopliae, diatomaceous earth, and kaolin powder can be used as alternatives to chemical pesticides in the integrated management of this stored pest.