Pathogenic effects of Beauveria bassiana and Bacillus thuringiensis on the population dynamics of Ephestia Kuehniella

[摘要] The most dominant pest of date stored in Khuzestan Province is Ephestia kuehniella Zeller (Lepidoptera: Pyralidae). In this study, the effects of Bacillus thuringiensis Kurstaki bacteria and Beauveria bassiana pathogenic fungi on the population dynamics of E. kuehniella date stock pest were investigated. To fulfill this, insectariums were kept in vitro at an average temperature of 27 ± 5 °C and a RH of 40 ± 5% for a duration of 6 months, equivalent to the maximum permitted shelf life of date. For sampling from 3 heights in 3 rows, one hole was randomly selected and a sample equal to 20 g of date was taken. Three samples were taken from each insectarium. During 25-week storage period of date treated with B. bassiana and Btk, 6 outbreaks occurred in the population of E. kuehniella. The mechanism of the epidemic is in the way that, once the population has increased to a certain threshold, the incidence of the pathogenic epidemic will be mass-dependent, leading to a decreasing trend in the pest population. Therefore, population reduction was estimated to be at 6 to 32 times that of the control. The highest disease mortality rate occurred at the egg and larval developmental stages, so the pathogens caused the highest mortality before the population entered the reproductive stage. Gradually, from the egg growth stage to the complete insect stage, a reduction was observed in the number of individuals which entered the subsequent growth stage. At all stages, the reduction in the treatment population group was faster than the control population. The highest reduction in the number of individuals entering the next developmental stage was associated with the larval developmental stage, followed by developmental stages of the adult, pupal, and egg. Regarding the highest potential of B. bassiana and BtK in reducing the stock pest population, it is very possible to exploit this interaction for biocontrol.

[学科分类] 化学工程（综合）

[关键词] Date palm;Mill moth;Entomopathogens;Ephestia kuehniella;Pathogenic effects