Susceptibility of Cotton Mealy Bugs, Phenacoccus solenopsis and Paracoccus marginatus at Different Developmental Stages to Entomopathogenic Fungi

摘要

Cotton mealy bugs, Phenacoccus solenopsis and Paracoccus marginatus have been reported from 15 genera of family Malvaceae, including cotton and many other plants of economic importance (Ben-Dov 1994). P. solenopsis appeared during the year 2005 and attained the status of serious pest in the cotton growing areas of India. Out break of mealy bugs on cotton and other hosts has threatened the economic production of many crops including cotton (Arif et al. 2009). The large populations reached by this insect are attributed, in large measure, to its polyphagous nature, short developmental cycles and high fecundity. Although mainly chemical control has been used against mealy bug, it is not always successful, possibly due to the waxy nature of the cuticle and nature of hiding (Blumberg and Van Driesche 2001; Ujjan and Shahzad 2007). The reduced efficiency of insecticidal control and ecological awareness have revived the interest in biological control. With the increasing importance of mealy bug control worldwide, there is more interest in the use of fungi for sustainable management of these important pests (Latge and Papierok 1988; Hajek and St Leger 1994). For the successful introduction of a fungal agent, information is not only needed on the biology ofcontrol agent but also on the most susceptible stage of pest species (Cubbertson et al. 2003). Hence, this study was conducted to determine the pathogenicity of Metarrhizium anisopliae, Beauveria bassiana and Verticillium lecanii on various developmental stages of cotton mealy bugs viz., P solenopsis and P. marginatus.