TOXICITY OF PHOSPHINE TO 4TH INSTAR LARVAE OF SIX DIFFERENT POPULATIONS OF Trogodermagranarium (Everts) (COLEOPTERA:DERMESTIDAE) COLLECTED FROM GODOWNS IN PUNJAB (PAKISTAN)

The khapra beetle, Trogodermagranarium (Everts), is considered as one of the most significant stored product pests worldwide. In Pakistan T. granarium is one of the major pests of stored grains especially wheat. It damage by directly feeding on grains (Azeem et al., 1976; Khattak et al., 1996; Ram and Singh, 1996). Khapra beetle is also an important pest affecting international trade among uninfested countries, while infested countries suffer major damage through loss of stored grain both in quality and quantity. Young larvae usually attack the embryo point or a weak place in the pericarp (Pasquerault et al., 2008) or feed on damaged seed, while older larvae feed on whole grains. Finding khapra beetles in imported commodities will lead an immediate quarantine of the infested goods followed by either rejection or chemical treatment. Pest control chemicals used incorrectly or for prolonged periods may select for pesticide resistance. The continuous and indiscriminate use of pesticides has resulted in resistance development and field control failures in China, India, Japan and Taiwan (Flores et al., 2006; Corbel et al., 2007; Djouaka et al., 2007; Jirakanjanakit et al ., 2007; Margaritopoulos et al., 2007; Montella, 2007; Oliveira et al., 2007; Stara and Kocourek, 2007). The cost and residues associated with fumigants is lower than of contact or systemic insecticides. There are many different fumigants e.g., methyl bromide, aluminium phosphide, chloropicrin, magnesium phosphide, sulfuryl fluoride and ethyl formate. However phosphine has proven to be the most widely used. Fumigants enter the insect’s body via respiratory system and depends on fumigant application, temperature and concentration; mortality rate should be 100%. Fumigants have become the most successful method for controlling stored grain pests. Many scientists have studied the application and effectiveness of fumigants to control stored grain pests (Bell and Wilson, 1995; Rajendran and Muralidharan, 2001). J. Glob. Innov. Agric. Soc. Sci., 2016, 4(4): 188-196 ISSN (Online): 2311-3839; ISSN (Print): 2312-5225 DOI: https://doi.org/10.22194/JGIASS/4.4.769 http://www.jgiass.com