Response of Some Biochemical Components in Phosphine Susceptible and Resistant Populations of 4th Instar Larvae of Trogoderma Granarium (Coleoptera: Dermestidae)

Stored grain pests are controlled by a number different pesticides and fumigants. This study, investigated the effect of phosphine on khapra beetle (Trogoderma granarium) which is a notorious pest in stored grain godowns in Pakistan and a significant trade pest around the world. For this purpose, the LC50 of phosphine against 4th instar larvae of two different strains of T. granarium (collected from different cities of Punjab, Khaniwal (Khw) and Chishtian (Chi) were determined. The LC50 values shown by these strains were 3.8 and 7.0 ppm respectively. On the basis of LC50 the Chishtian strain was considered as resistant to phosphine, whereas Khaniwal strain was regarded as a susceptible strain. The effect of sub lethal doses (LC10, LC20, and LC30) on the larval stages of two T. granarium strains were evaluated. The toxic effect of phosphine was observed on glucose, glycogen, total lipid, FAA, protein and trehalose of the strains after 24 hours of exposure. The treatment showed significant increase in glucose content in Khaniwal (susceptible) and decrease in resistant strains throughout the treatment. Lipid content showed a highly significant increase for all doses of phosphine in both strains. Glycogen, Trehalose, protein and FAA contents depicted highly significantly increases in the resistant strain at LC10, LC20, and LC30