Abstract:
Khapra beetle, Trogoderma granarium is one of the most notorious pests of stored grains. This study was aimed to evaluate the toxicity of phosphine to 4 th , 6 th instar larvae and adult beetle in phosphine resistant populations viz., Gujranwala, Mandi Bahauddin-I (M.B.Din-I), Mandi Bahauddin-II (M.B.Din-II),Gujrat and Sargodha and a susceptible population of T. granarium. The 4 th , 6 th instar larvae and adult beetles of T. granariumwere exposed to different sub lethal concentrations of phosphine for 20 hours. Based on LC50 data, Gujranwala population was found to be most resistant to phosphine whereas Sargodha population was found the least resistant population. Gujranwala population required 113.5, 128.8 and 168.1% more phosphine concentration in 4 th , 6 th instar larvae and adult beetles, respectively with reference to susceptible population of T. granarium.The various insect populations based on LC50 of phosphine is graded as Gujranwala ? MBDin-I ? Gujrat ? MBDin-II ? Sargodha ? control.The LC50 values of phosphine against adult were always less than of 6 th instar larvae and likewise LC50 of phosphine against 6 th instar larvae is always less compared to 4 th instar larvae in all populations. The 4 th instar of Gujranwala required 17.03 and 25.39% more phosphine than 6 th instar larvae and adult beetle, respectively. Based on LC50 data, gradation followed by developmental stages is 4 th instar ? 6 th instar ? adult. Adult insects seemed to be more sensitive to phosphine compared to 6 th and 4 th instar larvae.
Page(s):
25-30
DOI:
DOI not available
Published:
Journal: Punjab University Journal of Zoology, Volume: 31, Issue: 1, Year: 2016