Abstract
Seven insect growth regulators (IGRs) (One juvenile hormone analogues [Pyriproxyfen 10.8EC], two ecdysone agonist [Tebufenozide 20SC, Methoxyfenozide 240SC] and four chitin synthesis inhibitor [Lufenuron 50EC, Flufenoxuron 10DC, Triflumuron 20SC, and Buprofezin 25% WP]) were tested under laboratory conditions against the larvae of Trogoderma granarium (Everts) and Tribolium castaneum (Herbst). Four concentrations of these IGRs (2.5, 5, 7.5, and 10ppm) were applied to observe their effects at 30 +/- 2 degrees C and 65 +/- 5% r.h. after 7 and 14 days of treatment application. The overall results showed that all the tested IGRs showed significant larvicidal activity against the larvae of both T. granarium and T. castaneum. Results revealed that the highest larval mortality of T. castaneum was 77.30 and 83.54% with flufenoxuron followed by methoxyfenozide (70.40, 76.65%), pyriproxyfen (56.61, 62.86%) and lufenuron (53.16, 59.41%) at 7 and 14 days after treatment (DAT). The lowest mortality 42.81 and 49.06% was resulted in case of triflumeron treatment after 7 and 14 days, respectively. Similarly, In case of T. granarium the highest mortality was 66.96 and 73.20% due to the effect of flufenoxuron, and was lowest 32.47 and 38.72% where triflumeron was applied after 7 and 14 days, respectively. Results regarding the comparative effect of different concentrations showed that highest mortality 65.23% in T. castaneum and 54.88% in T. granarium larvae was noted at 10 ppm and mortality was lowest at 2.5 ppm against both the test insects. Bioactivities of all the tested IGRs were found to be dose and exposure period dependent. The results regarding the relative potency of the entire tested IGRs indicated that they were more effective when applied on wheat as compared to rice and maize. From these results, it is concluded that the applications of IGRs have proved to be very effective against both species examined in the present study. These compounds particularly chitin synthesis inhibitors (CSIs) (flufenoxuron and lufenuron) should be considered as potential components in IPM of stored grains insect pests.