DOI: 10.4103/0972-9062.392257 ISSN: 0972-9062
Evaluation of Insect Growth Regulators (IGRs) as Biological Pesticides for Control of Aedes aegypti Mosquitoes
Adnan Ur Rahman, Inamullah Khan, Amjad Usman, Hasnain Khan ABSTRACT
Background & objectives:
Insect growth regulators (IGRs) are biological hormone analogue or mimics used as pesticides to inhibit the growth of larva their molting and skin shedding. To test the effect of IGRs on the eggs hatching and post-hatching inhibition of Aedes for understanding its effect in the mosquito breeding habitats for reduction in adult emergence.
Methods:
Experiments on the evaluation of three insect growth regulator (IGRs) for the control of different stages of Aedes aegypti was carried out in the Medical Entomology Laboratory of Nuclear Institute for food and Agriculture (NIFA) Peshawar, Pakistan during 2020–21. Each experiment consisted four treatments i.e Pyrifroxyfen, Novaluron, and Larvicol at 1.0 ppm and control with distilled water. All experiments were carried out in completely randomize design (CRD) except eggs which was carried out in factorial design each with three replication.
Results:
Results revealed that all tested IGRs performed better in affecting eggs, larval and pupal stages of Ae. aegypti. Highest eggs hatching inhibition (80%) of fresh eggs occurred in Pyriproxyfen followed by Novaluron (66%) and lowest by Larvicol (62%). Eggs hatch inhibition of embryonated eggs was lower than fresh eggs. Pyriproxyfen caused 69%, Novaluron 59% and Larvicol 39% eggs hatch inhibition of embryonated eggs. Both Pyrifroxyfen and Novaluron performed better in causing 98–100% larval mortality followed by Larvicol (39%). Larval development to pupal stage was completely prevented by both Pyrifroxyfen and Novaluron. Although Larvicol resulted in lowest egg’s hatch & larval inhibition but prevented pupae to emerge as adults. Results further showed 70–89% mortality of 3rd instar larvae of Ae. aegypti when exposed to Pyriproxyfen and Novaluron solutions after 30 days storage at lab. temperature (27±2oC), RH 70±5.
Interpretation & conclusion:
In conclusion to whatever we have observed is that none of the IGRs was more effective at the pupal stage but showed carryon activity of growth inhibition and mortality of the successive stages of development when used against eggs stages. Therefore, we recommend the early application of IGRs at mosquito habitats during the beginning and onset of season when very early stages of mosquitoes will be available in the field.