Realized heritability, inheritance and cross-resistance patterns in imidacloprid-resistant strain of Dysdercus koenigii (Fabricius) (Hemiptera: Pyrrhocoridae).

BACKGROUND

Imidacloprid, a neonicotinoid insecticide, is widely sprayed alone or mixed with other insecticides against Dysdercus koenigii, a potential pest of cotton in Pakistan. Recently, resistance to imidacloprid in field populations of D. koenigii has developed because of its overuse. Herein, we have investigated inheritance of imidacloprid resistance in D. koenigii and its cross-resistance to other insecticides.

RESULTS

The imidacloprid-selected population had a 91 421-fold increase in resistance to imidacloprid after six generations. Overlapping 95% fiducial limits of LC of the F (Imida-Sel ♂ × Sus-ST ♀) and F (Imida-Sel ♀ × Sus-ST ♂) suggested an autosomal and incomplete dominant resistance to imidacloprid (D = 0.84 for F and 0.86 for F ). Reciprocal backcrosses of the F and F with Sus-ST predicted a polygenic inheritance. Realized heritability of imidacloprid resistance was 0.38. When mean slope = 1.74 and h = 0.38, then 3-13 generations would be required for a ten-fold increase in LC at 90-20% intensity of selection. Very high cross-resistance to emamectin benzoate (143-fold), deltamethrin (1675-fold) and lambda-cyhalothrin (140-fold), and moderate cross-resistance to acetamiprid (37-fold) in the imidacloprid-selected strain compared to the field population were observed.

CONCLUSION

Imidacloprid resistance developed very quickly under continuous selection pressure in the laboratory. These factors might lead to an increasing likelihood of resistance development in field populations, if imidacloprid is used continuously without insecticide rotation for prolonged periods. The present results would be supportive for better management of D. koenigii by devising an effective resistance management strategy. © 2020 Society of Chemical Industry.