Inheritance, fitness cost and mechanism of resistance to tebufenozide in Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae).

Background: Tebufenozide has been used as a key insecticide for controlling beet armyworm, Spodoptera exigua (Hübner). To evaluate the risk of resistance evolution and to develop a better resistance management strategy, a field-collected population was selected with tebufenozide in the laboratory. Thereafter, the inheritance and fitness cost of tebufenozide resistance in S. exigua were investigated.

Results: After being selected with tebufenozide for 61 generations, S. exigua developed a 92-fold resistance to the chemical. The degrees of dominance for the reciprocal cross progeny were - 0.2698 and - 0.2785. The resistant strain had a relative fitness of 0.71, with substantially lower rates of larval survival, pupal weight, pupation and oviposition per female, and prolonged larval and pupal duration. PBO significantly increased the toxicity of tebufenozide (SR = 2) against resistant insects, and DEM and DEF also showed synergism with tebufenozide.

Conclusion: Tebufenozide resistance in S. exigua was inherited as autosomal, incompletely recessive and controlled by more than one gene. Development of the resistance may cost significant fitness for the resistant population. Mixed-function oxidases might play an important role in tebufenozide resistance in S. exigua. This study provided valuable information for further understanding tebufenozide resistance and for facilitating the development of resistance management strategies.