Spinosad resistance affects biological parameters of Musca domestica Linnaeus

Hafiz Azhar Ali Khan

doi:10.1038/s41598-018-32445-8

Abstract

Musca domestica is one of the major cosmopolitan insect pests of public health importance. Spinosad is considered an eco-friendly insecticide used for the management of M. domestica and other pests of significant concern. Cases of resistance against spinosad in M. domestica have been reported from some parts of the world; however, there are no reports of any negative effects of spinosad resistance on the fitness/biological parameters of M. domestica. To investigate fitness costs, a near isogenic M. domestica resistant strain (Spin-R) was constructed using Spin-UNSEL-susceptible and Spin-SEL-resistant strains sharing a close genetic background. We found significantly reduced rates of adult eclosion, fecundity, egg hatching, survival, and lengthened developmental time in the Spin-R strain. Moreover, the values of different fitness parameters like biotic potential, mean relative growth rate, intrinsic rate of natural increase, and net reproductive rate, were also significantly reduced in the Spin-R strain, which reflect fitness costs most probably linked with spinosad resistance. The presence of fitness costs suggests likely instability of resistance to spinosad in M. domestica, which can be reverted by relaxing spinosad selection pressure and rotation with alternate insecticides. The wise use of insecticides will ultimately help to manage resistance in this pest and minimize environmental pollution.

Highlights

Musca domestica Linnaeus is an economic pest of animal agriculture and public health which grows rapidly in unhygienic environmental conditions
In the process of isolating the near isogenic line with spinosad resistance, the resistance ratio (RR) values in the BCnF1 progeny decreased significantly after backcrossing with the susceptible recurrent parent; these values increased in the BCnF2 progeny after self-breeding
The comparison of various biological parameters of Spin-UNSEL, Spin-SEL and Spin-R strains revealed significant differences (Table 2), that might reflect the presence of fitness costs in M. domestica

Summary

Introduction

Musca domestica Linnaeus is an economic pest of animal agriculture and public health which grows rapidly in unhygienic environmental conditions It is a source of nuisance and plays a role in disease transmissions through its rapid expansion and forcing the affected communities to rely on the heavy use of various insecticides[1]. There are some important factors which contribute to an insect pest developing resistance to a particular insecticide These factors include the performance of biological parameters of a species in the presence of insecticide selection pressure, fitness costs, frequency of resistance allele(s), pest management practices and population dynamics[19,20]. Studies on fitness costs in resistant populations are important for devising an effective resistance management strategy, and to prevent the misuse of insecticides[32] Such studies help to minimize environmental pollution and negative impacts on public health. A near isogenic strain of M. domestica resistant to spinosad was established since such an approach is generally regarded asthe best for fitness assessments[33]

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