Monitoring Susceptibility to Spinosad in Three Major Stored-Product Insect Species from Punjab, Pakistan

Haider

2022

Sci Rep

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The widespread use of insecticides for the management of insect pests in storage facilities and food industries have caused insecticide resistance a frequent issue worldwide. Nonetheless, this issue has been little explored in Pakistan that resulted in control failures and increased dosage of insecticides. In the present study, insecticide resistance to chlorpyrifos-methyl, pirimiphos-methyl, permethrin and spinosad was surveyed in five field strains of Sitophilus oryzae: FSD-SO, GJR-SO, DGK-SO, MTN-SO and BWP-SO, collected from five different localities of Punjab, Pakistan, and contrasted with an insecticide susceptible reference strain (Lab-SO). Dose-mortality bioassays were performed in glass vials containing insecticide-treated rice grains, and lethal doses (LD50 and LD95) were calculated and compared using the ratio tests. In comparison to the Lab-SO strain at LD50 and LD95 levels, field strains exhibited: 24.51 to 52.80 and 36.55 to 69.31 resistance ratios (RRs), respectively, for chlorpyrifos-methyl; 15.89 to 45.97 and 55.12 to 194.93 RRs, respectively, for pirimiphos-methyl; 39.76 to 108.61 and 61.33 to 130.12 RRs, respectively, for permethrin; 4.23 to 27.50 and 6.28 to 41.00 RRs, respectively, for spinosad. In the synergism experiments using the Lab-SO and the most resistant strains against each insecticide, the enzyme inhibitors (PBO and DEF) failed to synergize toxicity of insecticides in the Lab-SO strain; however, toxicity of chlorpyrifos-methyl, pirimiphos-methyl and permethrin significantly enhanced in the resistant strains of S. oryzae, suggesting possibility of metabolic mechanism of resistance. In addition, activities of detoxification enzymes (CarE, MFO and GST) were significantly higher in resistant strains compared to the Lab-SO strain. The results revealed presence of insecticide resistance in field strains of S. oryzae that necessitate the need to develop a resistance management strategy.

Section: Methodssupporting

confidence: 76%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Resistance to grain protectants and synergism in Pakistani strains of Sitophilus oryzae (Coleoptera: Curculionidae)

Haider

2022

Sci Rep

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“…The rice weevil, Sitophilus oryzae (Linnaeus), has been included in the list of major stored insects with the potential to cause more than 20% losses at postharvest stages in developing countries, including Pakistan (Khan et al . , ). Synthetic insecticides have been the choice to control these pests, but problems (stated above) associated with these insecticides have limited their scope.…”

Section: Introductionmentioning

confidence: 99%

Toxic potential of some indigenous plant oils against the rice weevil, Sitophilus oryzae (Linnaeus)

Akram

Lee

et al. 2019

Entomological Research

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The present study was conducted to evaluate the toxic potential of five indigenous plant oils: black pepper (Piper nigrum), Chinese cinnamon (Cinnamomum cassia), garlic (Allium sativum), river red gum (Eucalyptus camaldulensis), and yellow oleander (Thevetia peruviana), against laboratory reared Sitophilus oryzae adults. The bioassays were done by the diet incorporation method with concentrations ranging from 50 ppm to 500 ppm. Based on lethal concentrations to kill 50% (LC50) of the subjected weevils, T. peruviana proved to be the most toxic having the lowest LC50 values, 414.58, 201.94, and 129.52 ppm, after 7, 14, and 21 days of exposure, respectively, followed by E. camaldulensis (475.51, 366.65, and 251.28 ppm, respectively). The rest of the plant oils also showed toxic potential, but these were less toxic compared with T. peruviana and E. camaldulensis. With respect to the time taken to cause 50% mortality (LT50) of the exposed weevils, T. peruviana had LT50 at 14.54 days followed by P. nigrum (22.09 days), E. camaldulensis (24.29 days), and C. cassia (28.71 days). Whereas, A. sativum took the longest time (44.47 days) to cause 50% mortality of the exposed weevils. In conclusion, the result revealed toxic potential of tested plant oils, and suggests further studies under simulated‐field conditions should be included in the management plan for S. oryzae.

“…Among these relatively new insecticides, spinosad (derivative of a soil actinomycete Saccharopolyspora spinosa ), has been considered safe due to very low toxicity towards mammals and other non-target organisms 9 – 12 . However, different insect pests like Aedes albopictus (Skuse) 13 , Drosophila melanogaster Meigen 14 , Plutella xylostella L. 15 , Helicoverpa armigera (Hübner) 16 , Tribolium castaneum 17 and M . domestica 6 , 18 have developed resistance against spinosad in some parts of the world.…”

Section: Introductionmentioning

confidence: 99%

Spinosad resistance affects biological parameters of Musca domestica Linnaeus

2018

Sci Rep

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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.