Author
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GUEDES, NELSA MARIA - UNIVERSIDADE FEDERAL DE VICOSA |
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GUEDES, RAUL NARCISO - UNIVERSIDADE FEDERAL DE VICOSA |
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Campbell, James - Jim |
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THRONE, JAMES |
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Submitted to: Annals of Applied Biology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 11/29/2016 Publication Date: 5/15/2017 Citation: Guedes, N.P., Guedes, R.C., Campbell, J.F., Throne, J.E. 2017. Mating behavior and reproductive output in insecticide-resistant and -susceptible strains of the maize weevil (Sitophilus zeamais). Annals of Applied Biology. 170(3):415-424. https://doi.org/10.1111/aab.12346. DOI: https://doi.org/10.1111/aab.12346 Interpretive Summary: Resistance to pesticides is a major issue that negatively impacts our ability to manage pest insect species. Individuals that have developed resistance often have a reduced reproductive rate in insecticide-free environments, so that resistant individuals are at a disadvantage and this can reduce the spread of resistance within a pest population. However, in cases where resistance does not have an apparent negative impact, other factors such as preferential selection of resistant or susceptible individuals during mating may also impact the spread of insecticide resistance. Using insecticide-resistant and -susceptible strains of the maize weevil, a key pest of stored cereals, it was shown that there was no preference for either the resistant or susceptible strain during mating, but that pairs of susceptible individuals produced the fewest offspring, while pairs of resistant individuals produced more offspring and pairs of resistant and susceptible individuals produced the most offspring. Female weevils were consistent in their mate selections, but this choice was based on some other unidentified characteristic of the males and not related to the presence of pesticide resistance. These findings indicate that this form of insecticide resistance would be favored to be maintained and to spread in a population, even in the absence of insecticide treatments which complicates resistance management programs. Technical Abstract: Insecticide resistance is the most broadly recognized and well studied ecological problem resulting from intensive insecticide use, which also provides useful evolutionary models of newly adapted phenotypes to changing environments. Two common assumptions in such population-oriented models are the existence of fitness costs associated with insecticide resistance, which will place the resistant individuals at a disadvantage in insecticide-free environments, and the prevalence of random mating among insecticide-resistant and -susceptible individuals. However, cases of insecticide resistance lacking apparent fitness disadvantages do exist impacting the evolution and management of insecticide resistance. Assortative mating, although rarely considered, may also favor the evolution and spread of insecticide resistance. Thus, the possible existence of both conditions in the maize weevil (Sitophilus zeamais), a key pest of stored cereals, led to the assessment of the mating behavior and reproductive fitness of insecticide-resistant and -susceptible weevil strains and their reciprocal crosses. The patterns of female and male mating choice were also assessed. Although the mating behavior within and between weevil strains was similar without mate choice, mating within the resistant strain led to higher reproductive output than within the susceptible strain; interstrain matings led to even higher fertility. Thus, no apparent fitness cost associated with resistance seem to exist in these weevils, favoring the evolution of this phenotype that is further aided by the higher fertility of interstrain matings. Mate choice reduced latency to mate and no interstrain preference was detected, but female weevils were consistent in their mate selection between 1st and 2nd matings indicating existence of female mating preference among maize weevils |
