Abstract
Hydrochara affinis (Coleoptera: Hydrophilidae), a water scavenger beetle, was recently identified as a natural and effective agent for biological mosquito control; it was reported to exhibit high rates of mosquito larvae predation. However, maintaining the quality (i.e., natural ecological attributes, such as genetic variation) of laboratory-reared populations is essential for ensuring the long-term success of biological control programs. Accordingly, here, we aimed to use mitochondrial Cytochrome c oxidase subunit I (COI) sequences to document the genetic diversity, population structure, and phylogenetic position of natural and lab-reared H. affinis populations in South Korea and use geometric morphometric analysis to investigate the populations’ morphological divergence. The natural H. affinis populations possessed high genetic diversity and numerous COI haplotypes, suggesting that these populations were healthy and could be directly applied to mosquito habitats without alterations to their natural genetic attributes. The lab-reared populations also possessed high genetic diversity and, thus, the potential for high adaptive capacity to new environments. Although no distinct population genetic structures were observed, quantitative variation was observed in the body shape of both the natural and lab-reared populations. The high levels of genetic and morphologic variation observed in the H. affinis populations examined here indicate the species’ favorable conservation status, genetic diversity, adaptive capacity, and, thus, “suitability” for field application as an effective mosquito control agent.
Highlights
The Hydrophilidae is one of the largest families of aquatic insects [1], and the larvae of some hydrophilid species have been reported as effective predators of mosquito larvae [2]
Genetic analysis of the root-crown mining weevil (Ceutorhynchus scrobicollis), which was being considered as a biological control agent for garlic mustard (Alliaria petiolata), provided an estimate of the number of individuals required from a focal area to obtain the high level of genetic diversity of control agent [7], and analysis of cultured and naturalized populations of the mirid bug Eccritotarsus catarinensis, a water hyacinth biological control agent, revealed that genetic bottleneck events did not affect the genetic diversity of introduced biocontrol populations [8]
The high levels of genetic and morphologic variation observed in the H. affinis populations examined in the present study indicate the species’ favorable conservation status, genetic diversity, adaptive capacity, and, “suitability” for field application as an effective mosquito control agent
Summary
The Hydrophilidae (i.e., water scavenger beetles) is one of the largest families of aquatic insects [1], and the larvae of some hydrophilid species have been reported as effective predators of mosquito larvae [2]. Systems for the mass rearing of insects in the lab are likely to incur high rates of inbreeding and, reductions in fitness (e.g., fecundity), growth rate, and viability [9,10,11]. Such issues have been noted since the advent of biocontrol research in the 1970s [9], and biocontrol efforts should aim to prevent any negative effects of agent release on the genetic attributes of natural populations
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