Core‐marginal dynamics interact with sex and temperature to influence morphology of the rapidly expanding invasive kudzu bug (Megacopta cribraria)

Abstract

1. Invasive species present unique natural experiments through which to study evolutionary processes associated with spatial spread, especially with respect to rapid morphological evolution of dispersal-related traits.2. The kudzu bug, Megacopta cribraria (Fabricius), established and expanded radially across the southeastern United States beginning in 2009. Here, M. cribraria is used as a model for studying rapid morphological change across an introduced range.3. Kudzu bugs were collected throughout the invasive range to test the hypothesis that body and wing size would increase with greater distance from the invasion source owing to dispersal-related selection. The effects of sex, local temperature, and latitude were also evaluated to investigate how such factors might influence body and wing size across this range expansion.4. Females were significantly larger than males across all traits. Distance from the invasion core, temperature, and their interaction significantly influenced body size and wing length, suggesting that M. cribraria were larger near the invasion periphery. This was especially pronounced at cooler sites. Sex and distance were found to both weakly influence wing length after removing the effect of body size, suggesting that wing size may be disproportionally larger along the invasion front.5. The combined results indicate that a combination of spatial, environmental, and sexual factors must be considered when examining or predicting invasive species responses to new selective pressures and environments.

Morphological shifts in response to spatial sorting of dispersal behaviour in red flour beetles across multiple generations

“…In another ground beetle species (Carabus hortensis), pronotum width and body condition were increased at the expansion front (Yarwood et al, 2021), but notably, these changes were only significant in males. Body size in the kudzu bug (Megacopta cribraria) increased with proximity to the invasion front in a similar manner for both sexes in one study (Lovejoy & Lozier, 2021), but pronotum width decreased with proximity to the invasion front in a different study, which was largely explained by sex differences (Merwin, 2019). The body mass of an organism and the size of their relevant morphology to support locomotion (e.g.…”

Species boundary and phylogeographical pattern provide new insights into the management efforts of Megacopta cribraria (Hemiptera: Plataspidae), a bean bug invading North America

“…24 Ruberson et al found no difference in morphology and genitalia based on specimens from Japan, China and India. 16 A recent study showed that the body and wing size of this invasive species could change during dispersal in the invasive region, 25 indicating that some morphological characteristics are unstable. Successful hybridization between these two forms may also indicate that these differences are intraspecific variations.…”

Susceptibility of Different Life Stages of Kudzu Bug Megacopta cribraria (F.) (Hemiptera: Plataspidae) to Two Different Native Strains of Beauveria bassiana

“…Models indicate that much of Central America, South America, and the eastern United States are susceptible to future invasion by this species [6], but thermal limits should restrict establishment north of the state of Maryland [7]. Assumed to have established from a single introductory location in Georgia, kudzu bugs also vary in size and flight potential in relation to the distance from the original introduction [8,9].…”