No abstract

Although blueberry growers have experienced severe economic crop losses due to D. suzukii, we have found that blueberries were the least preferred of the fruits tested. This suggests that D. suzukii are largely opportunistic and highlights the importance of fruit phenology in fruit susceptibility. © 2016 Society of Chemical Industry.

After its initial discovery in California in 2008, Drosophila suzukii Matsumura has become one of the most important invasive agricultural pest insects across climate zones in much of Asia, Europe, North America, and South America. Populations of D. suzukii have demonstrated notable behavioral and physiological plasticity, adapting to diverse environmental and climatic conditions, interspecific competition, novel food sources, and potential predators. This adaptability and plasticity have enabled rapid range expansion and diversified niche use by D. suzukii, making it a species particularly suited to changing habitats and conditions. This article reviews factors and evidence that influence plasticity in D. suzukii and promotes this species’ invasiveness.

Drosophila suzukii Matsumura (Diptera: Drosophilidae) is a significant invasive pest in soft-skin fruits and berries in Asia, Europe, and North and South America. Many herbivorous insects use multiple cues for host selection, particularly olfactory and visual stimuli. The visual system of closely-related Drosophila melanogaster is well-documented, expressing strong sensitivity to short-wavelength colors (ultraviolet to green) and only limited sensitivity to long-wavelength colors (red to infrared). Our results suggest that D. suzukii have limited ability to distinguish red consistent with visual sensitivity range within the melanogaster subgroup. We propose that color contrast rather than color appearance may be of greater importance in orientation and attraction. We propose that differences in reflectance between light wavelengths important for color opponency are key to color discrimination to provide color contrast between foreground and background, as occurs between fruit and foliage, during host-finding.

Drosophila suzukii Matsumara (Diptera: Drosophilidae) has become a serious pest in soft-skin fruits and berries, infesting both ripe and ripening fruits. Crop damage in highbush blueberry has been particularly severe. During blueberry fruit development, fruits of various degrees of ripeness are present simultaneously. In addition, foliage color changes as the season progresses. We investigated the influence of blueberry fruit and leaf color on host-finding behavior in D. suzukii. Opposing shifts between reflectance spectra of ripening fruits and senescing leaves increased contrast between ripe fruit and senesced foliage. Developmental changes in contrast between fruit color and leaf color may act as a visual contextual cue in finding suitable host fruits. Opposing shifts in reflectance spectra of ripening fruits and senescing leaves increased the contrast between ripe fruit and senesced foliage. These opposing changes in color may contribute to the attractiveness of blueberry fruit as a late season host for D. suzukii.

The past 100 yr have seen dramatic philosophical shifts in our approach to controlling or managing pest species. The introduction of integrated pest management in the 1970s resulted in the incorporation of biological and behavioral approaches to preserve ecosystems and reduce reliance on synthetic chemical pesticides. Increased understanding of the local ecosystem, including its structure and the biology of its species, can improve efficacy of integrated pest management strategies. Pest management strategies incorporating insect learning paradigms to control insect pests or to use insects to control other pests can mediate risk to nontarget insects, including pollinators. Although our understanding of insect learning is in its early stages, efforts to integrate insect learning into pest management strategies have been promising. Due to considerable differences in cognitive abilities among insect species, a case-by-case assessment is needed for each potential application of insect learning within a pest management strategy.

No abstract

Continued range expansion of Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) is exposing new species of soft fruits and berries to potential infestation. Our understanding of cues that drive host-finding and selection in this highly polyphagous pest insect is still incomplete. Fruit firmness influences host choice behaviour by limiting suitability for oviposition and larval development. Other factors such as fruit sweetness and acidity act as cues for fruit ripening. Here we assess the role of these cues and fruit colour on host selection. We demonstrate that the use of objective and nonanthropocentric methods of quantifying colour in studies of colour preference is critical to understanding the cues evoking responses from insects. Acidity but not sweetness increased D. suzukii attraction and larval success. Differences in D. suzukii attraction were most strongly correlated with short-wavelength reflectance (blue, cyan, and green (470–560 nm)). Growers could select for fruit varieties with relatively higher reflectance values upon maturity to reduce susceptibility to D. suzukii.