Adaptation of an Invasive Pest to Novel Environments: Life History Traits of Drosophila suzukii in Coastal and Mainland Areas of Greece during Overwintering

Abstract

Drosophila suzukii is a polyphagous pest of small and soft fruit, originating from Asia, which has spread and established in Europe and the USA. Adults exhibit seasonal phenotypes, i.e., summer morphs (SM) and winter morphs (WM) to cope with fluctuating environmental conditions. WM have a darker cuticle and larger wings compared to SM, while WM females experience reproductive dormancy. We studied the life history traits (lifespan, female reproductive status and number of produced offspring) of WM and SM that were exposed to winter field conditions of a coastal and a mainland agricultural area, with mild and cold winter climates, respectively. Mated adults of each phenotype were individually placed in vials bearing nutritional/oviposition substrate, and transferred to the field from November 2019 to May 2020, when the death of the last individual was recorded. Almost all SM females (90%) and no WM female carried mature ovarioles before being transferred to the field. WM exhibited a longer lifespan than SM adjusting for location and sex. Differences in survival between the two phenotypes were more pronounced for adults kept in the mainland area. The majority of SM females produced offspring during overwintering in the mild coastal area, but only a few SM were reproductively active in the cold mainland area. Some WM females produced progeny during overwintering in the mild conditions of the coastal area, but all WM females were in reproductive arrest in the mainland area. Overwintering females in the coastal area had a shorter lifespan and produced more progeny than those kept in the mainland area. High survival rates of WM provide indications of the successful performance of this phenotype in the adverse conditions of the cold climates. Additionally, the continuous reproductive activity of SM females and the onset of progeny production by WM females during overwintering in the coastal area indicate that the insect remains reproductively active throughout the year in areas with mild climatic conditions. Our findings support the successful adaptation of D. suzukii in both areas tested and can be used for the development of area-specific population models, based on the prevailing climatic conditions.

Modeling-informed Engineered Genetic Incompatibility strategies to overcome resistance in the invasive Drosophila suzukii

“…In a recent analysis of >10,000 wild SWD, targetable regions can be found with SNP frequencies <0.1% for single targets and could be expected at ≤ 0.2% for 2 targets ( 26 ). However, as evidence grows for SWD overwintering, the population replacement behavior of EGI in the late season may allow the treatment of a field one year to seed such genotypes in the next ( 33 , 34 ). In warmer climates, with year round SWD populations, enduring resistance would be even more damaging to the efficacy of EGI.…”

High promiscuity among females of the invasive pest species Drosophila suzukii

“…Polyandry, associated with the observed high intrinsic rate of D. suzukii , may help to buffer the inbreeding effect due to the winter bottleneck, allowing the long‐term stability and variability of the summer population. It is noteworthy that D. suzukii females continue to oviposit until an advanced age (Papanastasiou et al, 2021). Polyandry also hedges against the subfertility of males that emerge from the winter bottleneck (Grassi et al, 2018; Panel et al, 2020; Papanastasiou et al, 2021).…”

“…It is noteworthy that D. suzukii females continue to oviposit until an advanced age (Papanastasiou et al, 2021). Polyandry also hedges against the subfertility of males that emerge from the winter bottleneck (Grassi et al, 2018; Panel et al, 2020; Papanastasiou et al, 2021).…”

“…It is noteworthy that D. suzukii females continue to oviposit until an advanced age (Papanastasiou et al, 2021). Polyandry also hedges against the subfertility of males that emerge from the winter bottleneck (Grassi et al, 2018;Panel et al, 2020;Papanastasiou et al, 2021). Scattered information is available on the physiological and molecular mechanisms that regulate mating behaviour and female remating (Krüger et al, 2019;Revadi et al, 2015;Xing et al, 2022;Young & Long, 2020).…”

“…Consequently, in temperate regions, D. suzukii populations undergo seasonal morphological, physiological, and reproductive dynamics with a severe winter population bottleneck. Life history analyses of this fly in laboratory and wild conditions provided basic information on the adaptability of populations to novel environments (Papanastasiou et al, 2021; Tochen et al, 2014). But despite its economic importance, no data are available on the behavioural aspects of the reproductive strategies of this fly.…”