Drosophila Suzukii Research Articles

Non-nutritive sugar feeding alters the genetic profile of diuretic hormones and their receptors in Drosophila suzukii (Diptera: Drosophilidae)

Abstract Non-nutritive sugars such as erythritol and sucralose are active ingredients in artificial sweeteners. In the past decade, research has demonstrated insecticidal properties of non-nutritive sugars across several arthropod species. It is now a prospective chemical control option for spotted-wing drosophila, Drosophila suzukii, one of the most economically important pests of small fruits. D. suzukii die quicker, excrete waste in large amounts, and become desiccated when fed a mixture of erythritol and sucralose. The toxicity of non-nutritive sugars to the fly is not clearly elucidated but is likely due to nutritional and physiological failures associated with an excess fluid excretion and water imbalance, caused a hyperosmotic in the body. The diuretic processes in insects are primarily regulated by 3 neuropeptides: the CAPA hormone, diuretic hormone 31 (DH31), diuretic hormone 44 (DH44). To explore the genetic effects of non-nutritive sugars on D. suzukii, we investigated the genetic regulation of 3 key hormone genes—capa, dh31, and dh44—and their 7 corresponding receptors under different dietary conditions: erythritol + sucrose, sucralose + sucrose, and erythritol + sucralose. Molecular analyses revealed that the expression levels of capa, dh31, dh44, and their receptors were significantly altered in non-nutritive sugar-fed flies compared to the control group fed only sucrose. Through trials testing synergistic effects of peptide injection and non-nutritive sugar consumption, DH44 peptide consistently and significantly increased the mortality of non-nutritive sugar-fed flies across all diet groups. These genetic and physiological findings offer molecular insights for the development of novel pest management strategies targeting D. suzukii.

Assessing Wine Grape Cultivar Susceptibility to Spotted Wing Drosophila and Melanogaster-Type Drosophila in Hungarian Vineyards: Effects of Berry Integrity and Insights into Larval Interactions

The invasive spotted wing Drosophila (SWD) represents new challenges for European and North American fruit producers. The aim of our study was to examine wine grape cultivar susceptibility to this pest and melanogaster-type Drosophila (MTD) by surveying drosophilid populations using field traps and conducting emergence tests. We assessed fly development from intact and artificially injured berries collected from four cultivars. Berries were incubated individually and in pooled samples to evaluate infestation patterns and potential larval interactions. Although grapes are generally considered less favorable hosts for SWD, the pest was consistently present across all vineyard plots. Infestation levels differed significantly among cultivars, with the Hungarian white cultivar Furmint being the most susceptible, while French-origin red cultivars Cabernet Franc and Cabernet Sauvignon, along with the other Hungarian cultivar Rózsakő, were less susceptible. Berry integrity played a crucial role: intact berries showed minimal infestation, whereas physical injuries led to a substantial and significant increase in infestation rates and fly emergence. In contrast to SWD-dominated trap catches and the nearly equal proportions of SWD and MTD observed in intact berries, injured berries were predominantly colonized by MTD. This dominance became even more pronounced in pooled samples, suggesting that larval competition in shared environments favors MTD over SWD. These findings underscore the importance of grape cultivar traits and berry condition in shaping Drosophila infestation dynamics. Further research into the chemical and ecological drivers of host selection and interspecific interactions is warranted to improve vineyard pest management strategies.

An Environmentally-Friendly RNAi Yeast-Attractive Targeted Sugar Bait Turns off the Drosophila suzukii Rbfox1 Gene

Spotted wing drosophila (SWD), Drosophila suzukii (Diptera: Drosophilidae), are invasive vinegar flies of East Asian origin that are an increasingly global threat to the small fruit industry. It is essential that new classes of eco-friendly insecticides and cost-effective strategies for SWD control are developed. Here, we describe the preparation of a strain of RNA interference (RNAi) Saccharomyces cerevisiae expressing shRNA that specifically targets the SWD RNA-binding Fox protein 1 (Rbfox1) gene. The yeast effectively silences the SWD Rbfox1 gene, resulting in significant loss of fly neural activity. Laboratory trials demonstrated that the RNAi yeast can be mixed with soda, which functions as SWD attractive targeted sugar bait (ATSB) that can be delivered in a soda bottle feeder. The ATSB, mixed with yeast that was heat-killed prior to suspension in the ATSB, resulted in 92 ± 1% mortality of SWD flies that consumed it, yet had no impact on non-target dipterans. Rbfox.687 yeast delivered in ATSB feeders may one day be a useful component of integrated SWD control programs.

CAPA Neuropeptide and Its Receptor in Insects: A Mini Review.

A neuropeptide, the CAPA, and its cognate receptor have been diversely characterized in different orders of class Insecta. CAPA peptides are synthesized in the abdominal neurohemal system and activate their corresponding receptor, CAPA receptor (CAPA-R), a type of G protein-coupled receptor (GPCR), to initiate cellular signals for diverse physiological functions in insects. Activation of the CAPA-R in Malpighian tubules results in ion-water homeostasis via antidiuresis in the majority of insect species; however, diuresis and myotropic activities are also known to result. Antidiuretic activity of CAPA peptides has been reported from mosquitoes, assassin bugs, spotted wing drosophila, and more; hence, this group of peptides also holds importance as potential targets when it comes to medical and agricultural entomology. GPCRs form a diverse family of cell membrane receptors responsible for signal transduction across the cell membrane in humans as well as in insects. With the advances in knowledge of human GPCRs, their physiological functions in agriculturally important insects have offered an opportunity for designing and implementing GPCR-targeting compounds in integrated pest management programs. In this review, we present a comprehensive view on physiological factors and peptides responsible for the diuresis/anti-diuresis in insects with special reference to the CAPA peptide-receptor interaction. The major focus is on the role of CAPA peptides in fluid and energy homeostasis, stress tolerance, muscle functioning, regulation of reproduction, and diapause-related processes. We end by outlining the significance of insect excretion with respect to the capa-r gene silencing and pest management.

Plant Domestication Alters the Nutritional Content of Guttation Droplets with Multi-Trophic Consequences.

Domestication often alters plant traits, leading to cascading effects on ecological interactions, particularly in tri-trophic relationships among plants, herbivores, and their natural enemies. While recent studies have investigated the influence of domestication on plant-derived food sources, its effect on guttation-a nutrient-rich exudate produced by many plants-remains unexplored. In this study, we examined the effects of guttation droplets from wild and cultivated highbush blueberries on the fitness (longevity and fecundity) and feeding preferences of three insect species from different trophic guilds: an herbivore (Drosophila suzukii), a parasitoid (Trichopria drosophilae), and a predator (Chrysoperla carnea). Additionally, we analyzed and compared the size and nutritional composition-specifically, total sugar and protein content-of guttation droplets between wild and cultivated blueberry plants. Our results indicated that guttation from wild plants enhanced the longevity of all three insect species, often surpassing that of cultivated plants and diets containing only sugar or sugar plus protein. In choice assays, all three insect species consistently preferred guttation from wild plants over that from cultivated ones. Although the guttation droplets from cultivated plants were larger, those from wild plants contained higher concentrations of sugars (six times more) and proteins (five times more), which likely contributed to the insects' enhanced fitness and preference for wild plant guttation. These findings indicate that domestication has reduced the ecological functionality of guttation in blueberries by potentially influencing tri-trophic interactions. Understanding how domestication affects plant-derived food sources like guttation could have important implications for the conservation of natural enemies in agricultural landscapes.

Different effects of Drosophila suzukii oviposition and larval activity on fruit rot and mold

Different effects of Drosophila suzukii oviposition and larval activity on fruit rot and mold

Does rearing host alter host stage preference? Implications for mass rearing of two common pupal parasitoids of Drosophila suzukii.

Pachycrepoideus vindemiae Rondani (Hymenoptera: Pteromalidae) and Trichopria drosophilae (Perkins) (Hymenoptera: Diapriidae) are pupal parasitoids capable of successfully developing on Drosophilidae species, including the invasive pest Drosophila suzukii (Matsumura) (Diptera: Drosophilidae). Both parasitoids are considered potential biological control agents for managing D. suzukii. We conducted a long-term laboratory rearing study to assess whether different rearing host species, specifically D. suzukii and Drosophila melanogaster Meigen (Diptera: Drosophilidae), influence the parasitoids' preference for D. suzukii pupae at different developmental stages. In no-choice tests, T. drosophilae reared on either D. suzukii or D. melanogaster exhibited a preference for parasitizing younger D. suzukii pupae over older ones. In contrast, P. vindemiae reared on both host species did not show a significant difference in parasitism rates across D. suzukii pupal stages. Additionally, there were no significant differences in the performance of T. drosophilae and P. vindemiae after 10 generations of rearing on D. melanogaster when tested on D. suzukii pupae, compared to those reared on D. suzukii. These results suggest that long-term rearing on an alternative host does not alter the host stage preference of these parasitoids for D. suzukii.

Propagule production of regional entomopathogenic fungi against Drosophila suzukii , an emerging fruit pest in southern Chile

Background: Berry crops in Southern Chile with a temperate humid climate are threatened by emerging invasive Drosophila suzukii , and there is urgent need to provide efficient tools for integrated control of this pest. Objective: This study aims to compare the potential of selected entomopathogenic Beauveria bassiana and Metarhizium spp. strains to produce fungal propagules and new conidia on microsclerotia. Materials: Strains isolated from soil samples collected in affected berry plantations and highly virulent against D. suzukii were tested in standard culture conditions, and conidial production on microsclerotia determined at 15°C and 25°C. Results: The capacities to produce conidia, microsclerotia and blastospores depended on strains. The lower temperature did not affect conidial production on microsclerotia. Conclusions: There are promising candidates for the immediate development of a specific mycoinsecticide with the most appropriate propagule; ability of microsclerotia to produce high numbers of conidia in lower temperature encourages the search for innovative formulations to control D. suzukii in Southern Chile.

Impact of Irradiated Drosophila melanogaster Pupae on the Quality and Population Parameters of Trichopria drosophilae.

Trichopria drosophilae is a globally distributed pupal parasitoid that targets various species within the Drosophilidae family, including the invasive Drosophila suzukii. The mass rearing of T. drosophilae is a crucial step in ensuring their successful application for field D. suzukii control. The pupae of Drosophila melanogaster are currently used as a host for the mass rearing of T. drosophilae. After irradiation, the immune system function of Drosophila pupae was weakened, leading to an increase in the parasitism efficiency of the T. drosophilae. Our results showed that irradiated pupae had a significant impact on the parasitism rate, offspring eclosion rate, offspring number, and female body size of F1 T. drosophilae, all of which were significantly lower than those in the normal group. However, there was no significant difference in the parasitism rate, body size, offspring eclosion rate, offspring number, or offspring sex ratio between F2 T. drosophilae emerging from treated or untreated Drosophila pupae. Compared with F2, F1 had a significantly higher net reproductive rate (R₀), mean generation time (T), and doubling time (DT), while the intrinsic rate of increase (r) was significantly lower. Using irradiated D. melanogaster pupae provides an efficient method for the mass rearing of T. drosophilae and offers valuable insights into its potential effectiveness in field D. suzukii control.

Environmental conditions influencing seasonal population dynamics of Drosophila suzukii (Diptera: Drosophilidae) in mid‐latitude organic farms

Abstract The local population dynamics of an invasive species are important for determining proper management. Temporal and spatial distribution can influence monitoring and treatment decisions, and understanding climatic influences on population size can help predict peak numbers. Drosophila suzukii (Matsumara, 1931) is an invasive fruit pest, and its seasonal dynamics vary across its range. We conducted a three‐year trapping study with various modelling approaches to determine the environmental variables influencing D. suzukii population dynamics across all seasons in Kentucky, a temperate state with overwintering D. suzukii. Male and female flies were active in all seasons, visiting traps located on the ground and at plant height. Most flies were caught in the wooded edge habitat in all seasons, and crops only had more catches than the forest during summer. Population size was best predicted by a general additive model that included the average temperature 8 weeks before sampling and relative humidity in the two weeks before sampling, which differs from other models that have extremely low temperature as the most predictive weather variable. Our results indicate that the factors influencing D. suzukii population dynamics in Kentucky differ from those at higher or lower latitudes. We recommend monitoring average temperature leading up to fruiting to predict pest pressure. Further, our results suggest that the optimal time to monitor is when average temperatures exceed 21°C. Broadly, our findings highlight the need to investigate these factors on an appropriate scale to develop region‐specific monitoring and management recommendations.

Spatio-temporal dynamics of the invasive fly Drosophila suzukii (Diptera: Drosophilidae) in the irrigated valleys of Northern Patagonia, Argentina

. Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) also known as “spotted wing Drosophila” is a po-lyphagous herbivore of Asian origin with a short life cycle, and high dispersal and reproduction rates. The ar-rival of this invasive pest forced a reevaluation of management strategies in Northern Patagonia. The aims of this work were to quantify the inter-annual variation of population levels, explore the influence of cultivat-ed and wild hosts, assess the dispersal of the pest, and adjust a statistical model to describing population patterns as a function of degree days and relative humidity. We selected a cherry and raspberry orchard lo-cated in Plottier, Neuquén. Transect sampling was carried out and 33 traps were placed across an área of 12.5 km2 between 2018 and 2023. D. suzukii used fruit crops such as peach, vineyard, and plum trees as alternate hosts. D. suzukii exhibited seasonal behavior, with higher captures observed during summer and autumn. The adjusted GAMM model showed an increase in captures at 1,500 degree days (DD) and popula-tion peaks between 3,000 and 3,200 DD. This model is the first to be used in Argentina with trap capture count. Unlike conventional models, it allows for the integration of nonlinear variables.

The transformer gene controls sexual development in Drosophila suzukii.

The genetic network of sex determination in the model organism Drosophila melanogaster was investigated in great detail. Such knowledge not only advances our understanding of the evolution and regulation of sexual dimorphism in insects, but also serves as a basis for developing genetic control strategies for pest species. In this study, we isolated the sex determination gene transformer (Dstra) from a global fruit pest, the spotted-wing Drosophila (Drosophila suzukii), and characterized its gene organization. By comparing the deduced protein sequence of Dstra with its orthologs from 22 species, we found that tra genes from Dipteran species are divergent. Our research demonstrated that Dstra undergoes sex-specific splicing, and we validated its developmental expression profile. We engineered a piggyBac-based transformation vector expressing the complete Dstra coding sequence under the control of the Tetracycline-Off system. Through germ-line transformation, we generated 4 independent transgenic lines, producing pseudo-females from chromosomal males in the absence of tetracycline. This observation indicated ectopic expression of Dstra, confirmed by the detection of female Dstra transcripts in transgenic males. The pseudo-females exhibited altered wing patterns, feminized abdomen, abnormal reproductive organs, and disrupted sexual behavior. Ectopic expression of Dstra affected the sex-specific splicing pattern of the downstream gene fruitless, but not doublesex. In conclusion, our study provides comprehensive genetic, morphological, and behavioral evidence that Dstra controls sexual development in D. suzukii. We discuss the potential applications of this research for genetic control strategies targeting Dstra or using its gene elements.

Biosynthesized Chitosan-Coated Silver Nanoparticles: Insecticide Activity and Sublethal Effects Against Drosophila suzukii (Diptera: Drosophilidae).

The overuse of synthetic pesticides has triggered resistance in insect pests and caused severe environmental impacts, emphasizing the urgent need for sustainable alternatives in Integrated Pest Management (IPM). This study aimed to biosynthesize and characterize chitosan-coated silver nanoparticles (AgChNPs) using Galega officinalis leaf extract and evaluate their insecticidal effects against Drosophila suzukii (Diptera: Drosophilidae), a key pest of fruit crops worldwide. The biosynthesized AgChNPs (257.2 nm) were polydisperse, crystalline, and stable, as confirmed by UV-vis spectroscopy, dynamic light scattering (DLS), X-ray diffraction (XRD), and transmission electron microscopy (TEM). AgChNPs exhibited strong toxicity across multiple developmental stages. Combined larvicidal and pupicidal activity reached 48.3% and 73.3% at 500 and 1000 ppm, respectively, significantly affecting immature stages. As a consequence, adult emergence declined to 46.7%, 51.7%, and 26.7% at 250, 500, and 1000 ppm. Among emerged adults, 71.7% displayed sublethal effects, with 62.8% showing morphological malformations (deformed wings, dehydration) and 37.2% presenting cuticle demelanization. Adulticidal bioassays revealed progressive mortality over 48 h, with 96% mortality at 1000 ppm. Overall, AgChNPs caused acute and chronic toxicity, reduced adult emergence, and induced severe morphological alterations, demonstrating their potential as a sustainable nanotechnological tool for effective pest control within IPM programs.

Reliable mass production of Ganaspis kimorum (Hymenoptera: Figitidae), a larval parasitoid of Drosophila suzukii (Diptera: Drosophilidae).

Spotted wing drosophila, Drosophila suzukii (Matsumura), native to Asia, has become a significant threat to soft fruit crops globally. To develop a classical biological control program for this pest, the obligate parasitoid Ganaspis kimorum (Buffington) was approved in the United States for field release in 2021 as a biological control agent. However, challenges in mass production and maintenance of parasitoid colonies have been common. Here, we share improved methods and offer insights into mitigating issues that limit parasitoid production. Additionally, we present a modified rearing protocol using 2-l plastic containers to produce an average of 307 G. kimorum per container. This information is crucial for implementing successful classical biological control programs against spotted wing drosophila with this parasitoid.

La Jolla Virus: The Pathology and Transmission in Its Host Drosophila suzukii.

Drosophila suzukii, commonly known as spotted-wing drosophila, has emerged as a highly destructive pest in global fruit and wine production. The effectiveness of chemical control is significantly compromised by rapid resistance development and a limited range of insecticide options. Biological control presents a promising sustainable alternative. Our previous work suggested the La Jolla Virus (LJV) as a suitable candidate for the development of an insect virus-based control option. Here, we characterized the natural transmission and pathology of the virus. We tested various modes of horizontal transmission, including airborne, venereal and oral, and fecal routes. To understand LJV pathology in infected flies, we studied feeding behavior and demonstrated changes in food absorption compared to non-infected flies. We also investigated the impact on fecundity and egg-to-adult success rate. Altogether, these results collectively improve our understanding of LJV transmission in natural populations and the implication of infected flies in food ingestion and overall fitness.

The incidence of cultural practices for managing Drosophila suzukii in raspberry farms: a case study from northwestern Patagonia

ABSTRACT The spotted wing drosophila (SWD), Drosophila suzukii, is a global pest of soft-skinned fruit. Managing SWD is mainly difficult due to its rapid life cycle, polyphagy and insecticide resistance, which also harms beneficial arthropods. Agroecological Crop Protection offers sustainable alternatives, like frequent harvesting, canopy thinning, and low ground cover. Our study in Northwestern Patagonia, Argentina, evaluated these practices in small-scale raspberry farms. Results showed a significant reduction in SWD larvae in treated farms, though effectiveness varied by area. The study underscores the need for tailored management strategies and suggests combining cultural practices with other tactics for better SWD control.

Corticotropin-releasing factor-like diuretic hormone 44 and five corresponding GPCRs in Drosophila suzukii: Structural and functional characterization.

Corticotropin-releasing factor-like diuretic hormone 44 and five corresponding GPCRs in Drosophila suzukii: Structural and functional characterization.

The Efficacy of Protective Nets Against Drosophila suzukii: The Effect of Temperature, Airflow, and Pest Morphology

Drosophila suzukii is an invasive pest that poses a significant threat to fruit crops worldwide, leading to considerable agricultural losses and economic damage. Unlike chemical control measures against D. suzukii, integrating insect-proof nets within an IPM framework offers a more sustainable solution. This study evaluates the efficacy of nine commercial protective nets against this pest, focusing on determining optimal hole dimensions based on the effects of airflow velocity, temperature, and pest morphometry on net performance. To simulate field conditions in the laboratory, we developed a tubular device divided into three chambers with the tested net placed between the two, incorporating a fan to generate airflow and a thermo-anemometer. Our results confirm that higher air velocities and elevated temperatures reduce net efficacy. Additionally, morphometric analyses of lab-reared flies revealed significant sexual dimorphism and a strong temperature–size relationship, with flies reared at lower temperatures being consistently larger, an aspect that also affects net effectiveness. These findings highlight the importance of considering both abiotic factors and pest morphology when evaluating protective screens, challenging the assumption that exclusion net efficacy remains constant. Some tested nets proved completely effective against SWD, supporting their use as a preventive measure in IPM programs.

Potential interactions of larval and pupal drosophila parasitoids and their implications for biological control of Drosophila suzukii

Potential interactions of larval and pupal drosophila parasitoids and their implications for biological control of Drosophila suzukii

Geographic Variation in Resistance of the Invasive Drosophila suzukii to Parasitism by the Biological Control Agent, Ganaspis brasiliensis.

Host-parasitoid interactions are tied in coevolutionary arms races where parasitoids continuously have to evolve increased virulence as hosts evolve increased resistance. Over time, geographic structure in virulence and resistance can arise because of spatial and temporal differences in parasitoid communities, in the strength of reciprocal selection pressures, in genetic variation in local populations, and as trade-offs are balanced between defense and fitness traits. It is crucial to understand the resistance structure of pest populations to successfully implement biological control programs against invasive insect hosts. We investigated spatial and temporal variations in the resistance of the invasive Drosophila suzukii in seven geographically distinct populations in Michigan and of one population from Oregon against a newly approved biocontrol agent, the larval parasitoid Ganaspis brasiliensis. We found regional and temporal variations in the resistance (encapsulation rates of parasitoid eggs) of D. suzukii populations that ranged from 11% to 48%. The northernmost, and thus the coldest site, had the highest rate of parasitism and the lowest encapsulation rate. Large regional differences in the resistance of D. suzukii populations can render the ensuing biocontrol program more variable and less predictable, and release strategies may need to be altered at sites where flies have high resistance.