Drosophila Suzukii Research Articles

Using Red Panel Traps to Detect Spotted-Wing Drosophila and its Infestation in US Berry and Cherry Crops.

Spotted-wing drosophila (SWD), Drosophila suzukii Matsumura (Diptera: Drosophilidae), is an invasive pest of thin-skinned fruits in the United States. Monitoring traps are an integral part of SWD integrated pest management, allowing early detection and timely management of this pest. An ideal monitoring trap should be easy to use, effective in capturing SWD, sensitive and selective to male SWD which are easy to identify due to their spotted wings, and able to predict fruit infestation from trap captures. Deli-cup-based liquid traps (grower standard), which make in-situ observations difficult, were compared with red-panel sticky traps, both baited with commercial lures (Scentry, Trécé Broad-Spectrum (BS), and Trécé High-Specificity (HS)), across several US states in blueberries (lowbush and highbush), blackberry, raspberry, and cherry crops during 2018 and 2021. Results showed that red-panel traps effectively captured SWD, were able to detect male SWD early in the season while also being selective to male SWD all season-long, and in some cases linearly related male SWD trap captures with fruit infestation. Scentry and Trécé BS lures captured similar numbers of SWD, though Trécé BS and Trécé HS were more selective for male SWD in red panel traps than liquid traps in some cases. In conclusion, due to its ease of use with less processing time, red-panel traps are promising tools for detecting and identifying male SWD in-situ and for predicting fruit infestation. However, further research is needed to refine the trap captures and fruit infestation relationship and elucidate the trap-lure interactions in berry and cherry crops.

Control of spotted wing drosophila (Drosophila suzukii) in sweet cherry and raspberry using bait sprays

Spotted wing drosophila (Drosophila suzukii Matsumura) is a major pest of fruit crops with global significance. Effective control is reliant on uniformly spraying insecticides on all crop foliage. To encourage pest attraction and ingestion of insecticides, phagostimulant baits can be employed in ‘attract and kill’ strategies. In semi-field trials, we compared (1) full-field foliar sprays of two insecticides spinosad and cyantraniliprole, with (2) reduced [40%] and (3) low [4%] rates of the insecticides to control D. suzukii and reduce insecticide residues in fruit in sweet cherry and raspberry. The low rates of the insecticides were also combined with baits, (4) Combi-protec, a proprietary mixture of plant extracts, proteins and sugars and (5) molasses; treatment (6) was an untreated control. In both crops, when combined with baits, low rates of insecticides gave comparable control of D. suzukii in fruits compared with the full-rate sprays in most cases, and D. suzukii was significantly lower in these treatments compared with the untreated controls. Crop spray coverage was eight and thirty times higher in the full-rate applications compared with the bait and low-rate sprays, in raspberry and cherry, respectively. The reduction in applied insecticide was achieved by lower concentrations and volumes and a narrower band spray applied across the middle of the crop canopy. Spinosad and cyantraniliprole residues were detected in cherries taken from trees sprayed with full-rate applications but not in fruit from trees given the low rates of insecticides with bait. This study demonstrates that bait sprays can be effectively employed on crops with complex canopies for D. suzukii control.

The predation impact of ruby-throated hummingbird, Archilochus colubris, on spotted-wing drosophila, Drosophila suzukii, in raspberry, Rubus idaeus

Hummingbirds require arthropods in their diet and may consume 2000 small insects per day, including drosophilids, when nesting. In New York, we investigated the use of feeders to attract Ruby-throated Hummingbirds, Archilochus colubris (Linnaeus, 1758), into red raspberry, Rubus idaeus L., to encourage predation of the spotted-wing drosophila, Drosophila suzukii Matsumura. We investigated whether fly populations and fruit infestation would be reduced in the half of the field with feeders compared to the half without. Over four years, 2015–2018, 81% of 266 hourly observations of hummingbird behavior found they were occupying the field when utilizing the feeders, supporting opportunities for predation on D. suzukii. In 2016 to 2018, when maximal hummingbird sightings were reached, significant reductions in D. suzukii trap counts and fruit infestation levels were obtained in some weeks in the half of the field provided with feeders at a density of 62 feeders/hectare. Compared to the half without feeders, the final tally of cumulative trap counts and fruit infestation levels were lower in the half of the field treated with feeders in all years. In comparing two paired commercial raspberry fields (in 2020), one with feeders at a density of 151 feeders/hectare and the other without feeders, presence of feeders significantly reduced trap counts in most weeks during the fruiting season. No Ruby-throated Hummingbirds were observed in the commercial field without feeders. Hummingbirds may protect fruit from D. suzukii when they are encouraged with feeders to visit and occupy raspberry plantings. The presence of hummingbirds in raspberry fields has the potential to contribute to a D. suzukii integrated management program and reduce the reliance on pesticides.

Pathogenicity of La Jolla Virus in Drosophila suzukii following Oral Administration.

Drosophila suzukii (Ds) is an invasive pest insect that causes severe and widespread damage to soft fruit crops. Chemical control based on topical insecticides is inefficient and harmful to consumers and the environment, prompting interest in the development of biological control measures such as insect viruses with narrow host specificity. We previously described a strain of La Jolla virus (LJV) found in moribund Ds specimens in Germany. We demonstrated a pathogenic effect following the intrathoracic injection of LJV into adult Ds flies. However, the development of an effective biocontrol product based on LJV would require the characterization of (1) virulence following oral delivery, particularly in larvae, and (2) stability under different pH and temperature conditions reflecting realistic exposure scenarios. Here we describe the pathogenicity of LJV following oral delivery to Ds adults and larvae. The oral infection of Ds adults with LJV reduced survival in a concentration-dependent manner, whereas the oral infection of Ds larvae caused the arrest of development during pupation. LJV remained stable and infectious following exposure to a broad pH range and different temperatures. We, therefore, demonstrated that LJV is promising as a candidate biological control agent against Ds.

Drosophila suzukii preferentially lays eggs on spherical surfaces with a smaller radius

Drosophila suzukii is an agricultural pest that predominantly harms small fruits, having a serrated ovipositor that is able to pierce the skin of ripening fruits. Its oviposition preference has been studied from various aspects including chemical and physical properties of oviposition substrates. However, its preference for certain shapes or sizes of substrates has not been explored. In this study, we tested the oviposition preference of D. suzukii for artificial oviposition substrates with different surface curvatures using 27 strains recently established from wild populations collected in Japan. We found that D. suzukii laid more eggs on a surface with smaller radii (4.8 and 5.7 mm) compared with larger radii (7.7 and 9.6 mm). We also found that the most preferred radius differed among strains. Notably, the preference was independent of the volume of substrates, suggesting that D. suzukii uses the surface curvature as a cue for its oviposition site selection. These results provide an additional explanation for why D. suzukii preferentially uses small fruits as its oviposition sites.

Essential Oils as a Source of Ecofriendly Insecticides for Drosophila suzukii (Diptera: Drosophilidae) and Their Potential Non-Target Effects.

The spotted wing drosophila (Drosophila suzukii) is one of the main invasive pests of small fruits in the world. Thus, 19 essential oils (EOs) were selected to analyze the effects through toxicity and repellency on oviposition and D. suzukii adults. In addition, their lethal and sublethal effects on the pupal endoparasitoid Trichopria anastrephae were evaluated. The EOs of C. flexuosus and Mentha spp. had the highest toxicity observed in the topical application bioassay for D. suzukii. In contrast, the EOs of C. verum, C. citratus QT citratus, and C. winterianus showed the highest toxicity in the ingestion bioassay for D. suzukii. The dry residues of C. verum and C. citratus QT citratus reduced the oviposition of D. suzukii. In the repellency bioassays, the 19 EOs analyzed repelled ≅ 90% of the D. suzukii females. All EOs evaluated using the LC90 values of the products provided mortality of less than 20% of T. anastrephae adults and did not cause a reduction in the parasitism of surviving T. anastrephae females. We conclude that the EOs evaluated have the potential to be used in the management of D. suzukii. They can also serve as selective active ingredients for the formulation and synthesis of new biopesticides.

HUGE pipeline to measure temporal genetic variation in Drosophila suzukii populations for genetic biocontrol applications.

Understanding the fine-scale genome sequence diversity that exists within natural populations is important for developing models of species migration, temporal stability, and range expansion. For invasive species, agricultural pests, and disease vectors, sequence diversity at specific loci in the genome can impact the efficacy of next-generation genetic biocontrol strategies. Here we describe a pipeline for haplotype-resolution genetic variant discovery and quantification from thousands of Spotted Wing Drosophila (Drosophila suzukii, SWD) isolated at two field sites in the North-Central United States (Minnesota) across two seasons. We observed highly similar single nucleotide polymorphism (SNP) frequencies at each genomic location at each field site and year. This supports the hypotheses that SWD overwinters in Minnesota, is annually populated by the same source populations or a combination of both theories. Also, the stable genetic structure of SWD populations allows for the rational design of genetic biocontrol technologies for population suppression.

Molecular and behavioral studies reveal differences in olfaction between winter and summer morphs of Drosophila suzukii.

Spotted-wing drosophila, Drosophila suzukii (Matsumura), is a major economic pest of several fruit crops in Europe, North and South America, and other parts of the world because it oviposits in ripening thin-skinned fruits. This vinegar fly exhibits two distinct morphotypes: a summer and a winter morph. Although adaptations associated with the winter morph enhance this invasive pest’s capacity to survive in cold climates, winter is still a natural population bottleneck. Since monitoring early spring populations is important for accurate population forecasts, understanding the winter morph’s response to olfactory cues may improve current D. suzukii management programs. In this study, a comparative transcriptome analysis was conducted to assess gene expression differences between the female heads of the two D. suzukii morphs, which showed significant differences in 738 genes (p ≤ 0.0001). Out of twelve genes related to olfaction determined to be differentially expressed in the transcriptome, i.e., those related to location of food sources, chemosensory abilities, and mating behavior, nine genes were upregulated in the winter morph while three were downregulated. Three candidate olfactory-related genes that were most upregulated or downregulated in the winter morph were further validated using RT-qPCR. In addition, behavioral assays were performed at a range of temperatures to confirm a differing behavioral response of the two morphs to food odors. Our behavioral assays showed that, although winter morphs were more active at lower temperatures, the summer morphs were generally more attracted to food odors. This study provides new insights into the molecular and behavioral differences in response to olfactory cues between the two D. suzukii morphs that will assist in formulating more effective monitoring and physiological-based control tools.

Results of monitoring spotted wing drosophila (Drosophila suzukii, Matzumura) in the Republic of Srpska (Bosnia and Herzegovina) for the 2017-2021 period with reference to seasonal population movement

Spotted wing drosophila (SWD) - Drosophila suzukii, Matzumura is an important pest of soft and pome fruits. It originates from Asia, now spread throughout Europe, North, and South America. High reproductive potential, many generations per year, and their overlapping have made this pest hard to control. In Bosnia and Herzegovina, SWD has been present at least eight years and for that time little data has been collected on how it spreads and behaves in the agroecological conditions of the Republic of Srpska. Monitoring was conducted in the 2017-2021 period in orchards of different plant hosts. SWD was found in all agriculture regions of the Republic of Srpska with difference in population number. SWD adults are most active from the end of August and are most harmful for grape, blackberry, and late raspberry varieties. Considering climate conditions, population movement was most influenced by precipitation and air temperature.

Metabarcoding and applied ecology with hyperdiverse organisms: Recommendations for biological control research.

Metabarcoding is revolutionizing fundamental research in ecology by enabling large-scale detection of species and producing data that are rich with community context. However, the benefits of metabarcoding have yet to be fully realized in fields of applied ecology, especially those such as classical biological control (CBC) research that involve hyperdiverse taxa. Here, we discuss some of the opportunities that metabarcoding provides CBC and solutions to the main methodological challenges that have limited the integration of metabarcoding in existing CBC workflows. We focus on insect parasitoids, which are popular and effective biological control agents (BCAs) of invasive species and agricultural pests. Accurately identifying native, invasive and BCA species is paramount, since misidentification can undermine control efforts and lead to large negative socio-economic impacts. Unfortunately, most existing publicly accessible genetic databases cannot be used to reliably identify parasitoid species, thereby limiting the accuracy of metabarcoding in CBC research. To address this issue, we argue for the establishment of authoritative genetic databases that link metabarcoding data to taxonomically identified specimens. We further suggest using multiple genetic markers to reduce primer bias and increase taxonomic resolution. We also provide suggestions for biological control-specific metabarcoding workflows intended to track the long-term effectiveness of introduced BCAs. Finally, we use the example of an invasive pest, Drosophila suzukii, in a reflective "what if" thought experiment to explore the potential power of community metabarcoding in CBC.

Preparation of Lambda-Cyhalothrin-Loaded Chitosan Nanoparticles and Their Bioactivity against Drosophila suzukii

The encapsulation of pesticides within nanoparticles is a promising approach of advanced technology in sustainable agriculture. Lambda-cyhalothrin (LC) was encapsulated by the ionotropic gelation technique into chitosan (CS)/tripolyphosphate (TPP) and CS/alginate (ALG) matrixes. CS-LC nanoparticles were characterized, and their efficacy was then evaluated against the key pest of soft fruits in Europe and the United States, Drosophila suzukii. The encapsulation efficiency (74%), nanoparticle yield (80%), polydispersity index (0.341), zeta potential (−23.1 mV) and particle size (278 nm) were determined at the optimum conditions. FTIR confirmed the cross-linkage between CS and TPP/ALG in the nanoparticles. The optimum formula recommended by the fractional factorial design was associated with the formulation variables of CS of high or low molecular weight, cross-linking agent (TPP), LC concentration (1.5% w/v) and stirring rate (1500 rpm), showing the highest desirability value (0.5511). CS-LC nanoparticles of the lowest particle size (278 nm) exhibited the highest percent mortality of D. suzukii males (86%) and females (84%), exceeding that caused by the commercial product (Karate-zeon® 10% CS) at 2 HAT. This is the first work to use the ionic gelation technique to make LC nanoparticles, to the best of our knowledge. The encapsulation of chemical pesticides within biodegradable polymeric nanoparticles could be helpful for establishing a sustainable IPM strategy with benefits for human and environmental health and the lifetime of pesticides.

Field, semi‐field and greenhouse testing of HOOK SWD, a SPLAT‐based attract‐and‐kill formulation to manage spotted‐wing drosophila

AbstractNative to Southeast Asia, the spotted‐wing drosophila (Drosophila suzukii) has become a major pest of small fruit crops in the Americas and Europe because females can oviposit in ripening fruit. Currently, D. suzukii management relies heavily on chemical control; thus, more sustainable approaches like attract‐and‐kill need to be evaluated to reduce insecticide use. In previous studies, HOOK SWD, an attract‐and‐kill product that combines attractants, phagostimulants and an insecticide (spinosad), showed promise for D. suzukii control; still, little is known about its performance under field conditions and under varying pest and host‐fruit densities, as well as its residual activity. Here, we evaluated the efficacy of HOOK SWD when applied in commercial blueberry farms, when deployed in semifield cages under different D. suzukii adult and fruit densities and when aged for 30 days in the greenhouse. Results from field experiments showed that HOOK SWD could reduce fruit infestation in blueberry farms; however, its efficacy varied in space and time. Semifield cage studies revealed that relatively high densities of both D. suzukii adults and fruit can reduce the effectiveness of HOOK SWD, which might explain the variation in its efficacy in the field. Ageing HOOK SWD in a greenhouse for at least 30 days yielded no significant decrease in insecticidal activity. Altogether, these studies show that HOOK SWD can potentially suppress D. suzukii populations in the field, but it should be used as part of an integrated pest management program instead of a stand‐alone control tool, especially under high pest and fruit densities.

Propensity for resistance development in the invasive berry pest, spotted-wing drosophila (Drosophila suzukii), under laboratory selection.

Over the past 14 years, the invasive vinegar fly, spotted-wing drosophila (Drosophila suzukii), has become one of the most damaging fruit pests in the United States. With regional economic losses estimated as high as $500million for moderate infestations, D. suzukii control represents an often-untenable cost to growers. Management relies heavily on chemical control, which may be applied up to nine times in one season. The widespread use of chemical controls has led to concerns about insecticide resistance, and resistant field populations have already been documented in California and Michigan. We cultured sub-populations of three different Minnesota field populations of D. suzukii in the laboratory and exposed them to increasing concentrations of two commonly-used insecticides, zeta-cypermethrin (pyrethroid) and spinetoram (spinosyn). Over the exposure period, the sub-populations experienced an 8- to 45-fold increase in insecticide concentration. We saw significant increases in the median lethal concentration (LC50 ) values of one sub-population exposed to zeta-cypermethrin and one exposed to spinetoram. Across the spinetoram exposures, we also observed significant reductions in the top mortality values for three different sub-populations. Our results suggest that field populations of D. suzukii can develop resistance to zeta-cypermethrin and spinetoram in short periods of time under laboratory selection but that resistance to spinosyns occurs more readily than to pyrethroids. These results support other studies that have documented spinosyn resistance in field populations and in laboratory selections. Resistance evolution to spinosyns is a particularly important issue, as they represent one of few organic insecticide options for D. suzukii. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Development of a Disease and Pest Management Program to Reduce the Use of Pesticides in Sweet-Cherry Orchards

A protocol for managing the main diseases and pests of sweet cherry in Spain (New IPM) has been implemented in order to reduce the use of pesticides. This New IPM includes nonchemical strategies, such as biological products against diseases and mass trapping of pests, and adjusts the timing and number of pesticide applications according to damage thresholds and a predictive model of diseases based on climatic factors. The New IPM was compared—in commercial orchards from the main cherry-producing areas in Spain (Aragon and Extremadura)—to the integrated management usually carried out in these areas (Standard IPM). Furthermore, a multiresidue method for the determination of the residues in cherries was developed. The number of applications, active ingredients used, and residue levels in fruit were reduced very significantly with this New IPM without affecting the effectiveness in the control of the main cherry diseases (brown rot, shot-hole, and leaf-spot) and pests (European cherry fly, spotted wing drosophila, and black cherry aphid). Neither significant differences in the abundance and diversity of microorganisms in flowers and fruit nor soil and canopy dwelling arthropods were observed between the two protocols, although some positive effects of this New IPM were seen on some groups of natural enemies.

Characterization of Field-Derived Drosophila suzukii (Diptera: Drosophilidae) Resistance to Pyrethroids in California Berry Production.

The spotted-wing drosophila, Drosophila suzukii (Matsumura), is a global economic pest of berry crops and stone fruit. Since management of this pest primarily relies on calendar insecticide applications, and field-derived resistance to spinosad has already been documented in California caneberry production, there is significant concern for development of resistance to other insecticides. In this study, susceptibility of D. suzukii populations collected from caneberry and strawberry fields to two pyrethroids, zeta-cypermethrin, and bifenthrin, was assessed in 2019 and 2020. Resistance to both pyrethroids were observed in flies from all sampling sites. For flies collected from caneberries in 2019, the LC50 values ranged from 4.5 to 5.2 mg liter-1 with RR50s ranging from 7.5- to 8.7-fold. Our 2020 assays showed that susceptibility of flies to the discriminating dose of zeta-cypermethrin decreased significantly as the season progressed. For flies collected from strawberries in 2020, the LC50s ranged from 19.0 to 36.1 mg liter-1 and from 30.3 to 90.7 mg liter-1 for zeta-cypermethrin and bifenthrin, respectively. The RR50 values varied from 19.0- to 36.1-fold for zeta-cypermethrin and from 15.9- to 47.7-fold for bifenthrin. This study is the first report of field-derived pyrethroid resistance in D. suzukii from two major California berry production areas. Adoption of informed insecticide resistance management practices would be essential to prolong the efficacy of products available to control D. suzukii. Future molecular work is needed to unravel the underlying genetic mechanisms conferring the observed pyrethroid resistance and to develop robust diagnostics that can inform integrated pest management of this pest.

Expression of antimicrobial peptides associated with different susceptibilities to environmental chemicals in Drosophila suzukii and Drosophila melanogaster

Drosophila suzukii is a serious agricultural pest. The evolved morphology of the female D. suzukii assists in penetrating the surface of fresh fruit and spawns eggs with its unique ovipositor. Conversely, Drosophila melanogaster, a taxonomically close species with D. suzukii, largely inhabits decaying and fermenting fruits and is consistently exposed to extensive environmental chemicals, such as 2-phenylethanol, ethanol, and acetic acid, produced by microorganisms. Considering the distinct habitats of the two flies, D. suzukii is thought to be more susceptible to environmental chemicals than D. melanogaster. We investigated the significantly higher survival rate of D. melanogaster following exposure to 2-phenylethanol, ethanol, and acetic acid. A comparison of the expression of antimicrobial peptides (AMPs) between the two flies treated with chemicals established that AMPs were generally more abundantly induced in D. melanogaster than in D. suzukii, particularly in the gut and fat body. Among the AMPs, the induction of genes (Diptericin A, Diptericin B, and Metchnikowin), which are regulated by the immune deficiency (IMD) pathway, was significantly higher than that of Drosomycin, which belongs to the Toll pathway in chemical-treated D. melanogaster. A transgenic RNAi fly (D. melanogaster) with silenced expression of AMPs and Relish, a transcription factor of the IMD pathway, exhibited significantly reduced survival rates than the control fly. Our results suggest that AMPs regulated by the IMD pathway play an important role in the chemical tolerance of D. melanogaster, and these flies are adapted to their habitats by physiological response.

Invasion Adaptation: A Socio-ecological Assessment of Cherry Growers’ Adaptation Potential to Spotted Wing Drosophila

Invasion Adaptation: A Socio-ecological Assessment of Cherry Growers’ Adaptation Potential to Spotted Wing Drosophila

First record of the agricultural pest Drosophila suzukii (Matsumura, 1931) (Diptera: Drosophilidae) in Algeria

AbstractThe spotted wing drosophila Drosophila suzukii (Matsumura, 1931) could potentially become a serious invasive pest of fruit crops in the North of Africa in the coming years, leading to substantial economic losses. This pest is reported for the first time in Algeria. It was detected in M'sila in the north‐east of the country within an pomegranate agroecosystem near the salt lake Chott Zahrez Echergui. Trapping was conducted from 21 March 2018 to 23 January 2019 in two orchards. The prevalence (flies/trap/day) and population dynamics of D. suzukii and two other fruit flies (Zaprionus indianus and D. melanogaster) trapped in the same orchards are reported. Low numbers of these three fly species were found in trap samples. At present, the ecological and economic impact of D. suzukii on pomegranate are poorly known in North Africa.

Precision Guided Sterile Males Suppress Populations of an Invasive Crop Pest

The Drosophila suzukii invasion of western countries has created an immense agricultural and economic threat to crop production. Despite many attempts to suppress its population, D. suzukii continues to destroy soft-flesh fruits. Precision guided sterile insect technique (pgSIT) utilizes the accuracy of programmable CRISPR gene targeting to generate sterilized males that can be deployed to suppress populations. Here, we generate pgSIT in D. suzukii and empirically and mathematically demonstrate that sterilized males are fit, competitive, and can eliminate populations of D. suzukii. Altogether, we describe an efficient way to generate sterile D. suzukii for release and safe effective population suppression.

The effects of non‐crop habitat on spotted wing drosophila (Drosophila suzukii) abundance in fruit systems: A meta‐analysis

Abstract Drosophila suzukii (SWD) poses a threat to soft and stone fruit globally. SWD inhabits non‐crop areas adjacent to farms from where it moves into crops to cause damage. Effective IPM control strategies, considering both the crop and non‐crop area, are needed to control this economically important pest. We conducted a meta‐analysis to quantify the impacts of different non‐crop habitats around fruit farms on SWD populations, comparing abundance of SWD trapped in crop and non‐crop habitats. Overall, SWD abundance was greater in non‐crop habitats than in cropped areas and this difference was greatest in farms adjacent to woodland, or field margins containing known SWD host plants. The difference in SWD abundance between crop and non‐crop habitats was not affected by crop type but was greatest in the winter months and in conventional compared to organic farms, indicating conventional approaches can reduce relative SWD abundance. Drosophila suzukii overwinter in non‐crop habitats which provide refuge outside the cropping season. However, certain habitats support greater relative abundance of SWD than others and this is also affected by farm management. We discuss what these findings mean for effective control of SWD.