Modelling thermal reaction norms for development and viability in Drosophila suzukii under constant, fluctuating and field conditions.

Phenological models for insect pests often rely on knowledge of thermal reaction norms. These may differ in shape depending on developmental thermal conditions (e.g. constant vs. fluctuating) and other factors such as life-stages. Here, we conducted an extensive comparative study of the thermal reaction norms for development and viability in the invasive fly, Drosophila suzukii, under constant and fluctuating thermal regimes. Flies, were submitted to 15 different constant temperatures (CT) ranging from 8 to 35 °C. We compared responses under CT with patterns observed under 15 different fluctuating temperature (FT) regimes. We tested several equations for thermal performance curves and compared various models to obtain thermal limits and degree-day estimations. To validate the model's predictions, the phenology was monitored in two artificial field-like conditions and two natural conditions in outdoor cages during spring and winter. Thermal reaction norm for viability from egg to pupa was broader than that from egg to adult. FT conditions yielded a broader thermal breadth for viability than CT, with a performance extended towards the colder side, consistent with our field observations in winter. Models resulting from both CT and FT conditions made accurate predictions of degree-day as long as the temperature remained within the linear part of the developmental rate curve. Under cold artificial and natural winter conditions, a model based on FT data made more accurate predictions. Model based on CT failed to predict adult's emergence in winter. We also document the first record of development and adult emergence throughout winter in D. suzukii. Population dynamics models in D. suzukii are all based on summer phenotype and CT. Accounting for variations between seasonal phenotypes, stages, and thermal conditions (CT vs. FT) could improve the predictive power of the models.

Chemical and Electrophysiological Characterisation of Headspace Volatiles from Yeasts Attractive to Drosophila suzukii.

Chemical control of Drosophila suzukii (Diptera: Drosophilidae) based on the use of insecticides is particularly challenging as the insect attacks ripening fruits shortly before harvest. An alternative strategy may rely on the use of yeasts as phagostimulants and baits, applied on canopy as attract-and-kill formulations. The aim of this research was to identify the most attractive among six yeast species for D. suzukii: Saccharomyces cerevisiae, Hanseniaspora uvarum, Clavispora santaluciae, Saccharomycopsis vini, Issatchenkia terricola, and Metschnikowia pulcherrima. The volatile profile of C. santaluciae was described for the first time. Behavioural experiments identified H. uvarum and S. vini as the most attractive yeasts. The characterization of yeast headspace volatiles using direct headspace (DHS) and solid-phase microextraction (SPME) revealed several strain-specific compounds. With DHS injection, 19 volatiles were characterised, while SPME revealed 71 compounds constituting the yeast headspace. Both analyses revealed terpenoids including ß-ocimene, citronellol, (Z)-geraniol (nerol), and geranial as distinct constituents of S. vini. H. uvarum and S. vini were further investigated using closed-loop stripping analysis (CSLA) and electroantennography. Out of 14 compounds quantified by CSLA, ethyl acetate, isoamyl acetate, ß-myrcene, benzaldehyde and linalool were detected by D. suzukii antennae and might generate the strong attractiveness of S. vini and H. uvarum. Our results highlight a strong attraction of D. suzukii to various yeasts associated with both the flies and their habitat and demonstrate how different sampling methods can impact the results of volatile compound characterization. It remains to be demonstrated whether the distinct attraction is based on special adaptations to certain yeasts and to what extent the metabolites causing attraction are interchangeable.

Studying foraging behavior to improve bait sprays application to control Drosophila suzukii.

BACKGROUND: Foraging behavior in insects is optimised for locating scattered resources in a complex environment. This behavior can be exploited for use in pest control. Inhibition of feeding can protect crops whereas stimulation can increase the uptake of insecticides. For example, the success of a bait spray, depends on either contact or ingestion, and thus on the insect finding it. METHODS: To develop an effective bait spray against the invasive pest, Drosophila suzukii, we investigated aspects of foraging behavior that influence the likelihood that the pest interacts with the baits, in summer and winter morphotypes. We video-recorded the flies' approach behavior towards four stimuli in a two-choice experiment on strawberry leaflets. To determine the most effective bait positioning, we also assessed where on plants the pest naturally forages, using a potted raspberry plant under natural environmental conditions. We also studied starvation resistance at 20 °C and 12 °C for both morphs. RESULTS: We found that summer morph flies spent similar time on all baits (agar, combi-protec, yeast) whereas winter morphs spent more time on yeast than the other baits. Both morphs showed a preference to feed at the top of our plant's canopy. Colder temperatures enhanced survival under starvation conditions in both morphs, and mortality was reduced by food treatment. CONCLUSIONS: These findings on feeding behavior support informed decisions on the type and placement of a bait to increase pest control.

A sweet tooth makes a fly a pest.

The major insect pest of soft and stone fruits, the spotted-wing drosophila, Drosophila suzukii, has evolved a greater preference for laying eggs on ripe fruits over fermented ones. In a recent study, Cavey et al. found that higher responsiveness to low sugar concentrations has had an important role in this evolutionary shift in egg-laying behavior.

Compatibility of Entomopathogenic Nematodes with Chemical Insecticides for the Control of Drosophila suzukii (Diptera: Drosophilidae).

The spotted-wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), is a pest that reduces the productivity of small fruits. Entomopathogenic nematodes (EPNs) and chemical insecticides can suppress this pest, but the compatibility of the two approaches together requires further examination. This laboratory study evaluated the compatibility of Steinernema brazilense IBCBn 06, S. carpocapsae IBCBn 02, Heterorhabditis amazonensis IBCBn 24, and H. bacteriophora HB with ten chemical insecticides registered for managing D. suzukii pupae. In the first study, most insecticides at the recommended rate did not reduce the viability (% of living infective juveniles (IJs)) of S. braziliense and both Heterorhabditis species. The viability of S. carpocapsae was lowered by exposure to spinetoram, malathion, abamectin, azadirachtin, deltamethrin, lambda-cyhalothrin, malathion, and spinetoram after 48 h. During infectivity bioassays, phosmet was compatible with all the EPNs, causing minimal changes in infectivity (% pupal mortality) and efficiency relative to EPN-only controls, whereas lambda-cyhalothrin generally reduced infectivity of EPNs on D. suzukii pupae the most, with a 53, 75, 57, and 13% reduction in infectivity efficiency among H. bacteriophora, H. amazonensis, S. carpocapsae, and S. brazilense, respectively. The second study compared pupal mortality caused by the two most compatible nematode species and five insecticides in various combinations. Both Heterorhabditis species caused 78-79% mortality among D. suzukii pupae when used alone, and were tested in combination with spinetoram, malathion, azadirachtin, phosmet, or novaluron at a one-quarter rate. Notably, H. bacteriophora caused 79% mortality on D. suzukii pupae when used alone, and 89% mortality when combined with spinetoram, showing an additive effect. Novaluron drastically reduced the number of progeny IJs when combined with H. amazonensis by 270 IJs and H. bacteriophora by 218. Any adult flies that emerged from EPN-insecticide-treated pupae had a shorter lifespan than from untreated pupae. The combined use of Heterorhabditis and compatible chemical insecticides was promising, except for novaluron.

A method for sampling parasitized Drosophila suzukii (Diptera: Drosophilidae) puparia from soil.

Methods to measure the diversity and biological control impact of parasitoids for the control of spotted-wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) are being developed in support of biological control programs around the world. Existing methods to determine parasitism levels and parasitoid species composition focus on sampling D. suzukii within fresh and rotting fruit. However, many D. suzukii pupate in the soil or in dropped fruit, where additional parasitism could occur and where their parasitoids are thought to overwinter. Here we introduce a method for extracting parasitized D. suzukii puparia from the soil through a sieve and flotation system, allowing for effective collection of puparia, from which parasitoids can then be reared. Although the method considerably underestimates the absolute number of puparia in soil samples, it nonetheless yields a high number of puparia relative to sampling effort and provides a robust estimate of the relative abundance of puparia among samples. Using this method, we confirmed that at least 5 species of parasitoids, including some that have rarely been detected in past studies, overwinter in their immature stages inside D. suzukii puparia in south coastal British Columbia, Canada. The ability to sample puparia from the soil will lead to a more comprehensive view of both D. suzukii and parasitoid abundance throughout the season, help confirm parasitoid establishment following intentional releases, and provide a way to measure the diversity of parasitoid species and potential interactions among parasitoids (e.g., hyper- or klepto-parasitism) that may often occur on the soil surface.

Diffuse Associations Between Drosophila suzukii and Filamentous Fungal Microbes May Alter Caneberry Disease Dynamics.

Interactions between microorganisms and frugivorous insects can modulate fruit rot disease epidemiology. Insect feeding and/or oviposition wounds may create opportunities for fungal infection. Passive and active dispersal of fungal inoculums by adult insects also increases disease incidence. In fall-bearing raspberries and blackberries, such vectoring interactions could increase crop damage from the invasive pestiferous vinegar fly Drosophila suzukii (spotted-wing drosophila). Periods of peak D. suzukii activity are known to overlap with several species of primary fruit rot pathogen, particularly Botrytis cinerea and Cladosporium cladosporioides, and previous work indicates that larvae co-occur with and feed on various filamentous fungi at low rates. To further our understanding of the epidemiological consequences that may emerge from these associations, we surveyed the filamentous fungal community associated with adult D. suzukii, isolating and molecularly identifying fungi externally and internally (indicating feeding) from field-collected adults over 3 years. We isolated and identified 37 unique genera of fungi in total, including known raspberry pathogens. Most fungi were detected infrequently, and flies acquired and carried fungi externally at higher richness, frequency, and density relative to internally. In a worst-case scenario laboratory vectoring assay, D. suzukii adults were able to transfer B. cinerea and C. cladosporioides to sterile media at 0, 24, 48, and 72 h after exposure to sporulating cultures in Petri dishes. These results collectively suggest an adventitious vectoring association between D. suzukii and fruit rot fungi that has the potential to alter caneberry disease dynamics.

Methyl N,N-dimethylanthranilate and ethyl propionate: repellents effective against spotted wing drosophila, Drosophila suzukii.

BACKGROUND: Spotted wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), is an economically important pest of soft and stone fruit crops. The aim of this study was to identify repellents, formulated in dispensers, which could protect crops from D. suzukii. Fourteen potential repellents were screened against summer- and winter-morph D. suzukii through electroantennography and behavioural bioassays. Repellents effective in the laboratory were tested in polytunnels to determine their efficacy in reducing catches in fruit-baited traps. Further trials of three potential repellents were conducted to determine the distances over which repellent dispensers could reduce D. suzukii emergence in a strawberry crop. RESULTS: All 14 chemicals screened were detected by the antennae of both D. suzukii morphs. Hexyl acetate and geosmin both elicited a significantly greater corrected EAG response in summer morphs than winter morphs. Summer-morph D. suzukii were repelled by butyl acetate, ethyl propionate, methyl N,N-dimethyl anthranilate, geosmin, methyl salicylate, DEET and benzaldehyde at one or more doses test in laboratory bioassays. Winter morphs were repelled by ethyl propionate, methyl anthranilate, methyl N,N-dimethyl anthranilate, DEET, benzaldehyde and butyl anthranilate at one or more of the doses tested in the laboratory. Ethyl propionate, methyl N,N-dimethylanthranilate and benzaldehyde repelled both morphs from fruit-baited traps in polytunnel trapping trials. Ethyl propionate and methyl N,N-dimethylanthranilate reduced emergence of D. suzukii in a strawberry crop over 3-5 m. CONCLUSIONS: Ethyl propionate and methyl N,N-dimethylanthranilate may protect strawberry crops against D. suzukii. Future work should test these repellents in combination with attractants in a 'push-pull' strategy. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Visual stimulus brightness influences the efficiency of attractant-baited traps for catching Drosophila suzukii Matsumura (Diptera: Drosophilidae).

Drosophila suzukii (Matsumura) is an exotic pest of economic importance that affects several soft-skinned fruits in Mexico. Previously, we found that yellow or yellow-green rectangular cards inside a transparent trap baited with attractants improved D. suzukii capture. In this study, we evaluated the influence of rectangular cards with different yellow shades inside a transparent multi-hole trap baited with apple cider vinegar (ACV) on D. suzukii capture in the field. Second, we tested whether ACV-baited traps with cards of other geometric shapes affected D. suzukii catches compared to traps with rectangular cards. Third, we evaluated the effects of commercial lures combined with a more efficient visual stimulus from previous experiments on trapping D. suzukii flies. We found that ACV-baited traps plus a yellow-shaded rectangle card with 67% reflectance at a 549.74 nm dominant wavelength captured more flies than ACV-baited traps with yellow rectangle cards with a higher reflectance. Overall, ACV-baited traps with rectangles and squares caught more flies than did ACV-baited traps without visual stimuli. The traps baited with SuzukiiLURE-Max, ACV and Z-Kinol plus yellow rectangles caught 57, 70 and 101% more flies, respectively, than the traps baited with the lure but without a visual stimulus.

The Population Dynamics and Parasitism Rates of Ceratitis capitata, Anastrepha fraterculus, and Drosophila suzukii in Non-Crop Hosts: Implications for the Management of Pest Fruit Flies.

Understanding the seasonal dynamics inherent to non-crop host-fruit fly-parasitoid interactions is vitally important for implementing eco-friendly pest control strategies. This study assessed the abundance and seasonal infestation levels of three pest fly species, Ceratitis capitata (Wiedemann), Anastrepha fraterculus (Wiedemann), Drosophila suzukii (Matsumura), as well as the related saprophytic drosophilids, and their natural parasitism in a disturbed wild habitat characterized by non-crop hosts in northwestern Argentina over 40 months. Juglans australis Griseb (walnut), Citrus aurantium L. (sour orange), Eriobotrya japonica (Thunb.) Lindley (loquat), Prunus persica (L.) Batsch (peach), and Psydium guajava L. (guava) were sampled throughout their fruiting seasons. Fruits were collected from both the tree canopies and the ground. The most abundant puparia was A. fraterculus, followed by C. capitata and D. suzukii. Drosophila species from the D. melanogaster group were highly abundant only in fallen fruits. Spatiotemporal overlaps of different host fruit availability provided suitable sources for pest proliferation throughout the year. The populations of both invasive pests peaked from December to January, and were related to the highest ripe peach availability, whereas the A. fraterculus population peaked from February to April, overlapping with the guava fruiting period. The three pest fly species were parasitized mainly by three generalist resident parasitoids, which are potential biocontrol agents to use within an integrated pest management approach.

A fast and reliable larval sampling method for improving the monitoring of fruit flies in soft and stone fruits.

The spotted-wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), threatens both the soft-skinned and stone fruit industry in Asia, Europe, and America. Integrated pest management requires monitoring for infestation rates in real time. Although baited traps for adult D. suzukii are widely used for field monitoring, trap captures are weakly correlated to larval infestation rates. Thus, monitoring for larvae instead of adult flies represents the most reliable monitoring technique. Current methods for larval monitoring (e.g., sugar or salt floatation) are time-consuming and labor-intensive. In this study, we develop a new "sleeve method" for detecting larvae in strawberries through the inspection of individual fruits crushed within transparent plastic sleeves. Samples can be optionally frozen until further processing. Based on count data from non-expert observers, the estimation of larval infestation with the sleeve method is fast, precise, and highly repeatable within and among observers. Mean processing time is half the time compared to previous methods (33-80 s per sample depending on infestation levels). As the accuracy of the sleeve method decreases with infestation levels, we suggest ways to improve its accuracy by incubating fruits for 48 h and calibrating data using fruits with a known number of larvae. The method could also be used in other fruits, as it is easier to use, faster, and requires less equipment than previous monitoring methods. Finally, the method represents a promising tool for growers or researchers to effectively monitor and manage D. suzukii and other insect pests of soft and stone fruits.

Effects of nonnutritive sugar inclusion in laboratory diets and attracticidal spheres on survivorship and mobility of 2 Dipteran species, Rhagoletis pomonella (Diptera: Tephritidae) and Drosophila suzukii (Diptera: Drosophilidae).

Native apple maggot fly, Rhagoletis pomonella, and invasive spotted-wing drosophila, Drosophila suzukii, are key pests of apple and small fruit, respectively, in the United States. Both species are typically managed with standard insecticide applications. However, interest in alternative strategies that result in insecticide reductions has led to evaluations of nonnutritive sugars as toxicants for Drosophila species and development of attracticidal spheres for both species. Here, we evaluated the survivorship of R. pomonella and D. suzukii when provided with standard diets that substituted saccharin, sucralose, aspartame, erythritol, dextrose, or mannitol for the sucrose component and compared them with standard diets and water-only controls for up to 15 days. Presence of erythritol and mannitol significantly decreased survivorship of R. pomonella and erythritol significantly decreased the survivorship of D. suzukii. However, mobility trials following a 2 h exposure to aqueous solutions of each sugar treatment resulted in no strong impact on either species. Survivorship after 30 min exposure to erythritol or mannitol alone, or in combination with varying concentrations of sucrose (serving as a phagostimulant) at 30 min and 24 h were evaluated for both species. Only D. suzukii survivorship was affected with decreased survivorship on erythritol:sucrose solutions of 20:0% and 15:5% for 24 h. Based on all results, erythritol appeared most promising, and was integrated into attracticidal spheres as a toxicant but even at the highest concentration, survivorship remained unaffected for either species, thus making this nonnutritive sugar impractical and ineffective as a toxicant substitute in attracticidal spheres.

Potential of Ocotea indecora Essential Oil for Controlling Drosophila suzukii: Molecular Predictions for Toxicity and Selectivity to Beneficial Arthropods.

The protection of soft-skinned fruits against Drosophila suzukii has relied primarily on the efficacy of a few synthetic molecules. Despite their short-term efficacy, these molecules can cause environmental pollution, unintendedly affect non-target organisms, and fail to provide sustainable control. The shortfalls of using synthetic pesticides warrant the search for alternatives, such as essential oils extracted from plants, with greater eco-friendlier properties. Here, we chemically characterized and evaluated the toxicity of the essential oil extracted from leaves of Ocotea indecora (Schott) Mez (Lauraceae) against D. suzukii via two exposure pathways (ingestion and contact). We also assessed the selectivity of the essential oil to two predatory natural enemies, Eriopis connexa and Chrysoperla externa and two pollinator bees, Apis mellifera and Partamona helleri. In addition, we conducted in silico predictions to investigate potential interactions between the major compound of the essential oil and the insects' transient receptor potential (TRP) channels. Our chromatographic analysis revealed sesquirosefuran (87%) as the major compound. Higher toxicity to adults of D. suzukii was observed in contact exposure (LC50 = 0.43 µL mL-1) compared to ingestion (LC50 = 0.72 µL mL-1). However, the essential oil did not cause mortality to the non-target organisms tested here, even when applied at 2.20 µL mL-1. Molecular predictions demonstrated that sesquirosefuran binds more stably to the TRP channels of D. suzukii than to those expressed in beneficial arthropods. Collectively, our findings provide the initial framework for the potential use of O. indecora essential oil as a sustainable alternative for managing D. suzukii infestations.

Assessing Natural Incidence of Resident Pupal Parasitoids on the Drosophila suzukii (Diptera: Drosophilidae) Population in Non-crop Fruits.

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), world-renowned as spotted-wing drosophila, is an invasive pest mainly affecting healthy, soft and stone fruit crops throughout Argentinian fruit-growing regions. Natural environments overgrown by exotic feral host plants apparently favour D. suzukii proliferation. This is common in the subtropical northwestern Argentina's berry-producing region. An assemblage of resident parasitoid species has been associated with D. suzukii in crop and non-crop areas of Tucumán, the Argentina's leading berries producer and exporter. Consequently, the hypothesis that the combined action of two pupal parasitoid species, Pachycrepoideus vindemiae Rondani (Hymenoptera: Pteromalidae) and Trichopria anastrephae Lima (Hymenoptera: Diapriidae), occurring in non-crop fruit areas, has a significant impact on D. suzukii natural regulation in such invaded habitats was tested. A survey of D. suzukii puparia from both feral peach [Prunus persica (L.) Batsch] (Rosaceae) and guava (Psydium guajava L.) (Myrtaceae) fallen fruits and soil surrounding them was performed in a wilderness area of Tucumán. Abundance of D. suzukii and associated parasitoids, and parasitism levels were assessed. Whole of 3437 D. suzukii puparia were recovered; 78% and 22% were surveyed from fruits and soil underneath the fruit, respectively. Tested fruits are important D. suzukii multiplying hosts. Both P. vindemiae and T. anastrephae accounted for 99.8% of total parasitoid individuals. Pupal parasitoids contribute to the D. suzukii natural mortality, as they killed a quarter of all puparia. Mostly T. anastrephae foraged on host puparia located in the fruit and P. vindemiae in both microhabitats. This information supports an augmentative biological control strategy in non-crop areas.

Trichopria anastrephae as a Biological Control Agent of Drosophila suzukii in Strawberries.

In South America, the resident pupal parasitoid Trichopria anastrephae Costa Lima (Hymenoptera: Diapriidae) is a potential biological control agent of the pest Drosophila suzukii Matsumura (Diptera: Drosophilidae). In the present study, we (1) examined the behavior of T. anastrephae towards different host (D. suzukii) and host-substrate (strawberry) cues in choice and non-choice bioassays in laboratory, and (2) examined the density-dependent parasitism of T. anastrephae in D. suzukii-infested strawberries in a greenhouse. When given a choice, female parasitoids walked longer over chambers with fruits infested with eggs, larvae, or pupae of D. suzukii, when compared to healthy uninfested strawberries, and over overripe fruits when compared to unripe or ripe fruits. In the greenhouse assay, we observed an increase in parasitism and a decrease in the number of D. suzukii emerging per fruit with an increase in the number of parasitoids released. Our results allow a better understanding of the behavior and parasitism of T. anastrephae in D. suzukii-infested strawberries and provide useful data for potential biological control programs using this parasitoid.

Survey on Drosophila suzukii and Ceratitis capitata (Diptera: Drosophilidae, Tephritidae) and Associated Eucoilinae Species (Hymenoptera: Figitidae) in Northwestern Argentina. First Record of Dicerataspis grenadensis and Leptopilina boulardi as Parasitoids of D. suzukii.

The Southeast Asian-native Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), also known as "spotted-wing Drosophila," is one of the most globally invasive agricultural species. Although D. suzukii is a pest spread throughout all the Argentinian fruit-growing regions, few information has been published on its impact on local fruit production. Parasitoid species associated with D. suzukii in Argentina belong to Pteromalidae (Chalcidoidea), Diapriidae (Diaprioidea), both attacking host pupae, and Figitidae (Cynipoidea), which attack host larvae. Nine Eucoilinae (Figitidae) species, belonging to Dicerataspis, Dieucoila, Euxestophaga, Ganaspis, Hexacola, and Leptopilina genera, have been associated with D. suzukii in Argentina. Ceratitis capitata (Wiedemann), commonly known as "medfly," is native to Africa and has a worldwide distribution, covering many tropical, subtropical, and temperate regions. In Argentina, C. capitata has been associated with several native hymenopterous parasitoids belonging to Braconidae (Ichneumonioidea), Eulophidae (Chalcidoidea), Pteromalidae, Diapriidae, and Figitidae families. Only two eucoline species, Ganaspis pelleranoi (Brèthes) and Leptopilina haywardi (Blanchard) have been related to medfly in Argentina. We report new trophic associations between the parasitoids Dicerataspis grenadensis Ashmead and Leptopilina boulardi (Barbotin, Carton and Kelner-Pillault) and D. suzukii, and between the parasitoid Odontosema albinerve Kieffer and C. capitata, after surveys conducted in Tucumán, northwestern Argentina. An annotated checklist and a taxonomic key of Eucoilinae associated with both invasive pests, in Argentina, are also provided.

Drosophila suzukii in Argentina: State of the Art and Further Perspectives.

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), commonly known as spotted-wing drosophila or SWD, is an invasive, severe, and damaging pest, which is able to inflict huge economic losses on soft thin-skinned fruits worldwide. Argentina was not excluded from the rapid invasion of this new and aggressive pest. Berries and cherries are among the most economically important fruits, showing an increasing demand from both domestic and export markets, which make necessary the application of effective and early protection measures. Although SWD is currently established almost everywhere in Argentina, the scarcity of research on and rapid regulatory actions against this pest have probably contributed to its fast spread throughout the country. In view of that, the article reviews first the current threat status of SWD in Argentina, provides summarized information on crop and non-crop host fruits, seasonal variation and population dynamics, resident natural enemy assemblages, and describes control actions implemented to date. Finally, the need to focus local control actions within an integrated national SWD management program is emphasized. The development and application of complementary eco-friendly strategies, such as Sterile Insect Technique, biological control, mass trapping, and the use of innovative lactone-derived synthetic insecticides with extremely low toxicity for SWD parasitoids, in environmentally distinguishable Argentinian regions is also highlighted.

A Performance Index as a Measure of the Host Suitability to Drosophila suzukii Matsumura (Diptera: Drosophilidae).

Drosophila suzukii Matsumura, known as spotted wing drosophila (SWD), is an Asiatic invasive fruit pest that has spread over the world in the last 15 years, due to its high reproductive rate, its tolerance to different environmental conditions, the international fruit trade, and its wide range of host plants. In Buenos Aires, Argentina, blueberry is a major susceptible crop, although other cultivated and non-cultivated fruit species are frequent. The aim of this study was to evaluate the host suitability of commercial and non-cultivated fruit species (blueberries, plums, mulberries, and cherries) at two stages of maturity by estimating an index that takes into account biological and biometric parameters. The development and survival of SWD cohorts reared on different fruits were followed from egg to adult emergence. Then, adults were sexed and some biometric traits were measured. The indices: Wing loading, Wing aspect, and the Relative Performance Index (RPI) were estimated. The shortest developmental time and the maximum egg to adult survival were observed in the specimens developed in mulberry, in both stages of maturity. Only the length of the thorax showed significant differences between treatments in both sexes, and the largest adults were those reared in the ripe mulberries. The RPI, which relates performance and biometric variables, was the best index to evaluate the host suitability of SWD. So, it could be used as an indicator of the nutritional quality of fruits available in a region and to evaluate the importance of alternative hosts in the population dynamic of SWD.

Does monitoring pests pay off? a bioeconomic assessment of Drosophila suzukii controls.

BACKGROUND: Drosophila suzukii is a significant invasive pest that has caused high management costs and economic losses for blueberry growers in the United States. The status quo control strategy commonly used by growers is to apply pesticides proactively and frequently to reduce infestation. Recent studies have shown that the calendar-based spraying strategy might be unsustainable in the long term, making the reduction of pesticide reliance a top priority for the berry industry. Incorporating pest monitoring into the control strategy could be an option to improve efficiency while reducing pesticide usage. This study assesses the economic implications of monitoring-based control strategies compared to calendar-based spraying control strategies for organic blueberry production in Oregon. We combine a D. suzukii population model into the economic simulation framework, evaluate two monitoring methods (adult trapping and fruit sampling), and identify the profit-maximizing control strategy under different scenarios. RESULTS: In the baseline scenario, control strategies that incorporate fruit sampling exhibit the highest average profits. Although the status quo control strategy (spraying every 3 days) generates higher average revenue than monitoring-based strategies, the cost from the higher number of pesticide application offsets the returns. CONCLUSION: This study uses a novel bioeconomic simulation framework to show that incorporating fruit sampling can be a promising tool to reduce pesticide reliance while controlling D. suzukii infestation. These findings provide clearer information on the economic viability of using monitoring-based pest control strategies in organic berry production, and the assessment framework sheds light on the economics of pest management. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

The Potential of Plant-Based Biorational Products for the Drosophila suzukii Control: Current Status, Opportunities, and Limitations.

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) is an invasive species that causes serious damage to soft-skinned fruits. The use of plant-based biorational insecticides (plant extracts and essential oils) to control this pest has grown extensively. We conducted a systematic review and meta-analysis to examine the current status, trends, and perspectives of these studies, with a focus on the plant families and major compounds used as insecticides to control D. suzukii. The first article in this research field was published in 2015, and there has been exponential growth in subsequent years. Thirty-six botanical families were studied in these articles, with a prevalent interest in Myrtaceae and Lamiaceae plant species. The major constituents of these plant-based biorational molecules belong to monoterpenoids, followed by monoterpenes, benzene derivatives, and others. Geranial was the most frequent major constituent of these plant-based compounds. Our analysis revealed a few crucial consequences of the bias provided by the investigations using plant-based biorational insecticides for controlling D. suzukii. Firstly, there is a major focus on the pest species, with little or no attention paid to undesired effects on non-target beneficial organisms (e.g., pollinator bees, predators; parasitoids) and non-target pests. Secondly, the poor knowledge of how these plant-based biorational insecticides act on target and non-target organisms. Finally, there is a need to assess the efficacy of these substances under field conditions. Thus, attention is needed to address these gaps so that plant-based biorational insecticides can become a viable pest management tool for controlling D. suzukii.