Effect of humidity on the development and fecundity of <Emphasis Type="Italic">Ophraella communa</Emphasis> (Coleoptera: Chrysomelidae)

Ophraella communa, an unintentionally introduced leaf beetle in China, has good control efficiency on ragweed, Ambrosia artemisiifolia. Aspects of the climatic requirements for development, survival, longevity and fecundity of O. communa were studied under the conditions of constant temperature (25 ± 1°C), photoperiod of 14 L:10 D and three relative humidities (60%, 75% and 90% RHs). The results showed that the developmental periods of O. communa at different stages shortened along with the increasing relative humidity, except that of the pupal stage. Although no differences were observed in the pupal survival rate, ovipositional period, fecundity, longevity and adult female age-specific survivorship of O. communa under the three humidity conditions, the survival rates during the egg, larva and entire immature stage were significantly higher at 75% RH and 90% RH than at 60% RH. The innate rate of increase (r _m), net reproductive rate (R ₀), finite rate of increase (λ) reached the maximum at 75% RH, with values of 0.181, 1116.4 and 1.198, respectively. These results indicated that the optimum relative humidity for the development of O. communa ranged from 75% RH to 90% RH. Thus O. communa prefers moist microclimate habitats. Its population may expand rapidly during mid-May to late August in south, east and central China, when the humidity is relatively high.     

Efficacy of commercially available predators,nematodes and fungal entomopathogens for augmentative control of Drosophila suzukii

The recent arrival of Drosophila suzukii, an invasive pest of soft‐skinned fruit with a wide host range, has resulted in increased production costs for growers and the need for additional insecticide applications each growing season. There are few effective organic insecticides for D. suzukii, and insecticide use in conventional farms may be disruptive to natural enemies, suggesting a need for effective biological control to combat D. suzukii. Commercially available natural enemies were evaluated for their potential use in augmentative releases, including: the predators Orius insidiosus and Dalotia coriaria; the entomopathogenic fungi Metarhizium anisopliae, Beauveria bassiana and Paecilomyces fumosoroseus; and the entomopathogenic nematodes Heterorhabditis bacteriophora, Steinernema feltiae and S. carpocapsae. This suite of natural enemies was chosen to target D. suzukii adults as well as larvae in hanging or dropped fruit. Of the cultured fungal strains tested, only M. anisopliae significantly decreased D. suzukii survival, but it had low residual activity and no effect on D. suzukii fecundity. O. insidiosus decreased D. suzukii survival in simple laboratory arenas but not on potted blueberries or bagged blueberry branches outdoors. D. coriaria did not decrease D. suzukii survival in infested blueberries in simple laboratory arenas. The nematodes tested showed low infection rates and were not able to affect D. suzukii survival. Although this suite of natural enemies showed limited ability to suppress D. suzukii under the tested conditions, these and related natural enemies are present as part of the endemic natural enemy community in agricultural fields, where they may contribute to D. suzukii suppression.     

Diet quality mitigates intraspecific larval competition in Drosophila suzukii

The invasive frugivore Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) utilizes a wide range of host plants and damages important fruit crops, including blueberries, cherries, blackberries, raspberries, and strawberries. Field infestations of D. suzukii often exceed one larva per berry, suggesting that intraspecific competition may frequently occur. Because dietary resources are also likely to vary across the host range of D. suzukii, we designed a laboratory assay to measure larval performance across diets of varying quality: a standard artificial diet, a fruit‐based medium, a low‐protein, and a low‐carbohydrate diet. We manipulated egg density across these diets to provide increasing levels of competition and measured larval performance by observing survival to pupation and adulthood, and development times for both life stages. Although increasing density generally negatively impacted D. suzukii performance across diets, the magnitude of these impacts varied by diet type. Drosophila suzukii performance was generally similar in fruit and standard diets, although larval development was more rapid in fruit diets at lower densities. Even at low densities (5 or 10 eggs per arena), survival was reduced and development time increased in low‐protein diets relative to standard and fruit diets. At the two highest larval densities (20 or 40 eggs per arena), survivorship was reduced in low‐carbohydrate diets as compared to standard and fruit diets. There is evidence that larvae compensated in both low‐quality diets by extending development time, which could have consequences for population dynamics. Population models for use in D. suzukii management may need to account for both host nutritional quality and relative competition to accurately predict turnover and geographic expansion.     

Variation of within‐crop microhabitat use by Drosophila suzukii (Diptera: Drosophilidae) in blackberry

Drosophila suzukii Matsumara (Diptera: Drosophilidae) is an invasive vinegar fly that infests ripe and ripening soft skinned fruits. In the south‐eastern United States, blackberry (Rubus spp.) crops are heavily impacted by D. suzukii, and current management tactics rely on the use of broad‐spectrum insecticides targeted to adult populations. An improved understanding of D. suzukii biology and ecology are necessary to create sustainable management options. Knowledge of how D. suzukii interacts with resources will enable targeted management actions in the future. In this present study, we monitored larval infestation throughout the blackberry canopy and found that infestation was highest in the inner portion of the canopy and lower in more exposed locations. We also documented higher humidity within the cane canopy relative to the edge of the field. A difference in abiotic conditions may create within‐crop microhabitats that D. suzukii is able to exploit. Future research will explore how to take advantage of these microhabitats in pest management programs.     

Effect of relative humidity on population growth of <Emphasis Type="Italic">Apolygus lucorum</Emphasis> (Heteroptera: Miridae)

Apolygus lucorum (Meyer-Dür) (Heteroptera: Miridae) is a significant insect pest of cotton, Chinese dates, grapes and many other crops in China, and its populations typically increase after heavy rains. However, the intrinsic mechanism of the rainfall-dependent outbreak is not yet fully understood. In our study, the effect of different relative humidity (RH), 40, 50, 60, 70, and 80% RH, on population growth of A. lucorum was evaluated in the laboratory. High humidity (e.g. 70 and 80% RH) was observed to significantly increase egg and nymph survival, prolong adult life longevity, and improve female fecundity. However, low humidity (e.g. 40 and 50% RH) led to unfavorable effects on survival and fecundity. As a result, the intrinsic capacity for increase (r _m), net production (R _o), and the finite rate of increase (λ) of A. lucorum population greatly increased with increasing relative humidity. Additionally, the relationships between r _m and R _o and relative humidity were good fits to the logistic models y = 36.82/(1 + Exp(10.76 − 0.19x)) (p < 0.001) and y = 0.10/(1 + Exp(9.26 − 0.19x)) (p = 0.003), respectively. This study provides insight into the phenology of A. lucorum, and may contribute to modeling of its population dynamics.     

Seasonal morphotypes of Drosophila suzukii differ in key life‐history traits during and after a prolonged period of cold exposure

Seasonal polyphenism in Drosophila suzukii manifests itself in two discrete adult morphotypes, the “winter morph” (WM) and the “summer morph” (SM). These morphotypes are known to differ in thermal stress tolerance, and they co‐occur during parts of the year. In this study, we aimed to estimate morph‐specific survival and fecundity in laboratory settings simulating field conditions. We specifically analyzed how WM and SM D. suzukii differed in mortality and reproduction during and after a period of cold exposure resembling winter and spring conditions in temperate climates. The median lifespan of D. suzukii varied around 5 months for the WM flies and around 7 months for the SM flies. WM flies showed higher survival during the cold‐exposure period compared with SM flies, and especially SM males suffered high mortality under these conditions. In contrast, SM flies had lower mortality rates than WM flies under spring‐like conditions. Intriguingly, reproductive status (virgin or mated) did not impact the fly survival, either during the cold exposure or during spring‐like conditions. Even though the reproductive potential of WM flies was greatly reduced compared with SM flies, both WM and SM females that had mated before the cold exposure were able to continuously produce viable offspring for 5 months under spring‐like conditions. Finally, the fertility of the overwintered WM males was almost zero, while the surviving SM males did not suffer reduced fertility. Combined with other studies on D. suzukii monitoring and overwintering behavior, these results suggest that overwintered flies of both morphotypes could live long enough to infest the first commercial crops of the season. The high mortality of SM males and the low fertility of WM males after prolonged cold exposure also highlight the necessity for females to store sperm over winter to be able to start reproducing early in the following spring.     

The effect of border sprays and between‐row soil tillage on Drosophila suzukii in organic blackberry production

Drosophila suzukii (Matsumura) is a major pest of soft‐skinned fruit. Females have an enlarged serrated ovipositor that is used to cut into ripening fruit and lay their eggs. Larvae develop inside infested fruit, rendering fruit unmarketable. Previous research has indicated that D. suzukii can move from adjacent woodlands into cultivated fields. Furthermore, multiple generations can occur in a single season as a result of fallen, infested fruit in the fields. Our hypothesis was that border sprays and soil tillage of field aisles can reduce D. suzukii presence in commercial blackberry fields (Rubus spp.). To test our hypothesis, we conducted split‐plot field trials in organic blackberry fields for 3 and 4 weeks in 2014 and 2015, respectively. Treatments were border sprays (whole plot, pyrethrins + azadirachtin) and tillage (subplot, ~15 cm). We evaluated adult D. suzukii in both years and berry infestation and natural enemies in 2015 only. We found that plots with border treatments had fewer D. suzukii (larvae and adults) than plots without border sprays. Tilling the soil between rows of blackberry bushes did not have a significant effect on adult captures or larval infestation of fruit. Natural enemies were unaffected by the border spray and tillage treatments. Our results confirmed our hypothesis that border sprays can be utilized to reduce populations of D. suzukii in organic blackberry fields, while maintaining populations of natural enemies. However, the effect of soil tillage is unclear and requires further investigation. Additional research should investigate the timing of border sprays and their effect on high infestations of D. suzukii as well as quantify fruit fall and depth of burial to reduce D. suzukii emergence using soil tillage.     

Effects of temperature and relative humidity on mating and survival of sterile Drosophila suzukii

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) is a widely distributed pest species of soft-skinned fruits. Recent studies suggest the use of sterile insect technique (SIT) as a control method for this species; however, many factors can impact effectiveness of a SIT programme, including the environmental conditions. Environmental condition is critical at the time of the release and in the days afterwards, since it may impact sterile insects’ survival and ability to mate. Thus, we verified the influence of temperature and relative humidity on mating and survival of fertile and sterile D. suzukii, when insects were food provided or deprived. Highest mating rates occurred when sterile or fertile flies provided with food were exposed to 25ºC or 81%–100% relative humidity, while temperatures of 10 and 35ºC and humidity below 60% impaired mating. Overall, mating rate among food-deprived flies was low in all temperatures and humidity levels tested, but fertile insects were more prone to mate when compared to sterile flies. Survival was negatively influenced by high temperatures, low relative humidity and food deprivation. The information present in this study is useful to be considered for release of sterile D. suzukii.     

Effect of temperature on reproduction,development, and phenotypic plasticity of Drosophila suzukii in Brazil

Temperature is a determining factor for the development and establishment potential of insect pests. The present study describes the impact of temperature (13, 18, 23, 25, 28, 30, and 33 °C) on the life cycle parameters and phenotypic plasticity of South American populations of Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) in the laboratory. Secondary objectives were to determine the lower thermal threshold and thermal constant to estimate the number of annual generations of the insect in small-fruit-producing regions in Brazil. The highest egg-to-adult survival was recorded at 23 and 25 °C. At 30 and 33 °C, no emergence of D. suzukii was observed. The egg-to-adult development time was shortest at 25 and 28 °C (ca. 10 days). The net reproductive rate (R₀), and the intrinsic rate of population increase (r_m) were highest at 23 and 25 °C. In contrast, temperatures of 13 and 28 °C generated largest and smallest body sizes, respectively, and caused reductions of 99 and 93% in R₀. The estimated lower thermal threshold was 7.8 °C for egg-to-adult survival. The estimated thermal constant was 185.8 degree days, and the estimated annual number of generations of D. suzukii ranged from 17.1 in cold regions to 27.2 in warm regions. The results of the present study are important for understanding D. suzukii occurrence in the field, contributing to more informed and precise pest management.     

Seasonal monitoring of Drosophila suzukii (Diptera: Drosophilidae) in a mixed fruit production system

Drosophila suzukii Matsumura (Diptera: Drosophilidae), an invasive pest native to Southeast Asia, is now reported throughout North America and Europe. We used traps baited with apple cider vinegar to monitor D. suzukii adult presence in multiple crops and associated fruiting plants at the Wolfskill USDA Germplasm Repository in Winters, CA, USA from 2011 to 2013. Traps were placed in small (~ 160 m × 40 m on average) almond, apricot, cherry, fig, grape, mulberry, peach, persimmon, plum, and pomegranate deciduous fruit orchard blocks as well as a citrus block and evergreen trees located near a house at the repository. D. suzukii was present in all blocks with the greatest monthly deciduous fruit captures in the cherry and fig blocks. Few D. suzukii were captured in almond, apricot, pomegranate and grape blocks. Deciduous fruit blocks had two distinct periods of trap capture: spring through midsummer and again in fall. Most deciduous fruit blocks had low trap captures during the hottest summer months (August to September) and the coldest winter months (December to April). However, from late December through mid-January, high trap captures were associated with the citrus and house sites. This study provides seasonal trapping data of D. suzukii adults in an unsprayed multi-crop mosaic, and may serve as a model of adult capture patterns across smaller mixed-crop commercial orchards and associated urban landscapes.     

Distribution and activity of Drosophila suzukii in cultivated raspberry and surrounding vegetation

Spotted wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), may utilize wild ‘Himalaya’ blackberry (HB) Rubus armeniacus Focke or other non‐crop plants as refugia and possibly exploit adjacent field margins before colonizing cultivated fruiting crops. Studies were conducted to determine the role of field margins containing HB and their effect on D. suzukii activity, density and distribution in an adjacent commercial red raspberry crop. One‐ha plots adjacent to field margins containing HB or known non‐host (NH) grass crops were established in 2011 and 2012 and replicated three times. Each plot contained two transects with monitoring traps for D. suzukii in the field margin (0 m) and spaced approximately 10 (crop boundary), 40, 70 and 100 m into the adjacent crop (n = 10 traps/plot). Field margin vegetation was treated with a 10% chicken egg white mark solution weekly from pre‐harvest until the end of harvest using a cannon sprayer. Adult D. suzukii were collected from traps weekly and analysed for the presence of the egg white mark using an egg white‐specific enzyme‐linked immunosorbent assay (ELISA). During both years, marked flies and total flies were captured in higher numbers in HB field margins, whereas virtually no flies were captured in field margins containing no known alternative host. Similarly, more flies were captured in the crop near HB than near NH. Spatial Analysis by Distance IndicEs (SADIE) and mean D. suzukii trap captures additionally displayed significantly higher fly densities in the raspberry field near HB than near NH. These results suggest that HB may contribute to elevated D. suzukii populations and pest pressure in comparison with field margins containing no known alternate host vegetation for D. suzukii. Having closely adjacent non‐crop alternate host landscapes may result in increased D. suzukii pest pressure.     

Physiological status of Drosophila suzukii (Diptera: Drosophilidae) affects their response to attractive odours

An improved understanding of the biology of the invasive pest, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), is critical for the development of effective management strategies. Trapping is one technique used for both detection and control; however, the efficacy of trapping can vary depending on the target insect's physiological state, its behavioural priorities and the type of attractant used in the trap. We conducted a series of caged trapping experiments and a greenhouse trapping experiment to investigate the effects of D. suzukii feeding status, age, mating status, ovipositional status and seasonal morph type on the capture rate of traps baited with fermentation odours. Starved flies were trapped at greater rates compared to fed flies; more virgin flies were trapped than mated flies; flies deprived of an oviposition substrate were trapped more frequently than flies given an oviposition substrate. It is still unclear whether age or seasonal morphology affect bait response. Lastly, a caged choice experiment investigated the relationship between female reproductive status and attraction to fermentation or fruit odours. Fermentation‐based traps captured female flies regardless of their reproductive status but, ripe fruit‐based traps were more attractive to flies with more than seven eggs. In summary, studies that use fermentation‐based traps should recognize that capture rates of D. suzukii will depend on the feeding, mating and oviposition experiences of the population; also, fruit‐based traps may better target gravid females.     

Susceptibility of cold hardy grapes to Drosophila suzukii (Diptera: Drosophilidae)

Drosophila suzukii (Diptera: Drosophilidae), known commonly as spotted wing drosophila, is a vinegar fly originating from South‐East Asia and a major pest to many soft‐skinned fruits. Due to the species recent arrival in North America in 2008, many fruit varieties are yet untested for susceptibility to infestation. While previous work has focused on Vitis vinifera, this study aimed to determine grape susceptibility of cold hardy varieties based on hybrids of V. labrusca, V. riparia and V. vinifera. Field sampling was conducted in Southern Wisconsin (USA) vineyards to establish adult and larval abundance and determine whether the number of adults caught in traps correlates with fruit infestation. Host susceptibility was further assessed through no‐choice bioassays of both intact and damaged fruits. The field study found D. suzukii adults present in all varieties, low larval abundance and no correlation between adult abundance and larval presence. Peak adult abundance occurred mid‐season between veraison and harvest, while larval infestation rates were highest near harvest. In laboratory no‐choice tests, significantly more eggs, larvae and adults occurred in damaged than undamaged grapes. In damaged grapes, larvae and adult abundance was comparable between varieties and to the highly susceptible control of undamaged raspberry; however, D. suzukii developed significantly faster in raspberry than grapes. Fruit characteristics (°Brix, titratable acidity, pH) in grapes were uncorrelated with D. suzukii performance. Together, these findings suggest that cold hardy grapes are overall resistant to D. suzukii if intact and highly susceptible if damaged.     

Humidity‐controlled cold storage of Neoseiulus californicus (Acari: Phytoseiidae): effects on male survival and reproductive ability

Humidification can suppress water loss from an organism and has great potential for improving the cold storage of short‐lived arthropods, such as predatory mites. The effectiveness of humidity‐controlled cold storage was recently verified for Neoseiulus californicus (McGregor) females but was not examined for males. Combining both males and females in one storage protocol might increase the predator population because it would enhance the opportunity for multiple mating, which is necessary for females to maximize their egg production. Newly emerged adult males were stored at an air temperature of 5°C and relative humidity (RH) of 100% or 80%. The median survival time (LT₅₀) was 32 days at 100% RH and 14 days at 80% RH; the survival curves differed significantly. Males stored at 100% RH for 0, 10, 20 and 30 days were introduced to virgin females for mating at 25°C to evaluate their reproductive ability. The pre‐oviposition period was significantly prolonged in the females mated with males stored for ≥20 days. No negative effects of storage were observed on the oviposition period, total number of eggs or net reproduction rate (R₀) in the females mated with males stored for ≤20 days or on the mean generation time (T) for those stored for 30 days. A slight decrease in the intrinsic rate of increase (r_m) was observed in the females mated with males stored for ≥20 days. Our storage method can preserve N. californicus males for 20 days with only a minor reduction in their survival and reproductive ability.     

Improving monitoring tools for spotted wing drosophila,Drosophila suzukii

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) were trapped in the field using colored plastic sphere traps coated with insect Tangle‐trap. Red and black spheres captured significantly more D. suzukii than white spheres. Translucent deli‐cup traps deployed in cherry orchards and baited with yeast, the Alpha Scents lure, or the Scentry lure captured significantly more flies than the Trécé lure and Suzukii bait; all attractants had poor selectivity for D. suzukii. No‐choice evaluations of attractants conducted in field cages corroborated the cherry orchard field study, though translucent deli‐cup traps provisioned with the yeast bait captured significantly more flies than those baited with the Alpha Scents lure. Red sphere traps baited with the Scentry lure captured 3–6× more flies than the deli‐cup trap baited with the same lure, and 3–4× more flies than the deli‐cup trap baited with yeast bait, demonstrating that a trap integrating both visual and olfactory cues is a superior tool for monitoring D. suzukii. Moreover, this simple sticky, dry trap design requires far less labor and maintenance than does a liquid‐based deli‐cup trap.     

Effect of temperature on the development time and life-time fecundity of Trichopria anastrephae parasitizing Drosophila suzukii

The aim of this study was to evaluate the effect of temperature (10, 15, 20, 25, 30 and 35°C), on the development time and life-time fecundity of Trichopria anastrephae Lima, 1940 (Hymenoptera: Diapriidae) parasitizing Drosophila suzukii (Matsumura, 1931) (Diptera: Drosophilidae). D. suzukii pupae that were up to 24-hr old were submitted to T. anastrephae parasitism for 24 hr. They were placed in plastic containers (50 ml) (ten pupae per container) in climatic chambers at temperatures of 10, 15, 20, 25, 30 and 35°C ± 1°C with a relative humidity of 70% ± 10% and a 12 hr photoperiod. For the adult phase, T. anastrephae couples that were up to 24 hr old were each placed in plastic cages (300 ml) and kept at the same temperatures cited above until their deaths. The higher numbers of parasitism and offspring production were obtained at temperatures between 15 and 25ºC. At the temperatures of 10 and 35ºC, there was no emergence of individuals. The lower thermal threshold (Tt) for the egg to adult period was ≈ 14.6°C for males and females with thermal constants (K) of 384.61 and 432.90, respectively. In terms of the fertility life table, T. anastrephae at 20 and 25°C presented shorter generation time (T) and higher net reproductive rates (Ro) in relation to other temperatures. The data show the ability of T. anastrephae to adapt to different thermal conditions, which is important for biological control programmes of D. suzukii.     

Nutritional geometry and fitness consequences in Drosophila suzukii,the Spotted‐Wing Drosophila

Since its arrival to North America less than a decade ago, the invasive Spotted‐Wing Drosophila (Drosophila suzukii) has inflicted substantial economic losses on soft fruit agriculture due to its ability to oviposit into ripening fruits. More effective management approaches for this species are needed, but little is known about the factors that influence behavioral choices made by D. suzukii when selecting hosts, or the consequences that their offspring experience when developing in different environments. Using a nutritional geometry methodology, we found that the ratio of proteins‐to‐carbohydrates (P:C) present in media greatly influenced adult D. suzukii behavior and subsequent offspring development. Whereas adult flies showed a strong bias in their oviposition and association behaviors toward carbohydrate‐rich foods, larval survival and eclosion rate were strongly dependent on protein availability. Here, we explore the preference–performance hypothesis (PPH), in which females are predicted to oviposit on medias that provide the greatest offspring benefits, in regard to its relevance in D. suzukii behavior and consequences for management. Our results provide valuable insight into the ecology and evolution of this species that may hopefully lead to more effective management strategies.     

Life Table Parameters of Three Mirid Bug (Adelphocoris) Species (Hemiptera: Miridae) under Contrasted Relative Humidity Regimes

The genus Adelphocoris (Hemiptera: Miridae) is a group of important insect pests of Bt cotton in China. The three dominant species are A. lineolatus, A. suturalis, and A. fasciaticollis, and these species have different population dynamics. The causal factors for the differences in population dynamics have not been determined; one hypothesis is that humidity may be important for the growth of Adelphocoris populations. In the laboratory, the demographic parameters of the three Adelphocoris species were compared when the mirid bugs were subjected to various levels of relative humidity (40, 50, 60, 70 and 80% RH). Middle to high levels of RH (60, 70 and 80%) were associated with higher egg and nymph survival rates and increased adult longevity and female fecundity. Lower humidity levels (40 and 50% RH) had negative effects on the survival of nymphs, adult longevity and fecundity. The intrinsic rate of increase (r_m), the net reproductive rate (R₀) and the finite rate of increase (λ) for each Adelphocoris species increased with increasing RH. Significant positive relationships were found between RH and the life table parameters, r_m, R₀ and λ for the three Adelphocoris species. These results will help to better understand the phenology of the three Adelphocoris species, and the information can be used in population growth models to optimize pest forecasting and management strategies for these key pests.     

Integrating Temperature-Dependent Life Table Data into a Matrix Projection Model for Drosophila suzukii Population Estimation

Temperature-dependent fecundity and survival data was integrated into a matrix population model to describe relative Drosophila suzukii Matsumura (Diptera: Drosophilidae) population increase and age structure based on environmental conditions. This novel modification of the classic Leslie matrix population model is presented as a way to examine how insect populations interact with the environment, and has application as a predictor of population density. For D. suzukii, we examined model implications for pest pressure on crops. As case studies, we examined model predictions in three small fruit production regions in the United States (US) and one in Italy. These production regions have distinctly different climates. In general, patterns of adult D. suzukii trap activity broadly mimicked seasonal population levels predicted by the model using only temperature data. Age structure of estimated populations suggest that trap and fruit infestation data are of limited value and are insufficient for model validation. Thus, we suggest alternative experiments for validation. The model is advantageous in that it provides stage-specific population estimation, which can potentially guide management strategies and provide unique opportunities to simulate stage-specific management effects such as insecticide applications or the effect of biological control on a specific life-stage. The two factors that drive initiation of the model are suitable temperatures (biofix) and availability of a suitable host medium (fruit). Although there are many factors affecting population dynamics of D. suzukii in the field, temperature-dependent survival and reproduction are believed to be the main drivers for D. suzukii populations.     

Screening of 25 different natural crop protection products against Drosophila suzukii

Drosophila suzukii is a major pest of soft‐skinned fruits, and insecticides are often used to prevent fruit damage caused by oviposition. As D. suzukii produces many generations per year, repeated insecticide applications are required. Furthermore, D. suzukii attacks ripening and ripe fruits shortly before harvest. Therefore, the use of synthetic insecticides is limited by long pre‐harvest intervals and maximum residue limits. To be able to offer producers immediate and sustainable solutions, we tested 25 natural crop protection products with three different application methods in a laboratory screening. We show that application method is an important factor for the efficacy of the tested products. Of six natural insecticides, only Spinosad was toxic for D. suzukii and reduced the oviposition on treated blueberries. The tested oil products had no control effect and products based on different entomopathogenic fungi and Bacillus thuringiensis rather enhanced oviposition. Mineral products (Kaolin, CaCO₃, Ca(OH)₂ and clinoptilolith) applied as spray solutions were not toxic, but significantly reduced oviposition on blueberries. We provide the first study in which different application methods have been used to compare numerous, commercially available, natural crop protection products with different modes of action against adult D. suzukii. Our findings provide consultants and producers with important insights for the development of sustainable pest control strategies against D. suzukii.