Flies were constantly provided with water and artificial diet that served as both a food source and an oviposition medium. Before their use in experiments, all flies were allowed to mate for 8 d in mixed-sex cages. Some small fruit varieties were numbered since this information is proprietary.This trial was conducted in Oxnard, California, USA on highbush blueberry plots during 2020. Plants were irrigated with three drip stakes per plot ten times a day for ten-minute intervals delivering 1.1 liters of water per hour. Screenhouses were fully enclosed with screen material to prevent insects from entering. There were three 70 m x 5 m screenhouses with GUM or UTC treatment randomly assigned to the north or south end of each screenhouse for a total of 6 plots. Within each screenhouse, treatment plots contained twelve plants in two rows, and plots were separated by 45 m. one-hundred flies were released in each plot four times, once per week. Three GUM deployment plots were compared with three UTC plots. GUM dispensers were installed in every other plant with irrigation stakes placed directly through the pads. The GUM application was completed on 14 April. Plots were sampled every seven days from 14 April to 12 May. One sample consisted of 50 berries.Ten field trials were conducted from September to November 2020 across multiple coastal production regions in California, USA , at different ranches and on multiple varieties being grown under high tunnels. Each location was a replicate consisting of two plots and were randomly assigned at each ranch to GUM or to UTC. Plots within a ranch received similar irrigation, fertilizer, flower buckets wholesale and insecticides. Each plot received a minimum of four spinosad sprays timed 7-10 days apart during the cropping period and based on monitoring trends from fruit collections.

Additional peroxyacetic acid applications were applied at 2-3 day intervals after each spinosad application, followed by a C. subtsugae application 1-2 d after each peroxyacetic acid application. Throughout the experimental periods, GUM dispensers were distributed evenly throughout each plot and replaced every 21 days. GUM dispensers were staked directly under the drip line in soil plots, and irrigation stakes were placed directly through the dispenser in substrate plantings. Six fruit samples were collected from each treatment plot every week for 4 to 12 weeks. Samples were collected at least 2 m from each edge of the tunnel as well as from the center of the tunnel approximately 20- 30 m from the edge of the tunnel and at ~0.75 m from the ground. Each sample consisted of 50 berries. Sample berries were incubated at room temperature for 2-4 days to allow for larval growth and facilitate detection. Samples were evaluated by crushing fruit and submerging them in a saltwater solution . The crushed fruit solution was then poured into a tray where D. suzukii larvae subsequently floated to the top of the solution and were counted.The buildup of D. suzukii populations was modeled under four scenarios i.e.; no intervention , GUM only, insecticide , and GUM and insecticide . The model parameters were obtained from experimental work and iterations of the model have been used in previous studies . Recorded D. suzukii population levels and weather data were used as model inputs. Outputs from the model were directly compared with D. suzukii infestation data of the blueberry field trial 1 . This trial was selected because of its relatively long duration and is most suitable for describing population build-up. Ambient temperature influences the fecundity rates, mortality rates, and maturation delays of the four principal life stages . The simulations were based on daily mean temperature data recorded at Aurora, Oregon, USA, between June and September 2020. We assumed that the flies had access to unlimited fruit and that no other factors affected population dynamics .

Parameter values, including for fecundity rates, mortality rates, and maturation delays, were obtained from laboratory experiments on blueberry . The simulations were initialized on 30 June with a population composed equally of adult males and females. The model simulations track relative population densities, and the initial adult density was chosen so that the simulated egg density matched the final eggs/berry in the UTC treatment. The GUM dispensers were assumed to reduce D. suzukii fecundity by 49%, according to data from Tait et al. . Insecticide induced mortality rates caused by GS were calculated from laboratory data . Spinosad was used as insecticide model. The effects of GUM and GS were assumed to start on 9 July in accordance with the model design. Details on the model and on how the GS and GUM treatments were implemented can be found in the Supplementary Material. The simulations were implemented using Wolfram Mathematica 13.0 . The code for the simulations is available online1 .The current study supports findings from previous laboratory and small-scale field cage trials. Here we show through field collected and modeled data that food-grade gum use can reduce D. suzukii fruit damage . The aim of this work was to acquire detailed knowledge about limitations of food-grade gum in a range of commercial cropping systems including blueberry, blackberry, cherry, raspberry, strawberry, and winegrape. These studies were conducted in two key production regions i.e., California and Oregon in the USA. The overall results supported initial findings and provided additional evidence that this tool can reduce D. suzukii crop damage especially when applied together with the grower standard. Both field-collected data and model simulations indicates that there is a synergistic effect of food-grade gum when used in combination with a conventional insecticide. For most of the experiments , field plots receiving the food-grade gum resulted in either numerical or statistical differences in D. suzukii damage compared to untreated control plots. This was not recorded for the cherry, strawberry, and blackberry trials. Reasonable hypothesis about these data are discussed below. In trials where D. suzukii infestations were measured in buffer plots , there was evidence of a reduction in damage, but not at the same level as in plots treated by the food-grade gum. Overall, considering all the trials, crop damage was reduced up to 78% over a period of up to 21 days post application of the food-grade gum. The results from the current study indicate that the food-grade gum can be used in combination with standard insecticides , and in some cases as a stand-alone treatment to reduce the infestation level of D. suzukii. Similar reductions in D. suzukii damage were reported under laboratory and controlled semi-field conditions , suggesting that the food-grade gum resulted in lower damage due to oviposition. These findings support earlier results where the effects of semiochemical volatiles emanating from the food-grade gum resulted in significant behavioral changes . In several trials, data lower oviposition and fruit infestation in the presence of the food-grade gum under field conditions. Reasons of why in multiple trials a statistical difference was not reached, can be explained by multiple parameters observed by scientists and growers such as animals removing the cottons pads, water-irrigation issues, and wind. These factors are addressed in a future publication . In the Hood River cherry trial, constant windy conditions may have resulted in dispersion of volatiles, flower harvest buckets ultimately resulting in impacts that were less pronounced. There is little doubt that efficiency of the food-grade gum can vary depending on production conditions and crop . Host preference of D.suzukii was ranked 4th for cherry, followed by blueberry and winegrape . Such differences in host preference should be considered when applying food-grade gum.

Synthetic blends can be less attractive compared to the actual fruit; thus, additional adjustments may be required to minimize egg-laying in the fruit. Results showed that the application of the food-grade gum in grape shows clear impacts to protect berries from D. suzukii attack. Considering the vulnerability of several winegrape cultivars towards D. suzukii and the encouraging results collected, we have reasons to believe that the food-grade gum can be a useful tool for the winegrape production. For the food-grade gum applications in blueberry in open field experiments, the infestation rate for the food-grade gum and grower standard were 70% and 85% lower than that for untreated control respectively, with the food-grade gum treatment resulted in a significantly lower infestation rate compared with the control. Open and semi-field experiments conducted in California provide similar outcomes to those in Oregon. Blueberry experiments conducted in California within a screenhouse provided 45.5% egg reduction. There were sequential applications with differing timing and the results indicated that early applications resulted in lower egg reductions . A potential hypothesis for this phenomenon could be related to environmental conditions including temperature and humidity that could significantly change the emission of plant volatiles . Egg reduction in raspberry and blackberry varied from 42-90% and 24-70% respectively. Two cultivars of raspberry have been subjected to the trial and in both cases there was reduction in egg infestation. For blackberry the same cultivar has been evaluated but in three different farms. Results were consistent between the different locations. For strawberry, in several cases results showed numerically increased larval levels compared in the food-grade gum treatments. A potential hypothesis for this phenomenon could be related to either unreported production practices or environmental conditions that could significantly change the emission of plant volatiles or the food-grade gum. Other reasons that can justify the negative results, range from lack of irrigation to rodents removing food-grade gum within a day of placement . The trial run in Watsonville, California, showed a numerical reduction of eggs when the foodgrade gum was applied as standalone and in combination with pesticide. As discussed previously, multiple factors may have impacted the trial. Meta-analysis to determine differences between food-grade gum and untreated control and mean larvae resulted in a highly significant difference. Despite the non-statistical significant results gotten in multiple trials, the meta-analysis showed that by analyzing together all the trials, the food-grade gum has a significant positive effect on protecting fruits from D. suzukii infestation. The data originated clearly indicate that the presence of the food-grade gum substrate is a valid approach to keep D. suzukii away from berries. This analysis seems extremely valuable because it provides a general idea of how, overall, the use of the new tool has the potential to bring benefits to the small berry industries all over the world. For this study, the initial D. suzukii adult densities were fitted to match the untreated control treatment. The relatively similar trends displayed between simulations and real data suggest that model assumptions are close to representative of treatments. Simulation outputs however differed slightly from the field data in the earlier phase of the season. The simulations suggest an earlier buildup of D. suzukii populations compared to the sudden increase of infestation in the field trial. A reason for this difference could be that the model output was compared with the experimental data by assuming that the simulated egg population is proportional to the mean number of eggs found per fruit in the experiments. This assumption is reasonable for constant fruit levels, but the availability of ripe fruit in the trials were not constant. Under commercial field conditions, fruit is harvested every 7-10 days for this cultivar. This means that less susceptible fruit is available directly after every harvest event, likely negatively impacting D. suzukii population levels. Therefore, a high availability of ripe fruit in the middle portion of the experiment likely resulted in fewer eggs laid per berry compared to later in the season when fruit are less available. These differences in ovipositional resources likely resulted in the sudden increase in recorded infestation levels towards the latter portion of the experiment. Future work should focus on these relationships of pest population level and crop availability to determine risk. Finally, data collected under different environmental conditions over periods ranging from 10 to 60 days do not appear to impact the efficacy of the food-grade gum. Treated fruits were less damaged by D. suzukii. Additional factors such as active distance, commercial field longevity and improved formulation will result in additional improvements and future adoption.The Berry phase has played significant roles in many aspects of physics, ranging from atoms to molecules to condensed-matter systems.