Oregon weather data were used to illustrate the impact of the different levels of parasitism on D. suzukii populations.In the U.S.A. and Italy, the current suite of parasitoids attack only late larval and early pupal life stages of D. suzukii, and field rates of parasitism are estimated to be around 2 % . In the biological control model runs, we made the simplifying assumptions that parasitism remains constant and that parasitism is attributable only to limited biological control agents based on field observations . For Oregon, we also assumed abundance of alternate hosts in surrounding vegetation from March 1, and that oviposition is possible as soon as the reproductive thresholds are met . Collections from South Korea show parasitism rates as high as 17 % . For these reasons, 2 and 15 % parasitism on the late larvalearly pupal life stages of D. suzukii were incorporated into the model on a season-long basis and compared to populations exhibiting no parasitism. These model runs would illustrate current and potential future population impact because of classical biological control using parasitoids.This research suggests that DD are very useful for estimating physiological time, and their use extends beyond phenology models. In addition, we describe the impacts of IPM strategies on early-season D. suzukii populations presumed to consist mainly of adults. The data presented are an alternative to the model developed by Wiman et al. to estimate populations of D. suzukii within environmentally known thermal thresholds. Previously, 10 plastic plant pots insects were forced to progress through the age-structured matrix with mandatory daily advancement without taking into consideration physiological age.
An advantage of the current model structure is that it allows flies to proceed through the physiological age-structured matrix contingent on accumulation of physiological time as approximated by DD. This refinement to the model allows survival and reproduction of concurrent cohorts comprising a population to be more precisely estimated. The two functions that describe mortality and fecundity within thermal thresholds in physiological time provided good fit using standard population survival and fecundity fitting techniques. We realize that a partial or complete shift of phenotypes inresponse to temperature extremes is not taken into account. However, future modeling efforts will be aimed at capturing phenotypic plasticity and its implications for survival and reproduction of populations experiencing extreme environmental conditions. We provided parameters of D. suzukii survival outside of thermal development thresholds, simulating a sudden transition to extreme cold. The fitted exponential function describes the survival rates of un-acclimated D. suzukii populations under prolonged environmental conditions. When exposed to suboptimal temperatures, un-acclimated D. suzukii populations clearly display high mortality rates. Theoretically, the horizontal asymptote of the fitted exponential function will not result in the extinction of winter or summer populations under these extreme conditions, and in the field, this phenomenon is observed as populations build during periods of favorable temperatures. Investigation of this observation, however, falls outside the scope of the current study where we focused on the growing season.
We therefore realize that the ability to estimate population response to a wide range of changing environmental conditions will further improve population estimation of adaptive invasive species such as D. suzukii. One step was made to more clearly understand how improving environmental conditions impact winter-surviving D. suzukii reproductive potential. Dissections of latedormant female D. suzukii from Oregon and Washington, U.S.A., and Trentino, Italy, displayed increasing levels of reproductive maturity as DD accumulated. Our laboratory data show that egg laying is initiated at 210 DD, whereas field increases in reproductive potential range from 50 to 800 DD. There may be various explanations for these differences, including year, microclimate, genetic variability, and trapping techniques. Although the timing of reproductive maturity with DD in these studies differed, the data nevertheless show a clear relationship between reproductive potential and physiological time. These data illustrate the importance of more suitable environmental conditions as a factor contributing to increased reproductive potential of D. suzukii. We realize that temperature is not the only factor contributing toward such increased reproductive potential, as the roles of humidity, alternate food sources, and host media during the late dormant period of D. suzukii may also need consideration . Our data suggest that in some regions, female sexual maturity may occur very early in the growing season before hosts become widely available. The lack of suitable fruit hosts in certain areas early in the growing season likely makes D. suzukii more dependent on alternate nutrient sources. These sources include pollen and nectar, which may be utilized by D. suzukii to increase reproductive potential and survival levels.
Such resource availability may be a factor resulting in variability of our data. For these reasons, it is important in the future to describe the contribution of these different factors to D. suzukii population dynamics. Clear parameters should be developed to more accurately model early-season D. suzukii population increase. We used a model to illustrate the importance of key periods when pest population structures can be exploited to the advantage of IPM . To the best of our current understanding of the structure of D. suzukii populations, adult females comprise the majority of overwintering individuals . Thus, early spring is a key period when only sexually maturing adults are present. Elimination of these initial adults before the population becomes established and spread among different ages would be ideal. In Parlier, California, U.S.A., a second key period exists during the summer when suboptimal hot temperatures prevail and D. suzukii populations decline. Insecticide A had a longer-lasting residual against adult stages and a shorter residual against immature stages as compared with Insecticide B, which explains the strongest effect on the early-season population. Insecticide B model runs simulated compounds designed to cause mortality at all life stages of D. suzukii . These compounds are of increasing importance as the population age structure becomes more diverse. In the early season, as in our simulation, adults dominate. During latter portions of the season, larger portions of D. suzukii populations are expected to be in immature life stages. During such latter portions of the growing season, there should be increased focus on pesticides that target all life stages of D. suzukii. The use of adulticides to prevent fruit rejections due to infestation before harvest when all ages of flies are present, however, will remain a key component of IPM programs. Additional considerations include the development of D. suzukii insecticide protocols to minimize the development of insecticide resistance. Genetic control using RNAi biopesticide technology with seven-day residual periods against all life stages resulted in minimal population reduction compared with untreated populations. Again, targeting of larvae makes more of a difference on structurally diverse populations. The utility of this technology to target immature life stages of D. suzukii may make it more effective at curatively managing pest populations compared to the adulticides during periods when immature life stages dominate the population structure. An additional advantage of such genetic pest management tools is that they can be designed to be species-specific and target D. suzukii only. Disadvantages currently include regulatory obstacles, wary public perception, and potential incompatibility with organic production practices. Both levels of biological control inputted into model runs resulted in D. suzukii suppression. Higher levels of parasitism will probably result in concomitantly lower levels of pest pressure during the harvest period. Currently, only low levels of biological control are found in most production regions . Model runs indicate that levels of parasitism close to 15 % will result in significant reductions of pest populations during the early portion of the season due to the loss of a portion of the initial crop-infesting population. Biological control is only effective, however, plastic pots large if it can suppress pest populations as the crop ripens. Model outputs estimate lower levels of suppression during the earlier portion of the season at the 2 % level of biological control. Clearly parasitism, particularly at the higher rate, helped to destabilize the D. suzukii population and is an effect that may be enhanced by additional compatible control measures.
Overall, these data suggest that biological control, as it currently stands, will not be effective as a standalone management tactic but will result in additive contributions to IPM programs targeting D. suzukii. Increased benefit will undoubtedly be gained from additional classic biological control introductions. We believe that the refined model presented here can be used as a comparative tool for practitioners and scientists, and such models will allow for the integration and optimization of multiple IPM technologies. This approach also illustrates that IPM practitioners should take advantage of environmental conditions that create vulnerability of the pest to management activities. During more suitable summer conditions, alternative factors such as pesticide use and biological control are considered as key management techniques. We realize that manipulations of D. suzukii populations are not the only factors that can be used in IPM strategies. Behavioral techniques including push–pull strategies, cultural methods, and insect barriers could also contribute to sustainable management of D. suzukii. In practice, IPM strategies often focus on single technologies including biological control, host plant resistance, chemical pesticides, or biopesticides. Typically, very little attention is given to the interaction or compatibility of the different technologies used and their timing . Future studies using stage-structured models such as the one presented here should be conducted to investigate these interactions. We realize that population modeling is only one approach for understanding how to manage this damaging pest. However, it can provide powerful insights into the relative performance of different tactics and combinations, and we expect that population modeling will allow rapid assessment of different integrated control programs and their expected performance under different environmental conditions.Cardiometabolic diseases encompass a cluster of cardiovascular, metabolic, prothrombotic, and inflammatory abnormalities that are recognized as disease states by the American Society of Endocrinology, the National Cholesterol Education Program, and the WHO . Food intake plays a key role in reducing the risk of cardiometabolic diseases, with data suggesting that >30% of all deaths could be prevented through dietary changes, particularly by increased consumption of plant based foods . Plant foods are rich sources of fiber and essential micronutrients, such as vitamins and minerals. They are also sources of a large group of bio-active compounds, which might not be essential throughout life or cause clinically manifested deficiencies, but when consumed with the diet, these phytochemicals may promote health and wellbeing in adulthood and the elderly population by reducing the risk of age-related chronic diseases . The major categories of dietary phytochemicals include polyphenols, such as flavonoids or phenolic acids, carotenoids, or plant sterols.Growing evidence from mechanistic studies, clinical trials, and prospective cohort studies suggest that these bio-active compounds may help in promoting health when consumed as part of the habitual diet. Polyphenols are secondary metabolites of plants and are found in fruits, vegetables, and their products . Carotenoids, including b-carotene, lycopene, lutein, and zeaxanthin, are phytochemicals found in many fruits and vegetables and account for the brilliant colors of these foods . Phytosterols are cholesterol-like molecules found in all plant foods, with the highest concentrations occurring in vegetable oils, but they can also be found in nuts, breads, or whole vegetables . Furthermore, caffeine ranks as one of the most commonly consumed dietary micronutrients; it is found in coffee beans, cacao beans, kola nuts, guarana berries, and tea leaves including yerba mate . Accumulating evidence from cohort studies suggests that an increased intake of polyphenols, which are the most abundant category of phytochemicals present in our foods, may reduce the risk of cardiovascular diseases . This evidence is supported by animal and clinical studies that have reported beneficial effects of the intake of polyphenol-rich foods or purified compounds on intermediate risk factors for CVD, including LDL cholesterol, blood pressure, and endothelial function . The most convincing clinical evidence for the cardioprotective benefits of the consumption of dietary polyphenols relates to their observed beneficial effect on endothelial function . For example, the consumption of suitable doses of plant sterols has repeatedly been shown in randomized controlled trials to reduce LDL cholesterol concentrations and thus reduce risk of subsequent CVD . Another phytochemical-rich source is coffee, one of the most widely consumed beverages worldwide. Coffee consumption may reduce the risk of type 2 diabetes mellitus and hypertension, as well as other conditions associated with cardiovascular risk , and epidemiological studies suggest that regular coffee drinkers have reduced mortality, predominantly as a result of their reduced risk of developing CVD .