Insect Population Dynamics Research Articles

Development of methods for application of pheromonic materials for monitoring and managing the number of apple phytophages

Synthetic sex pheromones have found wide application in plant protection as a mean of early detection of pests that allows observation of the phenology of insects to optimise protective measures. Insect sex pheromones can be applied for different purposes in protecting crops such as monitoring, determining the species composition and combating harmful species (by using sex pheromones for disorientation). The present work studies the species composition, dynamics of the number of basic pests of an apple tree, synchronisation of the seasonal and circadian activity of phytophages of an apple tree in the central zone of the Krasnodar Territory. The results of the field assessment of the male complex disorientation method of apple and eastern moths are presented. It was shown that the species-specificity of sex pheromones in the apple orchard depends on the faunistic diversity of Lepidoptera species with similar pheromone systems that develop at a given point in space and time. It was revealed that the behaviour of this complex changes during the season and over years, depending on the climate and natural dynamics of insect populations. The quantitative ratio and species-specificity of pheromones will probably be different in ecosystems with various species composition and different geographic zones. A novelty of this research is the division of the studied Lepidoptera phytophage species into three groups according to a decrease in the absolute species-specificity in the forest biotope in comparison with the garden one. The most widespread and coinciding in terms of summer synchronicity are apple (Cydia pomonella L.), plum (Grapholitha funebrana Tr.), eastern (Grapholitha molesta Tr.) and pomegranate moth (Euzophera bigella Zell.). The disorientation method, applied using a complex system of dispensers with apple and eastern moth pheromones, showed that installing 500 dispensers/ha allowed 99.3 % efficiency to be achieved. Fruit damage amounted to 1.2 % and 2.7 % in the experimental and control groups, respectively. The duration of the disorienting effect of the pheromone formulations lasted for over 4 months.

Eco-genetics of desiccation resistance in Drosophila.

Climate change globally perturbs water circulation thereby influencing ecosystems including cultivated land. Both harmful and beneficial species of insects are likely to be vulnerable to such changes in climate. As small animals with a disadvantageous surface area to body mass ratio, they face a risk of desiccation. A number of behavioural, physiological and genetic strategies are deployed to solve these problems during adaptation in various Drosophila species. Over 100 desiccation-related genes have been identified in laboratory and wild populations of the cosmopolitan fruit fly Drosophila melanogaster and its sister species in large-scale and single-gene approaches. These genes are involved in water sensing and homeostasis, and barrier formation and function via the production and composition of surface lipids and via pigmentation. Interestingly, the genetic strategy implemented in a given population appears to be unpredictable. In part, this may be due to different experimental approaches in different studies. The observed variability may also reflect a rich standing genetic variation in Drosophila allowing a quasi-random choice of response strategies through soft-sweep events, although further studies are needed to unravel any underlying principles. These findings underline that D. melanogaster is a robust species well adapted to resist climate change-related desiccation. The rich data obtained in Drosophila research provide a framework to address and understand desiccation resistance in other insects. Through the application of powerful genetic tools in the model organism D. melanogaster, the functions of desiccation-related genes revealed by correlative studies can be tested and the underlying molecular mechanisms of desiccation tolerance understood. The combination of the wealth of available data and its genetic accessibility makes Drosophila an ideal bioindicator. Accumulation of data on desiccation resistance in Drosophila may allow us to create a world map of genetic evolution in response to climate change in an insect genome. Ultimately these efforts may provide guidelines for dealing with the effects of climate-related perturbations on insect population dynamics in the future.

Assessing herbivorous insects as potential biological controls for the invasive species Miconia calvescens (Myrtales: Melastomataceae)

ABSTRACT Biological control methods may provide efficient and environmentally sustainable methods for curbing invasive weeds. Miconia calvescens DC (Melastomataceae) is an invasive weed of forest ecosystems on oceanic islands and one of the most invasive alien species. Therefore, the present study aimed to identify and assess the population dynamics of herbivorous insects that feed on M. calvescens in Brazil. The following species were found on M. calvescens plants at our three study locations: Apion sp. (Brentidae), Agrilus sp. (Buprestidae), Cryptorhynchus sp., Naupactus spp. (Curculionidae), Brasilaphthona sp., Cerotoma sp., Chrysodina sp., Colaspis sp., Diabrotica speciosa, and one unidentified species of the subfamily Cassidinae (Chrysomelidae). According to host specificity and impact caused to M. calvescens, the fruit-feeding Apion sp. and the stem-boring Cryptorhynchus sp. have high potential for this weed's biological control. Thus, our results provide useful information for potential biological control programmes for M. calvescens using herbivorous insects and will be helpful for companies working on natural weed control for this species.

Insect pests of stocks of Acacia macrostachya Reichenb and associated parasitoids in the province of Boulkiemde, central-western region of Burkina Faso

We investigated the diversity and the population dynamics of insects attacking seed stocks of Acacia macrostachya, an indigenous legume tree whose seeds constitute an important food source for rural and urban populations in Burkina Faso. For this purpose, six thousand four hundred and two seeds were collected from newly harvested dry pods in spontaneous vegetation around the research station of Saria, while 50kg of naturally infested seeds of A. macrostachya were purchased from nearby markets. To assess pest diversity and initial infestation, seeds collected from pods were divided into 3 batches of 2134 seeds, each batch representing a replication. Insect emergence in the laboratory was monitored for 45 days. The population dynamics of the pests was studied by incubating the seeds purchased on the market in 4 batches of 12.5kg each in polypropylene bags, which were kept under laboratory conditions and monitored for 8 months. Insects emerged from the samples included Coleoptera from three (3) families: Bruchidae (the most abundant), Tenebrionidae and Silvanidae, and Hymenoptera from four (4) families: Eulophidae, Pteromalidae, Eupelmidae, Eurytomidae. The initial seed infestation rate of the newly harvested pods was 50.67% with 47.14% caused by Bruchidius silaceus, 2.70% by Caryedon furcatus and 0.83% by Bruchidius sp. The most abundant species observed during the two first months of storage of the seeds obtained from the market was B. silaceus, but it disappeared from the stocks after March. Conversely, Caryedon furcatus populations remained steady and increased in February. Among the secondary pests observed, Oryzaephilus mercator was the most important. The initial seed perforation rate and weight loss were 16% and 2.8%, respectively, and increased to 35% and 7% after eight months of storage. The hymenopteran Eupelmus sp. was the most abundant parasitoid observed in storage. Our study allowed us to assess the diversity of A. macrostachya seed pests and their natural enemies. These results will contribute to a better understanding of their population dynamics and hence provide cues for further studies towards effective control methods.

A transdisciplinary research agenda for understanding insect responses to ecological light pollution informed by evolutionary trap theory.

Evolutionary traps are phenomena in which rapid environmental change causes environmental cues that historically guided adaptive behavioral or life-history decisions to become poor predictors of the consequences of such decisions for an organism's fitness. Evolutionary trap theory offers an ideal framework for understanding and mitigating the effects of ecological light pollution (ELP) on insects. We emphasize the utility of an evolutionary trap perspective in demonstrating the importance of an integrated understanding of the sensory, behavioral, evolutionary, and demographic mechanisms underlying insect responses to ELP. We also highlight neglected areas of research where greater focus can help enhance understanding of how ELP affects the persistence, evolutionary trajectory, and population dynamics of insects across space and time.

Field Translocation of Mountain Pine Beetles Suggests Phoretic Mite Communities Are Locally Adapted, and Mite Populations Respond Variably to Climate Warming.

Simple SummaryClimate warming has significant effects on forest insect populations, particularly bark beetles, which cause millions of hectares of forest tree damage. Bark beetles live alongside a diverse host of other organisms which affect the success of beetle attacks on trees and are also affected by climate changes. Here, we explore climate effects on symbiotic mite communities associated with the mountain pine beetle (Dendroctonus ponderosae). We show that warming causes significant shifts in the abundance of mites. These effects were dependent on source population, suggesting mite populations are adapted to their local climates. Understanding beetle–mite patterns is important because mites can directly affect beetle reproduction by feeding on eggs, or indirectly affect beetle health by introducing fungi. Our results provide foundational information for understanding how climate change will affect beetle–mite associations; and serve to help determine how these shifting associations will affect the success of bark beetles in forest ecosystems.Temperature is a key determining factor in the population dynamics of forest insects and their associated biota. Bark beetles, often considered key agents of change in forest ecosystems, are particularly affected by warming in their environment. Beetles associate with various phoretic mite species that have direct/indirect effects on beetle fitness and population dynamics, although there is limited knowledge of how temperature affects these communities. Here, we use a field reciprocal translocation experiment with the addition of a novel “warming” environment to represent future changes in local environment in two populations of a keystone bark beetle species (Dendroctonus ponderosae). We hypothesize that mite community abundances as carried by bark beetles are significantly altered when not in their native environments and when subjected to climate warming. We use multivariate generalized linear models based on species abundance data to show that mite community compositions significantly differ across different field climates; and that these patterns diverge between source populations, indicating local adaptation. Our study offers foundational information on the general effects of simulated climate-warming on the compositional shifts of common and abundant biotic associates of mountain pine beetles and may be used as a model system for other important insect–mite systems.

Developmental stages of peach, plum, and apple fruit influence development and fecundity of Grapholita molesta (Lepidoptera: Tortricidae)

Host plant attributes are essential factors determining the population dynamics of herbivorous insects. The developmental stage of host plants, in particular, may affect the biology of Grapholita molesta (Busck), a possibility that has rarely been examined. Here we assessed the effect of developmental stage of plum, peach, and apple fruits on the development and fecundity performance of G. molesta, along with an examination of the firmness and sugar content of the fruits. Among the fruits collected earliest (May 31), plum and apple were better food sources for G. molesta compared to peach in terms of development, reproduction, and life table parameters. However, despite the higher sugar content in peach, G. molesta larvae showed a lower rate of fruit penetration in peach, probably due to fruit firmness. In the later-collected fruit (June 25), both peach and apple were better than plum, as peach and apple were softer and had higher sugar content. Nevertheless, the penetration rate of larva was still low in peach probably due to pubescence on the fruit surface. Although the plum fruits in the later collection date were softer with higher sugar content, there was a negative impact on the development and reproduction because fruits started to liquefy earlier. In conclusion, the developmental stage of fruits with changes in fruit firmness or sugar content affected the development and reproduction of G. molesta, and apple would be the best food source.

Integrated modelling of insect population dynamics at two temporal scales

Population size of species with birth-pulse life-cycles varies both within and between seasons, but most population dynamics models assume that a population can be characterised adequately by a single number within a season. However, within-season dynamics can sometimes be too substantial to be ignored when modelling dynamics between seasons. Typical examples are insect populations or migratory animals. Numerous models for only between-season dynamics exist, but very few have combined dynamics at both temporal scales.In a new approach, we extend appreciably the models of Dennis et al. (2016b): we show how to adapt them for a generation time >1 year and fit an integrated population model for multiple data types, by maximising a joint likelihood for population counts of unmarked individuals and capture–recapture data from a study with marked individuals. We illustrate the approach using annual monitoring data for the endangered flightless beetle Iberodorcadion fuliginator from 18 populations in the Upper Rhine Valley for 1998–2016, with a 2-year life cycle. Standard likelihood methods are used for model fitting and comparison, and a concentrated (profile) likelihood approach provides computational efficiency.Additional information from the capture–recapture data makes the population model more robust and, importantly, enables true, rather than relative, abundance to be estimated. A dynamic stopover model provides estimates of both survival and phenology parameters within a season, and also of productivity between seasons. For I. fuliginator, we demonstrate a population decline since 1998 and how this links with productivity, which is affected by temperature. A delayed mean emergence date in recent years is also shown.A main point of interest is the focus on the two temporal scales at which perhaps most animal populations vary: in the short-term, a population is seldom truly closed within a single season, and in the long-term (between seasons) it never is. Hence our models may serve as a template for a general description of population dynamics in many species. This includes rare species with limited data sets, for which there is a general lack of population dynamic models, yet conservation actions may greatly benefit from this kind of models.

Temperature and Humidity Interact to Influence Brown Marmorated Stink Bug (Hemiptera: Pentatomidae), Survival.

High-temperature events can influence insect population dynamics and could be especially important for predicting the potential spread and establishment of invasive insects. The interaction between temperature and environmental humidity on insect populations is not well understood but can be a key factor that determines habitat range and population size. The brown marmorated stink bug, Halyomorpha halys (Stål), is an invasive agricultural pest in the United States and Europe, which causes serious economic damage to a wide range of crops. This insect's range continues to expand. It has recently invaded the Central Valley of California, which has a hotter and drier climate compared with the Eastern United States where this insect is established. We investigated how high-temperature events and relative humidity would impact the survival and reproduction of H. halys. Using incubators and humidity chambers, we evaluated the impact of humidity and short-term (2 d) high-temperature exposure on the survival and development of H. halys eggs, nymphs, and adults. We found that high temperatures significantly reduced H. halys survival. The impact of humidity on H. halys survival was dependent on temperature and life stage. Low humidity decreased first-instar survival but not third- to fourth-instar survival. High humidity increased first instar survival but decreased third- to fourth-instar survival. Humidity did not influence adult or egg survival. We also found that high temperatures decreased H. halys reproduction. Our findings have important implications for understanding the invasive ecology of H. halys and may be used to improve models predicting H. halys range expansion.

Landscape-scale biogeographic distribution analysis of the whitefly, Bemisia tabaci (Gennadius, 1889) in Kenya

Understanding the drivers of habitat use and the suitability of landscape patches by invasive insect species is crucial in their control and management. This simplifies the comprehension of the processes driving invasive insect population dynamics, their functioning, and potential disturbance within their introduced ecosystems. The whitefly, Bemisia tabaci (Gennadius, 1889), is ranked among the world’s 100 most invasive insect pests and is a major threat to many important cash and staple food crops. In this study, we identified levels and areas at risk of the invasive B. tabaci at a landscape scale in Kenya using elevation, land surface temperature, land cover, rainfall, and temperature of the present and future (the year 2050 of the community climate system model version 4 (CCSM4)), and using a maximum entropy (MaxEnt) model. Our results show that ~14% of Kenya’s land area is currently at risk of B. tabaci invasion. This area is likely to increase to 15% and 16% because of climate change using the representative concentration pathways (RCP) i.e. RCP 2.6 and RCP 8.5 of the year 2050, respectively. Land cover, particularly croplands, provided the highest permutation importance together with precipitation variables in determining the occurrence of the pest. A wide preference range within elevation, precipitation, temperature, and plant hosts was observed suggesting a great potential for B. tabaci to establish in many areas in Kenya and potentially in other countries with similar conditions in Africa. However, the predicted increases in global temperature could reduce the pest’s preferred environment, but this also imposes limitations on the productivity of many of its host crops. Therefore, our results can be used in adaptive management to control the pest and to prevent the introduction and spread of B. tabaci in areas where it is yet to establish.

Mathematical Modelling of the Sterile Insect Technique Using Different Release Strategies

We study simple mathematical models for the dynamics of interactive wild and sterile insect populations. As well as being mathematically tractable, these models can be used as first approximations to real situations occurring with the Sterile Insect Technique (SIT) in which sterile males are released to reduce or eradicate a pest population. This is a method of biological control which can effectively help contain the spread of many pest insects such as the Red Palm Weevil (RPW). Models formulated in this paper are continuous-time, include a strong Allee effect that captures extinction events, and incorporate different strategies of releasing sterile insects. We perform basic studies of dynamical features of these models, with an emphasis on the condition of excitation, and the impact of the different release methods is investigated. Our findings are also demonstrated with some numerical examples.

First record of a mermithid worm (Nematoda, Mermithidae) parasitizing a third instar nymph of Triatoma sordida (Stål, 1859) (Hemiptera, Reduviidae, Triatominae) from Mato Grosso, Brazil.

A juvenile specimen of a mermithid (Nematoda) was found parasitizing a third instar nymph of Triatoma sordida from Mato Grosso, Brazil. This is the first record of mermithid parasitism in a triatomine species. The Mermithidae represents a family of nematodes that are specialized insect parasites. Entomonematodes are one of the highly influential agents regulating the population dynamics of insects. This report introduces the opportunity to think about mermithids as a possible candidate for use as triatomine biological control.

The positive effects of the alpine cushion plant Arenaria polytrichoides on insect dynamics are determined by both physical and biotic factors

Cushion plants' significant role for alpine biodiversity has been demonstrated in particular through their positive effects on plant diversity. However, their effects on higher trophic levels (e.g. insects) remain largely unclear. In this study, by field sampling in the Hengduan Mountains (HDM) in southwestern China, we evaluated the effects of an alpine gynodioecious cushion species, Arenaria polytrichoides (Carophyllaceae), on insect richness, abundance and population dynamics at two different elevations (4427 m vs. 4732 m) separately at two time periods (day vs. night) and in two growing seasons (early vs. late). The results showed that the total insect diversity decreases from low to high elevation sites. Some insect species were exclusively detected within A. polytrichoides cushions, leading to an increase in local insect richness from 7% to 35%. The positive effects of cushions on insect diversity could be attributed to unique biotic properties provided by cushions. Firstly, the effects were determined by the sexual dimorphism of the cushion with hermaphroditic cushions supporting higher insect diversity than female cushions. This could be because hermaphroditic cushions provide more resources, such as nectar and pollen grains, for insects than female cushions. Secondly, the cushions' associated beneficiary plants can also provide extra resources for attracting more insects, but this effect was mediated by the micro-environmental conditions. Finally, the magnitude of cushions' positive effects on insect dynamics were stronger under higher than under lower environmental stress. This study confirmed that facilitation by A. polytrichoides cushions in HDM plays an important role in constructing the alpine insect community and further regulating its dynamics. Moreover, the positive effects of cushions on insect dynamics increase with increasing environmental stress. Therefore, the distribution range of insects would quite possibly be expanded into higher elevation under future climate changes, which will induce new challenges for the local alpine ecosystems.

Strong impacts of smoke polluted air demonstrated on the flight behaviour of the painted lady butterfly (Vanessa cardui L.)

1. A major component of biomass burning smoke is fine particulate matter (PM2.5), which has been shown to generate impacts on insect population dynamics and development. However, little is known about its effect on insect flight behaviour, even though this will influence insect dispersal and distribution, and potentially migration and ecosystem services such as pollination.2. Here we use a tethered flight mill setup to examine the behaviour of adult painted lady butterflies (Vanessa cardui L.) flying in different levels of combustion‐generated airborne PM2.5, comparison this to TFM flying under ‘clean air’ conditions.3. Descriptive statistics and paired sample t‐tests indicate that the smoke had a significantly deleterious impact on flight behaviour, with for example total flight distance covered declining by 65% during the first 20 min of flying in the least smoke contaminated air compared to ‘clean air’ control conditions, whilst average speed declined by 54% and flight duration by 32%. A strongly negative and highly significant linear correlation between flight speed and PM2.5 concentration was also observed.4. This study represents the first time that smoke effects on insect flight behaviour have been experimentally tested, and the longer the butterflies were exposed to the elevated PM2.5 concentrations the more obviously their flight behaviour declined. We conclude that the month(s)‐long episodes of air pollution often associated with agricultural burning and deforestation fires in the tropics may well be significantly affecting the behaviour of the flying insects living in those regions and/or who migrate through them.

Use of colored pan traps method for monitoring insect (Diptera and Hymenoptera) diversity in the Southern Tropical Andes of Ecuador

Insects are a dominant part of the megadiversity of the Tropical Andes but monitoring and studying them has been challenging. Here we employ colored pan trap method for collecting insects (Diptera and Hymenoptera) in the Andes of Ecuador in order to explore the use of the colored pan traps method. Sixty white, yellow, and blue colored pan traps were used twice every month for 24 months. A total of 17,661 insects were collected, of which 12,872 belong to Diptera (72.9%) and 4789 to Hymenoptera (27.1%).The sampled individuals belonged to a total of 90 families, of which 55 belonged to Diptera and 35 to Hymenoptera. There was not a significant difference between the number of families of each order collected by the differently colored traps. However, some families showed a distinct preference for a certain pan trap color. This study shows, that colored pan traps could be a useful method for collecting and monitoring insects (Diptera and Hymenoptera) in the Andes. Our results are of special importance today, as insects have been reported to dramatically declining around the world. Therefore, studies that focus on understanding insect diversity and population dynamics are key for implementing conservation measures in the future to protect this exceptionally diverse and poorly known fauna.

Comparison between sustained effects of spray and injection thiamethoxam on apple aphids and non-target insects in apple orchard

Spray application is considered to be the most common method of insecticide use in apple orchard, while trunk injection has often be used in labor-intensive areas. Here, a comparison of both methods in aphid control efficiency and non-target effects was conducted. We evaluated the effects of thiamethoxam by either spray or injection on apple aphid Aphis citricola, and examined the temporal dynamic of thiamethoxam in leaves by using residue analysis. Results showed that thiamethoxam had a remarkable suppression effect on Aphis citricola, and both application methods had obvious control efficiency with the highest value above 90%. The control effect of spray method on Aphis citricola reached the maximum at 7 days after application, while that of injection method reached the maximum at 14 days after application. Moreover, the control effect of injection after 14 days and that of spray after 7 days were not significant, suggesting the spray method had a higher quick-acting effect than the injection method, and the two methods had a similar persistence effect. The population dynamics of non-target insects (ladybugs, parasitoid wasps and predatory bugs) showed basically the same as that of blank controlled. The control effect evaluation of thiamethoxam on Aphis citricola suggest that injection treatment was more effective in protecting natural enemies than spray treatment, and thiamethoxam didn't interfere with natural enemies to control Aphis citricola with both two application methods.

Impact of Horizontal Edge-Interior and Vertical Canopy-Understory Gradients on the Abundance and Diversity of Bark and Woodboring Beetles in Survey Traps.

Simple SummaryTraps baited with sex attractants and plant odors are used by regulatory agencies to survey for alien invasive forest insects that may arrive via importation of goods from overseas. The performance of these surveys is affected not only by the type of traps and attractants used, but also by where the traps are placed at survey sites. We tested the effect of trap position along horizontal (relative to the forest edge) and vertical (canopy-understory) forest gradients on the diversity and abundance of species of bark and wood boring beetles detected. Both horizontal and vertical trap position affected trap performance, but trends differed among taxa and were context-dependent. For example, jewel beetles were detected mainly in canopy traps regardless of horizontal position, whereas bark and ambrosia beetles were detected mainly in understory traps placed along the forest edge. For optimal early detection of potentially invasive bark and wood boring beetles, surveys should place traps at multiple locations along horizontal and vertical gradients.Semiochemical-baited intercept traps are important tools used to collect information about the presence/absence and population dynamics of forest insects. The performance of these tools is influenced by trap location along both horizontal edge–interior and vertical understory–canopy gradients. Consequently, the development of survey and detection programs requires both the development of effective traps and semiochemical lures but also deployment protocols to guide their use. We used field trapping experiments to examine the impact of both horizontal edge–interior and vertical understory–canopy gradients and their interactions with the species richness and abundance of Buprestidae, Cerambycidae and Curculionidae. Both gradients had significant effects on the diversity and abundance of all three families collected in traps and the pattern of gradient effects differed between the two experiments. In the first experiment, traps were deployed along transects involving large (>100 m) forest gaps and in the second experiment traps transected small (ca. 15 m) forest gaps. These results were consistent with the idea that gradient effects on the abundance and diversity of these three families of forest Coleoptera are context dependent. The results of this study suggest that monitoring programs for bark and woodboring beetles should deploy traps at multiple locations along both vertical understory–canopy and horizontal edge–interior gradients.

Outbreaking forest insect drives phase synchrony among sympatric folivores: Exploring potential mechanisms

AbstractWe explore a common feature of insect population dynamics, interspecific synchrony, which refers to synchrony in population dynamics among sympatric populations of different species. Such synchrony can arise via several possible mechanisms, including shared environmental effects and shared trophic interactions, but distinguishing the relative importance among different mechanisms can be challenging. We analyze interannual time series of population densities of the larch budmoth, Zeiraphera griseana (Lepidoptera: Tortricidae), along with six sympatric larch‐feeding folivores from a site in the European Alps 1952–1979. These species include five lepidopterans, Exapate duratella, Ptycholomoides aeriferana, Spilonota laricana, Epirrita autumnata and Teleiodes saltuum, and one hymenopteran sawfly Pristiphora laricis. We document that the highly regular oscillatory behavior (period 9–10 years) of Z. griseana populations is similarly evident in the dynamics of most of the sympatric folivores. We also find that all of the sympatric species are phase synchronized with Z. griseana populations with half of the sympatric species exhibiting nonlagged phase synchrony and three of the species exhibiting 2–5 year lags behind Z. griseana populations. We adapt a previously developed tritrophic model of Z. griseana dynamics to explore possible mechanisms responsible for observed phase synchronization. Results suggest that either shared stochastic influences (e.g., weather) or shared parasitoid impacts are likely causes of nonlagged phase synchronization. The model further indicates that observed patterns of lagged phase synchronization are most likely caused by either shared delayed induced host plant defenses or direct density‐dependent effects shared with Z. griseana.

Seasonal variation of Drosophilidae communities in viticultural landscapes

Studies at the landscape scale are important to understand insect population and community dynamics. Despite numerous studies on the effects of landscape context on phytophagous insect communities, few studies were conducted on fruit flies and the seasonal variation in the effects of landscape context remains poorly explored. Here, we investigate how landscape composition affects Drosophilidae communities in vineyards and how these effects vary over time. To do this, we sampled Drosophilidae communities in 20 vineyards selected along a gradient of proportion cover of semi-natural habitats in the landscape over a whole year in southwestern France. We found an overall positive effect of increasing proportion of semi-natural habitats in the landscape on abundance of drosophilid species but not on the rarefied species richness. We also found strong seasonal changes in community composition with a major temporal differentiation between the two dominant species of the community, Drosophila subobscura and Drosophila suzukii. Our study revealed that the composition of the Drosophilidae communities in vineyards is strongly influenced by the proportion of semi-natural habitats and the time of year. Our results suggest that the variation in space and time of key resources such as host plants or overwintering habitats in the landscape is a key factor affecting community composition of Drosophilidae in crops.

Thermal effect on the fecundity and longevity of Bactrocera dorsalis adults and their improved oviposition model.

The oriental fruit fly, Bactrocera dorsalis, is a destructive polyphagous pest that causes damage to various fruit crops, and their distribution is currently expanding worldwide. Temperature is an important abiotic factor that influences insect population dynamics and distribution by affecting their survival, development, and reproduction. We examined the fecundity, pre-oviposition and oviposition periods, and longevity of adult B. dorsalis at various constant temperatures ranging from13°C to 35°C. The longevity of female B. dorsalis ranged from 116.8 days (18.8°C) to 22.4 days (34.9°C), and the maximum fecundity per female was 1,684 eggs at 28.1°C. Females were only able to lay eggs at 16.7°C to 34.9°C, and both the pre-oviposition and oviposition periods were different depending on the temperature. We modeled female reproduction in two oviposition models (OMs): 1) the current model developed by Kim and Lee, an OM composed of a fecundity model, age-specific survival model, and age-specific cumulative oviposition rate model, and 2) a two-phase OM modified the logic structure of the current model by separating pre-oviposition, so that oviposition was estimated with the female in oviposition phase who had complete pre-oviposition phase. The results of the two-phase OM provided more realistic outputs at lower and higher temperatures than those of the current model. We discussed the usefulness of the two-phase OM for the reproduction of insects with long pre-oviposition periods.