Mediterranean fruit fly population phenological patterns are strongly affected by elevation and host presence.

The Mediterranean fruit fly (medfly) (Ceratitis capitata, Diptera: Tephritidae), is an extremely polyphagous pest that threatens the fruit production and trading industry worldwide. Monitoring C. capitata populations and analysing its dynamics and phenology is considered of outmost importance for designing and implementing sound management approaches. The aim of this study was to investigate the factors regulating the population dynamics of the C. capitata in a coastal and semi-mountainous area. We focused on effects of topography (e.g. elevation), host presence and seasonal patterns of ripening on the phenological patterns considering data collected in 2008. The experimental area is characterized by mixed fruit orchards, and Mediterranean climate with mild winters. Two trap types were used for population monitoring. The female targeted McPhail type and the male targeted Jackson type. Traps were placed in farms located at different elevations and landscape morphology (coastal and semi-mountainous areas). The main crops included citrus, apples, peaches, plums, pears, figs, quinces and apricots. Adult captures were first recorded in May, peaked in mid-summer and mid-autumn and almost ceased at the end of the season (January 2008). Captures in the coastal areas preceded that of highlands by 15 days. Most of the adults detected during the fruit ripening of late stone fruit cultivars (first peak) and citrus (second peak). The probability of capturing the first adults preceded almost three weeks the peak of adult captures either considering the elevation or host focus analyses. The results provide valuable information on the seasonal population trend of C. capitata in mixed fruit Mediterranean orchards and can support the set-up of IPM systems in areas with various landscapes and different hosts throughout the fruit growing season.

Sterile Insect Technique (SIT) field trial targeting the suppression of Aedes albopictus in Greece.

The sterile insect technique (SIT) involves releasing large numbers of sterile males to outcompete wild males in mating with females, leading to a decline in pest populations. In the current study, we conducted a suppression trial in Greece against the invasive dengue vector mosquito Aedes albopictus (Skuse) through the weekly release of sterile males for 22 weeks from June to September 2019. Our approach included the long-distance transport of sterile mosquitoes, and their release at a density of 2,547 ± 159 sterile males per hectare per week as part of an area-wide integrated pest management strategy (AW-IPM). The repeated releases of sterile males resulted in a gradual reduction in egg density, reaching 78% from mid-June to early September. This reduction remained between 70% and 78% for four weeks after the end of the releases. Additionally, in the SIT intervention area, the ovitrap index, representing the percentage of traps containing eggs, remained lower throughout the trial than in the control area. This trial represents a significant advance in the field of mosquito control, as it explores the viability and efficacy of producing and transporting sterile males from a distant facility to the release area. Our results provide valuable insights for future SIT programmes targeting Ae. Albopictus, and the methodology we employed can serve as a starting point for developing more refined and effective release protocols, including the transportation of sterile males over long distances from production units to intervention areas.

Title: Essai sur le terrain de la Technique de l'Insecte Stérile (TIS) ciblant la suppression d'Aedes albopictus en Grèce. Abstract: La technique de l'insecte stérile (TIS) consiste à libérer un grand nombre de mâles stériles pour supplanter les mâles sauvages lors de l'accouplement avec les femelles, entraînant ainsi un déclin des populations de nuisibles. Dans la présente étude, nous avons mené un essai de suppression en Grèce contre le moustique vecteur invasif de la dengue, Aedes albopictus (Skuse), par le biais de la libération hebdomadaire de mâles stériles pendant 22 semaines de juin à septembre 2019. Notre approche comprenait le transport sur de longues distances de moustiques stériles, et leur lâcher à une densité de 2 547 ± 159 mâles stériles par hectare et par semaine dans le cadre d'une stratégie de lutte intégrée contre les nuisibles à l'échelle de la zone (AW-IPM). Les lâchers répétés de mâles stériles ont entraîné une réduction progressive de la densité des œufs, atteignant 78 % de la mi-juin au début septembre. Cette réduction est restée entre 70 % et 78 % pendant quatre semaines après la fin des lâchers. De plus, dans la zone d'intervention de la TIS, l'indice d'oviposition, représentant le pourcentage de pièges contenant des œufs, est resté plus faible que dans la zone témoin tout au long de l'essai. Cet essai représente une avancée significative dans le domaine de la lutte contre les moustiques, car il explore la viabilité et l'efficacité de la production et du transport de mâles stériles depuis une installation éloignée vers la zone de lâcher. Nos résultats fournissent des informations précieuses pour les futurs programmes de TIS ciblant Ae. albopictus et la méthodologie que nous avons utilisée pourra servir de point de départ pour développer des protocoles de libération plus raffinés et plus efficaces, y compris le transport de mâles stériles sur de longues distances depuis les unités de production jusqu'aux zones d'intervention.

Evidence that recent climatic changes have expanded the potential geographical range of the Mediterranean fruit fly.

The species distributions migration poleward and into higher altitudes in a warming climate is especially concerning for economically important insect pest species, as their introduction can potentially occur in places previously considered unsuitable for year-round survival. We explore the expansion of the climatically suitable areas for a horticultural pest, the Mediterranean fruit fly (medfly) Ceratitis capitata (Diptera, Tephritidae), with an emphasis on Europe and California. We reviewed and refined a published CLIMEX model for C. capitata, taking into consideration new records in marginal locations, with a particular focus on Europe. To assess the model fit and to aid in interpreting the meaning of the new European distribution records, we used a time series climate dataset to explore the temporal patterns of climate suitability for C. capitata from 1970 to 2019. At selected bellwether sites in Europe, we found statistically significant trends in increasing climate suitability, as well as a substantial northward expansion in the modelled potential range. In California, we also found a significant trend of northward and altitudinal expansion of areas suitable for C. capitata establishment. These results provide further evidence of climate change impacts on species distributions and the need for innovative responses to increased invasion threats.

Daily activity profiles over the lifespan of female medflies as biomarkers of aging and longevity.

The relationship between the early-age activity of Mediterranean fruit flies (medflies) or other fruit flies and their lifespan has not been much studied, in contrast to the connections between lifespan and diet, sexual signaling, and reproduction. The objective of this study is to assess intra-day and day-to-day activity profiles of female Mediterranean fruit flies and their role as biomarker of longevity as well as to explore the relationships between these activity profiles, diet, and age-at-death throughout the lifespan. We use advanced statistical methods from functional data analysis (FDA). Three distinct patterns of activity variations in early-age activity profiles can be distinguished. A low-caloric diet is associated with a delayed activity peak, while a high-caloric diet is linked with an earlier activity peak. We find that age-at-death of individual medflies is connected to their activity profiles in early life. An increased risk of mortality is associated with increased activity in early age, as well as with a higher contrast between daytime and nighttime activity. Conversely, medflies are more likely to have a longer lifespan when they are fed a medium-caloric diet and when their daily activity is more evenly distributed across the early-age span and between daytime and nighttime. The before-death activity profile of medflies displays two characteristic before-death patterns, where one pattern is characterized by slowly declining daily activity and the other by a sudden decline in activity that is followed by death.

Latitudinal variation in survival and immature development of Ceratitis capitata populations reared in two key overwintering hosts.

Ceratitis capitata, a major agricultural pest, is currently expanding its geographic distribution to northern, temperate areas of Europe. Its seasonal biology and invasion success depend on temperature, humidity and host availability. In coastal warmer Mediterranean regions and cooler temperature areas, bitter oranges and apples serve as overwintering hosts during the larval stage. We assessed the overwintering capacity of C. capitata populations obtained from different areas of the northern hemisphere by studying the survival and development rates of immature stages in both fruits under laboratory conditions. Eggs from each population were artificially inserted in the flesh of the two hosts and kept at 15, 20, or 25 °C until pupation and adult emergence. Climatic analysis of the area of the population origin showed combined effects of latitude, host and macroclimatic variables on immature survival and development rates. Egg to adult survival rates and developmental duration were longer in apples than in bitter oranges. For populations originated from southern-warmer areas, egg to adult developmental duration was prolonged and adult emergence reduced at 15 °C compared to those populations obtained from northern regions. Our findings reveal varying plastic responses of medfly populations to different overwintering hosts and temperatures highlighting the differential overwintering potential as larvae within fruits. This study contributes towards better understanding the medfly invasion dynamics in temperate areas of Northern Europe and other parts of the globe with similar climates.

Effect of water salinity on immature performance and lifespan of adult Asian tiger mosquito.

BACKGROUND: Aedes albopictus (Skuse, 1894) is a vector for pathogens like dengue, chikungunya, and Zika viruses. Its adaptive capacity enables reproduction in temperate climates and development mainly in artificial containers with fresh water in urbanized areas. Nevertheless, breeding in coastal areas may also occur along with its aggressive invasiveness. Global warming and the consequent rise in sea levels will increase saline (> 30 ppt) or brackish (0.5-30 ppt salt) water in coastal regions. To address whether Ae. albopictus can breed in brackish water, we initiated the current study that analyses the survival of immature stages at different salinity concentrations and explores whether carryover effects occur in the resulting adults. This possible adaptation is important when considering the potential for development in new habitats and expansion of one of the world's most invasive species. METHODS: We investigated the influence of salinity on the survival of Ae. albopictus larvae and adults under laboratory-controlled conditions. First instar larvae were exposed to different salinity concentrations (0 to 30 ppt) and their development time, pupation, adult emergence, and overall survival were monitored daily. We used Kaplan-Meier and Cox regression models to analyze the survival rates at different salinity levels. Furthermore, life tables were constructed under each salinity concentration. RESULTS: Increasing salt concentrations significantly increased the mortality risk during immature development, while no significant effect was observed on adult mortality risk. A comparison between distilled and bottled water revealed a notable increase in overall mortality risk for individuals developing in distilled water. However, no significant effects were found when analyzing survival from the first larval stage to adult emergence and adult lifespan. The life expectancy of immature stages decreased with increasing salt concentrations, although salinity concentration did not significantly impact adult life expectancy. CONCLUSIONS: Our findings suggest that Ae. albopictus, previously considered freshwater species, can successfully develop and survive in brackish waters, even in the absence of characteristic structures found in euryhaline species. These adaptations may enable Ae. albopictus to establish new breeding sites and colonize unexplored territories. Knowledge of these physiological adaptations of Ae. albopictus to salinity should be pursued to increase the range of control of the species, and to make more accurate predictions of its dispersal and vectoring ability.

Fruit Flies: Challenges and Opportunities to Stem the Tide of Global Invasions.

Global trade in fresh fruit and vegetables, intensification of human mobility, and climate change facilitate fruit fly (Diptera: Tephritidae) invasions. Life-history traits, environmental stress response, dispersal stress, and novel genetic admixtures contribute to their establishment and spread. Tephritids are among the most frequently intercepted taxa at ports of entry. In some countries, supported by the rules-based trade framework, a remarkable amount of biosecurity effort is being arrayed against the range expansion of tephritids. Despite this effort, fruit flies continue to arrive in new jurisdictions, sometimes triggering expensive eradication responses. Surprisingly, scant attention has been paid to biosecurity in the recent discourse about new multilateral trade agreements. Much of the available literature on managing tephritid invasions is focused on a limited number of charismatic (historically high-profile) species, and the generality of many patterns remains speculative.

Insecticide resistant mosquitoes remain thermal stress resistant, without loss of thermal plasticity.

A major component of mosquito's climate change response is their heat tolerance, and any ability to rapidly adjust to extreme environmental conditions through phenotypic plasticity. The excessive use of insecticides for the control of major mosquito species leads to resistant populations, however it is largely unclear if this concurrently impacts thermal stress resistance and their potential to adjust tolerance via phenotypic plasticity. Culex pipiens pipiens, Culex pipiens molestus and Aedes albopictus populations obtained from the same region were subjected for 12 generations to selection trials to larvicides Diflubenzuron (DFB) and Bacillus thuringiensis subsp. israelensis (Bti) to develop insecticide resistance. Adults emerging from the selected populations were acclimated at different temperatures and the upper and lower critical thermal limits (CTmax and CTmin) were estimated using dynamic thermal assays. In addition, the supercooling points (SCPs) of non-acclimated adults of resistant and control populations were determined. Our results revealed marked differences in thermal response among the three species, the different acclimation regimes and sexes. Aedes albopictus was more resistant in high than low temperatures compared to both Culex pipiens biotypes. Culex forms responded similarly to heat but differently to cold stress. In both forms, females responded better than males to all thermal stressors. Acclimation at higher and lower temperatures improves CTmax and CTmin values, respectively in both insecticide resistant and control populations of all three species. Overall, selection to insecticides did not affect the thermal performance of adults. Hence, insecticide-resistant mosquito populations perform similarly to untreated ones and are capable of readily adapting to new environmental changes rising concerns regarding their geographic range expansion and disease transmission globally.

Differential Cold Tolerance on Immature Stages of Geographically Divergent Ceratitis capitata Populations.

Cold tolerance of adult medflies has been extensively studied but the effect of subfreezing temperatures on the immature stages remains poorly investigated, especially as far as different populations are regarded. In this study, we estimated the acute cold stress response of three geographically divergent Mediterranean fruit fly populations originating from Greece (Crete, Volos) and Croatia (Dubrovnik) by exposing immature stages (eggs, larvae, pupae) to subfreezing temperatures. We first determined the LT50 for each immature stage following one hour of exposure to different temperatures. Then eggs, larvae and pupae of the different populations were exposed to their respective LT50 for one hour (LT50 = -11 °C, LT50 = -4.4 °C, LT50 = -5 °C for eggs, larvae and pupae, respectively). Our results demonstrate that populations responded differently depending on their developmental stage. The population of Dubrovnik was the most cold-susceptible at the egg stage, whereas in that of Crete it was at the larval and pupal stage. The population of Volos was the most cold-tolerant at all developmental stages. The egg stage was the most cold-tolerant, followed by pupae and finally the 3rd instar wandering larvae. This study contributes towards understanding the cold stress response of this serious pest and provides data for important parameters that determine its successful establishment to unfavorable environments with an emphasis on range expansion to the northern, more temperate regions of Europe.

Optimization of Brewer's Yeast Quantity in Liquid and Gel Larval Diets for the Mediterranean Fruit Fly.

Several artificial larval diets have been developed, evaluated and used for mass-rearing of the Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann) (Diptera: Teprhitidae). There are several efforts to reduce the cost of rearing and optimize the quality of the produced sterile males that are destined for release in sterile insect release programs. Survival, growth, longevity and reproductive capacity of sterile males are strongly connected with the most expensive ingredient, the brewer's yeast (protein), in the larval diet. The current study focused on settling the optimal content of brewer's yeast in a liquid diet and a gel diet. Egg hatch rates, developmental duration of immatures, pupation rate, pupae and adult survival were recorded as indicators of quantity and quality of the produced adults. Egg hatch was higher and larval developmental duration longer in the gel diet. In contrast to the liquid diet, an increase in brewer's yeast concentration was correlated with increased pupation rate and pupae survival in the gel diet. Reducing brewer's yeast up to 50% of its initial quantity had no significant effect on the survival of the emerging adults regardless of the diet type. Our findings may contribute to the production of low-cost and effective diets for use in mass-rearing facilities of medflies.

Effect of thermal acclimation on the tolerance of the peach fruit fly (Bactrocera zonata: Tephritidae) to heat and cold stress.

Understanding the thermal biology of insects is of increasing importance for predicting their geographic distribution, particularly in light of current and future global temperature increases. Within the limits set by genetic makeup, thermal tolerance is affected by the physiological conditioning of individuals (e.g., through acclimation). Considering this phenotypic plasticity may add to accurately estimating changes to the distribution of insects under a changing climate. We studied the effect of thermal acclimation on cold and heat tolerance of the peach fruit fly (Bactrocera zonata) - an invasive, polyphagous pest that is currently expanding through Africa and the Middle East. Females and males were acclimated at 20, 25 and 30 °C for up to 19 days following adult emergence. The critical thermal minimum (CTmin) and maximum (CTmax) were subsequently recorded as well adult survival following acute exposure to chilling (0 or -3 °C for 2 h). Additionally, we determined the survival of pupae subjected for 2 h to temperatures ranging from -12 °C to 5 °C. We demonstrate that acclimation at 30 °C resulted in significantly higher CTmax and CTmin values (higher heat resistance and lower cold resistance, respectively). Additionally, adult recovery following exposure to -3 °C was significantly reduced following acclimation at 30 °C, and this effect was significantly higher for females. Pupal mortality increased with the decrease in temperature, reaching LT50 and LT95 values following exposure to -0.32 °C and -6.88 °C, respectively. Finally, we found that the survival of pupae subjected to 0 and 2 °C steadily increased with pupal age. Our findings substantiate a physiological foundation for understanding the current geographic range of B. zonata. We assume that acclimation at 30 °C affected the thermal tolerance of the flies partly through modulating feeding and metabolism. Tolerance to chilling during the pupal stage probably changed according to temperature-sensitive processes occurring during metamorphosis, rendering younger pupae more sensitive to chilling.

Tethered-flight performance of thermally-acclimated pest fruit flies (Diptera: Tephritidae) suggests that heat waves may promote the spread of Bactrocera species.

BACKGROUND: Thermal history may induce phenotypic plasticity in traits that affect performance and fitness. One type of plastic response triggered by thermal history is acclimation. Because flight is linked to movement in the landscape, trapping and detection rates, and underpins the success of pest management tactics, it is particularly important to understand how thermal history may affect pest insect flight performance. We investigated the tethered-flight performance of Ceratitis capitata, Bactrocera dorsalis and Bactrocera zonata (Diptera: Tephritidae), acclimated for 48 h at 20, 25 or 30 °C and tested at 25 °C. We recorded the total distance, average speed, number of flight events and time spent flying during 2-h tests. We also characterized morphometric traits (body mass, wing shape and wing loading) that can affect flight performance. RESULTS: The main factor affecting most flight traits was body mass. The heaviest species, B. dorsalis, flew further, was faster and stopped less often in comparison with the two other species. Bactrocera species exhibited faster and longer flight when compared with C. capitata, which may be associated with the shape of their wings. Moreover, thermal acclimation had sex- and species-specific effects on flight performance. Flies acclimated at 20 °C stopped more often, spent less time flying and, ultimately, covered shorter distances. CONCLUSION: Flight performance of B. dorsalis is greater than that of B. zonata and C. capitata. The effects of thermal acclimation are species-specific. Warmer acclimation temperatures may allow pest fruit flies to disperse further and faster. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Daily Activity Profiles over the Lifespan of Female Medflies as Biomarkers of Aging and Longevity.

The relationship between the early age activity of Mediterranean fruit flies or other fruit flies and their lifespan has not been much studied, in contrast to the connections between lifespan and diet, sexual signaling and reproduction. The objective of this study is to assess intraday and day-to-day activity profiles of female Mediterranean fruit flies and their role as biomarker of longevity as well as to explore the relationships between these activity profiles, diet and age-at-death throughout the lifespan. Three distinct patterns of activity variations in early age activity profiles can be distinguished. A low-caloric diet is associated with a delayed activity peak, while a high-caloric diet is linked with an earlier activity peak. We find that age-at-death of individual medflies is connected to their activity profiles in early life. An increased risk of mortality is associated with increased activity in early age, as well as with a higher contrast between daytime and nighttime activity. Conversely, medflies are more likely to have a longer lifespan when they are fed a medium caloric diet and when their daily activity is more evenly distributed across the early age span and between daytime and nighttime. The before-death activity profile of medflies displays two characteristic before-death patterns, where one pattern is characterized by slowly declining daily activity and the other by a sudden decline in activity that is followed by death.

Acute cold stress and supercooling capacity of Mediterranean fruit fly populations across the Northern Hemisphere (Middle East and Europe).

The Mediterranean fruit fly, Ceratitis capitata (Diptera: Tephritidae), holds an impressive record of successful invasion events promoted by globalization in fruit trade and human mobility. In addition, C. capitata is gradually expanding its geographic distribution to cooler temperate areas of the Northern Hemisphere. Cold tolerance of C. capitata seems to be a crucial feature that promotes population establishment and hence invasion success. To elucidate the interplay between the invasion process in the northern hemisphere and cold tolerance of geographically isolated populations of C. capitata, we determined (a) the response to acute cold stress survival of adults, and (b) the supercooling capacity (SCP) of immature stages and adults. To assess the phenotypic plasticity in these populations, the effect of acclimation to low temperatures on acute cold stress survival in adults was also examined. The results revealed that survival after acute cold stress was positively related to low temperature acclimation, except for females originating from Thessaloniki (northern Greece). Adults from the warmer environment of South Arava (Israel) were less tolerant after acute cold stress compared with those from Heraklion (Crete, Greece) and Thessaloniki. Plastic responses to cold acclimation were population specific, with the South Arava population being more plastic compared to the two Greek populations. For SCP, the results revealed that there is little to no correlation between SCP and climate variables of the areas where C. capitata populations originated. SCP was much lower than the lowest temperature individuals are likely to experience in their respective habitats. These results set the stage for asking questions regarding the evolutionary adaptive processes that facilitate range expansions of C. capitata into cooler temperate areas of Europe.

Artificial diet alters activity and rest patterns in the olive fruit fly.

Olive fruit flies, Bactrocera oleae (Diptera: Tephritidae) reared in the laboratory on an artificial diet are essential for the genetic control techniques against this pest. However, the colony's laboratory adaptation can affect the quality of the reared flies. We used the Locomotor Activity Monitor to track the activity and rest patterns of adult olive fruit flies reared as immatures in olives (F2-F3 generation) and in artificial diet (>300 generations). Counts of beam breaks caused by the adult fly activity were used as an estimation of its locomotor activity levels during the light and dark period. Bouts of inactivity with duration longer than five minutes were considered a rest episode. Locomotor activity and rest parameters were found to be dependent on sex, mating status and rearing history. In virgin flies reared on olives, males were more active than females and increased their locomotor activity towards the end of the light period. Mating decreased the locomotor activity levels of males, but not of female olive-reared flies. Laboratory flies reared on artificial diet had lower locomotor activity levels during the light period and more rest episodes of shorter duration during the dark period compared to flies reared on olives. We describe the diurnal locomotor activity patterns of B. oleae adults reared on olive fruit and on artificial diet. We discuss how locomotor activity and rest pattern differences may affect the laboratory flies' ability to compete with wild males in the field.

Residual efficacy of selected larvicides against Culex pipiens pipiens (Diptera: Culicidae) under laboratory and semi-field conditions.

Mosquitoes are a threat worldwide since they are vectors of important pathogens and parasites such as malaria, dengue, yellow fever, and West Nile. The residual toxicity of several commercial mosquito larvicides was evaluated for the control of Culex pipiens pipiens under controlled laboratory and semi-field conditions during late spring and summer of 2013. The evaluation included six different active ingredient formulations, i.e., diflubenzuron Du-Dim), Bacillus thuringiensis var. israelensis (Bti) (Vectobac), spinosad (Mozkill), S-methoprene (Biopren), temephos (Abate), and polydimethylsiloxane (PDMS) (Aquatain), that are currently registered of and had been registered in the past for mosquito control. Under controlled laboratory conditions, the residual activity ranged from 1 week (S-methoprene) up to 2 months (spinosad, PDMS). Exposure of larvicides under semi-field conditions resulted in noticeable differences regarding their efficacy as compared to the laboratory bioassays. Exposure of S-methoprene, Bti, and spinosad, for up to 3 days, resulted in similar adult emergence to the controls. On the other hand, the residual efficacy of diflubenzuron, temephos, and PDMS ranged from 14 to 28 days, depending on the season of exposure. Longevity and fecundity of adults that had emerged from surviving larvae, in most of the cases tested, did not differ significantly from that of the controls. The results of the present study demonstrate the necessity of both field and laboratory studies to draw safe conclusions regarding the efficacy of larvicides against mosquitoes and the selection of the proper formulation for each application scenario. In addition, defining the seasonal variation in the residual toxicity of the tested formulations could be useful for improving mosquitos' management programs.

Winter survival of adults of two geographically distant populations of Aedes albopictus in a microclimatic environment of Athens, Greece.

Overwintering capacity is a major step towards establishment of invasive mosquitoes from the tropics in temperate zone areas and one of the main elements determining next seasons' population size that regulates disease transmission of competent invasive vector species. The Asian tiger mosquito, Aedes albopictus (Skuse) (Diptera: Culiciidae) is an aggressive invasive species that has greatly expanded its geographical boundaries over the last few decades. The species' ability to induce photoperiodic-based egg diapause allows its overwintering in temperate regions, which favors its establishment in higher latitudes. In warmer temperate areas winter survival can be accomplished in the adult stage as well especially in human-made shelters. Aedes albopictus is already showing signs of adaptation to colder climates which may result in disease transmission in new areas. Although the Asian tiger mosquito has invaded Greece since 2003-4, little is known regarding its overwintering capacity in the country, especially as far as adults are regarded. We studied the survival of Ae. albopictus adults during winter in a protected shelter in Athens, the capital city of Greece. The study involved two geographically isolated populations originating from Chania (Crete, most southern part of Greece), and Palaio Faliro (Athens, Central Greece). We exposed different cohorts of F3 adults of the above two populations that emerged from field collected eggs to "winter condition" from November 2018 to beginning of January 2019. in a protected microclimatic environment. Adult mortality was recorded systematically until the death of the last individual in the cohort. Results demonstrated evidence of winter survival of adults for both populations. Longevity of both females and males of the Palaio Faliro population was longer than that of the Chania population for almost all installation dates. Survival curves, regardless of the date of installation, were steeper for females of the Chania population compared to those from Palaio Faliro. In conclusion, overwinter survival of both populations in the adult stage highlights the need for future studies, considering local and microclimatic condition that vary significantly between regions. Winter climatic conditions play vital role in adult survival of this highly important public health species concerning distribution limits and knowledge on winter survival of Ae. albopictus transmitted viruses.

Fitness cost of Rhagoletis cerasi (Diptera: Tephritidae) adults emerged from pupae with different dormancy regimes: the case of prolonged chilling.

The European cherry fruit fly, Rhagoletis cerasi (Diptera: Tephritidae), is a univoltine species that overwinters at pupal stage. Under optimum overwintering conditions pupae will develop into adults the next spring. Shorter or longer than optimum chilling periods induce prolonged pupae dormancy. Pupae that enter prolonged dormancy due to a short chilling period exhibit high emergence rates after a second cycle of cold/warm periods. Adults found to be larger and less fecund compared to their counterparts from pupae with annual diapause. On the other hand, extreme long chilling periods at pupal stage results in high mortality rates. However, for one Greek population, a substantial number of adults emerged following prolonged chilling of pupae (ca. 18 consecutive months). In this study, we used three R. cerasi populations in order to address possible geographical variation in fitness cost of adults from pupae with prolonged dormancy. In addition, the fitness traits of these adults emerging after prolonged pupae chilling were compared with that of their counterparts from pupae with annual diapause or prolonged dormancy. Our results reveal no population-specific variation in fitness cost of adults from pupae with prolonged dormancy. Within a population, lifetime fecundity did not differ between adults emerged from pupae with prolonged dormancy and those emerged after prolonged pupae chilling. Adults emerged from pupae exposed to prolonged chilling suffer an additional reduction in adult longevity compared to adults from pupae with prolonged dormancy. Hence, fitness of R. cerasi adults is regulated by diapause regimes of pupae.

Chill coma recovery of Ceratitis capitata adults across the Northern Hemisphere.

The Mediterranean fruit fly, Ceratitis capitata (Diptera: Tephritidae), is an invasive pest, that is currently expanding its geographic distribution from the Mediterranean coasts to more temperate areas of Europe. Given that low temperature is a primary determinant of insect species' range boundaries especially in the Northern Hemisphere with pronounced seasonality, we used chill coma recovery time for assessing latitudinal clines in basal chill tolerance of C. capitata adults. We selected six populations obtained from areas with broad climatic variability based on the main bioclimatic variables of temperature and precipitation, spanning a latitudinal range of about 19° from Middle East to Central Europe. Adults were exposed to 0 °C for 4 h, and time to regain the typical standing position of a fly at 25 °C were recorded. The post-stress survival after a period of 8 days was also recorded. Results revealed that adults from Israel and Austria were less chill tolerant than those from Greece, resulting in curvilinear trends with latitude. Analysis of macroclimatic conditions revealed combined effects of latitude (as a proxy of photoperiod) and macroclimatic conditions on chill coma recovery time. Nonetheless, there was not a deleterious effect on post-recovery survival, except for flies obtained from the northern most point (Vienna, Austria). Overall, it seems that evolutionary patterns of basal chill coma recovery time of C. capitata adults are driven mainly by local climatic variability.

Effect of Wolbachia Infection and Adult Food on the Sexual Signaling of Males of the Mediterranean Fruit Fly Ceratitis capitata.

Sexual signaling is a fundamental component of sexual behavior of Ceratitis capitata that highly determines males' mating success. Nutritional status and age are dominant factors known to affect males' signaling performance and define the female decision to accept a male as a sexual partner. Wolbachia pipientis, a widespread endosymbiotic bacterium of insects and other arthropods, exerts several biological effects on its hosts. However, the effects of Wolbachia infection on the sexual behavior of medfly and the interaction between Wolbachia infection and adult food remain unexplored. This study was conducted to determine the effects of Wolbachia on sexual signaling of protein-fed and protein-deprived males. Our findings demonstrate that: (a) Wolbachia infection reduced male sexual signaling rates in both food regimes; (b) the negative effect of Wolbachia infection was more pronounced on protein-fed than protein-deprived males, and it was higher at younger ages, indicating that the bacterium regulates male sexual maturity; (c) Wolbachia infection alters the daily pattern of sexual signaling; and (d) protein deprivation bears significant descent on sexual signaling frequency of the uninfected males, whereas no difference was observed for the Wolbachia-infected males. The impact of our findings on the implementation of Incompatible Insect Technique (IIT) or the combined SIT/IIT towards controlling insect pests is discussed.