Male condition and seminal fluid affect female host-marking behavior in the Mexican fruit fly.

Mating and the transfer of seminal fluid components including male accessory glands (MAGs) proteins can affect oviposition behavior in insects. After oviposition, some species of fruit flies deposit a host-marking pheromone (HMP) on the fruit that discourages oviposition by other females of the same or different species or genus and reduces competition between larvae. However, we know very little about how mating, receiving seminal fluid, or male condition can affect female host marking behavior. Here, we tested how the physiological state of females (mated or unmated), the receipt of seminal fluid, and the condition of the male (wild or sterile) affect oviposition and host-marking behavior (HMB) in Anastrepha ludens (Diptera: Tephritidae). We also determined the efficiency of the host-marking pheromone from mated or unmated females in deterring oviposition. In a further examination of how seminal fluid may be affecting HMB we assessed if there were differences in the size of wild or sterile MAGs and the protein quantity transferred during mating. Our results indicate that receiving seminal fluid increased egg laying and increased time invested in host-marking (HM). Unmated females laid fewer eggs than mated females but invested the same amount of time in depositing host-marking pheromone, which had similar effectiveness in deterring oviposition as that of mated females. Females that mated with sterile males laid the same number of eggs as females that mated with wild males but spent less time depositing host-marking pheromone, which suggests that females detect the condition of the male and invest less in marking hosts. Finally, sterile males had larger accessory glands and transferred more MAGs proteins during mating compared to wild males. Seminal proteins could be manipulating HM behavior and female investment into their current reproductive effort. We are only beginning to understand how male condition and seminal fluid can affect female physiology and maternal investment in HMP.

Tracking and modeling the movement of Queensland fruit flies, Bactrocera tryoni, using harmonic radar in papaya fields.

Determining movement parameters for pest insects such as tephritid fruit flies is critical to developing models which can be used to increase the effectiveness of surveillance and control strategies. In this study, harmonic radar was used to track wild-caught male Queensland fruit flies (Qflies), Bactrocera tryoni, in papaya fields. Experiment 1 continuously tracked single flies which were prodded to induce movement. Qfly movements from this experiment showed greater mean squared displacement than predicted by both a simple random walk (RW) or a correlated random walk (CRW) model, suggesting that movement parameters derived from the entire data set do not adequately describe the movement of individual Qfly at all spatial scales or for all behavioral states. This conclusion is supported by both fractal and hidden Markov model (HMM) analysis. Lower fractal dimensions (straighter movement paths) were observed at larger spatial scales (> 2.5 m) suggesting that Qflies have qualitatively distinct movement at different scales. Further, a two-state HMM fit the observed movement data better than the CRW or RW models. Experiment 2 identified individual landing locations, twice a day, for groups of released Qflies, demonstrating that flies could be tracked over longer periods of time.

OBP83b and OBP49a Involved in the Perception of Female-Derived Pheromones in Bactrocera dorsalis (Hendel).

In Bactrocera dorsalis, both males and females release chemical signals to attract mates. In our previous study, we identified ethyl laurate, ethyl myristate, and ethyl palmitate as potent female-derived pheromones that contribute to mate attraction. However, the mechanisms underlying the olfactory recognition remain unclear. In this study, we observed strong antennal and behavioral responses in male B. dorsalis to these female-derived pheromones, and further investigation revealed significant upregulation of OBP49a and OBP83b following exposure to these compounds. Through fluorescence competitive binding assays and RNA interference techniques, we demonstrated the crucial roles of OBP49a and OBP83b in detecting female-derived pheromones. Finally, molecular docking analysis identified key residues, including His134 in OBP83b and a lysine residue in OBP49a, which formed hydrogen bonds with female-derived pheromones, facilitating their binding. These findings not only advance our understanding of olfactory recognition of pheromones in B. dorsalis but also offer potential targets for developing olfaction-interfering techniques for pest control.

Differential pheromone profile as a contributor to premating isolation between two sympatric sibling fruit fly species.

Bactrocera tryoni (Froggatt) and Bactrocera neohumeralis (Hardy) are sibling fruit fly species that are sympatric over much of their ranges. Premating isolation of these close relatives is thought to be maintained in part by allochrony-mating activity in B. tryoni peaks at dusk, whereas in B. neohumeralis, it peaks earlier in the day. To ascertain whether differences in pheromone composition may also contribute to premating isolation between them, this study used solid-phase microextraction and gas chromatography-mass spectrometry to characterize the rectal gland volatiles of a recently collected and a more domesticated strain of each species. These glands are typical production sites and reservoirs of pheromones in bactrocerans. A total of 120 peaks were detected and 50 were identified. Differences were found in the composition of the rectal gland emissions between the sexes, species, and recently collected versus domesticated strains of each species. The compositional variation included several presence/absence and many quantitative differences. Species and strain differences in males included several relatively small alcohols, esters, and aliphatic amides. Species and strain differences in females also included some of the amides but additionally involved many fatty acid esters and 3 spiroacetals. While the strain differences indicate there is also heritable variation in rectal gland emissions within each species, the species differences imply that compositional differences in pheromones emitted from rectal glands could contribute to the premating isolation between B. tryoni and B. neohumeralis. The changes during domestication could also have significant implications for the efficacy of Sterile Insect Technique control programs.

Seasonal fluctuation and alternative host plants of vegetable crop-infesting tephritids in non-vegetable growing areas in South Sudanese zone of Burkina Faso.

This study was carried out in 3 types of biotopes where vegetable crops are not grown to highlight their contribution to the dynamics of vegetable-infesting flies. To this end, a trapping system based on a sexual attractant, the Cuelure associated with an insecticide was set up in 18 biotopes (6 natural areas, 6 mango orchards, and 6 agroforestry parks) in the regions of Hauts Bassins and Cascades in the South-West of Burkina Faso. During the trapping monitoring, which was done every 2 wk to collect insects captured, fruits present in 3 types of biotopes were sampled and incubated for insect emergence. Ten Dacus (Fabricius) [Diptera: Tephritidae] species and Zeugodacus cucurbitae (Coquillett) [Diptera: Tephritidae] were trapped in the study area. The predominant species captured was Z. cucurbitae (52.93%) followed by Dacus punctatifrons (Karsch) [Diptera: Tephritidae] (29.89%) and Dacus humeralis (Bezzi) (12.71%). Six tephritid species were emerged from 6 wild fruit species belonging to Cucurbitaceae, Apocynaceae, and Passifloraceae families. Fruit flies were more abundant from Jul to Nov with peaks observed in Aug or Oct depending on the species. Citrullus colocynthis L. (Cucurbitaceae), Lagenaria sp. (Cucurbitaceae), Passiflora foetida L. (Passifloraceae), and Passiflora sp. acted as reservoir host plants of Dacus ciliatus (Loew), Dacus bivittatus (Bigot), Dacus vertebratus (Bezzi) [Diptera: Tephritidae], D. punctatifrons, and Z. cucurbitae, the major vegetable insect pests in West Africa. The 3 types of biotopes acted as suitable refuge areas of vegetable crop-infesting fruit flies either for the favorable microclimate or for the alternative host plants.

Variation in Thermal Sensitivity of Diapause Development among Individuals and over Time Predicts Life History Timing in a Univoltine Insect.

AbstractPhysiological time is important for understanding the development and seasonal timing of ectothermic animals but has largely been applied to developmental processes that occur during spring and summer, such as morphogenesis. There is a substantial knowledge gap in the relationship between temperature and development during winter, a season that is increasingly impacted by climate change. Most temperate insects overwinter in diapause, a developmental process with little obvious morphological change. We used principles from the physiological time literature to measure and model the thermal sensitivity of diapause development rate in the apple maggot fly Rhagoletis pomonella, a univoltine fly whose diapause duration varies substantially within and among populations. We show that diapause duration can be predicted by modeling a relationship between temperature and development rate that is shifted toward lower temperatures compared with typical models of morphogenic, nondiapause development. However, incorporating interindividual variation and ontogenetic variation in the temperature-to-development rate relationship was critical for accurately predicting fly emergence, as diapause development proceeded more quickly at high temperatures later in diapause. We conclude that the conceptual framework may be flexibly applied to other insects and discuss possible mechanisms of diapause timers and implications for phenology with warming winters.

The species and abundance of gut bacteria both positively impact Phortica okadai behavior.

BACKGROUND: Gut bacteria, which serve as essential modulators, exert a significant impact on insect physiology and behavior and have substantial application potential in pest management. The dynamics of gut bacteria and their impact on Phortica okadai behavior remain unclear. METHODS: In this study, the dynamics of gut bacteria at different developmental stages in P. okadai were analyzed using 16S ribosomal RNA (rRNA) gene sequencing, and the species and abundance of gut bacteria that affect host behavior were examined via behavioral experiments. RESULTS: A total of 19 phyla, 29 classes, 74 orders, 101 species, and 169 genera were identified. The results of the behavioral experiments indicated that the species Lactiplantibacillus argentoratensis, Acetobacter tropicalis, Leuconostoc citreum, and Levilactobacillus brevis effectively influenced the feeding preference of P. okadai, and the single-bacterium-seeded P. okadai exhibited feeding preferences distinct from those of the germ-free (GF) and wild-type P. okadai. CONCLUSIONS: The species and relative abundance of gut bacteria together positively impact P. okadai behavior. Lactiplantibacillus argentoratensis, as the most attractive bacteria to P. okadai, presents opportunities for novel pest control strategies targeting this vector and agricultural pest.

Odorant Receptor BdorOR49b Mediates Oviposition and Attraction Behavior of Bactrocera dorsalis to Benzothiazole.

The ability to recognize a host plant is crucial for insects to meet their nutritional needs and locate suitable sites for laying eggs. Bactrocera dorsalis is a highly destructive pest in fruit crops. Benzothiazole has been found to induce oviposition behavior in the gravid B. dorsalis. However, the ecological roles and the olfactory receptor responsible for benzothiazole are not yet fully understood. In this study, we found that adults were attracted to benzothiazole, which was an effective oviposition stimulant. In vitro experiments showed that BdorOR49b was narrowly tuned to benzothiazole. The electroantennogram results showed that knocking out BdorOR49b significantly reduced the antennal electrophysiological response to benzothiazole. Compared with wild-type flies, the attractiveness of benzothiazole to BdorOR49b knockout adult was significantly attenuated, and mutant females exhibited a severe decrease in oviposition behavior. Altogether, our work provides valuable insights into chemical communications and potential strategies for the control of this pest.

CRISPR/Cas9-mediated knockout of a male accessory glands-specific gene takeout1 decreases the fecundity of Zeugodacus cucurbitae female.

BACKGROUND: The melon fly, Zeugodacus cucurbitae (Coquillett), is an invasive Tephritidae pest with robust fertility. The male accessory glands (MAGs) form a vital organ that ensures insect reproductive efficiency. Most of the secreted proteins by MAGs exhibit a male bias expression. Takeout, one of these proteins, is abundantly present in the MAGs of many insects. RESULTS: In this study, we identified 32 takeout genes in Z. cucurbitae. The phylogenetic analysis and multiple sequence alignment results showed that Zctakeout1 is the most related homolog to the MAGs-specific takeout in Tephritidae. The real-time quantitative PCR results showed that Zctakeout1 was exclusively expressed in the male adult stage, and its expression level gradually increased with the increase in age and then remained stable at the sexually matured stage. The distribution among tissues demonstrated the specific expression of Zctakeout1 in the MAGs, and fluorescence immunohistochemical results confirmed the presence of Zctakeout1 in close proximity to binuclear cells of the mesoderm epidermal MAGs. In continuation, CRISPR/Cas9-mediated genome editing was employed, resulting in successfully generating a homozygous strain with an +8 bp insertion. The mating experiments with the Zctakeout1-/- males resulted in significant reductions in both the mating rate and egg production of females. CONCLUSION: These findings prove that the MAGs-specific Zctakeout1 is essential in regulating fecundity in female Z. cucurbitae fruit flies. Our data suggests its utilization in future essential insect-specific gene-directed sterility insect technique (SIT) by the genetic manipulation to keep these important Tephritidae populations under control. © 2024 Society of Chemical Industry.

OpsinLW2 serves as a circadian photoreceptor in the entrainment of circadian locomotor rhythm of a firebrat.

Photic entrainment is an essential function of the circadian clock, which enables organisms to set the appropriate timing of daily behavioral and physiological events. Recent studies have shown that the mechanisms of the circadian clock and photic entrainment vary among insect species. This study aimed to elucidate the circadian photoreceptors necessary for photic entrainment in firebrats Thermobia domestica, one of the most primitive apterygote insects. A homology search of publicly available RNA sequence (RNA-seq) data from T. domestica exhibited a cryptochrome 2 (cry2) gene and three opsin genes, opsin long wavelength 1 (opLW1), opLW2, and opUV, as candidate circadian photoreceptors. We examined the possible involvement of these genes in photic entrainment of firebrat locomotor rhythms. Firebrats had the highest entrainability to the light-dark cycle of green light. Treatment with dsRNA of the candidate genes strongly downregulated the respective targeted genes, and in the case of opsin genes, other untargeted genes were occasionally downregulated to various degrees. Under constant light, most control firebrats became arrhythmic, whereas a fraction of those treated with double RNAi of the two opLWs remained rhythmic. Behavioral experiments revealed that the transient cycles necessary for re-entrainment to shifted light cycles were lengthened when opLW2 expression was reduced. These results suggest that opLW2 is involved in the photic entrainment of circadian rhythm in firebrats.

Understanding the movement and dispersal patterns of released Fopius arisanus (Hymenoptera: Braconidae) parasitoids in a papaya orchard.

Implementation of augmentative biological control requires estimates of parasitoid dispersal from the release point to determine appropriate release density, spacing, and timing. This study evaluated the movement patterns of Fopius arisanus Sonan (Hymenoptera: Braconidae) parasitoids, which have historically been used to control invasive tephritid fruit flies. The wasps were released from the central point, and dispersal was monitored over time using parasitism in sentinel fruit and trap captures at 40 points radiating out from the center (15-240 m). The releases were conducted 4 times during June, July, September, and November 2006. The data showed that there were large declines in dispersal by distance. Parasitism was greatest closest to the release point, within 30 m. Parasitism was also greatest within the first 24 h of the release. After 1 wk, parasitism decreased from 41% to 1.5% within 30 m. These data correlated strongly with trap capture data, which also showed that parasitoid movement favored the SE region of our release site, roughly corresponding to the overall prevailing winds. Wind speed, relative humidity, and temperature all affected parasitoid movement during our trial, indicating the complex environmental factors that can affect release success. This is the first report of dispersal metrics for F. arisanus. Our findings are in agreement with other similar studies on braconid movement generally and suggest that frequent, high-density releases are most effective since the dispersal of F. arisanus is limited and retention in the environment is low. We discuss our results in the context of international augmentative biological control release programs.

An Odorant Receptor Expressed in Both Antennae and Ovipositors Regulates Benzothiazole-Induced Oviposition Behavior in Bactrocera dorsalis.

The oriental fruit fly,Bactrocera dorsalis (Hendel), is a notorious pest of fruit crops, causing severe damage to fleshy fruits during oviposition and larval feeding. Gravid females locate suitable oviposition sites by detecting the host volatiles. Here, the oviposition preference of antenna-removed females and the electrophysiological response of ovipositors to benzothiazole indicated that both antennae and ovipositors are involved in perceiving benzothiazole. Subsequently, odorant receptors (ORs) expressed in both antennae and ovipositors were screened, and BdorOR43a-1 was further identified to respond to benzothiazole using voltage-clamp recording. Furthermore, BdorOR43a-1-/- mutants were obtained using the CRISPR/Cas9 system and their oviposition preference to benzothiazole was found to be significantly altered compared to WT females, suggesting that BdorOR43a-1 is one of the important ORs for benzothiazole perception. Our results not only demonstrate the important role of antennae and ovipositors in benzothiazole-induced oviposition but also elucidate on the OR responsible for benzothiazole perception in B. dorsalis.

The maxillary palps of Tephritidae are selectively tuned to food volatiles and diverge with ecology.

The maxillary palp is an auxiliary olfactory organ in insects, which, different from the antennae, is equipped with only a few olfactory sensory neuron (OSN) types. We postulated that these derived mouthpart structures, positioned at the base of the proboscis, may be particularly important in mediating feeding behaviors. As feeding is spatio-temporally segregated from oviposition in most Tephritidae, this taxonomic group appears quite suitable to parse out sensory breadth and potential functional divergence of palps and antennae. Scanning electron microscopy and anterograde staining underlined the limited palpal olfactory circuit in Tephritidae: only three morphological subtypes of basiconic sensilla were found, each with two neurons, and project to a total of six antennal lobe glomeruli in Bactrocera dorsalis. Accordingly, the palps detected only few volatiles from the headspace of food (fermentation and protein lures) and fruit (guava and mango) compared to the antennae (17 over 77, using gas-chromatography coupled electrophysiology). Interestingly, functionally the antennae were more tuned to fruit volatiles, detecting eight times more fruit than food volatiles (63 over 8), whereas the number of fruit and food volatile detection was more comparable in the palps (14 over 8). As tephritids diverge in oviposition preferences, but converge on food substrates, we postulated that the receptive ranges of palpal circuits would be more conserved compared to the antennae. However, palpal responses of three tephritid species that differed in phylogenetic relatedness and ecologically niche, diverged across ecological rather than phylogenetic rifts. Two species with strongly overlapping ecology, B. dorsalis and Ceratitis capitata, showed inseparable response profiles, whereas the cucurbit specialist Zeugodacus cucurbitae strongly diverged. As Z. cucurbitae is phylogenetically placed between B. dorsalis and C. capitata, the results indicate that ecology overrides phylogeny in the evolution of palpal tuning, in spite of being predisposed to detecting food volatiles.

Copper nanoparticles interfere with insecticide sensitivity, fecundity and endosymbiont abundance in olive fruit fly Bactrocera oleae (Diptera: Tephritidae).

BACKGROUND: The potential of copper nanoparticles (Cu-NPs) to be used as an alternative control strategy against olive fruit flies (Bactrocera oleae) with reduced sensitivity to the pyrethroid deltamethrin and the impact of both nanosized and bulk copper hydroxide (Cu(OH)2) on the insect's reproductive and endosymbiotic parameters were investigated. RESULTS: The application of nanosized and bulk copper applied by feeding resulted in significant levels of adult mortality, comparable to or surpassing those achieved with deltamethrin at recommended doses. Combinations of Cu-NPs or copper oxide nanoparticles (CuO-NPs) with deltamethrin significantly enhanced the insecticide's efficacy against B. oleae adults. When combined with deltamethrin, Cu-NPs significantly reduced the mean total number of offspring compared with the control, and the number of stings, pupae, female and total number of offspring compared with the insecticide alone. Both bulk and nanosized copper negatively affected the abundance of the endosymbiotic bacterium Candidatus Erwinia dacicola which is crucial for the survival of B. oleae larvae. CONCLUSION: The Cu-NPs can aid the control of B. oleae both by reducing larval survival and by enhancing deltamethrin performance in terms of toxicity and reduced fecundity, providing an effective anti-resistance tool and minimizing the environmental footprint of synthetic pesticides by reducing the required doses for the control of the pest. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Plasticity of the olfactory behaviors in Bactrocera dorsalis under various physiological states and environmental conditions.

Insects rely heavily on their olfactory system for various behaviors, including foraging, mating, and oviposition. Numerous studies have demonstrated that insects can adjust their olfactory behaviors in response to different physiological states and environmental conditions. This flexibility allows them to perceive and process odorants according to different conditions. The Oriental fruit fly, Bactrocera dorsalis, is a highly destructive and invasive pest causing significant economic losses to fruit and vegetable crops worldwide. The olfactory behavior of B. dorsalis exhibits strong plasticity, resulting in its successful invasion. To enhance our understanding of B. dorsalis' olfactory behavior and explore potential strategies for behavior control, we have reviewed recent literature on its olfactory plasticity and potential molecular mechanisms.

Rearing and 60Co radiation do not affect attractiveness but alter the volatile profiles released by Anastrepha obliqua calling males.

Calling males of Anastrepha obliqua release volatile compounds to attract conspecific males to form leks and females to mate. Male volatiles from Mexican and Brazilian populations of A. obliqua have been previously identified. However, there are differences in the number and identity of volatile compounds between the populations. These differences in volatile profiles may be due to male origin (e.g. wild or mass-reared flies) or methodological issues (e.g. sampling techniques). In this study, we evaluated the attractiveness of wild, laboratory non-irradiated, and laboratory-irradiated flies under semi-field conditions. Male volatiles were collected using dynamic headspace sampling (DHS) and solid-phase microextraction (SPME) techniques, and identified using gas chromatography-coupled mass spectrometry. The results showed no difference in the attractiveness of wild, laboratory non-irradiated, and irradiated males to females. However, the number of captured females differed according to the origin; wild and non-irradiated females were captured more frequently than the irradiated flies. A total of 21 compounds were found using SPME, whereas only 12 were collected using DHS, although the relative amounts of these compounds were higher than those obtained using the former sampling technique. In addition, only laboratory non-irradiated males released α-pinene and menthol, which have not been previously reported in this fruit fly species. Additionally, we identified novel compounds in A. obliqua; however, certain compounds previously reported were not detected. This study suggests that despite the qualitative and quantitative variations in the volatile profiles of A. obliqua males, their attractiveness was unaffected.

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.

An Antenna-Enriched Chemosensory Protein Plays Important Roles in the Perception of Host Plant Volatiles in Bactrocera dorsalis (Diptera: Tephritidae).

Olfaction plays indispensable roles in insect behavior such as host location, foraging, oviposition, and avoiding predators. Chemosensory proteins (CSPs) can discriminate the hydrophobic odorants and transfer them to the odorant receptors. Presently, CSPs have been identified in many insect species. However, their presence and functions remain unknown in Bactrocera dorsalis, a destructive and invasive insect pest in the fruit and vegetable industry. Here, we annotated eight CSP genes in the genome of B. dorsalis. The results of quantitative real-time polymerase chain reaction (RT-qPCR) showed that BdorCSP3 was highly expressed in the antennae. Molecular docking and in vitro binding assays showed that BdorCSP3 had a good binding ability to host volatiles methyl eugenol (ME, male-specific attractant) and ß-caryophyllene (potential female attractant). Subsequently, CRISPR/Cas9 was used to generate BdorCSP3-/- mutants. Electroantennograms (EAGs) and behavioral assays revealed that male mutants significantly reduced the preference for ME, while female mutants lost their oviposition preference to ß-caryophyllene. Our data indicated that BdorCSP3 played important roles in the perception of ME and ß-caryophyllene. The results not only expanded our knowledge of the olfaction perception mechanism of insect CSPs but also provided a potential molecular target for the control of B. dorsalis.

Responses of two Anastrepha species' immature stages infesting preferential hosts to different temperature exposures.

Anastrepha fraterculus (Wiedemann) and A. obliqua (Macquart) are important pests of fruit crops. In Brazil, these species cause damage to fruit growing in the South (annual average temperature of 20.9 °C) and Northeast (average yearly temperature of 24 °C). We evaluated the effect of temperature on the viability and development time of A. fraterculus and A. obliqua immature stages in their respective preferred hosts, guava (Psidium guajava L., Myrtaceae) and mango (Mangifera indica L., Anacardiaceae). The duration of egg and pupal stages, egg to pre-pupa, and viability of egg and pupal stages under different temperatures (15, 20, 25, 30, and 35 °C) were assessed. For both species, development time decreased with increasing temperature. Viability in the evaluated stages was only observed between 15 and 30 °C. However, the species responded differently to the exposure temperatures (15 and 30 °C), especially in the pupal stage and from egg to pre-pupa. Anastrepha fraterculus showed a lower tolerance to high temperatures, especially in the pupal stage and from egg to pre-pupa, which may explain its lower importance and economic impact in warmer Brazilian regions. Anastrepha obliqua had a lower tolerance at 15 °C, indicating greater adequacy for temperatures above 20 °C, characteristic of Northeast Brazil, suggesting the capacity to spread to cooler areas with rising temperatures.

Spatio-temporal Distribution of Bactrocera carambolae with and without Irrigation using CLIMEX Modeling.

The carambola fruit fly Bactrocera carambolae Drew and Hancock (Diptera: Tephritidae) is an invasive fruit fly reported in North Brazil that threatens Brazilian fruit culture. Assessing the potential risk of establishing this pest is necessary to reduce the threat of B. carambolae dispersion to other countries and Brazilian regions and to avoid damage to the fruit trade. In this study, the CLIMEX model was used to understand the response of B. carambolae to climate change and to determine its potential global distribution with and without irrigation practices. Based on ecophysiological parameters, the model simulates factors limiting species distribution concerning the climate. To assess the seasonal variation in the density of B. carambolae, monitoring data in Uiramutã municipality, Roraima, from 2013 to 2019 was used. According to the CLIMEX forecast, large parts of America, Africa, and Asia, mainly in areas closest to the equator, are highly suitable for the survival of B. carambolae. Brazil is a good part of its territory with high suitability for B. carambolae, especially the North, South, and Southeast regions and the entire coastal area. The periods of the highest climatic suitability in the five Brazilian regions were January-May and October-December. The potential distribution area expands under irrigation and is highly suitable for most areas without cold stress. The CLIMEX model for B. carambolae generated in the present study provides important information for the Brazilian eradication program and other surveillance activities established in pest-free areas.