Behavior Of Flies Research Articles

Understanding sand fly sampling methods: sticky traps are attraction-based and not interceptive sampling tools of Phlebotomus orientalis

BackgroundSticky traps are generally viewed as interceptive sand fly sampling methods; although no previous experimental evidence has supported this assumption. In this study, we tested this assumption experimentally for Phlebotomus orientalis, the principal vector of visceral leishmaniasis in East Africa, and propose an explanation for the highly male-biased collection of sticky traps.MethodsA number of field experiments were carried out in March–June 2016–2019, in Gedarif state, eastern Sudan. In the first experiment, we compared numbers of P. orientalis caught on sticky traps made of black, red, transparent, white, yellow, green and blue A4 size papers set simultaneously at different lunar light conditions. In the second and third experiments, we compared numbers of P. orientalis captured on sticky traps placed side-by-side horizontally or vertically on the ground, or horizontally on a 15 cm height stool. We also witnessed mating behaviour of sand flies following their landing on un-sticky papers placed on the ground.ResultsPhlebotomus orientalis showed significant attraction to white, yellow and transparent traps, with negligible numbers caught on the black and the red traps. Similarly, significantly higher numbers of P. orientalis were attracted to the horizontal traps, resulting in an 8-fold increase in sand fly trapping efficacy as compared to the vertical traps. Placing the traps on the stools resulted in significant reduction in this attraction. In contrast to the sticky traps that captured only very few females; we found that when male sand flies land on un-sticky white paper they successfully lure females and copulate with them.ConclusionsWe demonstrate that, for P. orientalis, sticky traps are more attractant-based than interception-based sampling tools. Further, our findings support the notion that males of this sand fly species likely utilize the bright surface of the trap papers to perform mating rituals that attract the females for copulation. However, pre-mature death in the sticky oil hampers the completion of these rituals, and thus results in failure to attract the females. These findings inform our understanding of P. orientalis behaviour and have important implications for optimization of sticky trap design for vector surveillance purposes.

Molecular and functional characterization of the flightin gene in the Oriental fruit fly, Bactrocera dorsalis

AbstractFlightin is a protein in flight muscles and is crucial for the flight capacity. Flightin also has been proposed as a protein with deep ancestry and functions outside of flight muscles. However, functional and molecular characterization of flightin achieved so far is mainly in flight muscles of Drosophila. Here, we cloned the flightin (Bd‐flightin) gene and tested its expression and function in Bactrocera dorsalis, an important migratory pest. Phylogenetic analysis based on flightin orthologs revealed that the divergence of flightin is consistent with the taxonomic classification of insects. Motif analysis indicated obvious variations in flightin orthologs, which may have occurred during speciation and functional differentiation. The expression is quite low during egg and larval stages, which largely increased during pupal stage and then peaked at the beginning of the adult stage. Bd‐flightin also showed tissue‐ and age‐specific expression patterns during adult stage. The relative expression level is low in wing, head, ovary and testis, which is relatively higher in leg and abdominal wall and much higher in thorax. Injection of late pupae and newly eclosed adults with 1 μg flightin dsRNA per insect both significantly reduced the expression of flightin and the flight capacity in males and females. In addition, silencing the expression of flightin also decreased the weight ratio of thorax and whole‐body. These results suggested that flightin plays important roles in flight muscle development and flight function in B. dorsalis, which can potentially be used to control the flight behaviour of the fruit fly.

Studies of host preferences of wild-caught Phlebotomus orientalis and Ph. papatasi vectors of leishmaniasis in Sudan.

IntroductionUnderstanding the feeding behavior and host choice of sand flies provides valuable information on vector-host relationships and elucidates the epidemiological patterns of leishmaniasis transmission. Blood meal analysis studies are essential for estimating the efficiency of pathogen transmission, assessing the relative human disease risk, and assist in identifying the other potential hosts of leishmaniasis. In Sudan and most of East Africa, there are large remaining gaps in knowledge regarding the feeding habits of phlebotomine vectors. The study aimed to identify the blood meal sources and, therefore, the host preferences of the principal vectors Phlebotomus orientalis and Ph. papatasi in leishmaniasis endemic areas of eastern and central Sudan.Materials and methodsSand flies were collected from two endemic villages in eastern and central Sudan using CDC light traps and sticky traps. The phlebotomine sand flies were morphologically and then molecularly identified. The source of blood meal of the engorged females was determined using a multiplex PCR methodology and specific primers of cytochrome b gene of mitochondrial DNA for human, goat, cow, and dog. The detection of the Leishmania parasite was done using PCR.ResultsThe total number of collected female phlebotomine sand flies was 180. Morphological identification revealed the abundance of Ph. orientalis 103 (57.2%), Ph. papatasi 42 (23.3%), Ph. bergeroti 31 (17.2%), Ph. rodhaini 2 (1.1%) and Ph. duboscqi 2 (1.1%) in the study sites. Out of the 180 collected, 31 (17%) were blood-fed flies. Three species were blood-fed and molecularly identified: Ph. papatasi (N = 7, 22.6%), Ph. bergeroti (N = 9, 26%), and Ph. orientalis (N = 15, 48.4%). Blood meal analysis revealed human DNA in two Ph. orientalis (6.4%), hence, the anthropophilic index was 13.3%.ConclusionsMultiplex PCR protocol described here allowed the identification of blood meal sources of many vertebrate species simultaneously. The results indicate that wild-caught Ph. orientalis are anthropophilic in the study areas. Further studies on larger blood-fed sample size are required to validate the potential applications of this technique in designing, monitoring and evaluating control programs, particularly in investigating the potential non-human hosts of leishmaniasis.

Social Behavioral Deficits with Loss of Neurofibromin Emerge from Peripheral Chemosensory Neuron Dysfunction

Neurofibromatosis type 1 (NF1) is a neurodevelopmental disorder associated with social and communicative disabilities. The cellular and circuit mechanisms by which loss of neurofibromin 1 (Nf1) results in social deficits are unknown. Here, we identify social behavioral dysregulation with Nf1 loss in Drosophila. These deficits map to primary dysfunction of a group of peripheral sensory neurons. Nf1 regulation of Ras signaling in adult ppk23+ chemosensory cells is required for normal social behaviors in flies. Loss of Nf1 attenuates ppk23+ neuronal activity in response to pheromones, and circuit-specific manipulation of Nf1 expression or neuronal activity in ppk23+ neurons rescues social deficits. This disrupted sensory processing gives rise to persistent changes in behavior beyond the social interaction, indicating a sustained effect of an acute sensory misperception. Together our data identify a specific circuit mechanism through which Nf1 regulates social behaviors and suggest social deficits in NF1 arise from propagation of sensory misinformation.

Behavioral changes in Drosophila males after travel to international space station

Results of behavioral tests made postflight after two independent travels of Drosophila melanogaster to International Space Station (ISS) are presented. In Experiment 1, the first instar larvae were launched, and the eclosed imagoes gave the next generation that developed from the egg at ISS. After return to Earth the behavior of adult males of the next generation was examined. In Experiment 2, the newly emerged adult males were launched and after 7.5 days of staying at ISS were tested in the lab. In Experiment 1, we found pronounced influence of development in Space on subsequent locomotor behavior of adult flies. In flies developed in Space, all three independent parameters of locomotor behavior (run frequency, run duration and running speed) were increased, at least at certain time points, during the first hour of registration. At the same time, the climbing ability of experimental flies was reduced. In Experiment 2, no changes in the climbing ability were detected. During the first 30 min after registration beginning the flown flies performed less frequent but more extended runs than the control flies did. However, later the flown flies demonstrated an increased run frequency. Additionally, the interpulse interval in the pulse courtship song was shorter in the flown males. Taken together, the results point to a considerable activation of the central nervous system in flies developed at the ISS and to a minor one in the adult flies travelled to the ISS. This shows that earlier stages of development are more sensitive to spaceflight factors than the adult stage.

Object-Displacement-Sensitive Visual Neurons Drive Freezing in Drosophila

Visual systems are often equipped with neurons that detect small moving objects, which may represent prey, predators, or conspecifics. Although the processing properties of those neurons have been studied in diverse organisms, links between the proposed algorithms and animal behaviors or circuit mechanisms remain elusive. Here, we have investigated behavioral function, computational algorithm, and neurochemical mechanisms of an object-selective neuron, LC11, in Drosophila. With genetic silencing and optogenetic activation, we show that LC11 is necessary for a visual object-induced stopping behavior in walking flies, a form of short-term freezing, and its activity can promote stopping. We propose a new quantitative model for small object selectivity based on the physiology and anatomy of LC11 and its inputs. The model accurately reproduces LC11 responses by pooling fast-adapting, tightly size-tuned inputs. Direct visualization of neurotransmitter inputs to LC11 confirmed the model conjectures about upstream processing. Our results demonstrate how adaptation can enhance selectivity for behaviorally relevant, dynamic visual features.

Rationalized fruit fly optimization with sine cosine algorithm: A comprehensive analysis

The fruit fly optimization algorithm (FOA) is a well-regarded algorithm for searching the global optimal solution by simulating the foraging behavior of fruit flies. However, when solving high dimensional mathematical and practical application problems, FOA is not competitive in convergence speed, and it may quickly fall into the local optimum. Therefore, in this paper, an enhanced fruit fly optimizer, termed SCA_FOA, is developed by introducing the logic of the sine cosine algorithm (SCA). Specifically, in the process of searching for food utilizing the osphresis organ, the individual fruit fly adopts the way inspired by the SCA to fly outward or inward to find the global optimum. A comprehensive set of 28 benchmark functions were used to measure the exploitation and exploration abilities of the proposed SCA_FOA. The results demonstrate that SCA_FOA is superior to other competitive algorithms. Moreover, 10 practical problems from IEEE CEC 2011, three engineering problems, three shifted and asymmetrical functions, and optimization problems of kernel extreme learning machines (KELM) were also solved, effectively. The results and observations indicate that not only the proposed SCA_FOA can be used for simulated problems as a very efficient method, but also it can be employed for real-world applications.

The 18S ribosomal RNA m6 A methyltransferase Mettl5 is required for normal walking behavior in Drosophila.

RNA modifications have recently emerged as an important layer of gene regulation. N6-methyladenosine (m6 A) is the most prominent modification on eukaryotic messenger RNA and has also been found on noncoding RNA, including ribosomal and small nuclear RNA. Recently, several m6 A methyltransferases were identified, uncovering the specificity of m6 A deposition by structurally distinct enzymes. In order to discover additional m6 A enzymes, we performed an RNAi screen to deplete annotated orthologs of human methyltransferase-like proteins (METTLs) in Drosophila cells and identified CG9666, the ortholog of human METTL5. We show that CG9666 is required for specific deposition of m6 A on 18S ribosomal RNA via direct interaction with the Drosophila ortholog of human TRMT112, CG12975. Depletion of CG9666 yields a subsequent loss of the 18S rRNA m6 A modification, which lies in the vicinity of the ribosome decoding center; however, this does not compromise rRNA maturation. Instead, a loss of CG9666-mediated m6 A impacts fly behavior, providing an underlying molecular mechanism for the reported human phenotype in intellectual disability. Thus, our work expands the repertoire of m6 A methyltransferases, demonstrates the specialization of these enzymes, and further addresses the significance of ribosomal RNA modifications in gene expression and animal behavior.

Laboratory evaluation of effects of powdered sulphur on the oviposition, fruit detection and behaviour of Drosophila suzukii (Diptera: Drosophilidae) on strawberry

Drosophila suzukii (Matsumura, 1931) is an invasive pest from South-East Asia that can damage a wide range of soft-skinned fruit crops (especially berries) resulting in serious financial losses. At present, control of D. suzukii is still mainly based on adult-oriented chemical pesticides that is likely to result in resistance and environmental pollution. In this context, alternative methods that are compatible with sustainable management are required. Sulphur and its different formulations are widely used for a long time as a fungicide and insecticide on many crops as it is environmentally-friendly and compatible with organic management. In this study, the effect that powdered sulphur-treated strawberries had on oviposition were evaluated under laboratory conditions in order to confirm the findings of a previous report on blueberries. No-choice and choice experiments were carried out to assess whether powdered sulphur affected the ability of the fly to detect fruit, altered its behaviour or did both. The treatment of strawberries resulted in a reduction of over 79% in the total number of D. suzukii that developed. In the no-choice experiment, there was a reduction of over 70% in the time the flies spent on treated compared to untreated fruit. In the choice experiment, 57% of the females chose untreated and 43% treated strawberries, but this difference was not statistically significant. Furthermore, females took over 75% longer to visit the treated fruit than the control. Sulphur had no noteworthy effect on fly behavior, although oviposition only occurred on untreated fruit indicating that sulphur affects the acceptance and suitability of fruit for females. These results indicate that powdered sulphur could be an appropriate alternative to synthetic-organic insecticides for controlling D. suzukii and is compatible with organic crop management and waste reduction strategies.

Fast multiplex real-time PCR assay for simultaneous detection of dog and human blood and Leishmania parasites in sand flies

BackgroundThe blood-feeding behaviour of female sand flies may increase their likelihood of acquiring and transmitting Leishmania parasites. Studies on the host usage by these insects may thus improve our understanding of the Leishmania transmission risk in leishmaniasis-endemic areas. Here, we developed a fast multiplex real-time PCR assay for simultaneous detection of dog, human and Leishmania DNA in sand flies.MethodsPrimers and TaqMan probes targeting the mitochondrial cytochrome c oxidase subunit 1 and cytochrome b genes of dog and human, respectively, were combined in a multiplex assay, which also includes primers and a TaqMan probe targeting the Leishmania minicircle kinetoplast DNA.ResultsThe multiplex assay was 100% specific, with analytical sensitivities of 103 fg/reaction for dog and human and 1 fg for Leishmania. By testing field-collected engorged female sand flies (95 Migonemyia migonei and two Nyssomyia intermedia), 50 M. migonei were positive for one or two targets (positivity rates: 45.4% for human, 4.1% for dog and 12.4% for Leishmania DNA).ConclusionsThis multiplex real-time PCR assay represents a novel fast assay for detecting dog, human and Leishmania DNA in female sand flies and therefore a tool for assessing the risk of Leishmania transmission to these hosts in areas of active transmission.

Anti-instinctive Learning Behavior Revealed by Locomotion-Triggered Mild Heat Stress in Drosophila.

Anti-instinctive learning, an ability to modify an animal's innate behaviors in ways that go against one's innate tendency, can confer great evolutionary advantages to animals and enable them to better adapt to the changing environment. Yet, our understanding of anti-instinctive learning and its underlying mechanisms is still limited. In this work, we describe a new anti-instinctive learning behavior of fruit flies. This learning paradigm requires the fruit fly to respond to a recurring, aversive, mild heat stress by modifying its innate locomotion behavior. We found that experiencing movement-triggered mild heat stress repeatedly significantly reduced walking activity in wild type fruit flies, indicating that fruit flies are capable of anti-instinctive learning. We also report that such learning ability is reduced in dopamine 1-like receptor 1 (Dop1R1) null mutant and dopamine 2-like receptor (Dop2R) null mutant flies, suggesting that these two dopamine receptors are involved in mediating anti-instinctive learning in flies.

Oviposition preferences and antennal size in carrion flies

AbstractCarrion‐feeding flies use odours emanating from the decomposing corpse as cues for oviposition and are described as generalists because the larvae feed on the corpses of diverse species. Whereas several features of the corpse may influence the oviposition choices of these flies, it is not known whether there is a preference for a particular species of corpse. We provided carrion flies with ovipositional (and feeding) choices in a field experiment, in which various odour sources were presented simultaneously. We found novel evidence of broadly consistent choices of carrion by flies from four families. Traps baited with decaying fish flesh captured the greatest number of individuals, whereas traps baited with decaying pig liver typically attracted the least. We also asked whether individuals captured in the various baits vary in antennal size, perhaps reflecting different capacities for odour detection. There was a trend for individuals of Lucilia sericata Meigen (Diptera: Calliphoridae) and the platystomatid collected from the traps baited with pig liver to have significantly larger antennae, whereas individuals of Muscina stabulans (Fallen) (Diptera: Muscidae) captured in traps baited with marine fish flesh had relatively longer antennae for their body size. Our data reveal a more nuanced pattern of oviposition behaviour in these generalist carrion flies, which may reflect differences in their preference of carrion with different nutrients, and in their capacity to detect particular odours.

Dietary Sugars, bacterial colonization and the behavior of fruit flies

Cavity remains prevalent in young children today. One major contributor is the modern diet, specifically the large amounts of dietary sugars consumed. Another key factor is bacteria in our mouth that eat these sugars. Streptococcus mutans among other acid producing bacteria is one of the leading microbes that initiate and promote cavity (tooth decay). It metabolizes sugars to produce plaque, which can build up over time and simultaneously increase acid production that causes cavity. So studying how quickly different sugars affect Streptococcus mutans colonization is important to understand the development of cavity and its impact on host behavior. My hypothesis was that S. mutans breaks down some sugars more efficiently and as a result, can colonize more quickly with some than others and produce more acid, thus impacting host behavior.To study bacterial colonization, I used a fruit fly model because fruit flies like sugars and Streptococcus mutans can readily colonize fruit flies when is mixed with sugars. Each sugar solution was mixed with green fluorescent protein (GFP) labeled S. mutans and fed fruit flies. We then waited for 6 days to let flies eat and grow at room temperature. After this incubation period, we took flies out every 2 days to image the green color under the fluorescent microscope, which indicates S. mutans colonization. On the final day, we took all of the remaining flies, ground them up, and performed appropriate dilutions to plate and count bacterial colonies, which represents bacterial colonization of flies. Colonization of flies fed with five different sugars by S. mutans was monitored by direct imaging and counting bacterial colony forming units. Flies fed with sucrose exhibited the best colonization, while flies fed with xylitol did not show any colonization. The pH values of S. mutans cultures (pH adjusted to 7.5) fed with different sugars were monitored using a pH meter. With all sugars, the pH dropped significantly after five minutes. The pH dropped below 4.5 with sucrose that supports the best colonization. The pH dropped at an average of 2.91 during the 30 minutes testing period, suggesting sugars and bacteria fuel acid production.Furthermore, flies colonized by S. mutans fed with sucrose were monitored for their behavior (locomotion) using beam breaks and analyzed by DAMsystems308 software. Sucrose fed flies exhibited more bacterial colonization and became hyperactive. Overall the data indicated that S. mutans utilizes some dietary sugars more efficiently and as a result, can colonize better, produce more acid and become more active. Our studies demonstrated that the interactions between bacteria and sugars are important for the development of cavity and impact host behavior.

Mechanisms underlying attraction to odors in walking Drosophila.

Mechanisms that control movements range from navigational mechanisms, in which the animal employs directional cues to reach a specific destination, to search movements during which there are little or no environmental cues. Even though most real-world movements result from an interplay between these mechanisms, an experimental system and theoretical framework for the study of interplay of these mechanisms is not available. Here, we rectify this deficit. We create a new method to stimulate the olfactory system in Drosophila or fruit flies. As flies explore a circular arena, their olfactory receptor neuron (ORNs) are optogenetically activated within a central region making this region attractive to the flies without emitting any clear directional signals outside this central region. In the absence of ORN activation, the fly's locomotion can be described by a random walk model where a fly's movement is described by its speed and turn-rate (or kinematics). Upon optogenetic stimulation, the fly's behavior changes dramatically in two respects. First, there are large kinematic changes. Second, there are more turns at the border between light-zone and no-light-zone and these turns have an inward bias. Surprisingly, there is no increase in turn-rate, rather a large decrease in speed that makes it appear that the flies are turning at the border. Similarly, the inward bias of the turns is a result of the increase in turn angle. These two mechanisms entirely account for the change in a fly's locomotion. No complex mechanisms such as path-integration or a careful evaluation of gradients are necessary.

The depletion of ubiquilin in Drosophila melanogaster disturbs neurochemical regulation to drive activity and behavioral deficits

Drosophila melanogaster is a useful and highly tractable model organism for understanding the molecular mechanisms of human diseases. We previously characterized a new dUbqn knockdown model that induces learning-memory and locomotive deficits mediated by impaired proteostasis. Although proteinopathies are the main causes of neurodegenerative diseases, limited information is currently available on the relationship between proteostasis and neurodegenerative-related behavioral perturbations, such as locomotion, wakefulness, and sexual activities. Thus, the present study aimed to elucidate the mechanisms by which dUbqn depletion which is known to cause proteinopathies, affects neurodegenerative-related behavioral perturbations. Pan-neuronal dUbqn-depleted flies showed significantly reduced evening activity along with altered pre- and postsynaptic structural NMJ’s proteins by attenuating signals of Bruchpilot puncta and GluRIIA clustering. In addition, the neurochemical profiles of GABA, glutamate, dopamine, and serotonin were disturbed and these changes also affected courtship behaviors in dUbqn-depleted flies. Collectively, these results extend our understanding on how dUbqn depletion affects neurochemical regulation to drive behavioral disturbances that are generally found in the early stage of neurodegenerative diseases. Moreover, the present study may contribute a novel finding to the design of new agents that prevent disease progression or even treat diseases related to neurodegeneration.

CCAP regulates feeding behavior via the NPF pathway in Drosophila adults

The intake of macronutrients is crucial for the fitness of any animal and is mainly regulated by peripheral signals to the brain. How the brain receives and translates these peripheral signals or how these interactions lead to changes in feeding behavior is not well-understood. We discovered that 2 crustacean cardioactive peptide (CCAP)-expressing neurons in Drosophila adults regulate feeding behavior and metabolism. Notably, loss of CCAP, or knocking down the CCAP receptor (CCAP-R) in 2 dorsal median neurons, inhibits the release of neuropeptide F (NPF), which regulates feeding behavior. Furthermore, under starvation conditions, flies normally have an increased sensitivity to sugar; however, loss of CCAP, or CCAP-R in 2 dorsal median NPF neurons, inhibited sugar sensitivity in satiated and starved flies. Separate from its regulation of NPF signaling, the CCAP peptide also regulates triglyceride levels. Additionally, genetic and optogenetic studies demonstrate that CCAP signaling is necessary and sufficient to stimulate a reflexive feeding behavior, the proboscis extension reflex (PER), elicited when external food cues are interpreted as palatable. Dopaminergic signaling was also sufficient to induce a PER. On the other hand, although necessary, NPF neurons were not able to induce a PER. These data illustrate that the CCAP peptide is a central regulator of feeding behavior and metabolism in adult flies, and that NPF neurons have an important regulatory role within this system.

Individual, but not population asymmetries, are modulated by social environment and genotype in Drosophila melanogaster

Theory predicts that social interactions can induce an alignment of behavioral asymmetries between individuals (i.e., population-level lateralization), but evidence for this effect is mixed. To understand how interaction with other individuals affects behavioral asymmetries, we systematically manipulated the social environment of Drosophila melanogaster, testing individual flies and dyads (female-male, female-female and male-male pairs). In these social contexts we measured individual and population asymmetries in individual behaviors (circling asymmetry, wing use) and dyadic behaviors (relative position and orientation between two flies) in five different genotypes. We reasoned that if coordination between individuals drives alignment of behavioral asymmetries, greater alignment at the population-level should be observed in social contexts compared to solitary individuals. We observed that the presence of other individuals influenced the behavior and position of flies but had unexpected effects on individual and population asymmetries: individual-level asymmetries were strong and modulated by the social context but population-level asymmetries were mild or absent. Moreover, the strength of individual-level asymmetries differed between strains, but this was not the case for population-level asymmetries. These findings suggest that the degree of social interaction found in Drosophila is insufficient to drive population-level behavioral asymmetries.

Pymetrozine inhibits reproductive behavior of brown planthopper Nilaparvata lugens and fruit fly Drosophila melanogaster

Pymetrozine is a promising chemical used to control brown planthopper, which developed resistance to imidacloprid and buprofezin in the past decade. Field efficacy indicates that pymetrozine can reduce the number of offsprings of brown planthopper, but the specific physiological mechanism is unknown. In this study, we systematically described the mating process of brown planthopper including 8 steps (abdominal vibration, following, positioning, wing extension, attempted copulation, copulation, terminated copulation and leaving) and explored the optimal mating time after adult eclosion (3–5 days) and observation time (30 mins). Also, behavioral data showed that pymetrozine can affect the mating behavior and female fecundity of brown planthopper and fruit fly. As one of the target genes for pymetrozine, Nanchung (Nan), the nan36a mutant male courtship index, female receptivity and the number of offsprings were significantly decreased. Behavioral defects in nan36a mutant flies can be rescued by expressed NlNan. Our results indicated that Nan plays essential roles in the mating behavior and female fecundity. These findings provide useful information for demonstrating that pymetrozine effectively reduce the reproduction of brown planthopper and contribute to our understanding of reproductive strategies controlled by pymetrozine in insects.

Spatial behavior of corn leaf aphid and syrphid flies in corn crop in the northeast of Pará

The aim of this study was to verify the spatial and temporal behavior of corn leaf aphid (Rhopalosiphum maidis Fitch.) and hoverflies in corn crop in the municipality of Igarapé-Açu, northeast of Pará, Brazil, as well as the influence of adjacent areas on the occurrence of these insects. An experimental area of 1.0 ha (100 x 100 m) was used in the years 2015 and 2016, adjacent areas consisted of mango agroecosystem, pasture and secondary forest. The area was divided into grid with 100 plots of 100 m² (10 x 10 m). Ten plants were randomly selected, totaling 1,000 plants per sampling date. Corn leaf aphid colonies (= or> 15 aphid) and syrphid flies adult was visually analyzed throughout the aerial parts of the plants. The spatial behavior was analyzed by semivariogram modeling and kriging interpolation maps. The semivariograms and kriging maps were made by the R software for Windows. Gaussian, spherical and exponential models were the best fit for corn leaf aphid in both harvests, showing aggregate behavior. The strong and moderate spatial dependence index prevailed, with range ranging from 12.46 to 93.04 m for R. maidis. The syrphids flies showed spatial interaction with the corn leaf aphid and they also show aggregate behavior, confirmed by most adjustments in the spherical and exponential models. The spatial dependence index of the prevailing syrphids flies were moderate and weak, ranging from 14.00 to 101.33 m. Adjacent areas showed influence on occurrence and dispersal of both corn leaf aphid and syrphids flies.

Seasonal surveillance of deer and horse flies (Diptera: Tabanidae), Gyeonggi province, Republic of Korea

• A total of 9985 tabanid flies comprising 2 subfamilies, 4 genera and 17 species. • The predominant species collected was Chrysops mlokosiewiczi . • The highest numbers of tabanids were collected from June-August. • A bimodal peak was observed for Chrysops mlokosiewiczi in June and late-July. Deer and horse flies, Family Tabanidae, are biological, mechanical, and potential vectors of approximately 27 viral, bacterial, and helminthic pathogens of veterinary and medical importance. Biting fly surveillance was conducted using New Jersey light traps and Mosquito Magnet® traps from May-October during 2015–2018 at eight sites (villages and US military installations and training areas) near/in the Demilitarized Zone and at a US military installation in southern Gyeonggi province, Republic of Korea. A total of 9985 deer and horse flies, comprising 4 genera and 17 species, were collected. The predominant species collected was Chrysops mlokosiewiczi (95.39%), followed by Chrysops suavis (1.48%) and Haematopota koryoensis (1.07%), while the remaining species accounted for only 2.06% of the specimens collected. A bimodal peak was observed for C. mlokosiewiczi in June and late-July, but not for the other two predominant species during the whole of the study period. This study provides and insight into ecological behavior and seasonal abundance of deer and horse flies in Gyeonggi province, Republic of Korea.