Diurnal biting of malaria mosquitoes in the Central African Republic indicates residual transmission may be "out of control".

Malaria control interventions target nocturnal feeding of the Anopheles vectors indoors to reduce parasite transmission. Mass deployment of insecticidal bed nets and indoor residual spraying with insecticides, however, may induce mosquitoes to blood-feed at places and at times when humans are not protected. These changes can set a ceiling to the efficacy of these control interventions, resulting in residual malaria transmission. Despite its relevance for disease transmission, the daily rhythmicity of Anopheles biting behavior is poorly documented, most investigations focusing on crepuscular hours and nighttime. By performing mosquito collections 48-h around the clock, both indoors and outdoors, and by modeling biting events using circular statistics, we evaluated the full daily rhythmicity of biting in urban Bangui, Central African Republic. While the bulk of biting by Anopheles gambiae, Anopheles coluzzii, Anopheles funestus, and Anopheles pharoensis occurred from sunset to sunrise outdoors, unexpectedly ∼20 to 30% of indoor biting occurred during daytime. As biting events did not fully conform to any family of circular distributions, we fitted mixtures of von Mises distributions and found that observations were consistent with three compartments, corresponding indoors to populations of early-night, late-night, and daytime-biting events. It is not known whether these populations of biting events correspond to spatiotemporal heterogeneities or also to distinct mosquito genotypes/phenotypes belonging consistently to each compartment. Prevalence of Plasmodium falciparum in nighttime- and daytime-biting mosquitoes was the same. As >50% of biting occurs in Bangui when people are unprotected, malaria control interventions outside the domiciliary environment should be envisaged.

Can insecticide resistance increase malaria transmission? A genetics-epidemiology mathematical modeling approach.

The great successes recorded in the fight against malaria over the last two decades, resulting from the wide scale implementation of insecticide-based interventions in malaria-endemic areas, has prompted a renewed global effort to eradicate malaria. The widespread emergence of insecticide resistance in the population of adult female malaria mosquitoes is considered to pose a potential challenge to such effort. In this study, we address one of the key questions in malaria ecology, namely whether or not insecticide resistance increase malaria transmission. We developed a genetics-epidemiology modeling framework that incorporates a detailed genotype structure of the gene that confers insecticide resistance in mosquitoes, malaria epidemiology in mosquitoes and humans (stratified based on whether or not they are protected by Long-lasting insecticide-treated nets (LLINs) indoors), genotype-specific mosquito repellance property of LLINs and mosquito biting behavior (indoor and outdoor bites). Conditions for the existence and local asymptotic stability of the various disease-free equilibria (by genotype) of the resulting genetic-epidemiology model are derived. This study identifies four parameters of the model that play a crucial role on quantifying the impact of insecticide resistance on malaria transmission, namely the parameters related to the level of the dominance of the resistant allele in heterozygous mosquitoes, the coverage of long-lasting insecticidal nets in the community, the probability of endophilic mosquitoes to successfully take a bloodmeal indoors and the proportion of new adult mosquitoes that are endophilic. We showed that, depending on the values of these four identified parameters, insecticide resistance can increase, decrease, or have no effect on malaria transmission. Our simulations show that malaria eradication can indeed be achieved using the currently-available chemical insecticides, even in the wake of the prevailing widespread insecticide resistance in malaria-endemic areas, if the insecticide-based interventions implemented can result in the attainment of the optimal values of the four identified parameters in malaria-endemic areas.

Opsin1 regulates light-evoked avoidance behavior in Aedes albopictus.

BACKGROUND: Mosquitoes locate a human host by integrating various sensory cues including odor, thermo, and vision. However, their innate light preference and its genetic basis that may predict the spatial distribution of mosquitoes, a prerequisite to encounter a potential host and initiate host-seeking behaviors, remains elusive. RESULTS: Here, we first studied mosquito visual features and surprisingly uncovered that both diurnal (Aedes aegypti and Aedes albopictus) and nocturnal (Culex quinquefasciatus) mosquitoes significantly avoided stronger light when given choices. With consistent results from multiple assays, we found that such negative phototaxis maintained throughout development to adult stages. Notably, female mosquitoes significantly preferred to bite hosts in a shaded versus illuminated area. Furthermore, silencing Opsin1, a G protein-coupled receptor that is most enriched in compound eyes, abolished light-evoked avoidance behavior of Aedes albopictus and attenuated photonegative behavior in Aedes aegypti. Finally, we found that field-collected Aedes albopictus also prefers darker area in an Opsin1-dependent manner. CONCLUSIONS: This study reveals that mosquitoes consistently prefer darker environment and identifies the first example of a visual molecule that modulates mosquito photobehavior.

Review of Issues on Residual Malaria Transmission.

Residual malaria transmission is the actual maintained inoculation of Plasmodium, in spite of a well-designed and implemented vector control programs, and is of great concern for malaria elimination. Residual malaria transmission occurs under several possible circumstances, among which the presence of exophilic vector species, such as Anopheles dirus, or indoor- and outdoor-biting vectors, such as Anopheles nili, or specific behavior, such as feeding on humans indoors, then resting or leaving the house the same night (such as Anopheles moucheti) or also changes in behavior induced by insecticides applied inside houses, such as the well-known deterrent effect of permethrin-treated nets or the irritant effect of DDT. The use of insecticides may change the composition of local Anopheles populations, such as A. arabiensis taking up the place of A. gambiae in Senegal, A. aquasalis replacing A. darlingi in Guyana, or A. harrisoni superseding A. minimus in Vietnam. The change in behavior, such as biting activity earlier than usually reported-for example, Anopheles funestus after a large-scale distribution of long-lasting insecticidal nets-or insecticide resistance, in particular the current spread of pyrethroid resistance, could hamper the efficacy of classic pyrethroid-treated long-lasting insecticidal nets and maintained transmission. These issues must be well documented in every situation to elaborate, implement, monitor, and evaluate tailored vector control programs, keeping in mind that they must be conceived as integrated programs with several well and appropriately coordinated approaches, combining entomological but also parasitological, clinical, and social methods and analyses. A successful integrated vector control program must then be designed to reduce transmission and incidence rates of malaria morbidity and overall mortality.

Symptoms and management of temporohyoid osteoarthropathy and its association with crib-biting behavior in 11 Japanese Thoroughbreds.

There have been few reports about temporohyoid osteoarthropathy in Japanese horses. The aim of this study was to describe the symptoms and management of temporohyoid osteoarthropathy and to investigate its association with crib-biting behavior, which is commonly observed in Japanese horses. The data concerning case details, signs, diagnosis procedures, treatment, and outcomes were collected retrospectively from the medical records of 11 Thoroughbreds with temporohyoid osteoarthropathy. The trainers and owners were asked whether the horses had displayed crib-biting behavior. Nine of the horses were diagnosed by guttural pouch endoscopy, and two were diagnosed by skull radiography. Eight horses were treated medically, of which three (37%) showed improvement; the other three horses underwent ceratohyoidectomy, with two (67%) showing improvement. Crib-biting behavior was observed in eight (73%) of the horses. A comparison of data regarding crib-biting behavior among 437 Thoroughbreds from six local riding schools indicated a significant association between temporohyoid osteoarthropathy and crib-biting behavior: the odds ratio for a horse with temporohyoid osteoarthropathy to exhibit crib-biting behavior compared with the general population was 12 (95% confidence interval, 3-45), and horses exhibiting crib-biting behavior were significantly more likely to have temporohyoid osteoarthropathy (P<0.001, Fisher's exact test). This suggested that crib-biting behavior may be a risk factor for temporohyoid osteoarthropathy.

Host attraction and biting behaviour of Anopheles mosquitoes in South Halmahera, Indonesia.

BACKGROUND: Indonesia is home to a variety of malaria vectors whose specific bionomic traits remain largely uncharacterized. Species-specific behaviours, such as host feeding preferences, impact the dynamics of malaria transmission and the effectiveness of vector control interventions. METHODS: To examine species-specific host attraction and feeding behaviours, a Latin square design was used to compare Anopheles mosquitoes attracted to human, cow, and goat-baited tents. Anopheles mosquitoes were collected hourly from the inside walls of each baited tent. Species were morphologically and then molecularly identified using rDNA ITS2 sequences. The head and thorax of individual specimens were analysed for Plasmodium DNA using PCR. Bloodmeals were identified using a multiplex PCR. RESULTS: A total of 1024, 137, and 74 Anopheles were collected over 12 nights in cow, goat, and human-baited tents, respectively. The species were identified as Anopheles kochi, Anopheles farauti s.s., Anopheles hackeri, Anopheles hinesorum, Anopheles indefinitus, Anopheles punctulatus, Anopheles tessellatus, Anopheles vagus, and Anopheles vanus, many of which are known to transmit human malaria. Molecular analysis of blood meals revealed a high level of feeding on multiple host species in a single night. Anopheles kochi, An. indefinitus, and An. vanus were infected with Plasmodium vivax at rates comparable to primary malaria vectors. CONCLUSIONS: The species distributions of Anopheles mosquitoes attracted to human, goat, and cow hosts were similar. Eight of nine sporozoite positive samples were captured with animal-baited traps, indicating that even predominantly zoophilic mosquitoes may be contributing to malaria transmission. Multiple host feeding and flexibility in blood feeding behaviour have important implications for malaria transmission, malaria control, and the effectiveness of intervention and monitoring methods, particularly those that target human-feeding vectors.

Differences in malaria vector biting behavior and changing vulnerability to malaria transmission in contrasting ecosystems of western Kenya.

BACKGROUND: Designing, implementing, and upscaling of effective malaria vector control strategies necessitates an understanding of when and where transmission occurs. This study assessed the biting patterns of potentially infectious malaria vectors at various hours, locations, and associated human behaviors in different ecological settings in western Kenya. METHODS: Hourly indoor and outdoor catches of human-biting mosquitoes were sampled from 19:00 to 07:00 for four consecutive nights in four houses per village. The human behavior study was conducted via questionnaire surveys and observations. Species within the Anopheles gambiae complex and Anopheles funestus group were distinguished by polymerase chain reaction (PCR) and the presence of Plasmodium falciparum circumsporozoite proteins (CSP) determined by enzyme-linked immunosorbent assay (ELISA). RESULTS: Altogether, 2037 adult female anophelines were collected comprising the An. funestus group (76.7%), An. gambiae sensu lato (22.8%), and Anopheles coustani (0.5%). PCR results revealed that Anopheles arabiensis constituted 80.5% and 79% of the An. gambiae s.l. samples analyzed from the lowland sites (Ahero and Kisian, respectively). Anopheles gambiae sensu stricto (hereafter An. gambiae) (98.1%) was the dominant species in the highland site (Kimaeti). All the An. funestus s.l. analyzed belonged to An. funestus s.s. (hereafter An. funestus). Indoor biting densities of An. gambiae s.l. and An. funestus exceeded the outdoor biting densities in all sites. The peak biting occurred in early morning between 04:30 and 06:30 in the lowlands for An. funestus both indoors and outdoors. In the highlands, the peak biting of An. gambiae occurred between 01:00 and 02:00 indoors. Over 50% of the study population stayed outdoors from 18:00 to 22:00 and woke up at 05:00, coinciding with the times when the highest numbers of vectors were collected. The sporozoite rate was higher in vectors collected outdoors, with An. funestus being the main malaria vector in the lowlands and An. gambiae in the highlands. CONCLUSION: This study shows heterogeneity of anopheline distribution, high outdoor malaria transmission, and early morning peak biting activity of An. funestus when humans are not protected by bednets in the lowland sites. Additional vector control efforts targeting the behaviors of these vectors, such as the use of non-pyrethroids for indoor residual spraying and spatial repellents outdoors, are needed.

Current observations on shifts in malaria vector biting behavior and changing vulnerability to malaria transmission in contrasting ecosystems in Western Kenya.

Background: Designing, implementing, and upscaling effective malaria vector control strategies necessitates understanding of when and where transmission occurs. This study assessed the biting patterns of potentially infectious malaria vectors at various hours, locations, and human behavior in different ecological settings in western Kenya. Methods: Hourly indoor and outdoor catches of human-biting mosquitoes were sampled from 1900 to 0700 hours for four consecutive nights in four houses per village using human landing collection method. The nocturnal biting activities of each Anopheles species were expressed as the mean number of mosquitoes landing per person per hour. The human behavior study was conducted via observations and questionnaire surveys. Species within Anopheles gambiae and Anopheles funestus complexes were differentiated by polymerase chain reaction (PCR) and the presence of Plasmodium falciparumcircumsporozoite proteins (CSP) determined by enzyme-linked immunosorbent assay (ELISA). Results: Altogether, a total of 2,037 adult female Anophelines were collected comprising of An. funestus s.l. (76.7%), An.gambiae s.l.(22.8%) and Anopheles coustani (0.5%). Overall, Anopheles funestus was the predominant species collected in Ahero (96.7%) while An. gambiae s.l was dominant in Kisian (86.6%) and Kimaeti (100%) collections. PCR results revealed that An. arabiensis constituted 80.5% and 79% of the An.gambiae s.l samples analysed from Ahero and Kisian respectively. An. gambiae s.s (hereafter An.gambiae) (98.1%) was the dominant species collected in Kimaeti. All the An. funestus s.l samples analysed belonged to An. funestus s.s (hereafter An. funestus). Indoor biting densities of Anopheles gambiae and An. funestus exceeded the outdoor biting densities in all sites. The peak biting occurred early morning between 0430-0630 hours in the lowlands for An. funestus both indoors and outdoors. In the highlands (Kimaeti), the peak biting of An.gambiae occurred between 0100-0200 hours indoors. Over 50% of the study population stayed outdoors from 1800 to 2200 hours and woke up at 0500 hours coinciding with the times highest numbers of vectors were collected. The sporozoite rate was higher in vectors collected outdoors, with An. funestus being the main malaria vector in the lowlands and An. gambiaein the highland. Conclusion: The study shows heterogeneity of Anophelines distribution, high outdoor malaria transmission, and peak biting activity by An. funestus (early morning) when humans are not protected by bed nets in the lowland sites. Additional vector control efforts targeting the behaviors of these vectors i.e using non-pyrethroids-based indoor residual spraying and spatial repellents outdoors are needed.

Comparative data on emotional (psychotic) aggressive biting behavior in mice of ddY strain measured by using two devices; Aggressive response meter and powerlab-compatible type aggressive response meter.

The Aggressive Response Meter (ARM) has been validated for measuring emotional (psychotic) aggression triggered by mental irritation in mice. In the present article, we newly developed a device, pARM (PowerLab-compatible type ARM). We collected on the aggressive biting behavior (ABB) intensity and ABB frequency of 20 male and female mice of ddY strain studied over a period of 6 days by using pARM and the former ARM. We calculated Pearson's correlation between the values of pARM and those of ARM. The accumulated data can be referred as a basis for demonstrating the consistence of pARM and the former ARM, and used in future research to augment the understanding of stress-induced emotional aggression in mice.

Influence of meteorological and seasonal parameters on the activity of Culicoides paraensis (Diptera: Ceratopogonidae), an annoying anthropophilic biting midge and putative vector of Oropouche Virus in Rondônia, Brazilian Amazon.

Biting midges of the genus Culicoides are insects of proven medical and veterinary importance, because of their role in the transmission of viruses, bacteria, protozoa and nematodes. Culicoides paraensis has been considered the main vector of the Oropouche Virus (OROV) in the urban cycle of the disease in the neotropics. Due to the great abundance of Culicoides spp. in the State of Rondônia and its epidemiological history of OROV, we investigated the biting activity in humans, the abundance as a function of meteorological parameters and seasonality, and the detection of OROV. Entomological collections occurred in three municipalities from Brazilian State of Rondônia: Porto Velho, Ariquemes, and Ouro Preto do Oeste. GLMM's were used to determine if Culicoides spp. abundance was predicted by seasonal, diurnal, and meteorological factors. Total RNA was extracted from insects and viral RNA detection was performed using the S segment as the target region of OROV via RT-qPCR. In total, 7315 individuals were captured and identified as C. paraensis. In the dry season, 1488 individuals (24.5%) were recorded, 4591 (75.5%) in the rainy season, with peaks of biting activity between 4pm and 6pm. All variables showed a significative effect on the midge abundance. The rainy season, temperature between 30 °C and 32 °C and relative air humidity between 75% and 85% were the main predictive parameters for capturing the highest average number of insects. Our results confirm diurnal activity of C. paraensis and its greatest abundance in rainy periods. No sample was positive for the OROV, which could be explained by the virus absence in local human populations, C. paraensis as a minor vector species in the sampled localities, and probable low rate of infection of biting midges. Our findings on hourly and seasonal biting activities can provide support to intervention actions regarding vector control and surveillance of this species. This was the first study to collect and analyze biting midges in a region where human OROV cases had already been detected, but without previous information on entomovirological surveillance.

An electrophysiological method for evaluation of topical antipruritic drugs on itch-related neuronal activities in the spinal cord in hairless mice.

To evaluate the effects of antipruritic drugs, it is important to determine whether the neural responses induced by physiological itch stimuli are suppressed. Although there are several behavioral assessments for topical antipruritic drugs applied to the skin, there are few established methods at neuronal levels using in vivo electrophysiological recordings for predicting local efficacy of antipruritic drugs for cutaneous application. To establish an assessment of topical antipruritic drugs applied to skin using in vivo extracellular recording from neurons in the superficial dorsal horn, we examined the relationships between itch-related biting behavior and spinal neuronal responses elicited by intradermal injection of pruritogen serotonin (5-HT) in hairless mice. The efficacy of topical occlusive application of local anesthetics was also evaluated by an in vivo electrophysiological method. 5-HT significantly increased the firing frequency in spinal neurons. The spinal firing frequency time course was similar to that of the biting behavior after the 5-HT injections. The 5-HT-induced spinal responses were significantly decreased by topical occlusive application of lidocaine or a Nav 1.7 channel blocker to the calf. The intradermal 5-HT injection-induced spinal neuronal responses appeared to be suppressed by topical occlusive application of lidocaine or a Nav1.7 channel blocker. The electrophysiological method for evaluating topical antipruritic drugs may be beneficial in assessing local effects on the skin.

Latent Genetic Effects of Past Selection on Blood Feeding: History Matters.

Conventional wisdom is that selection decreases genetic variation in populations, variation that should enable and be essential for population persistence in an ever-changing world. Basically, we find the opposite. Response to selection on biting in the pitcher-plant mosquito, Wyeomyia smithii, increases from 20 to 80% in 19 generations, but reverts back to the original 20% after seven generations of relaxed (not reversed) selection. At the same time, biting in the control line remains at the original 20% through 30 generations without blood feeding. Imposition of selection on biting in both lines elicits a rapid response in the previously selected line, but, importantly, not in the control line. Genetic variation for biting has increased, not decreased, as a consequence of long-term directional selection, contrary to expectations. Convergent phenotypes belie the underlying difference in future adaptive potential. Selection events over time in the background of individuals or populations will determine outcomes of applied research, be it in the fields of medicine, agriculture, or conservation. In short, history matters.

Malaria vector feeding, peak biting time and resting place preference behaviors in line with Indoor based intervention tools and its implication: scenario from selected sentinel sites of Ethiopia.

In Ethiopia, malaria incidence has significantly reduced in the past decade through the combined use of conventional vector control approaches and treatment using antimalarial drugs. However, the sustainability of this achievement is threatened by the shift in biting and resting behaviors and emergence of insecticide resistance by the primary malaria vector. Therefore, continuous monitoring of the behaviour of malaria mosquitoes in different sentinel sites is crucial to design effective prevention and control methods in the local context. Entomological investigations were conducted in three sentinel sites for five consecutive months during the major malaria transmission season. The species composition, population dynamics, biting and resting behaviours of malaria vectors were determined using center for disease control and prevention (CDC) light trap, human landing catch (HLC), pyrethrum spray catch (PSC) and Pitfall shelter collection (PFS). Accordingly, 10 households for CDC, 10 households for PSC, 10 households for PFS and 5 households for HLC from each site were randomly enrolled for mosquito collection. A total of 8,297 anopheline mosquitoes were collected from the three sites, out of which 4,525 (54.5 %) were An. gambiae, s.l. 2,028 (24.4 %) were An. pharoensis, 160 (1.9 %) were An. funestus and the rest 1,584 (19 %) were other anophelines (An. coustani, An. cinerus and An. tenebrosus). No significant variation (P = 0.476) was observed between indoor (25.2/trap-night and outdoor collections (20.1/trap-night). Six hundred seventy six (43.3%) of An. gambiae s.l. (primary vector) were collected between 18:00 and 22:00 h. Biting activity declined between 00:00 and 02:00 h. The national malaria control program should pay close attention to the shifting behavior of vector mosquitoes as the observed outdoor feeding tendency of the vector population could pose challenges to the indoor intervention tools IRS and LLINs.

Human and vector behaviors determine exposure to Anopheles in Namibia.

BACKGROUND: Although the Republic of Namibia has significantly reduced malaria transmission, regular outbreaks and persistent transmission impede progress towards elimination. Towards an understanding of the protective efficacy, as well as gaps in protection, associated with long-lasting insecticidal nets (LLINs), human and Anopheles behaviors were evaluated in parallel in three malaria endemic regions, Kavango East, Ohangwena and Zambezi, using the Entomological Surveillance Planning Tool to answer the question: where and when are humans being exposed to bites of Anopheles mosquitoes? METHODS: Surveillance activities were conducted during the malaria transmission season in March 2018 for eight consecutive nights. Four sentinel structures per site were selected, and human landing catches and human behavior observations were consented to for a total of 32 collection nights per site. The selected structures were representative of local constructions (with respect to building materials and size) and were at least 100 m from each other. For each house where human landing catches were undertaken, a two-person team collected mosquitoes from 1800 to 0600 hours. RESULTS: Surveillance revealed the presence of the primary vectors Anopheles arabiensis, Anopheles gambiae sensu stricto (s.s.) and Anopheles funestus s.s., along with secondary vectors (Anopheles coustani sensu lato and Anopheles squamosus), with both indoor and outdoor biting behaviors based on the site. Site-specific human behaviors considerably increased human exposure to vector biting. The interaction between local human behaviors (spatial and temporal presence alongside LLIN use) and vector behaviors (spatial and temporal host seeking), and also species composition, dictated where and when exposure to infectious bites occurred, and showed that exposure was primarily indoors in Kavango East (78.6%) and outdoors in Ohangwena (66.7%) and Zambezi (81.4%). Human behavior-adjusted exposure was significantly different from raw vector biting rate. CONCLUSIONS: Increased LLIN use may significantly increase protection and reduce exposure to malaria, but may not be enough to eliminate the disease, as gaps in protection will remain both indoors (when people are awake and not using LLINs) and outdoors. Alternative interventions are required to address these exposure gaps. Focused and question-based operational entomological surveillance together with human behavioral observations may considerably improve our understanding of transmission dynamics as well as intervention efficacy and gaps in protection.

Safety and Efficacy of Botulinum Toxin in the Treatment of Self-Biting Behavior in Lesch-Nyhan Disease.

BACKGROUND: Lesch-Nyhan disease (LND) is a disease of purine metabolism linked to chromosome X due to the absence or near-absence of enzyme hypoxanthine-guanine phosphoribosyltransferase. Patients with LND have a compulsive autoaggressive behavior that consists of self-mutilation by biting. METHODS: The objective of this study was to explore the safety and efficacy of botulinum toxin (BoNT) injected into the masticatory muscles and biceps brachii to reduce self-mutilation in patients with LND. We retrospectively analyzed six patients with LND who were treated with BoNT to prevent automutilatory behavior. RESULTS: The patient ages when started on treatment with BoNT were 4, 4.5, 6.6, 7.9, 13.9, and 32.3 years. Patients received a mean number of injections of 20, ranging from 3 to 29, over a period that ranged from 1.5 to 7.1 years. The maximum total dose of Botox was 21.3 units/kg mean and the maximum total dose of Dysport was 37.5 units/kg mean. A total of 119 injections were performed. Of these 113 (95%) were partially or completely effective. Only three of 119 injections (2.5%) produced adverse effects. CONCLUSIONS: Botulinum toxin is useful and safe for the treatment of self-biting behavior in patients with LND.

Automatic monitoring and detection of tail-biting behavior in groups of pigs using video-based deep learning methods.

Automated monitoring of pigs for timely detection of changes in behavior and the onset of tail biting might enable farmers to take immediate management actions, and thus decrease health and welfare issues on-farm. Our goal was to develop computer vision-based methods to detect tail biting in pigs using a convolutional neural network (CNN) to extract spatial information, combined with secondary networks accounting for temporal information. Two secondary frameworks were utilized, being a long short-term memory (LSTM) network applied to sequences of image features (CNN-LSTM), and a CNN applied to image representations of sequences (CNN-CNN). To achieve our goal, this study aimed to answer the following questions: (a) Can the methods detect tail biting from video recordings of entire pens? (b) Can we utilize principal component analyses (PCA) to reduce the dimensionality of the feature vector and only use relevant principal components (PC)? (c) Is there potential to increase performance in optimizing the threshold for class separation of the predicted probabilities of the outcome? (d) What is the performance of the methods with respect to each other? The study utilized one-hour video recordings of 10 pens with pigs prior to weaning, containing a total of 208 tail-biting events of varying lengths. The pre-trained VGG-16 was used to extract spatial features from the data, which were subsequently pre-processed and divided into train/test sets before input to the LSTM/CNN. The performance of the methods regarding data pre-processing and model building was systematically compared using cross-validation. Final models were run with optimal settings and evaluated on an independent test-set. The proposed methods detected tail biting with a major-mean accuracy (MMA) of 71.3 and 64.7% for the CNN-LSTM and the CNN-CNN network, respectively. Applying PCA and using a limited number of PCs significantly increased the performance of both methods, while optimizing the threshold for class separation did result in a consistent but not significant increase of the performance. Both methods can detect tail biting from video data, but the CNN-LSTM was superior in generalizing when evaluated on new data, i.e., data not used for training the models, compared to the CNN-CNN method.

Data-driven and interpretable machine-learning modeling to explore the fine-scale environmental determinants of malaria vectors biting rates in rural Burkina Faso.

BACKGROUND: Improving the knowledge and understanding of the environmental determinants of malaria vector abundance at fine spatiotemporal scales is essential to design locally tailored vector control intervention. This work is aimed at exploring the environmental tenets of human-biting activity in the main malaria vectors (Anopheles gambiae s.s., Anopheles coluzzii and Anopheles funestus) in the health district of Diébougou, rural Burkina Faso. METHODS: Anopheles human-biting activity was monitored in 27 villages during 15 months (in 2017-2018), and environmental variables (meteorological and landscape) were extracted from high-resolution satellite imagery. A two-step data-driven modeling study was then carried out. Correlation coefficients between the biting rates of each vector species and the environmental variables taken at various temporal lags and spatial distances from the biting events were first calculated. Then, multivariate machine-learning models were generated and interpreted to (i) pinpoint primary and secondary environmental drivers of variation in the biting rates of each species and (ii) identify complex associations between the environmental conditions and the biting rates. RESULTS: Meteorological and landscape variables were often significantly correlated with the vectors' biting rates. Many nonlinear associations and thresholds were unveiled by the multivariate models, for both meteorological and landscape variables. From these results, several aspects of the bio-ecology of the main malaria vectors were identified or hypothesized for the Diébougou area, including breeding site typologies, development and survival rates in relation to weather, flight ranges from breeding sites and dispersal related to landscape openness. CONCLUSIONS: Using high-resolution data in an interpretable machine-learning modeling framework proved to be an efficient way to enhance the knowledge of the complex links between the environment and the malaria vectors at a local scale. More broadly, the emerging field of interpretable machine learning has significant potential to help improve our understanding of the complex processes leading to malaria transmission, and to aid in developing operational tools to support the fight against the disease (e.g. vector control intervention plans, seasonal maps of predicted biting rates, early warning systems).

Biting Behavior and Molecular Identification of Aedes aegypti (Diptera: Culicidae) Subspecies in Some Selected Recent Yellow Fever Outbreak Communities in Northern Ghana.

Aedes aegypti (L.) (Diptera: Culicidae) is a diurnal feeder that lives in close association with human populations. It is the principal vector of yellow fever, dengue fever and the Zika Virus. Issues of arboviral diseases have been on the ascendency in most countries including Ghana where Aedes mosquito is the main vector of yellow fever. A comparative study of the biting behavior of Ae. aegypti and the identification of subspecies were undertaken using molecular technique. Standard human landing technique was used to collect both indoor and outdoor biting mosquitoes at three zones located in the Upper East (Bolgatanga), Upper West (Nadowli), and Northern (Damongo) Regions of Ghana during the dry and rainy seasons between 0600 and 1800 Greenwich Mean Time (GMT). All collected mosquitoes were identified morphologically using taxonomic keys. random amplified polymorphic DNA polymerase chain reaction was used to categorize Ae. aegypti into subspecies. Adult female Aedes mosquitoes identified formed 62% (n = 1,206) of all female mosquitoes collected. Aedes aegypti 98% and Aedes vittatus 2% were the only Aedes species identified. Bolgatanga recorded the largest number of Ae. aegypti 42%, whereas Nadowli 22% recorded the least. Aedes vittatus was observed in Nadowli. Aedes aegypti exhibited a bimodal biting behavior peaking at 0600-0800 GMT and 1500-1600 h GMT. Molecular findings revealed 69% Ae. aegypti aegypti and 31% Ae. aegypti formosus as the two subspecies (n = 110). This information is important for implementing effective vector control programs in the three regions of the northern Ghana.

Population Dynamics of Anopheles gambiae s.l. and Culex quinquefasciatus in Rural and Urban Settings Before an Indoor Residual Spraying Campaign in Northern Benin.

Background: The purpose of this report is to provide information on Culicidae diversity; biting behavior and spatio-seasonal variation of abundance of Anopheles gambiae s.l. and Culex quinquefasciatus in rural and urban settings of the Alibori and Donga regions, Northern Benin, where an indoor residual spraying (IRS) campaign to control malaria is planned. Methods: Both human landing catches, associated with pyrethrum spray catches were used to monitor the mosquito populations in 12 sites with 1 urban and 1 rural located in each of the 6 districts randomly selected in the two targeted regions. After morphological identification of all mosquito specimens, biting behavior and density of An. gambiae s.l. and Cx quinquefasciatus were studied. PCR was also performed on An. gambiae s.l., to identify sibling species and its seasonal variation. Results: A total of 10,367 mosquitoes were captured, related to 14 species of the genera, Anopheles, Aedes, Culex and Mansonia. Of the total species collection, 40.39% were An. gambiae s.l. and 56.85% were Cx. quinquefasciatus. An. gambiae s.l. was more abundant in Donga (2521 specimens) compared with Alibori (1666 specimens). The opposite trend was observed with Cx. quinquefasciatus (2162 specimens in Donga against 4028 in Alibori). An. gambiae s.l. was predominant and displayed a higher blood feeding rate in rural areas, whereas Cx. quinquefasciatus was in majority in urban areas. An. gambiae s.l. was more endophagic, whereas Cx. quinquefasciatus showed similar indoor and outdoor biting behavior. An. gambiae s.l. was composed of An. coluzzii found in majority in the drought, and An. gambiae, which was predominant in the rainy season. Conclusion: The predominance of the malaria vector, An. gambiae s.l. and their higher blood feeding rate and their significantly high endophagy in rural areas indicate that these areas should be primarily targeted with the IRS operations to have a substantial impact on malaria transmission. Endophagy, characteristic of An. gambiae s.l. in our study area, suggests that IRS will have a positive impact on vector control if implemented 1 week before June that is the onset of the rainy season.

Genetic diversity of Nyssorhynchus (Anopheles) darlingi related to biting behavior in western Amazon.

BACKGROUND: In the Amazon Basin, Nyssorhynchus (Anopheles) darlingi is the most aggressive and effective malaria vector. In endemic areas, behavioral aspects of anopheline vectors such as host preference, biting time and resting location post blood meal have a key impact on malaria transmission dynamics and vector control interventions. Nyssorhynchus darlingi presents a range of feeding and resting behaviors throughout its broad distribution. METHODS: To investigate the genetic diversity related to biting behavior, we collected host-seeking Ny. darlingi in two settlement types in Acre, Brazil: Granada (~ 20-year-old, more established, better access by road, few malaria cases) and Remansinho (~ 8-year-old, active logging, poor road access, high numbers malaria cases). Mosquitoes were classified by the location of collection (indoors or outdoors) and time (dusk or dawn). RESULTS: Genome-wide SNPs, used to assess the degree of genetic divergence and population structure, identified non-random distributions of individuals in the PCA for both location and time analyses. Although genetic diversity related to behavior was confirmed by non-model-based analyses and FST values, model-based STRUCTURE detected considerable admixture of these populations. CONCLUSIONS: To our knowledge, this is the first study to detect genetic markers associated with biting behavior in Ny. darlingi. Additional ecological and genomic studies may help to understand the genetic basis of mosquito behavior and address appropriate surveillance and vector control.