Fly Counts Research Articles

PSI-1 Genetic and non-genetic factors influencing beef cattle attractiveness to horn fly

Abstract Horn flies are the most common summer pests of cattle, leading to substantial economic losses due to impaired production and decreased animal welfare. Genetic and non-genetic factors have been reported to influence cattle susceptibility to horn flies. However, the wide range of heritability estimates, and few identified genomic regions associated with cattle resistance to horn fly may be due to subjective assessment in collecting the fly load phenotype and the small size of the population assessed. Here, beef calves from the UF purebred Brahman (BRA) and Multibreed Angus-Brahman (MAB) populations were video recorded at weaning using a GoPro camera mounted on the top of the chute. Fly infestation was determined as the average fly count obtained from five longitudinal images of each animal using ImageJ software. A total of 748 crossbred and 415 purebred calves born from 2021 to 2023 were evaluated during summer (August or September). Analysis of variance (ANOVA) was performed within herd by fitting linear models that included collection date, age, skin color, coat color, and pre-weaning average daily gain (ADG) as fixed effects, and residual as a random effect. For MAB calves, breed groups (BG) determined based on the percentage of Brahman breed, with BG1 ranging from 0 to 19%, BG2 from 20 to 39%, BG3 from 40 to 59%, BG4 from 60 to 79%, BG5 from 80 to 100%, were also fit in the model. Fly count was transformed to a natural log value (log[count +1]) ensuring normally distribute residuals. As expected, darker colors were significantly more attractive to horn flies, while animals with greaterr percentage of Brahman were less susceptible than animals with greater percentage of Angus breed. Considerable variability in fly load was observed within purebred Brahmans, indicating that additional genetic factors, other than breed, influence cattle resistance to flies. Positive estimates were observed between horn fly load and average daily gain in both herds, which can be due to the fly load below the previously reported economic injury level of 200 flies (BRA: 28.78 ± 38.20, MAB: 19.31 ± 26.72). Variance components were estimated within herds by fitting the same aforementioned effects and a genomic-based relationship matrix (G) constructed with genotypes from the GeneSeek Genomic Profiler F250 SNP chip. The moderate heritability estimate demonstrates the feasibility of selecting cattle resistant to horn flies. Overall, our findings have the potential to contribute to reducing losses and costs in beef cattle operations, while reducing the impact on the environment of overuse of insecticides.

The Defensive Behaviors and Milk Production of Pastured Dairy Cattle in Response to Stable Flies, Horn Flies, and Face Flies.

Thirty-four crossbred dairy cows were observed on pasture six times per week from June to August 2014 at the University of Minnesota West Central Research and Outreach Center grazing dairy in Morris, MN, for defensive behaviors in response to three species of muscid flies. Counts of stable flies (Stomoxys calcitrans (L.)), horn flies (Haematobia irritans (L.)), and face flies (Musca autumnalis DeGeer) were recorded before and after pasture observation. Individual cows were monitored for 5 min intervals to observe the frequencies of five different defensive behaviors: front and back leg stomps, head tosses, skin twitches, and tail swishes. Fly numbers averaged 5 stable flies per leg, 37 horn flies per side, and 1 face fly per face during the study. The fly counts and behavior frequencies increased with ambient temperature. The results showed a very strong relationship between the numbers of flies and numbers of defensive behaviors, though correlations between specific flies and behaviors were low. Younger cows had fewer stable flies and horn flies than older cows. The thresholds of flies to lower production for pastured organic dairy cows may be greater than 5 for stable flies, 37 for horn flies, and 1 for face flies.

Genetic parameters of subjective and image-based horn fly abundance phenotypes

The genetic basis of horn fly abundance remains largely unknown and only few heritability estimates are available based on small scale studies. In this study, one subjective and two image-based fly abundance phenotypes were analyzed. Each animal was assessed subjectively for fly abundance by at least one trained agent (SUB). Additionally, several digital images were taken and the best image for each animal was used to assess fly abundance. A box that runs roughly from the withers to the hook and from the chest floor to the fore of the udder was established and all horn flies (PA) and sampling-based estimated number of flies (PR) within the box were calculated. Horn fly counts (SUB, PA, and PR) were discretized into 4 classes based on the quartiles of their respective distributions. Heritability estimates ranged between 0.10 and 0.15 and between 0.14 and 0.16 for the continuous and discrete cases, respectively. The genetic correlation was 0.66 between PA and PR and decreased significantly between the image-based (PA and PR) and the subjective (SUB) assessments for the continuous case. For the discrete case, the genetic correlations between the three traits were very similar, indicating a high concordance between traits.

131 How Horn Flies Could Be Affecting Your Beef herd's Reproductive Success

Abstract Horn flies (HF) are one of the most prevalent external parasites on pastured cattle in North America, although they can be found worldwide. HF cause animals severe stress leading to increased cardiac and respiratory rates, and decreased feed efficiency, average daily gain, and milk production. All these detrimental effects caused by HF contribute to over $1 dollars in economic loss in the United States, annually. Current methods of reducing fly numbers, including manure management, feed additives, and insecticides, are being utilized with varying degrees of success. However, these methods require extensive management, are temporary, and are costly to producers. While several studies have investigated the effects of horn flies on growth and milk production traits, there have been very few studies on their potential impacts on reproduction in beef cattle. Insemination and calving data collected on cows and yearling heifers at Northwest Georgia Research and Education Center between 2015 to 2022 was used to determine the effect of HF abundance on fertility. Each animal was exposed to two insemination events. Artificial Insemination (AI) was used except for cows that did not get pregnant from the first AI which were placed on pasture with a proven bull for natural service. The outcomes (success/failure) of each insemination event and calving were recorded. Still births where the dam carried the calf to term, but the calf passed during parturition were recorded as successes. As part of a research project, no fly control methods were carried out on the farms during 2019 and 2022. During these years, images of each animal were taken twice between May and August. The best image of each animal was used to estimate HF count. Animals were placed in three abundance classes (Low: 0-150, Med: 151-400, High: 401+) to analyze the effects of fly abundance on reproduction. For the remaining years (2015-2018, 2020-2021) animals received fly control and were not assessed for fly abundance. As shown Table 1, conception rates of each breeding attempt and calving rates were lower in both years where no horn fly control was used (2019 and 2022) compared with the remaining years where fly control was utilized. The decrease in conception rates when no fly control was used suggests a detrimental effect of HF on reproductive success. Additionally, for the animals measured in 2022, the average fly count for the dams who did not calf successfully was 357 which is significantly higher than the average count for the dams who did successfully calf (290). This suggests that animals with greater fly loads are less likely to carry to term. These adverse effects on reproductive health could be mitigated by genetically selecting for animals that can tolerate a greater fly load.

Vertical Distribution of Fruit Flies (Diptera: Drosophilidae) in Deciduous Forests in the Center of European Russia.

Research of Diptera in temperate forests has demonstrated uneven vertical distributions of insects. In this study, we examined the vertical distribution, seasonal fluctuations, and species diversity of Drosophilidae species in the Mordovia State Reserve. This research marks the first exploration of drosophilid vertical stratification in the European part of Russia. Using traps, we collected flies in four deciduous forest sites between early June and mid-September in 2020. A total of 27,151 individuals from 10 genera and 34 drosophilid species were identified, with 6 species from 4 genera being new to the Republic of Mordovia. Drosophila obscura Fll. and Scaptodrosophila rufifrons Lw. were the most abundant species in traps. The total highest number of drosophilid flies (10,429 individuals) was captured at a height of 1.5 m, while the lowest number (5086 individuals) was recorded at 12 m. The average number of flies was 6240 and 5387 individuals at heights of 7.5 m and 3.5 m, respectively. However, the prevalence of drosophilid numbers at the 1.5-m height was not constant during the season. We found that in the second part of July the total fly counts at heights of 7.5 m and 12 m exceeded those at 1.5 m. We have described five different types of vertical distribution of drosophilids throughout the season, which differs markedly in mycetobionts and xylosaprobionts ecological groups. Species diversity demonstrated variations across different sites and tiers during the season, with peak diversity observed in June and September.

Mango Fruit Fly Trap Detection Using Different Wireless Communications

Fruit flies cause production losses in mango orchards affecting fruit quality. A National Campaign against Fruit Flies (NCFF) evaluates farm status using the fruit flies per trap per day index (FTD). Traps with attractant are installed manually within orchards in Mexico, but counting the flies trapped every week requires excessive numbers of trained personal. Electronic traps (e-traps) use sensors to monitor fruit fly population, saving labor and obtaining the real-time orchard infestation. The objective of this work was to acquire an image within a e-trap at 17:00 when an insect was detected and binarize the information in real-time to count the number of flies. Each e-trap was implemented with a polyethylene PET bottle screwed to a tap containing an ESP32-CAM camera. E-traps from several hectares of mango trees were sampled and transmitted through WSN wireless sensor networks. This original system presents a star topology network within each hectare with the long range LoRa transceiver at the central tower. It receives the fly count from five e-traps and finally transmits data to the house tower end point. Another contribution of this research was the use of a DJI mini2 for acquiring the e-trap data, and the 8-ha flight took 15 min and 35 s. This period can be reduced if the drone flies higher.

54 Image Based Sampling to Assess Horn Fly Abundance on Cattle

Abstract Horn flies are a major irritant to livestock. In cattle, horn flies can cause increased heart and respiratory rates, decreased feed efficiency, decreased weaning weights, and reduced milk production, resulting in substantial economic loss. Fly abundance varies within and across breeds, and genetic analyses have shown sufficient variation to permit selection of hosts for resistance to horn flies. A major limitation for selecting against horn fly abundance is the difficulty associated with measuring on-animal fly counts under pasture conditions. Traditionally, trained evaluators examine cattle in the pasture and estimate fly numbers. Fly movement and animal movements, as well as evaluator expertise are major sources of variation. Image analysis has also been proposed as a means to evaluate horn fly abundance. However, several issues related to image acquisition and processing need to be resolved before reliable estimates can be obtained. Cows (n = 752) and heifers (n = 129) were assessed by trained evaluators and several digital images were taken for each animal twice during the summers of 2019 and 2022. For each image, a box that runs roughly from the withers to the hooks and from the chest floor to the fore of the udder was established. Using ImageJ software, all horn flies within the box were manually counted. Additionally, a density region-based method was used. It consisted of dividing the box into regions of high, moderate, and low fly density. A grid was placed over the box and 20%, 10%, and 5% of squares were sampled randomly within the high, medium, and low-density regions of the grid, respectively. The total counts were used to assess the accuracy of the density region method and the subjective assessment by trained evaluators method. The Pearson correlation between fly counts assessed based on and the methods was 0.954. A lower correlation was obtained between subjective assessment and (0.403) and (0.432). When fly abundance was discretized into 4 classes, the image-based methods showed high concordance (~0.90). However, the subjective method yielded only a 37% concordance. These results seemed to indicate that the proposed collection can be used with high accuracy to estimate the total number of flies on the animal. It significantly reduced the amount of time it takes to estimate fly counts from images. Furthermore, it has a greater accuracy than subjective evaluations. Despite its good performance, the proposed method still does not overcome the difficulties associated with capturing images under pasture settings. Alternative approaches that can cheaply and efficiently estimate fly abundance should be explored.

Urban Onsite Sanitation Upgrades and Synanthropic Flies in Maputo, Mozambique: Effects on Enteric Pathogen Infection Risks.

Synanthropic filth flies transport enteric pathogens from feces to food, which upon consumption poses an infection risk. We evaluated the effect of an onsite sanitation intervention─including fly control measures─in Maputo, Mozambique, on the risk of infection from consuming fly-contaminated food. After enumerating flies at intervention and control sites, we cultured fecal indicator bacteria, quantified gene copies for 22 enteric pathogens via reverse transcription quantitative polymerase chain reaction (RT-qPCR), and developed quantitative microbial risk assessment (QMRA) models to estimate annual risks of infection attributable to fly-contaminated foods. We found that the intervention reduced fly counts at latrine entrances by 69% (aRR = 0.31, [0.13, 0.75]) but not at food preparation areas (aRR = 0.92, [0.33, 2.6]). Half of (23/46) of individual flies were positive for culturable Escherichia coli, and we detected ≥1 pathogen gene from 45% (79/176) of flies, including enteropathogenic E. coli (37/176), adenovirus (25/176), Giardia spp. (13/176), and Trichuris trichiura (12/176). We detected ≥1 pathogen gene from half the flies caught in control (54%, 30/56) and intervention compounds (50%, 17/34) at baseline, which decreased 12 months post-intervention to 43% (23/53) at control compounds and 27% (9/33) for intervention compounds. These data indicate flies as a potentially important mechanical vector for enteric pathogen transmission in this setting. The intervention may have reduced the risk of fly-mediated enteric infection for some pathogens, but infrequent detection resulted in wide confidence intervals; we observed no apparent difference in infection risk between groups in a pooled estimate of all pathogens assessed (aRR = 0.84, [0.61, 1.2]). The infection risks posed by flies suggest that the design of sanitation systems and service delivery should include fly control measures to prevent enteric pathogen transmission.

Thrombin as a Potential Proxy to Select for Horn Fly Abundance in Beef Cattle.

Horn flies are a major nuisance to cattle and induce significant economic losses. Fly abundance varies within and across breeds and genetic analyses have shown sufficient genetic variation to permit selection. A major bottleneck for selecting against horn fly abundance is the complexity of measuring fly attraction phenotypes. Easy-to-measure proxy phenotypes could be an attractive option to indirectly estimate fly abundance. In the current study, thrombin was investigated as a potential proxy to assess fly abundance. Fly counts and blood samples were collected on 355 cows. Pearson correlation between subjective fly count and thrombin was -0.13, indicating a decrease in fly abundance with the increase in thrombin concentration. When thrombin was discretized into three classes, there was a 22% difference in fly count between the top and bottom classes. Heritability estimates of thrombin were 0.38 and 0.39 using linear and threshold models, respectively. The correlation between estimated thrombin breeding values and fly count was around -0.18. There was a noticeably lower density of high fly counts among animals with high breeding values for thrombin. These results indicate that thrombin could be used in combination with other biological factors to estimate fly abundance and as a proxy for selection against fly abundance.

PS-4 Evaluating the Effects of Artificial Rainfall and Permethrin Resistance Status on the Efficacy of Common Pour-On Formulation Delivered to Beef Heifers in a Controlled Environment

Abstract The objective of this study is to determine the impact of rainfall on the duration of efficacy of a commercial pour-on against susceptible (SS) and permethrin resistant (PR) horn flies. Eighteen Angus-Hereford crossbred heifers (BW) were used in a completely randomized design with repeated measures to determine the efficacy and longevity of a permethrin-based pour-on. Animals were randomly assigned to one of two fly infestations (SS or PR) and within infestation to one of three rainfall regimens [no rain (NR), no rain with a pour-on (NP) treatment, and rain with a pour-on (RP) treatment]. All heifers were housed in outdoor roofed pens within the corresponding treatment group and animals with NP and RP groups were treated once on day 0 at the label rate. Once a week for four weeks all animals were placed into individual indoor screened rooms where the fly infestations were administered. Live fly counts were acquired 24 h following each infestation. Animal with RP received approximately 2.54 cm of artificially provided rainfall within 2 hours following each weakly horn fly count. A treatment × day x fly interaction (P < 0.01) was observed. In general, NR groups maintained higher (P < 0.05) populations of SS and PR for 22 and 8 days post-treatment, respectively. Regardless, of fly species, rainfall had no (P > 0.05) influence on product efficacy. In conclusion, insecticide resistance status appears to be more influential than heavy rainfall in the longevity of permethrin-based pour-on products.

The effect of improving solid waste collection on waste disposal behaviour and exposure to environmental risk factors in urban low-income communities in Pakistan.

ObjectiveTo estimate the effect of improving waste collection services on waste disposal behaviour and exposure to environmental risk factors in urban, low‐income communities in Pakistan.MethodsWe enrolled six low‐income communities in Islamabad (Pakistan), four of which received an intervention consisting of a door‐to‐door low‐cost waste collection service with centralised waste processing and recycling sites. Intervention communities underwent community‐level and household‐level mobilisation. The effect of the intervention on waste disposal behaviour, exposure to waste and synanthropic fly counts was measured using two cross‐sectional surveys in 180 households per community.ResultsIntervention communities had less favourable socio‐economic indicators and poorer access to waste disposal services at baseline than control communities. Use of any waste collection service increased from 5% to 49% in the intervention communities (difference 44%, 95% CI 41%, 48%), but the increase was largely confined to two communities where post‐intervention coverage exceeded 80% and 90%, respectively. An increase in the use of waste collection services was also found in the two control communities (from 21% to 67%, difference 47%, 95% CI 41%, 53%). Fly counts decreased by about 60% in the intervention communities (rate ratio 0.4, 95% CI 0.3, 0.4) but not in the control communities (rate ratio 1.52, 95% CI 1.1, 2.2). The decrease in fly counts was largely confined to the two high‐coverage intervention communities.ConclusionIntroduction of a low‐cost waste collection service has the potential for high uptake in low‐income communities and for decreasing the exposure to waste and synanthropic flies at household level. Intervention success was constrained by low uptake in half of the intervention communities.

Field Trial on the Control of Flies in Cattle by Spraying Aqueous Extract of Leaves and Seeds of Moringa Oleifera

Cattle flies are external, blood-sucking parasites. Their control can be done by using repellents from plant extracts. The objectives of the research were, to determine the number of flies that infest cattle and to evaluate how long the aqueous extract of leaves and seeds of M. oleifera took to make effect. Through the study, fly counts on the wither or hump region were taken between 8:00-9:00 am and 5:00-6:00 pm. To obtain the aqueous extract, 2.5 kg of leaf and seed powder were used, diluted in 20 L of distilled water. The solution was left to stand for 24 h in a dark room. With the liquid obtained, four clinically healthy bovines, two females of the Gray Brahman and Suizbu breeds and two bulls of the Guzerat and Red Brahman breeds, were sprayed until the aqueous extract runoff. Once the treatment was applied, the fly count was performed on the surface of the animals. During the three days of the study, a total of 1,256 flies were counted in the four animals, with an average of 608 flies on days 1 and 3 of the experiment, while on day 2 it decreased to 52 flies, with an average of 10 flies in the morning. and 42 in the afternoon. The spraying with the extract of leaves and seeds prevented the flies from landing on the animals; however, a long-lasting repellent effect was not observed.

Insecticidal efficacy against Phlebotomus perniciosus in dogs treated orally with fluralaner in two different parallel-group, negative-control, random and masked trials

BackgroundDogs are the reservoir host of Leishmania infantum, the agent of zoonotic visceral leishmaniasis (VL), which is transmitted by the bite of phlebotomine sand flies. The sand fly Phlebotomus perniciosus is the main vector of zoonotic VL in the western Mediterranean region. Fluralaner has been shown to effectively kill this vector. The aim of this study was to evaluate the insecticidal efficacy of oral fluralaner in dogs bitten by P. perniciosus.MethodsTwo parallel-group, negative-controlled, randomized, masked laboratory trials with equivalent designs were performed in two different locations using two different pathogen-free laboratory-bred P. perniciosus strains for the challenge. In each trial, 12 purpose-bred beagles, initially ranked on natural attractiveness to sand flies, were randomly allocated to two groups (6 animals/group). Dogs in one group received fluralaner orally at the approved dose on day 0, and dogs in the control group were not treated. Each dog was subsequently exposed to an average of 70 unfed live sand fly females on days 1, 28, 56 and 84. Viability of blood-fed females was then evaluated for up to 96 h after exposure, and insecticidal efficacy was measured as the survival rate of flies fed on the fluralaner-treated dogs versus that of dogs in the control group. Significance was calculated for the proportion of live fed sand fly counts from treated versus control group dogs.ResultsComparison of the survival proportions between treated and control groups showed that fluralaner insecticidal efficacy was highly significant in both trials (P < 0.001 or P < 0.01 in different assessments) through to day 56. In the first trial, efficacy reached 100% on days 1 and 28, and 99.1% on day 56; in the second trial, the insecticidal efficacy was 98.5, 100 and 85.9%, respectively on the same days. On day 84, efficacy was in the range of 53–57% (P < 0.05) in the first trial and 0% in the second trial.ConclusionA single oral fluralaner administration to dogs under laboratory conditions results in strong and reproducible insecticidal efficacy against P. perniciosus for at least 8 weeks.Graphical

The Effect of Horn Fly (Diptera: Muscidae) Infestation on Behavior, Water, and Feed Intake, and Digestion Characteristics of Beef Cattle.

Seven mature Angus × Hereford crossbreed cows (544 ± 23.2 kg of body weight) fitted with duodenal and ruminal cannulas were used in a crossover design to evaluate the effects of horn fly (Haematobia irritans) (L.) infestation on horn fly-induced defensive behaviors, feed and water intake, as well as digestion characteristics of beef cows. Cows were randomly assigned to one of two treatment groups: 1) a horn fly infested (1,000 flies per cow) or 2) a noninfested control group. All cows were housed in individual screened pens. Fly counts and infestations were performed daily to maintain consistent populations throughout the study. Sudan hay (11.4 % crude protein, dry matter basis) was selected to mimic forage quality that range cattle frequently graze in the southwest region. Horn fly-induced host defensive behaviors were greater (P ≤ 0.0002) for horn fly infested cattle. Intake of water, dry matter, organic matter, crude protein, and neutral detergent fiber were similar (P ≥ 0.4765) among infested and noninfested cows. However, total volatile fatty acid concentration tended to increase (P = 0.0967) when horn flies were present. Dry matter fecal excretion and total tract digestion were not affected (P ≥ 0.2602) by horn fly infestation. These data indicate that horn fly infestations do not affect forage intake or digestion characteristics of beef cattle (Bos taurus) in confinement settings.

PSIX-16 Association between Thrombin and horn fly abundance in beef cattle

Abstract It has been reported that differences in horn fly tolerance in beef cattle could be associated with variation in blood enzymes. Thrombin (TH), a major enzyme for hemostasis that plays an important role in the activation of several pro-coagulation factors through the conversion of fibrinogen to fibrin, has been associated with horn fly prevalence on cattle. Although this assumption is reasonable, as fast-coagulating blood tends to complicate the feeding process for flies, there is little meaningful field data that clearly supports this hypothesis. Therefore, the objective of this study was to assess TH levels in relation to horn fly abundance using 360 cows at two University of Georgia farms (Northwest Georgia REC, 34.5°N, 85.0°W and Eatonton Beef Research Unit, 33.4°N, 83.5°W). Horn fly counts were taken twice by trained evaluators during the summer of 2019 (June and August). Additionally, blood samples were collected twice on each cow to quantify serum TH levels using an ELISA assay (MyBioSource, San Diego, CA). The Pearson correlation between serum TH level and horn fly count was -0.19, indicating a decrease in the number of flies with increasing TH in the blood. In order to reduce the impact of the uncertainty associated with the subjective assessment of horn fly abundance and the potential nonlinear relationship between both parameters, TH was categorized into four classes (1=TH &amp;gt;500 ng/mL; 2=250&amp;lt; TH&amp;lt; 500 ng/mL; 3=100&amp;lt; TH&amp;lt; 250 ng/mL; 4=&amp;lt; 100 ng/mL). Average fly counts were 336, 353, 391, and 464 for the four classes, respectively. Between the first (high TH) and fourth (low TH) classes, there was a 38% reduction in fly abundance. Across sire families, fly abundance ranged between 190 and 650. Collectively, these results indicate that selection for higher serum TH levels could be used as a proxy for improving horn fly tolerance in beef cattle.

PSVIII-5 Genetic parameters of thrombin as a proxy for horn fly abundance in beef cattle

Abstract Horn flies (Haematobia irritans) are a major nuisance to cattle, especially in warm, humid regions, and are estimated to cause economic losses in excess of $1 billion annually to the U.S. beef cattle industry. Variation in horn fly tolerance has been reported within and across breeds, and heritability estimates ranging between 10 and 80% show a clear genetic basis. However, collecting fly abundance phenotypes is costly and logistically demanding, which precludes large-scale implementation. Consequently, finding correlated phenotypes and endo-phenotypes that are heritable and relatively easy to measure would facilitate implementation of horn fly tolerance genetic improvement programs. Thrombin (TH), a blood coagulation precursor, has a reported association with horn fly count variation within and across cattle breeds. In this study, the genetic basis of thrombin in beef cattle was investigated. Blood samples and horn fly count were collected on 360 cows and heifers twice during the summer of 2019 (June and August). Due to uncertainty associated with assessment of horn fly abundance and thrombin and the fact that economic losses occur only when fly abundance exceeds a certain threshold, thrombin was categorized into 4 classes (1=TH &amp;gt; 500 ng/ml; 2=250&amp;lt; TH&amp;lt; 500 ng/ml; 3=100&amp;lt; TH&amp;lt; 250 ng/ml; and 4=TH&amp;lt; 100 ng/ml). The trait was analyzed using linear (continuous) and threshold (discrete) mixed models. Both models included farm, pregnancy status, and cow age as fixed effects and additive and permanent environment random effects. The pedigree included 642 animals. Estimates of heritability were 0.24 and 0.29 using linear and threshold models, respectively. Estimates of repeatability were slightly higher using the threshold model (0.21 vs 0.19). Despite the small data size, all estimates were non-zero based on their respective highest posterior density intervals. These results indicate reasonable genetic variation for thrombin that could be harnessed for improvement of horn fly tolerance in cattle.

Stable fly activity is associated with dairy management practices and seasonal weather conditions.

Stable flies (Stomoxys calcitrans) are blood-sucking insects commonly associated with cattle production systems worldwide and are known to cause severe irritation to cattle due to painful bites. Cattle react to biting stable flies with an aggregating behavior known as bunching. Bunching behavior reduces grazing or feed consumption and thus reduces cattle productivity and welfare. Cattle’s fly-repelling behaviors include foot stomping, head tossing, tail switching and skin twitching. A longitudinal study was conducted in 2017 on 20 California dairies (average lactating herd size = 2,466 (SE±28.392)) during the stable fly season from April to July. The study objectives were to estimate the association between environmental factors and dairy characteristics including facility design, feed and manure management, total mixed ration (TMR) components fed to cattle, and operational pest management procedures and the outcome stable fly activity on California dairies. Stable fly activity was measured by counting stable flies on cow forelimbs (leg count) and on Alsynite traps (trap count) over the 13-week study period. Weekly leg counts were performed for cattle in lactating cow pens (31 pens from 10 study dairies) with counts made during the morning (AM) and again during the afternoon (PM). Trap counts were performed on all 20 study dairies. Data were analyzed using linear mixed models which revealed temporal variation in the average leg and trap counts with stable fly activity increasing from May to June and then decreasing to the lowest activity in July. Leg counts were higher during the afternoon compared to morning. Ambient temperatures ≤30⁰C and relative humidity (RH) measurements <50% were associated with higher leg and trap counts. Traps located at the periphery of study dairies had higher stable fly counts compared to traps located in the interior of the dairy. Cow pens with trees on the periphery had higher leg counts in comparison to pens away from trees. Specific TMR components were associated with both leg and trap counts. Dairies feeding by-products including almond hulls, wet distillers’ grain, fruits, and vegetables had higher trap counts compared to dairies that did not feed these ingredients. At the pen level, pens with rations that contained straw had lower average leg counts compared to pens fed with rations that did not contain straw. A similar association was observed for pens with rations that contained wheat silage when ambient temperatures were ≤30⁰C. In contrast, pens with water added to the TMR while the RH was ≥50% had higher average leg counts compared to pens without water added to the TMR. Dairies that applied insecticides for fly control to their entire facility had lower trap counts compared to dairies that did not apply insecticides. Stable fly activity measured on California dairies using leg and trap counts varied according to the month, environmental factors, pen surroundings, trap location, TMR components, and insecticide use.

Environmental and Spatial Predictors of the Distribution Patterns of the Host-Seeking Black Fly, Simulium jenningsi (Diptera: Simuliidae).

Black flies are nuisance pests as adults, yet they are best managed in the larval stage in flowing waters. As a result, more effort is put into understanding the distribution of the immature life stages than the blood-seeking females that form nuisance. The seemingly localized nature of Simulium jenningsi Malloch (Diptera: Simuliidae) pest problems in western Maryland offered a study system to investigate the spatial and environmental correlates to their severity. Collections of adult black flies were taken at 260 sites within a 2,000 km2 region centered on Washington County, Maryland, during June, July, and August of 2 yr. Average S. jenningsi counts were greater in the June of both years compared to July and August. Although S. jenningsi was found at the majority of sampling sites, higher fly counts were significantly clustered in the southern portion of the county where the majority of resident complaints originated. A generalized linear mixed-model (GLMM) approach was used to determine the correlates to S. jenningsi abundance. The highest performing model showed a negative relationship of S. jenningsi counts with the amount of surrounding impervious surface, distance to the riffles along the confluence of the Shenandoah and Potomac Rivers, distance to the closest body of flowing water, and light intensity, as well as a positive relationship with elevation and air temperature. The results suggest S. jenningsi females are not readily found in urban environments in this study region, and the most relevant monitoring locations for S. jenningsi may be outside of human population centers.

101 Impact of Equi-Shield as a nutraceutical fly protectant in adult horses

Biting insects commonly irritate horses resulting in annoyance behaviors. Owners will attempt to alleviate the annoyance through topical sprays, insecticides, physical barriers, predators, and nutraceuticals. Equi-Shield (ES, Probiotech International, Inc.) is a nutraceutical designed to help protect horses from biting insects via a proprietary blend of botanical oils (eucalyptus, citronella, peppermint, garlic, and anise). This blend has been shown to reduce the number of flies landing on the head and neck of cattle after 7d of consumption. The objective of this preliminary trial was to determine the impact of ES on the number of flies landing on adult horses throughout the day after 7d of consumption. Because flies are active in Summer in VA, USA, the trial was conducted in August. Twelve adult horses were assigned to control (C:no supplement) or ES (20g/d top-dressed on morning concentrate). After 7d of consumption, daily observations (O) began for the subsequent 7d by blinded, trained observer pairs. Daily O consisted of 3–30min periods (P) during stalled meals (930–1000, 1230–1300, 1630–1700) offered at opposite ends of the barn separated by 3.66m breezeway. Number of visible flies were immediately counted and grouped by head and neck (H), front legs (FL), hind legs (HL), and remainder of the body (B). Total flies (F) were calculated from the addition of the groups. Horses did not receive any additional fly protection during the trial. Fly counts were analyzed using the repeated statement in PROC MIXED procedure of SASv9.3. There was no impact ( P > 0.10) of P on F, HL, FL, H, or B for each treatment. There was no effect ( P > 0.29) of day*treatment on B or H. A tendency ( P = 0.08) for less flies on ES than C for B (ES:0.60 ± 0.12; C:0.91 ± 0.13) and H (ES:0.46 ± 0.09; C:0.71 ± 0.10) was seen. There was an effect ( P < 0.05) of day*treatment on F, HL, and FL. On d 1 (ES:2.5 ± 0.63; C:5.87 ± 0.69), 4 (ES:3.39 ± 0.63; C:6 ± 0.67), 5 (ES: 3.28 ± 0.63; C:5.07 ± 0.67), 6 (ES:3.39 ± 0.63; C:5.47 ± 0.67), and 7 (ES:2.67 ± 0.63; C:4.67 ± 0.67), there were less ( P < 0.05) F on ES horses than C. The HL of ES had less ( P < 0.05) flies on d 1 (ES:0.44 ± 0.30; C:1.4 ± 0.33) and 4 (ES:0.56 ± 0.30; C:1.67 ± 0.33). C had more flies on FL on d 1 (ES:0.78 ± 0.38; C:3.07 ± 0.41), 5 (ES:0.89 ± 0.38; C:1.93 ± 0.41), and 6 (ES:1.28 ± 0.38; C:2.4 ± 0.41) compared with ES. Within ES, only d 3 (4.67 ± 0.63) differed ( P < 0.01) from d 1 (2.5 ± 0.63). Although environment may have had an impact on the trial with rain on the morning d 2, the preliminary results indicate that ES may reduce flies on horses after 7d of consumption. More research is warranted to determine if the reductions demonstrated lead to fewer annoyance behaviors.

Spatiotemporal analysis of distribution of pest and predator in corn crops

ABSTRACT Crop pests have negative impacts on yield. This paper proposes a spatiotemporal geostatistical modeling to compare data of adult Syrphidae fly count and corn leaf aphid Rhopalosiphum maidis (Fitch, 1856) colonies in corn crops. The use of a geostatistical model that allows the space-time variation makes the approach more interesting because it is a more complete model. Multiple regression was used to model the trend component for the variable response adult Syrphidae fly count and corn leaf aphid colonies, with the coordinates serving as covariates and the spatiotemporal variations around the deviation are described by a random spacetime residual field. Finally, the prediction map obtained by kriging may be a biological indicator of possible corn leaf aphid colonies in the corn crop. It was possible to verify that the occurrence of the pest provided a significant increase in adult predators and seminatural habitats may favor populations of natural enemies.