Livestock Pests Research Articles

Amplified Fragment Length Polymorphism Used to Investigate Genetic Variability of the Stable Fly (Diptera: Muscidae) Across North America

The stable fly, Stomoxys calcitrans (L.), is a cosmopolitan pest of livestock and humans. The pestiferous nature and painful bite cause stress to cattle and other animals. The stress and resulting avoidance behaviors manifest as reductions in weight gain or milk production in cattle; estimated annual economic loss in the United States exceeds US$2 billion. Understanding the population genetics of stable flies could provide information on their population dynamics, origins of outbreaks, and geographical patterns of insecticide resistance, resulting in a tactical advantage for developing management strategies. Previous studies, mostly on a local scale, reported a high level of gene flow between locations. Here, we report results wherein amplified fragment length polymorphism was used to determine genetic diversity of stable fly samples consisting of 11-40 individuals from 12 locations representing the United States, Canada, and Panama. The Analysis of Molecular Variance showed that the majority of genetic diversity was within groups; very little was among groups. The F(ST) and G(ST) values were low (< 0.4), Nm values high (> 1.0). The tests of neutrality suggested population expansion, and no genetic differentiation was found between locations. These results show that stable flies have a high level of gene flow on a continental scale, with limited isolation owing to distance or geographical barriers.

Inter- and Intraspecific Identification of the Screwworm,Cochliomyia hominivorax, Using Random Amplified Polymorphic DNA-Polymerase Chain Reaction

The screwworm, Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae), is one of the most devastating arthropod pests of livestock in the Western Hemisphere. Early instars are very difficult to distinguish morphologically from several closely related blow fly species. Random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) markers were developed for identifying C. hominivorax from other wound inhabiting species. Forty decameric primers were screened; nine showed clear reproducible RAPD profiles suitable for distinguishing all life stages of C. hominivorax from 7 other species, including C. macellaria (Fabricius). The results from RAPD-PCR with field-collected samples of unknown first instars agreed with morphological identification that the samples were not C. hominivorax. Three different primers showed DNA polymorphisms (intraspecific) for samples originating from Mexico, Costa Rica, Panama, Jamaica, and Brazil. Therefore, RAPD-PCR may be useful for determining the geographic origin of C. hominivorax samples. Comparing products from these primers, used with known and unknown screwworm samples from an outbreak in Mexico, clearly showed that the outbreak did not originate from the mass rearing facility. Accurate identification of suspected C. hominivorax samples is possible using RAPD-PCR. Further development to identify the geographic origin of samples would benefit the ongoing surveillance programs against C. hominivorax and the decision process during suspected outbreaks of this important pest.

Oxidative damage to human red blood cells treated with chlorfenvinphos, an organophosphate insecticide (in vitro)

Chlorfenvinphos (CFVF) is an organophosphorus insecticide, which was used to control insect pest on livestock and household pests such as flies, fleas, and mites. The molecular basis of toxic properties of CFVF in animals has been insufficiently studied. Blood can transport oxygen and nutrients as well as toxic compounds. Xenobiotics can enter to red blood cells and cause damage. Therefore, investigation of the toxicity of different compounds to erythrocytes is very important. The purpose of the present experiment was to evaluate the effect of this compound on human erythrocytes. We have evaluated the hemolysis, hemoglobin oxidation (met-Hb formation) and lipid peroxidation in human erythrocytes. Moreover, the changes in the level of reactive oxygen species (ROS) were assessed using flow cytometry as well as those in morphological changes of erythrocytes using phase contrast microscopy. This study describes the interaction of low concentrations of CFVF with human erythrocytes as well as the concentrations, which may enter human organism as a result of acute poisoning (0.5–250 μM). It was shown that CFVF only at high concentration induced changes in human erythrocytes. We have observed hemolysis (at 250 μM), changes in morphological parameters including echinocytes formation (at 250 μM), as well as increase in lipid peroxidation in erythrocytes (at 250 μM), ROS formation (at 100 μM) in red blood cells treated 1 hour with CFVF. Additionally, CFVF after 4 h of incubation oxidized hemoglobin, however, to a lower degree.

Conservation and Sex-Specific Splicing of the transformer Gene in the Calliphorids Cochliomyia hominivorax, Cochliomyia macellaria and Lucilia sericata

Transformer (TRA) promotes female development in several dipteran species including the Australian sheep blowfly Lucilia cuprina, the Mediterranean fruit fly, housefly and Drosophila melanogaster. tra transcripts are sex-specifically spliced such that only the female form encodes full length functional protein. The presence of six predicted TRA/TRA2 binding sites in the sex-specific female intron of the L. cuprina gene suggested that tra splicing is auto-regulated as in medfly and housefly. With the aim of identifying conserved motifs that may play a role in tra sex-specific splicing, here we have isolated and characterized the tra gene from three additional blowfly species, L. sericata, Cochliomyia hominivorax and C. macellaria. The blowfly adult male and female transcripts differ in the choice of splice donor site in the first intron, with males using a site downstream of the site used in females. The tra genes all contain a single TRA/TRA2 site in the male exon and a cluster of four to five sites in the male intron. However, overall the sex-specific intron sequences are poorly conserved in closely related blowflies. The most conserved regions are around the exon/intron junctions, the 3′ end of the intron and near the cluster of TRA/TRA2 sites. We propose a model for sex specific regulation of tra splicing that incorporates the conserved features identified in this study. In L. sericata embryos, the male tra transcript was first detected at around the time of cellular blastoderm formation. RNAi experiments showed that tra is required for female development in L. sericata and C. macellaria. The isolation of the tra gene from the New World screwworm fly C. hominivorax, a major livestock pest, will facilitate the development of a “male-only” strain for genetic control programs.

Seasonality and daily flight activity of stable flies (Diptera: Muscidae) on dairy farms in Saraburi Province, Thailand

Knowledge of seasonal abundance and flight activity patterns are required to design effective management programs for insect pests of humans and livestock. In this study, the seasonality and daily flight activity of Stomoxys species were observed on two dairy farms in Saraburi Province, Thailand. Data were assessed throughout 1 year using Vavoua traps from September 2010 to August 2011. A total of 2,520 individuals belonging to four species were collected. Most Stomoxys species peaked in September (rainy season) and gradually decreased in number toward February (dry season); a second peak occurred between March and April (hot season). Stomoxys calcitrans was caught throughout the year and was the most abundant species in this study. The total number of males and females of S. calcitrans differed significantly among seasons and time intervals. The weather parameters of relative humidity and light intensity were significantly correlated with S. calcitrans abundance.

Toxic effects of Carbaryl on the Vasculature of Liver in Adult Albino Rat, Rattus norvegicus

The excessive use of pesticides and insecticides on agricultural crops, poultry, livestock, home and garden pest control has become one of the major health concerns as humans are exposed to these environment pollutants constantly. Carbaryl, a 1-Naphthyl N-methyl carbamate insecticide has been one of the most commonly and extensively used insecticide in the recent years due to its broad spectrum activity and short residual life on treated crops. However, studies have revealed their presence in the food and fruit products available in the market. Since liver plays an important role in the first pass metabolism of carbaryl, which has seen to cause various disturbances in the liver enzymes, the present work was conducted to study the morphological and morphometric changes in the vasculature of the liver produced by the insecticide carbaryl. Inbred adult Wistar albino rats (150200gm) were injected with 200mg/kg body weight of carbaryl intraperitoneally, five days a week for thirty days. Controls were maintained. The animals were group housed with ad libitum access to food and water. The animals were sacrificed within twenty four hours of the last injection, liver was processed and sections (7μ) cut and stained. Microscopic examination revealed a statistically significant dilatation of the hepatic vasculature along with various histomorphological changes in the liver parenchyma.

Histopathological Effects of Carbaryl on Liver in Albino Rats

Pesticides are one of the most alarming toxic substances that are deliberately added to our environment. Carbaryl, a synthetic 1-naphthyl-N-methylcarbamate insecticide, is being used extensively or its broad-spectrum activity in commercial agriculture, poultry, livestock, home and garden pest control. However, there is paucity of information about the role of carbaryl on the liver. Wistar rats were administered with carbaryl and the effects of this liver histology were analyzed. Profound damage of the liver of rats administered with carbaryl was noted. More studies would be required to assess the real implication of this pesticide on the liver.

Detecting mutation in sodium channel gene in Rhipicephalus (Boophilus) microplus collected from northern India for genotyping deltamethrin-susceptible and deltamethrin-resistant alleles

Rhipicephalus (Boophilus) microplus is an economically significant pest of livestock in India. Allele-specific polymerase chain reaction (PCR) was employed to detect Phe→Ile substitution in the sodium channel gene in different populations of Rhipicephalus microplus collected from foothills (Kashipur, Pantnagar, Nagla and Dehradun) and high-altitude areas (Pithoragarh, Almora and New Tehri) of Uttarakhand state in northern India. The allele-specific PCR assay revealed 85% larvae to be homozygous susceptible, 3% to be homozygous resistant and 12% to be heterozygous. Homozygous resistant genotypes were recorded in two tick populations (Kashipur, 13% and Pantnagar, 4%); heterozygous genotypes in four tick populations (Kashipur, 45%; Pantnagar, 17%; Almora, 14%; and New Tehri, 3%) and 100% homozygous susceptible genotypic frequencies in three tick populations (Nagla, Dehradun and Pithoragarh). The highest rate of mutant allele (R) occurred in tick populations of Kashipur (35%) (p < 0.05), followed by Pantnagar (13%), Almora (7%) and New Tehri (1%). The results of the study suggested that frequent monitoring of the level of pyrethroid resistance was required to formulate any control strategy against ticks and hence extend the life of the existing acaricide(s).

Horn Fly Management

Horn flies are one of the livestock pests with the greatest impact on the health and productivity of cattle. Economic losses due to horn fly damage are estimated at $36 million annually in Florida alone. In the U.S.A. annual losses total between $700 million and $1 billion, with up to $60 million spent on insecticidal control. Horn fly damage is caused by blood feeding. The flies feed frequently and exclusively on blood, piercing the skin of cattle with their proboscis and taking around 20 small blood meals each day. Pain and irritation due to the constant presence of the flies and their bites causes defensive behavior in the cattle that prevents adequate food consumption and rest. This 4-page fact sheet was written by P. E. Kaufman and E. N. I. Weeks, and published by the UF Department of Entomology and Nematology, September 2012. ENY288/IN952: Horn Fly Management (ufl.edu)

Molecular characterization of Bm86 gene orthologs from Hyalomma excavatum, Hyalomma dromedarii and Hyalomma marginatum marginatum and comparison with a vaccine candidate from Hyalomma scupense

The ixodid ticks from the Hyalomma genus are important pests of livestock, having major medical and veterinary significance in Northern Africa. Beside their direct pathogenic effects, these species are vectors of important diseases of livestock and in some instances of zoonoses. Anti-tick vaccines developed in Australia and Cuba based on the concealed antigen Bm86 have variable efficacy against H. anatolicum and H. dromedarii. This variation in vaccine efficacy could be explained by the variability in protein sequence between the recombinant Bm86 vaccine and Bm86 orthologs expressed in different Hyalomma species. Bm86 orthologs from three Hyalomma tick species were amplified in two overlapping fragments and sequenced. The rate of identity of the amino acid sequence of Hm86, He86 and Hdr86, the orthologs of Bm86, respectively, in H. marginatum marginatum, H. excavatum and H. dromedarii, with the Bm86 proteins from Rhipicephalus microplus (Australia, Argentina and Mozambique) ranged between 60 and 66%. The obtained amino-acid sequences of Hmm86, He86 and Hdr86 were compared with the Hd86-A1 sequence from H. scupense used as an experimental vaccine. The results showed an identity of 91, 88 and 87% for Hmm86, He86 and Hdr86, respectively. A specific program has been used to predict B cells epitopes sites. The comparison of antigenic sites between Hd86-A1 and Hm86/Hdr86/He86 revealed a diversity affecting 4, 8 and 12 antigenic peptides out of a total of 28 antigenic peptides, respectively. When the Bm86 orthologs amplification protocol adopted in this study was applied to H. excavatum, two alleles named He86p2a1 and He86p2a2 were detected in this species. This is the first time that two different alleles of Bm86 gene are recorded in the same tick specimen. He86p2a1 and He86p2a2 showed an amino acid identity of 92%. When He86p2a1 and He86p2a2 were compared to the corresponding sequence of Hd86-A1 protein, an identity of 86.4 and 91.0% was recorded, respectively. When compared to He86, Hdr86 and Hm86, Bm86 used in commercial and experimental vaccines, showed a greater extent of diversity than noted when the same Hyalomma orthologs were compared to Hd86-A1. Although significant, these variations were less extensive within the Hyalomma genus. Accordingly, thus suggesting that Hd86-A1 vaccine candidate might be more appropriate to target Hyalomma tick species than corresponding Bm86 commercial vaccines. However, vaccination trials with both antigens are required to validate this hypothesis.

Laboratory Evaluation of Novaluron as a Development Site Treatment for Controlling Larval Horn Flies, House Flies, and Stable Flies (Diptera: Muscidae)

A granular formulation of novaluron (Novaluron 0.2G, 0.2% [AI]), a newer benzoylphenyl urea insecticide, was evaluated for its efficacy in controlling the larval stage of horn flies, Haematobia irritans (L.); house flies, Musca domestica L.; and stable flies, Stomoxys calcitrans (L.), in cow manure. Various rates and insecticide placement locations (top, middle, and bottom of manure) were evaluated in this study and all combinations of these variables reduced adult emergence of all three species when compared with the untreated controls. The presence of deformed pupae indicated that novaluron had an insect growth regulator effect on the developing fly larvae. Top, middle, or bottom application rates of 0.125, 0.195, 0.25, and 0.375 g novaluron onto manure samples, reduced adult horn fly emergence by > 90%. Middle and bottom application rates of 0.195, 0.25, and 0.375 g novaluron reduced adult house fly emergence >93%. All rates and placement combinations resulted in >98% reduction of adult stable fly emergence. The level of control efficacy observed against these three fly species along with the ease of use of a granular formulation, make this product an ideal candidate for use in an integrated livestock pest management program.

Using abattoir surveillance and producer surveys to investigate the prevalence and current preventative management of Caseous lymphadenitis in Merino flocks in Australia

The prevalence of Caseous lymphadenitis (CLA) in Australia was estimated to be 5.2% using 2009 abattoir surveillance data from all States supplied by Animal Health Australia involving 5029 lines comprising 1 339 463 sheep. This is a decrease from the 26% estimated in a similar study in 1995. There was a significant difference (P &lt; 0.001) in CLA prevalence between all states except Tasmania and Victoria (P = 0.75) with prevalences of 12.8 and 12.9%, respectively. Western Australia recorded the lowest prevalence with 1.0%. The average CLA prevalence for New South Wales was 5.3% and within three surveyed Livestock Health and Pest Authority regions (Tablelands, Central North and Central West) was 2.9, 4.9 and 4.4%, respectively. The attitude of the majority of producers surveyed in these three Livestock Health and Pest Authority areas was that CLA was of little or no significance (75%) but were aware of the need for CLA control with ~68% using 6-in-1 vaccine, though only 39.9% as recommended. It appears that the prolonged use of CLA vaccination has been successful in reducing the prevalence of CLA across Australia and particularly in New South Wales. Further improvements in communication of information on preventative management practices associated with lice control, importance of using an approved vaccination program, plus increasing producers’ awareness of the importance of CLA control, are indicated.

The prevalence of lice (Bovicola ovis) in sheep flocks on the central and southern Tablelands of New South Wales

In response to suggestions that the incidence of louse infestations in New South Wales has increased markedly, a survey of 173 producers was conducted in the Tablelands Livestock Health and Pest Authority region using visual detection and a questionnaire to document retrospective lice history. An estimated apparent prevalence of 16.5% is a moderate increase from the 10% reported in 2004. On a subset of the surveyed sheep flocks sheep, lice-specific immunoassay conducted by the New South Wales Department of Primary Industries were used to detect low levels of infestation that were not identified by visual detection. This provided a true prevalence estimate of 30%. These results will be used to promote improved control and preventative strategies.

Carbaryl, A Pesticide Causes “Toxic Hepatitis” in Albino Rats

Pesticides are one of the most alarming toxic substances that are deliberately added to our environment. Food and agricultural organization (FAO) has defined the term pesticide as: Any substance or mixture of substances intended for preventing, destroying or controlling any pest including vectors of human or animal disease, unwanted species of plants or animals causing harm during or otherwise interfering with the production, processing, storage, transport or marketing of food, agricultural commodities, wood and wood products or animal feedstuffs or substances which may be administered to animals for control of insects, arachnids or other pests in or on their bodies [1]. But it is a matter of concern that along with the pests, they prove harmful to many other living beings on this planet as well as human beings including newborns [2]. CARBARYL, a synthetic 1-napthyl-N-methyl carbamate is being used extensively or its broad-spectrum activity in commercial agriculture, poultry, livestock, home and garden pest control. It was the most frequently detected carbamate in juice samples studied [3]. Thorough scanning reveals that there is dearth of literature regarding the histopathological changes in liver associated with administration of carbaryl which has prompted us to initiate this study as liver plays an important role in the first pass metabolism of carbaryl. The present study was conducted on 40 albino rats. The adult albino rats (150-200 gm) were injected with 200 mg/ kg body weight of carbaryl intrapeitoneally, five days a week for 30 days. Controls were maintained. There was a significant increase in weight of the experimental rats recorded before the onset of the experiment & prior to their sacrifice (p<0.001) as compared to the controls. The rats were sacrificed within 24 hours of the last injection. The blocks of the liver were prepared for section cutting with a microtome by paraffin wax embedding method. Sections of 5-7 µm thickness were cut and stained with Haematoxylin and Eosin stain. In the study, the histomorphological changes, in the liver of Carbaryl treated rats was significantly different from that of the normal and the control rats. The disheveled pattern of the one cell thick orderly arrangement of hepatocytic cords, evidence of increased cellular metabolism co-existent with ballooning degeneration, councilman bodies, inflammatory infiltrate around the portal triads along with the dilatation of the blood vessels and the bile canaliculi were seen as signs of degeneration. B enucleated hepatocytes were suggestive of regenerative attempts by the degenerative cells. These findings are highly conclusive of toxic hepatitis induced by an insecticide, Carbaryl.

Climate Change and Livestock Production in Nigeria: Issues and Concerns

The article reviewed the major issues concerning climate change and livestock production in Nigeria. The mechanism of the greenhouse effect (GHE) of the earth’s atmosphere as well as the relative importance of greenhouse gases (GHGs) in terms of greenhouse effect (GHE) and global warming potential (GWP) are presented. The probable changes in global climate as a result of atmospheric enrichment with greenhouse gases from results of simulated changes in atmospheric greenhouse gases are also presented. Emission scenarios and climate change models, atmospheric enrichment with GHGs were shown to have a net negative impact on global climate leading to global warming, more variable and unpredictable climatic and weather patterns (including tendencies for extreme events), net decrease in yield of grain, forage and pasture crops for livestock as well as changes in the epidemiology and dynamics of livestock diseases, pests and vectors. These stressors meant greater challenges on livestock production in terms of well being, reproduction and performance. A number of adaptation schemes which include environmental modification, selective breeding and modifications in the nutritional environment of animals were suggested. The integration of these adaptive measures in livestock production systems in Nigeria will minimize and/or forestall the negative impacts of climatic change and climate variability on livestock production in Nigeria.

Genetic Structure and Demographic History of New World Screwworm Across Its Current Geographic Range

The phylogeographical history of the pest fly screwworm, Cochliomyia hominivorax (Coquerel), was studied using partial mitochondrial DNA sequences of the control region, Cytochrome c oxidase (CO) subunit I and CO subunit II from 361 individuals collected across its current geographic range. Analyses showed marked genetic differentiation on a macrogeographic scale. The genetic diversity in the species is structured into four main "regional groups," corresponding to Cuba, the Dominican Republic, and the North and South Amazon region. Results indicated that the distribution of screwworm genetic diversity was mainly shaped by historical events, i.e., colonization of Caribbean islands, vicariance in the Amazon region and population expansion. Demographic history analyses revealed that the population expansion started approximately 20-25,000 yr ago and recently increased exponentially. We hypothesized that the initial period of expansion was probably associated with environmental amelioration in the late Pleistocene and the exponential increase with resource availability in recent times. The population expansion is probably responsible for the low divergence and the lack of genetic and geographic correlation in the South Amazon region but did not erase the genetic structure pattern on a continental scale. The screwworm is one of the most damaging livestock pests in South and Central America, and the pattern of genetic variability distribution reported here suggests that the Caribbean area and the North and South Amazon regions could be considered as independent units for future pest control programs.

Phylogenetic analyses of mitochondrial and nuclear data in haematophagous flies support the paraphyly of the genus Stomoxys (Diptera: Muscidae)

The genus Stomoxys Geoffroy (Diptera; Muscidae) contains species of parasitic flies that are of medical and economic importance. We conducted a phylogenetic analysis including 10 representative species of the genus including multiple exemplars, together with the closely related genera Prostomoxys Zumpt, Haematobosca Bezzi, and Haematobia Lepeletier & Serville. Phylogenetic relationships were inferred using maximum likelihood and Bayesian methods from DNA fragments from the cytochrome c oxidase subunit I (COI, 753bp) and cytochrome b (CytB, 587bp) mitochondrial genes, and the nuclear ribosomal internal transcribed spacer 2 (ITS2, 426bp). The combination of mitochondrial and nuclear data strongly supports the paraphyly of the genus Stomoxys because of the inclusion of Prostomoxys saegerae Zumpt. This unexpected result suggests that Prostomoxys should be renamed into Stomoxys. Also, the deep molecular divergence observed between the subspecies Stomoxys niger niger Macquart and S. niger bilineatus Grünbreg led us to propose that they should rather be considered as distinct species, in agreement with ecological data. Bayesian phylogenetic analyses support three distinct lineages within the genus Stomoxys with a strong biogeographical component. The first lineage consists solely of the divergent Asian species S. indicus Picard which appears as the sister-group to all remaining Stomoxys species. The second clade groups the strictly African species Stomoxys inornatus Grünbreg, Stomoxys transvittatus Villeneuve, Stomoxys omega Newstead, and Stomoxys pallidus Roubaud. Finally, the third clade includes both African occurring and more widespread species such as the livestock pest Stomoxys calcitrans Linnaeus. Divergence time estimates indicate that the genus Stomoxys originated in the late Oligocene around 30 million years ago, with the major lineages diversifying in the Early Miocene between 20 and 15 million years ago at a time when temperate forests developed in the Northern Hemisphere.

Soil fauna in sheep-grazed hill pastures under organic and conventional livestock management and in an adjacent ungrazed pasture

Abstract Organic pasture management includes a focus on mixed livestock grazing, restrictions on nutrient inputs and livestock pest control. These are all factors which influence the environment of soil invertebrates. In this study, soil macrofauna, mesofauna and microfauna were collected from duplicate 11 and 20 year old organic and conventional legume-based sheep-grazed pasture systems. Pastures in both systems had received the same annual input of reactive phosphate rock and elemental sulphur and were stocked with the same numbers of sheep. The major difference between the two systems was absence of the chemical control of livestock pests on the organic system, resulting in lower sheep liveweights. Two ungrazed pastures which had not received any nutrient inputs for 20+ years were also sampled as part of the study to provide an additional contrast. No significant differences in either the diversity or abundance of the soil invertebrate community were found between the organic and conventional systems, despite the use of chemicals in the conventional system. The lack of difference suggests that many of the observed and reported responses to organic management reflect altered nutrient inputs and grazing management (which were the same in the current study), rather than the cessation of chemical controls in the organic system. In contrast, the invertebrate community in the unfertilised, ungrazed pasture was distinctly different from both the grazed systems. The ungrazed pasture had a higher diversity with more New Zealand endemic species than the grazed pasture. This included twice as many large Oribatida as soil pore size increased. The lower litter quality from the lack of nutrient inputs in the ungrazed pasture was reflected in both lower earthworm abundance and the Nematode Channel Ratio (indicative of a higher proportion of fungal- than bacterial-feeding nematodes), than the grazed pasture. We conclude that organic management when limited to a comparison of livestock pest control is not beneficial to soil invertebrates. Management practices such as stocking rates and fertiliser regime, by altering the soil physical environment and food resources, are more important in influencing invertebrate populations in this soil. Some would argue these altered management practices are an integral part of an organic production system.

The impact of HIV on agricultural livelihoods in southern Uganda and the challenges of attribution

Changes in agriculture and rural livelihoods in Africa are often attributed to the HIV epidemic. While acknowledging that the epidemic has devastated many families and communities because of excess morbidity and mortality, this review explores other causes of change in agriculture practices and production in southern Uganda. Over the past 20 years labour shortages, because of labour migration and changing aspirations (as well as HIV), crop and livestock pests and diseases, declining soil fertility, changes in commodity markets and a growing off-farm sector have contributed to the changes seen in rural southern Uganda. Policy interventions outside agriculture and health have also had an impact on households. The HIV epidemic has not happened in isolation. The perceived impacts of the epidemic cannot be addressed in isolation from these other drivers of change.

Repellency of a Wax-Based Catnip-Oil Formulation against Stable Flies

Stable flies, Stomoxys calcitrans (L.), are one of the most serious livestock pests, which cause significant economic loss in the cattle industry. Current practices for managing stable flies are limited to costly sanitation techniques and unsustainable insecticide applications. The present study reports the initial efforts using catnip essential oil as a spatial repellent and the results of field trials using a wax-based formulation to repel stable flies in the cattle feedlot. Electroantennograms showed that catnip oil and its ingredient compounds elicit significant antennal responses from both sexes of stable flies. Catnip oil and ZE- and EZ-nepetalactone showed repellent activity in a single cage olfactormeter study. No behavioral activity was observed from another ingredient compound, caryophyllene. A laboratory dispersal bioassay also showed that stable flies avoided areas treated with catnip oil. Using a solid phase microextraction (SPME) method, the atmospheric concentration of catnip active ingredient compounds (nepetalactones) absorbed by SPME fiber in treated areas was detected at 4 times higher than those in control areas. Application of wax-based catnip pellets in cattle feedlots resulted in >99% repellency of stable flies in treated areas, compared with that in nontreated areas. However, the repellent efficacy of the formulation only lasted 3 h. This is the first study demonstrating the potential application of a plant-based repellent formulation that may be used as an alternative method against stable flies.