James F. Sutcliffe

Effects of natal habitat odour, reinforced by adult experience, on choice of oviposition site in the mosquito Aedes aegypti

The effects of natal experience on the oviposition behaviour of adult female mosquitoes were investigated in the laboratory using Aedes aegypti (L.) (Diptera: Culicidae). ‘Treatment’ mosquitoes were exposed to a dilute repellent (inducing stimulus) in their breeding water (aquatic stages) and/or in the air (adults) during various combinations of life stages [larval only (L regime); larval and pupal (LP regime); larval, pupal and emergent adult (LPE regime); larval, pupal, emergent adult and adult (LPEA regime); pupal, emergent adult and adult (PEA regime); adult only (A regime)]. ‘Control’ mosquitoes were raised in an identical manner, but were not exposed to the inducing stimulus. The oviposition behaviour of treatment and control females was assessed in an oviposition assay that presented a choice of water with or without the inducing stimulus. Of the 435 mosquitoes tested in the experiment, 176 were non‐distributors (i.e. laid all of their eggs in only one of the choices). Treatment females (distributors plus non‐distributors) reared in the presence of the inducing stimulus throughout their lives (LPEA regime) showed a significant preference for the oviposition option containing the inducing stimulus (24/36 females) compared with corresponding controls (5/39 females). Distributors reared under the LPEA and PEA regimes also showed this preference (6/6 treatment vs. 2/29 control females, and 13/18 treatment vs. 7/23 control females, respectively). Females that had been exposed to the inducing stimulus as either immatures or adults only showed no preference for, and some showed an aversion to, the treatment oviposition option. This is interpreted as evidence for a natal habitat preference induction (NHPI) in this species, albeit one that requires extensive reinforcement in the adult stage. This adult experience‐reinforced NHPI (AER‐NHPI) is discussed in terms of its adaptive significance for container breeders, the possible timing mechanism and sensory basis of induction and potential practical consequences.

Effect of adenine nucleotides on labellar chemoreceptive cells of the stable fly, Stomoxys calcitrans

Abstract The responsiveness of the sodium chloride-sensitive cell in stable fly labellar sensilla was decreased by the addition of adenine nucleotides to stimulating solutions of sodium chloride. This decrease was dose-dependent and was most pronounced for ATP, followed by ADP and AMP, potent phagostimulants for this fly. The responsiveness of the sucrose-sensitive cell(s) was enhanced by the addition of ATP to the stimulating solution. The role of adenine nucleotides in the chemoreception and blood-feeding behaviour of this insect is discussed.

Purinoceptors in blood feeding behaviour in the stable fly, Stomoxys calcitrans

Abstract Both sexes of the stable fly, Stomoxys calcitrans L. (Diptera: Muscidae), have receptors on their mouthparts that mediate blood feeding. The potency ranking of the adenine nucleotides (ATP > ADP > AMP > adenosine) in eliciting feeding and suppressing the NaCl‐sensitive cell may indicate the involvement of a P2‐type receptor. This is supported by the lack of effect on feeding by methyl xanthines. Feeding‐related behavioural and electrophysiological results demonstrate that the potency of CH3‐S‐ATP is not greater than that of ATP. These ATP‐mediated responses are antagonized by ANAPP3. Results support the conclusion that the putative ‘ATP receptor’ involved in stable fly phagostimulation resembles the P2x purinoceptor of vertebrates.

Field Measurements of Stable Fly (Diptera: Muscidae) Demography, Fecundity, and Survival Based on Daily Trap Catches at a Beef Farm in Southern Ontario Over a 5-yr Period

ABSTRACT We sampled stable fly, Stomoxys calcitrans (L.), populations using a CO2 baited cloth trap (Nzi trap) each day throughout the summer and autumn at a beef farm near Peterborough, Ontario, Canada, from 1997 to 2001. Females (2,512) were dissected for ovarian age-grading, to produce a demographic profile of farm populations. The number of follicles were counted to produce fecundity estimates. The developmental periods of adult female stages, measured as accumulated degree-days above 10°C, were determined for a lab colony of stable flies. These measurements were used to calculate survival in terms of degree-days of the farm populations each year. Of the 2,512 females caught, 42.4% were nulliparous on average each year. The median follicle size at insemination was 305 µm in the field populations, and 495 µm in the colony. Farm caught females had an average of 49.15 follicles per ovary overall, with the body size (leg length) and fecundity increasing slightly with age. On average, 44.5% (SE 3.2%) of nulliparous females survived to become parous, and of these, 45.7% (SE 2.1%) survived the uniparous state to become multiparous. Years of higher rainfall had increased fecundity; rainfall did not appear to affect survival.

Studies of host location behaviour in the black fly Simulium arcticum (IIS-10.11) (Diptera: Simuliidae): aspects of close range trap orientation

Field studies of orientation responses of the IIS-10.11 sibling of Simulium arcticum Malloch species complex and other simuliid species to host-mimicking cattle silhouette traps (CSTs) were carried out in the Athabasca region of Alberta, Canada. Simuliids were attracted to CSTs from downwind by a CO 2 bait but very few were attracted to an unbaited CST. Passively searching simuliids tended to fly at lower levels than actively host seeking ones. Simuliids appeared to fly at lower levels when within visual range of the CST than when outside of it. Higher flight levels may improve chances of eventually making visual contact with the host or CST. Experiments in which a CO 2 outlet was separated by increasing distances from a CST indicated that simuliids see the 1.1 m long CST at a range of approximately 8 m. Simuliids landing on the CST, whether CO 2 -baited or not, showed a strong preference for the traps ends followed by the downwind side, followed by the upwind side. Species composition of collections from CST collections differed significantly from the species composition of cattle sweeps taken at the same times. Simulium vittatum was over-represented in collector catches in comparison to cattle sweeps. This bias may be due to species-specific differences in responses after landing on the CST since sweeps taken around CSTs had compositions similar to cattle sweeps. Results are discussed in terms of host orientation in biting flies in general and the suitability of CST-type traps as components of attractant-based control strategies and in simuliid population monitoring.

Preliminary survey of odours that attract the black fly, Simulium arcticum (Malloch) (IIS-10.11) (Diptera: Simuliidae) to its cattle hosts in the Athabasca region of Alberta

Results of a field survey of certain host-related and off-the-shelf compounds as possible attractants for the black fly, Simulium arcticum (Malloch) (IIS-10.11) (Diptera: Simuliidae), are reported. Silhouette traps were baited with carbon dioxide and candidate attractants in an incomplete randomised block design. Carbon dioxide alone exerted a strong attractant effect on this species. Both acetone and crude whole body odour of cattle (tested in combination with carbon dioxide) were significantly more attractive than carbon dioxide alone (control). Although bovine urine produced larger catches than control (carbon dioxide only) traps, the effect was not statistically significant. Other odours tested in combination with carbon dioxide, including fractions of the crude bovine odour and l-octen-3-ol (a potent tsetse fly attractant), were without apparent attractant effect when compared to the carbon dioxide-only control.RésuméLes résultats d’une étude préliminaire menée au champ de certains composés dérivés de l’hôte ou disponible commercialement comme appât possible de la mouche noire [Simulium arcticum (Malloch) (IIS-10.11) (Diptera: Simuliidae)] sont présentés. Des piéges à silhouette émettant du dioxide de carbon ont été ammorçés avec les appâts selon un dispositif expérimental en blocs incomplets, Le dioxide de carbon a exercé un puissant pouvoir attractif sur cette espèce lorsqu’employé seul. L’acetone ainsi que l’odeur corporelle brute du bétail ont accru de façon significative l’attirance des trappes amettant du dioxide de carbon. L’urine de bovine n’a eu aucun effet significatif quoiqu’elle a permis la capture d’un plus grand nombre d’insectes que les trappes témoins. D’autres odeurs testées, telles que diverses fractions de l’odeur brute de bovin et l’octénol (un puissant appât de la mouche tsétsé), se sont avérées sans aucun effet apparent pour ce cytotype de S. arcticum.

Feeding response of the stable fly, Stomoxys calcitrant L., to blood fractions and adenine nucleotides

Abstract Feeding responses of the stable fly (Stomoxys calcitrans L., Diptera: Muscidae) to blood fractions and saline‐based diets were studied in an artificial feeding device. Flies fed equally on whole blood, plasma and erythrocyte fractions while resuspended platelets or the buffy layer did not stimulate feeding. Evidence from filtration studies indicates that plasma contains both less‐than‐5000D and greater‐than‐100,000D phagostimulatory components. ATP, ADP and AMP in saline stimulate feeding in this insect in a dose‐dependent manner. cAMP also stimulates feeding in the range of concentrations tested. It is argued that the less‐than‐5000D phagostimulant may be one or more of these adenine nucleotides.

Prevention and Control of Arthropodborne Diseases

The prevention and control of arthropodborne diseases combines tactics aimed at disease vectors, pathogens and hosts. This chapter emphasizes preventive measures. These are measures, approaches or practices that place a barrier (physical, chemical, immunologic, behavioral or ecological) between disease pathogens and susceptible hosts. In general, preventive measures apply to individual or to small groups of hosts, although some larger scale applications of preventive measures (such as vaccination) also are discussed. Preventive measures include repellents and other forms of individual protection, chemoprophylaxis and chemotherapy, and vaccines. Vector control strategies used for prevention of specific diseases are mentioned briefly. Chapter 14 discussed general approaches to vector control.

Blood‐feeding host preferences of the isomorphic species Simulium venustum and S.truncatum

Abstract. Animal‐baited traps, using fox, mink, rabbits and ducks, were used in host preference experiments in two habitats (Beach and Woods). A generalized linear model of blood‐feeding host preference is presented to test for significant differences between the isomorphic species Simulium venustum and Simulium truncatum. The S.truncatum population peaked before that of S.venustum. On any given day the two species divided their blood‐feeding efforts among the different hosts in the same proportions. On the Beach, fox was the preferred host at the beginning of the season, but by the end of the season flies fed with equal frequency on the fox and the mink. In the Woods fox remained the preferred host throughout the season (late May to early July). Possible reasons for these feeding trends are discussed.