Azadirachtin as a larvicide against the horn fly, stable fly, and house fly (Diptera: Muscidae)

Effects of azadirachtin, a triterpenoid extracted from neem seed, Azadirachta indica A. Juss., were similar to those of insect growth regulators against the immature stages of the born fly, Haematobia irritans (L.), the stable fly, Stomoxys calcitrans (L.), and the house fly, Musca domestica L. When an ethanolic extract of ground seed was blended into cow manure, LC50 and LC90's for larval horn flies were 0.096 and 0.133 ppm azadirachtin, respectively. An emulsifiable concentrate (EC) had an LC50 for larval horn flies of 0.151 ppm and an LC90 of 0.268 ppm. For larval stable flies, the EC formulation had an LC50 of 7.7 ppm and an LC90 of 18.7 ppm azadirachtin in manure. Against larval house flies, the LC50 and LC90 were 10.5 and 20.2 ppm, respectively. When the EC formulation was administered orally to cattle at a rate of greater than or equal to 0.03 mg azadirachtin per kg of body weight per day or when ground neem seed was given as a daily supplement of greater than or equal to 10 mg seed per kg body weight, horn fly development in the manure was almost completely inhibited. In contrast, ground seed mixed in cattle feed at the rate of 100-400 mg seed per kg of body weight per day caused less than 50% inhibition of stable flies in the manure.     

Stable fly, house fly (Diptera: Muscidae), and other nuisance fly development in poultry litter associated with horticultural crop production

Poultry litter usage in horticultural crop production is a contributor to nuisance fly populations, in particular stable flies (Stomoxys calcitrans L.) and house flies (Musca domestica L.). Extrapolation of adult emergence data suggests that approximately 1.5 million house flies and 0.2 million stable flies are emerging on average from every hectare of poultry litter applied as a preplant fertilizer for vegetable production in Perth, Western Australia. To a lesser extent, sideband applications to established crops may allow for the development of 0.5 million house flies and 45,000 stable flies per hectare. However, up to 1 million house flies, 0.45 million lesser house flies, Fannia cannicularis L., and 11,000 stable flies per hectare may be produced from surface dressings of poultry litter associated with turf production. Other nuisance flies present in poultry litter included the false stable fly, Muscina stabulans (Fallén), bluebodied blowfly, Calliphora dubia Hardy, black carrion fly, Hydrotaea rostrata Robineau-Desvoidy, Australian sheep blowfly, Lucilia cuprina Wiedemann, and flesh flies (Sarcophagidae). Only house flies developed in poultry litter for the first 4 d after application in the field. Stable flies were not present in poultry litter until 4-7 d after application, and were the only fly species developing in litter > 9 d after application.     

Evaluation of commercial and field‐expedient baited traps for house flies,Musca domestica L. (Diptera: Muscidae)

A comparison of nine commercial baited fly traps on Florida dairy farms demonstrated that Terminator traps collected significantly more (13,323/trap) house flies (Musca domestica L.) than the others tested. Final Flight, Fly Magnet, and FliesBeGone traps collected intermediate numbers of flies (834‐2,166), and relatively few were caught with ISCA, Advantage, Fermone Big Boy, Squeeze & Snap, or OakStump traps (<300). Terminator traps collected about twice as many flies (799.8/trap) as FliesBeGone traps (343.8) when each trap was baited with its respective attractant, but when the attractants were switched between the two trap types, collections were significantly lower (77‐108) than was observed with traps baited with their respective attractant. Solutions of molasses were significantly more attractive to house flies than honey, maple syrup, or jaggery (date palm sugar). Field‐expedient traps constructed from discarded PET water bottles were much less effective than commercial traps, but painting the tops of such traps with black spray paint resulted in a six‐fold increase in trap capture.     

Effects of horn fly and house fly (Diptera: Muscidae) larvae on the development of parasitic nematodes in bovine dung

Laboratory studies were conducted to determine the effects of horn fly, Haematobia irritans (L.), and house fly, Musca domestica L., larvae on the development of a mixed population of parasitic nematodes in compressed and crumbled bovine dung. Fresh dung (100 g per sample) from a single calf passing trichostrongyle type eggs was infested with 150 horn fly or 150 house fly eggs. After 14-15 d, more horn flies and house flies had emerged from the compressed dung than from the crumbled dung, but more third stage parasitic nematode larvae were recovered from the crumbled dung containing either fly species than from dung containing no flies.     

Synergism between ammonia, lactic acid and carboxylic acids as kairomones in the host-seeking behaviour of the malaria mosquito Anopheles gambiae sensu stricto (Diptera: Culicidae)

Host odours play a major role in the orientation and host location of blood-feeding mosquitoes. Anopheles gambiae Giles sensu stricto, which is the most important malaria vector in Africa, is a highly anthropophilic mosquito species, and the host-seeking behaviour of the females of this mosquito is guided by volatiles of human origin. Ammonia, lactic acid and several carboxylic acids are known to be present in the human odour blend. We investigated the effect of these compounds on naive female mosquitoes using a dual-port olfactometer. Ammonia was an attractant on its own, whereas lactic acid was not attractive. Carboxylic acids, offered as a mixture of 12 compounds, were repellent at the concentration tested. The addition of ammonia to the carboxylic acid mixture overruled the repellent effect of the latter. Combining ammonia with either lactic acid or the carboxylic acids did not enhance the attractiveness of ammonia alone. However, a synergistic effect was found when ammonia, lactic acid and the carboxylic acids were applied as a blend. Our findings indicate that An. gambiae s.s. relies on the combination of ammonia, lactic acid and carboxylic acids in its orientation to human hosts. The role of lactic acid in this tripartite synergism differs from that reported for the yellow fever mosquito Aedes aegypti.     

Linkage, expression, and distribution of the pyrethroid resistance gene in the horn fly (Diptera: Muscidae)

A sex-linked gene for pyrethroid resistance in the horn fly, Haematobia irritans (L.), showed complete linkage to the male-determining gene in a laboratory colony that had been inbred for 10 generations. Within susceptible, heterozygous, and resistant populations, the level of resistance that was expressed was greater for females than for males. The increase in level of resistance conferred by the gene was similar for females and males. Preliminary synergism and allelism tests supported our supposition that the same gene was responsible for resistance in California, Florida, and Texas populations.     

Twenty-three new microsatellite loci in the stable fly, Stomoxys calcitrans (L.) (Diptera: Muscidae)

The stable fly, Stomoxys calcitrans (L.), is a significant pest of cattle. Twenty-three microsatellite markers were isolated from a repeat-enriched genomic library of S. calcitrans. We characterized variation at these markers and found that 17 loci were polymorphic in two fly populations from Florida. Two to nine alleles were observed among the variable microsatellite loci and expected heterozygosities ranged from 0.03704 to 0.85115. These markers will be useful for characterizing population genetic differentiation and for tracking the migration patterns of stable flies in the USA and worldwide.     

The response of the malaria mosquito, Anopheles gambiae, to two components of human sweat, ammonia and l-lactic acid, in an olfactometer

In an olfactometer study on the response of the anthropophilic malaria mosquito Anopheles gambiae s.s. (Diptera, Culicidae) to human sweat it was found that freshly collected sweat, mostly of eccrine origin, was attractive, but that incubated sweat was significantly more attractive than fresh sweat. The behavioural response to l ‐lactic acid and ammonia, the main constituents of sweat, was investigated. l ‐lactic acid was attractive at one concentration only (11.11 mm ) and removal of the l ‐lactic acid from the sweat by enzymatic decomposition did not affect the attractiveness of sweat. Ammonia caused attraction over a range of 0.1–13.4 m on glass slides and at 0.84–8.40 μmol/min in an air stream. It is concluded that: human sweat contains kairomones for host‐seeking An. gambiae; ammonia is an important kairomone for this mosquito; and that l ‐lactic acid is not a prerequisite in the attraction of An. gambiae to sweat.     

The effect of male sandfly pheromone and host factors as attractants for female Lutzomyia longipalpis (Diptera: Psychodidae)

Abstract Male Lutzomyia longipalpis (Lutz & Neiva) pheromone extracted from tergal glands combined with heat, carbon dioxide gas and hamster urine was found to be attractive to virgin female sandflies. The host factors if offered in the absence of pheromone or a heat source were, however, unattractive to female flies. Pheromone stored for 6 days and then combined with the same host components remained attractive to female flies but storage failed to enhance its attractiveness. The effects of carbon dioxide gas, hamster urine, chicken uropygial gland extract and octenol plus acetone on the responses of females were inconsistent. A ceramic battery powered heat source was tested with pheromone and host attractants and showed potential for field application in developing a pheromone trap.     

Influence of permethrin, diazinon and ivermectin treatments on insecticide resistance in the horn fly (Diptera: Muscidae)

The history of insecticide resistance in the horn fly, Haematobia irritans, and the relationship between the characteristics of horn fly biology and insecticide use on resistance development is discussed. Colonies of susceptible horn flies were selected for resistance with six insecticide treatment regimens: continuous single use of permethrin, diazinon and ivermectin: permethrin-diazinon (1:2) mixture; and permethrin-diazinon and permethrin-ivermectin rotation (4-month cycle). Under laboratory conditions, resistance developed during generations 21, 31 and 30 to permethrin, diazinon and ivermectin, respectively. The magnitude of resistance ranged from < 3-fold with ivermectin to 1470-fold with permethrin. Field studies demonstrated that use of a single class of insecticidal ear tag during the horn-fly season resulted in product failure within 3-4 years for pyrethroids and organophosphates, respectively. In laboratory studies, use of alternating insecticides or a mixture of insecticides delayed the onset of resistance for up to 12 generations and reduced the magnitude of pyrethroid resistance. In field studies, yearly alternated use of pyrethroids and organophosphates did not slow or reverse pyrethroid resistance (Barros et al., unpublished data), while a 2-year alternated use with organophosphates resulted in partial reversion of pyrethroid resistance. When pyrethroid and organophosphate ear tags were used in a mosaic strategy at two different locations, efficacy of products did not change during a 3-year period.     

Effects of the veterinary antiparasitic drug eprinomectin on dung beetles (Coleoptera: Scarabaeidae), the non-pest fly Neomyia cornicina and pest fly Haematobia irritans (Diptera: Muscidae) in Japan

Effects of the antiparasitic drug eprinomectin were studied in the laboratory and field experiments in Hokkaido, Japan, by pour-on administrations (500 μg/kg) on the pest fly Haematobia irritans (Linnaeus), nontarget coprophagous fly Neomyia cornicina (Fabricius), and the dung beetles Caccobius jessoensis Harold and Liatongus minutus (Motschulsky). Eprinomectin excreted into cattle dung was highest at 3 days post-treatment in both experiments, then it declined rapidly at 7 days and was not detected on or after day 14 post-treatment. In laboratory experiments, pupation and emergence rates of H. irritans and N. cornicina were hampered from 1 to 14 days post-treatment. There were no significant differences in the numbers of brood balls constructed by C. jessoensis in dung from treated and control cattle. Adult emergence rates of C. jessoensis were significantly reduced on days 1 and 3 post-treatment in dung from treated cattle. There were no significant differences in the numbers of brood balls constructed by L. minutus in dung from treated and control cattle, but survival rates of larvae were significantly reduced on days 1 and 3 post-treatment. In field experiments, the numbers of brood balls by L. minutus recovered from beneath dung pats were significantly larger in number in dung from treated cattle, suggesting that adult beetles are attracted to dung pats from treated cattle. Survival rates of larvae in these brood balls of L. minutus were significantly reduced 1 day post-treatment in dung pats from treated cattle, and equivalent levels to the control were restored 7 days post-treatment. The results are discussed in relation to the effects of endectocides on nontarget insects in grazing pastures.     

Chronology of permethrin resistance in a southern Illinois population of the horn fly (Diptera: Muscidae) during and after selection by pyrethroid use

From 1985 through 1988, horn flies (Haematobia irritans (L)) collected at the Dixon Springs Agricultural Center (DSAC) in southern Illinois were tested in 22 h bioassays for permethrin resistance with residues on cotton cloths. The LC90 for a susceptible field population collected in June 1985 was 0.19 micrograms/cm2. In comparison, flies collected from pyrethroid-tagged cattle in 1985 and 1986 exhibited 25- to 116-fold resistance to permethrin. A 25-fold level of resistance allowed survival on treated cattle 8 wk after pyrethroid tag application. Flies representing the local background population were collected periodically from an untreated herd 2.4 km from the nearest cattle treated with a pyrethroid; these flies exhibited up to 18-fold resistance. Although pyrethroids were not used on DSAC animals after October 1986, all bioassays done in 1987 and 1988 indicated resistance levels of greater than or equal to 7-fold. The 95% confidence intervals for LC90s from all 1987 bioassays overlapped the confidence interval from the corresponding July 1986 estimate for resistant flies collected from pyrethroid-tagged cattle. Although some decline in resistance was evident in 1988, bioassays done at the end of the season produced resistance ratios of 7.4 and 15.3. Survivorship at a diagnostic dose indicated that resistance frequencies remained at 4-8% throughout 1988. Two years' abstinence from pyrethroid use was insufficient to allow an adequate decline in resistance levels.     

Host age and pathogen exposure level as factors in the susceptibility of the house fly,Musca domestica (Diptera: Muscidae) to Beauveria bassiana

Adult house flies, Musca domestica L., of four ages, <1, 3, 7, and 14 day post-eclosion, were exposed to three strains of Beauveria bassiana (P89, L90 and 447). Flies were exposed to moistened filter paper treated with either a low (1.57×10⁴ conidia/cm²) or high (1.57×10⁵ conidia/cm²) concentration of each fungal strain for 6 h. Strain 447 was superior to the two house fly-derived B. bassiana strains in inducing host infection and mortality. Significant spikes in infection and mortality occurred as early as 5 days post-exposure with higher concentration exposures acting more quickly. Few differences were observed in either infection or mortality among the four fly age classes. On Day 10 post-exposure, 77% of the high-concentration, 447-exposed flies were infected, compared with only 24% of the flies from the P89 low-concentration exposure. Potential applications of these results in integrated house fly management programs are discussed.     

Male courtship success and female discrimination in the mediterranean fruit fly (Diptera: Tephritidae)

The mating success of individually marked male Mediterranean fruit flies was monitored over 6 consecutive days in the laboratory. Mating frequency was nonrandom, as the numbers of both males that failed to mate and males that mated many (more than four) times were much higher than expected by chance alone. Differential mating success resulted in part from intermale variation in activity level. Male copulatory success was positively correlated with the numbers of courtships performed, attempted copulations (mountings), and females courted. Male-male aggression, on the other hand, and a negligible effect on male mating success. Female choice also appeared to influence male mating frequency. Fewer than 10% of courtships resulted in mating, and in most cases females terminated courtship by simply moving away from the male. Females that did mate generally selected males having higher copulatory scores than previously rejected males.     

Polymorphic microsatellite markers for the tsetse fly Glossina fuscipes fuscipes (Diptera: Glossinidae), a vector of human African trypanosomiasis

Our understanding of Glossina fuscipes fuscipes, a major vector of sleeping sickness, has been severely constrained by a lack of genetic markers for mapping and population genetic studies. Here we present 10 newly developed microsatellite loci for this tsetse species. Heterozygosity levels in Moyo, an Ugandan population, averaged 0.57, with only two loci showing very low heterozygosity. Five loci carried more than six alleles. Together with five recently published microsatellite loci, this brings the number of available microsatellite loci for this species to 15. Their availability will greatly facilitate future studies on the genetics of this important human disease vector.     

Olive fruit fly (Diptera: Tephritidae) in California: longevity, oviposition, and development in canning olives in the laboratory and greenhouse

The biology of olive fruit fly, Bactrocera oleae (Rossi), was studied in the laboratory, greenhouse, and in canning olives, Olea europaea L., in relation to California regional climates. Adults survived in laboratory tests at constant temperatures and relative humidities of 5 degrees C and 83%; 15 degrees C and 59%; 25 degrees C and 30%; and 35 degrees C and 29% for 15, 6, 3, and 2 d without provisions of food and water and for 37, 63, 25, and 4 d with provisions, respectively. In a divided greenhouse, adults survived for 8-11 d in the warm side (36 degrees C and 31% RH daytime); and in the cool side (26 degrees C and 63% RH daytime) 10 d without provisions and 203 d with provisions. A significantly greater number of adults survived in the cool side than the warm side, and with provisions than without. First and last eggs were oviposited in olive fruit when females were 6 and 90 d old, respectively. The highest number of eggs was 55 per day in 10 olive fruit oviposited by 10 28 d-old females, with maximum egg production by 13-37 d-old females. A significantly greater number of ovipositional sites occurred in all sizes of immature green fruit when exposed to adults in cages for 5 d than 2 d. Adults emerged from fruit with a height of > or = 1.0 cm or a volume of > or = 0.2 cm3. More than seven adults per 15 fruit emerged from field infested fruit with a height of 1.1 cm and volume of 0.1 cm3. Larval length was significantly different among the first, second, and third instars and ranged from 0.7 to 1.6, 2.4-4.3, and 4.8-5.6 mm at 14 degrees C; 0.8-1.1, 1.9-2.9, and 3.9-4.4 mm at 21 degrees C, and 0.7-1.3, 2.4-2.9, and 4.4-4.8 mm at 26 degrees C, respectively. Survival of pupae to the adult stage was significantly lower at 26 degrees C than 14 degrees C or 21 degrees C. The period of adult emergence began at 38, 14, and 11 d over a period of 8, 5, and 1 d at 14, 21, and 26 degrees C, respectively. Findings were related to the occurrence and control of California olive fruit fly infestations.