Laboratory Rearing of Stable Flies and Other Muscoid Diptera.

Stable flies, Stomoxys calcitrans, are serious pests of livestock, humans, companion animals and wildlife worldwide. During the last 20+ years, changes in agronomic practices resulted in serious outbreaks of stable flies in several countries. These outbreaks disrupted livestock production and human recreation resulting in public demands for increasing research and management efforts for this pest. A simple and inexpensive procedure for rearing stable flies for laboratory studies is presented. The procedure uses locally available diet components, equipment and supplies. The procedure can be adapted for rearing other muscoid flies including face fly (Musca autumnalis), horn fly (Haematobia irritans), and house fly (Musca domestica). The procedure produces stable fly puparia averaging 12.5 mg and ~35% egg to adult survival. Approximately 3000 flies are produced in each pan.

Augmenting Laboratory Rearing of Stable Fly (Diptera: Muscidae) Larvae With Ammoniacal Salts.

Stable flies are blood feeding parasites and serious pests of livestock. The immature stages develop in decaying materials which frequently have high ammonium content. We added various ammonium salts to our laboratory stable fly rearing medium and measured their effect on size and survival as well as the physical properties of the used media. The addition of ammonium hydroxide, ammonium phosphate and ammonium sulfate reduced larval survival. These compounds decreased pH and increased ammonium content of the used media. Ammonium bicarbonate had no effect on pH and marginally increased ammonium while increasing survival twofold. The optimal level of ammonium bicarbonate was 50 g (0.63 mol) per pan. Larval survival decreased when pH was outside the range of 8.5 to 9.0.

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.

Sugar feeding in adult stable flies.

Adult stable flies (Stomoxys calcitrans L.) are known to feed readily on sugars in the laboratory. However, little is known concerning the extent of stable fly sugar feeding in wild populations. We examined the frequency of sugar feeding in stable flies collected on Alsynite sticky traps in rural and urban environments. In addition, stable flies were visually examined to determine whether blood was present in the gut. In laboratory studies, sugars were detectable with the anthrone technique in stable flies for approximately 3 d after being imbibed, and blood could be visually detected in the gut for 24-48 h after feeding. Twelve percent of the field-collected flies had detectable sugar with a higher percentage of the urban flies having sugar fed than the rural flies, 21 and 8%, respectively. Female flies sugar fed at a slightly higher rate than males, 13 versus 11%, respectively. Less than 1% of the field-collected flies had blood in their guts. The frequency of observable blood was slightly higher in flies collected in an urban environment compared with those collected in a rural environment and did not differ between male and female flies. The number of flies with both blood and sugar was slightly higher than would be expected based on the frequencies of each alone. Seasonal patterns of both sugar feeding and blood feeding were similar in the rural and urban environments; both peaked in the early summer, May to mid-June, and dropped through the summer and fall. Sugar feeding in the urban environment increased again in October.

Stable fly population dynamics in eastern Nebraska in relation to climatic variables.

Stable flies, Stomoxys calcitrans (L.), are among the most economically important arthropod pests of livestock in North America. In this study, we monitored the seasonal dynamics of a stable fly population in eastern Nebraska for 5 yr. Models based upon temperature and precipitation were developed to determine the affects of these variables on population levels as well as to project population trends. Stable flies appear in eastern Nebraska in late March to early April, and they build to a peak population during the last week of June and first week of July. In most years, the population decreases in midsummer, and then it increases to a second peak in mid-September. Temperature 0 to 2 wk before collection and precipitation 3 to 6 wk before collection were the most important weather variables accounting for 63 and 11% of the variation, respectively. Temperature 7 wk before collection was also significant, accounting for 3% of the variation. Reduced precipitation levels explained the observed midsummer drop in the stable fly populations. Changes in stable fly population levels were positively correlated with precipitation 1 to 2 wk prior and temperature the week of the change. Population change was negatively correlated with precipitation 6-8 wk prior and temperature 6-15 wk prior. The addition of the previous weeks trap collections to the climate based model eliminated the significance of temperature 2 and 7 wk before collection. Temperature 0-1 wk before collection accounted for 60% of the variation, precipitation 3 to 6 wk prior 12% of the variation, and the previous weeks' trap collections accounted for 11% of the variation. Low temperatures during October through January were correlated with higher stable fly populations the following June and July.

Laboratory environment effects on the reproduction and mortality of adult screwworm (Diptera: Calliphoridae)

The New World screwworm, Cochliomyia hominivorax Coquerel, is mass reared for screwworm eradication initiatives that use the sterile insect technique. New methods for rearing have helped to reduce the cost of the eradication program. We examined the effect and interaction of three temperatures (24.5, 29.5 and 34.5°C), two diets (2 percent spray-dried blood plus 0.05 percent vitamins and corn syrup carrageenan) and three population densities (300, 400, and 500 flies/cage) on egg production, egg hatch, number of observable fertilized eggs, mortality (male and female) and ovarian development. The three population densities did not affect any of the parameters monitored. Using the protein diet increased egg production at all temperatures. Diet did not affect egg hatch or female mortality. Male mortality was significantly greater when fed the protein diet and reared at 24.5°C and 34.5°C. Egg hatch was significantly less when the flies were reared at 34.5°C. When exposed to high temperatures (37°C and 40°C) egg production, egg hatch, fertility and mortality were adversely affected. At the higher temperatures, yolk did not adequately form during oogenesis. When compared to the normal rearing photoperiod (12 L: 12 D), short photoperiod (1 L: 23 D) increased egg production, egg hatch and fertility but lowered mortality.

A mosca-da-bicheira, Cochliomyia hominivorax Coquerel, é criada em escala massal com o objetivo de fornecer insetos para programas para sua erradicação, através da técnica do inseto estéril. Novos métodos de criação têm auxiliado na redução dos custos desses programas de erradicação. Nós examinamos o efeito e a interação de três temperaturas (24,5, 29,5 e 34,5°C), duas dietas (carboidrato e carboidrato + proteína) e três densidades populacionais (300, 400 e 500 moscas/gaiola), na fecundidade eclosão de larvas, número de ovos fertilizados, mortalidade (macho e fêmea) e desenvolvimento dos ovários. As três densidades populacionais não afetaram nenhum dos parâmetros avaliados. O uso da dieta protéica aumentou a produção de ovos em todas as temperaturas testadas. O tipo de dieta não afetou a eclosão de larvas e mortalidade de fêmeas. A mortalidade dos machos foi significativamente maior quando alimentados com a dieta protéica e criados a 24,5°C e 34,5°C. A eclosão de larvas foi significativamente menor quando as moscas foram criadas a 34,5°C. Nas temperaturas mais elevadas (37°C e 40°C), a produção de ovos, eclosão de larvas, fertilidade e mortalidade foram afetadas desfavoravelmente. Ainda nessas mesmas temperaturas, durante a oogênese, não houve a formação adequada do estoque de alimento para os embriões. O fotoperíodo curto (1L: 23E) propiciou maior produção de ovos, eclosão de larvas e fertilidade, e diminuiu a mortalidade quando comparado ao fotoperíodo padrão em criações (12L: 12E).

Laboratory environment effects on the reproduction and mortality of adult screwworm (Diptera: Calliphoridae).

The New World screwworm, Cochliomyia hominivorax Coquerel, is mass reared for screwworm eradication initiatives that use the sterile insect technique. New methods for rearing have helped to reduce the cost of the eradication program. We examined the effect and interaction of three temperatures (24.5, 29.5 and 34.5 degrees C), two diets (2% spray-dried blood plus 0.05% vitamins and corn syrup carrageenan) and three population densities (300, 400, and 500 flies/cage) on egg production, egg hatch, number of observable fertilized eggs, mortality (male and female) and ovarian development. The three population densities did not affect any of the parameters monitored. Using the protein diet increased egg production at all temperatures. Diet did not affect egg hatch or female mortality. Male mortality was significantly greater when fed the protein diet and reared at 24.5 degrees C and 34.5 degrees C. Egg hatch was significantly less when the flies were reared at 34.5 degrees C. When exposed to high temperatures (37 degrees C and 40 degrees C) egg production, egg hatch, fertility and mortality were adversely affected. At the higher temperatures, yolk did not adequately form during oogenesis. When compared to the normal rearing photoperiod (12 L:12 D), short photoperiod (1 L:23 D) increased egg production, egg hatch and fertility but lowered mortality.

Synthesis of the four stereoisomers of 7-acetoxy-15-methylnonacosane, a component of the female sex pheromone of the screwworm fly, Cochliomyia hominivorax.

The four stereoisomers of 7-acetoxy-15-methylnonacosane (1), a component of the female sex pheromone of the New World screwworm fly (Cochliomyia hominivorax) were synthesized. The stereogenic center at C-15 of 1 originated from that of the enantiomers of citronellal, and that at C-7 was generated by lipase-catalyzed asymmetric acetylation of (3RS,11R)- and (3RS,11S)-17-methyl-1-trimethylsilylpentacos-1-yn-3-ol (13). Three of the stereoisomers of 1 showed equivalent good pheromone activity, while the activity of (7R,15R)-1 was weak.

Postlarval fitness of transgenic strains of Cochliomyia hominivorax (Diptera: Calliphoridae).

Eight transgenic strains of Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae) were compared with the wild-type parental laboratory strain (P95) in colony. Measurements of average weight of pupae, percentage of adults emerging from pupae, ratio of males to total emerged adults, and mating competitiveness were analyzed. The parental strain colony was subcultured and exposed to handling procedures equivalent to transgenic strains for valid comparison of overall colony fitness. None of the transgenic colonies exhibited significantly lower fitness characteristics than the control parental colony. One transgenic colony had a higher ratio of adults emerging from pupae, and five colonies had higher average pupal weight; because fitness cost would only be indicated by lower values, the statistical variations were not significant. Males of one transgenic strain were shown to mate with equal frequency compared with males of the parental strain. Hence, the presence of the transgene used to produce the strains tested did not incur a fitness cost to the colonies of laboratory-reared C. hominivorax.