Phenology of Stable Fly (Diptera: Muscidae) Larvae in Round Bale Hay Feeding Sites in Eastern Nebraska

The temporal and spatial patterns of adult stable fly, Stomoxys calcitrans (L.), emergence from six sites where large round baled hay had been provided to pasture cattle as winter feed were studied using emergence traps. The substrate at these sites, consisting of waste hay mixed with bovine manure and urine, provided an excellent developmental habitat for immature stable flies. Stable flies were the most frequently collected fly emerging from these sites with a yearly average of 1,581 emerging per square meter. Stable fly emergence from these sites began in early May (235 annual accumulated Day-Degree 10°C [DD10]), peaked in late June and early July (400-900DD10) and then dropped to very low levels in late July (\u3e900 DD10). The temporal pattern of stable fly emergence from the hay feeding sites differed from that of adult populations measured with sticky traps. Adult populations increased in the spring before significant emergence from the hay feeding sites was observed, dipped in midsummer soon after the hay feeding sites became nonproductive, and then rebounded in the late summer when emergence from the hay feeding sites was very low. The drop in productivity of the hay feeding sites appeared to be because of endogenous factors associated with decomposition of the substrate rather than temperature or precipitation. Winter hay feeding sites appear to be primary sources of stable flies during the early summer, however, they are not responsible for late summer and fall stable fly populations. Overall, the inner most 2-m annulus of the hay feeding sites was the most productive, however, spatial variation among sites was observed. The sex ratio of emerging flies did not differ from 1:1 and the temporal pattern of emergence was similar for males and females. Although several other species of flies were collected emerging from the hay feeding site substrate, house flies (Musca domestica L.) were notably absent

Effects of Diet Quality and Temperature on Stable Fly (Diptera: Muscidae) Development

The effects of diet quality and temperature on the development time and size of stable flies, Stomoxys calcitrans (L.), was evaluated. Both development time and size varied relative to diet quality and temperature, and their effects were additive. Diet quality and temperature made similar contributions to the variance in size whereas temperature was responsible for \u3e97% of the variance in development time. Regression analysis predicted the shortest development time, egg to adult, to be 12.7 days at 32 ◦C and 70% nutrients. Egg to adult development varied curvilinearly relative to diet quality and temperature on the degree day 10 (DD10) scale taking 261 DD10 at 30 ◦C and 50% nutrients. The thermal threshold was 11.5 ◦C with a thermal constant of 248. Very few stable flies developed to adult on the poorest diet (12.5% nutrients) and adults emerged from fewer than 1% of the puparia at 35 ◦C. The heaviest pupae (15.4 mg) were produced with the 100% diet at 15 ◦C and adults had a higher probability of emerging successfully from heavier puparia. The length of the discal-medial cell of adult wings had a cubic relationship with puparia weight and peaked at 21 ◦C. Egg to pupariation survival was predicted to peak at 27 ◦C and 71% diet whereas puparia to adult survival peaked at 24 ◦C and 100% diet. Diet quality and temperature had no effect on sex ratio and the rate of development did not differ between the sexes. Female stable flies were ͌5% larger than males. Composite metrics for egg to pupariation and egg to adult fitness were developed. The optimum for puparia fitness was 29 ◦C and 78% diet quality and for adult fitness 25 ◦C and 83% diet quality. Diet accounted for 31% of the variance in pupal fitness and 24% of the variance in adult fitness whereas temperature accounted for 17% and 20%, respectively

Permeabilization of \u3ci\u3eCochliomyia hominivorax\u3c/i\u3e (Diptera: Calliphoridae) Embryos

Embryos of the primary screwworm, Cochliomyia hominivorax (Coquerel), were successfully permeabilized for use in subsequent cryopreservation studies. Mortality was greater for eggs incubated for\u3c5 h before treatment. The mean survival of embryos to first instars was 55.7, 61.1, and 62.6% when the embryos were incubated for 5, 5.5, and 6 h before treatment, respectively. The survival to the pupal and adult stages was low. An improved media for culturing the embryos during and immediately after treatment needs to be devised and the procedure for rearing the larval stages also needs to be altered to improve survival for emerging adults

Effects of Diet Quality and Temperature on Stable Fly (Diptera: Muscidae) Development

The effects of diet quality and temperature on the development time and size of stable flies, Stomoxys calcitrans (L.), was evaluated. Both development time and size varied relative to diet quality and temperature, and their effects were additive. Diet quality and temperature made similar contributions to the variance in size whereas temperature was responsible for \u3e97% of the variance in development time. Regression analysis predicted the shortest development time, egg to adult, to be 12.7 days at 32 ◦C and 70% nutrients. Egg to adult development varied curvilinearly relative to diet quality and temperature on the degree day 10 (DD10) scale taking 261 DD10 at 30 ◦C and 50% nutrients. The thermal threshold was 11.5 ◦C with a thermal constant of 248. Very few stable flies developed to adult on the poorest diet (12.5% nutrients) and adults emerged from fewer than 1% of the puparia at 35 ◦C. The heaviest pupae (15.4 mg) were produced with the 100% diet at 15 ◦C and adults had a higher probability of emerging successfully from heavier puparia. The length of the discal-medial cell of adult wings had a cubic relationship with puparia weight and peaked at 21 ◦C. Egg to pupariation survival was predicted to peak at 27 ◦C and 71% diet whereas puparia to adult survival peaked at 24 ◦C and 100% diet. Diet quality and temperature had no effect on sex ratio and the rate of development did not differ between the sexes. Female stable flies were ͌5% larger than males. Composite metrics for egg to pupariation and egg to adult fitness were developed. The optimum for puparia fitness was 29 ◦C and 78% diet quality and for adult fitness 25 ◦C and 83% diet quality. Diet accounted for 31% of the variance in pupal fitness and 24% of the variance in adult fitness whereas temperature accounted for 17% and 20%, respectively

piggyBac transformation of the New World screwworm, \u3ci\u3eCochliomyia hominivorax\u3c/i\u3e, produces multiple distinct mutant strains

Sterile insect technique (SIT) programs are designed to eradicate pest species by releasing mass-reared, sterile insects into an infested area. The first major implementation of SIT was the New World Screwworm Eradication Program, which successfully eliminated the New World screwworm (NWS), Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae), from the Continental US, Mexico and much of Central America. Ionizing radiation is currently used for sterilization, but transgenic insect techniques could replace this method, providing a safer, more cost-effective alternative. Genetic transformation methods have been demonstrated in NWS, and verified by Southern blot hybridization, PCR and sequencing of element insertion junctions. A lethal insertional mutation and enhancer detection-like phenotypic expression variations are presented and discussed. In addition to supporting the eradication efforts, transformation methods offer potential means to identify genes and examine gene function in NWS

Environmental Parameters Associated With Stable Fly (Diptera: Muscidae) Development at Hay Feeding Sites

Substrates composed of hay residues, dung, and urine accumulate around winter hay feeding sites in cattle pastures, providing developmental habitats for stable flies. The objective of this study was to relate physiochemical and microbial properties of these substrates to the presence or absence of stable fly larvae. Properties included pH, temperature, moisture, ammonium concentration, electrical conductivity, and numbers of coliform, fecal coliform, Escherichia coli, and Enterococcus bacteria. Each physiochemical sample was classified as a function of belonging to one of the three 2-m concentric zones radiating from the feeder as well as presence or absence of larvae. In total, 538 samples were collected from 13 sites during 2005–2011. Stable fly larvae were most likely to be found in moist, slightly alkaline substrates with high levels of ammonium and low temperature. The probability of larvae being present in a sample was the highest when the moisture content was 347% relative to dry weight and the average pH was 8.4. Larvae were recovered within all zones, with a nonsignificant, but slightly higher, percentage of samples containing larvae taken 2–4m from the center. All methods used to enumerate bacteria, except total coliform, indicated decreasing concentrations in hay bale residue throughout the summer. In addition to the environmental parameters, cumulative degree day 10˚C had a significant effect on the probability of observing stable fly larvae in a sample, indicating that unidentified seasonal effects also influenced immature stable fly populations

Environmental Parameters Associated With Stable Fly (Diptera: Muscidae) Development at Hay Feeding Sites

Substrates composed of hay residues, dung, and urine accumulate around winter hay feeding sites in cattle pastures, providing developmental habitats for stable flies. The objective of this study was to relate physiochemical and microbial properties of these substrates to the presence or absence of stable fly larvae. Properties included pH, temperature, moisture, ammonium concentration, electrical conductivity, and numbers of coliform, fecal coliform, Escherichia coli, and Enterococcus bacteria. Each physiochemical sample was classified as a function of belonging to one of the three 2-m concentric zones radiating from the feeder as well as presence or absence of larvae. In total, 538 samples were collected from 13 sites during 2005–2011. Stable fly larvae were most likely to be found in moist, slightly alkaline substrates with high levels of ammonium and low temperature. The probability of larvae being present in a sample was the highest when the moisture content was 347% relative to dry weight and the average pH was 8.4. Larvae were recovered within all zones, with a nonsignificant, but slightly higher, percentage of samples containing larvae taken 2–4m from the center. All methods used to enumerate bacteria, except total coliform, indicated decreasing concentrations in hay bale residue throughout the summer. In addition to the environmental parameters, cumulative degree day 10˚C had a significant effect on the probability of observing stable fly larvae in a sample, indicating that unidentified seasonal effects also influenced immature stable fly populations

Genetic Research on Screwworm at Lincoln, Nebraska

The following interpretive summary refers to the 1st seminar given by Dr. Skoda at the IAEA-FAO 1st RCM Research Coordination Meeting for the CRP Coordinated Research Project, Jan-Feb 2002. Screwwoms, Cochliomyia hominivorax (Coquerel), are devastating pests of animals. They have been eradicated from mainland North America, with the exception of portions of eastern Panama, using the Sterile Insect Technique (SIT), a form of gtenetic control. Research at Lincoln, Nebraska has been in support of the international effort of SIT against screwworms. Successful cryopreservation of the screwworm has been achieved, is to be optimized, and will be a tool for preserving genetic stocks of screwworms. The molecular genetic techniques of random amplified polymorphic DNA - polymerase chain reaction and the amplified fragment length polymorphism have been shown useful as techniques for species identification when samples of \u27unknowns\u27 are collected by eradication preogram personnel; each technique has shown promise and they are being further explored for their utility in determining the geographic origin of screwworm samples. After one year of using a common organophosphate insecticide, Coumaphos, in an effort to develop an insecticide resistant strain of screwworm for use in developing a genetic-sexing strain, little progress has been made in developing a selection mechanism for eliminating female screwworms during the mass rearing process (\u3c10-fold resistance has been achieved). Future research into developing a genetic-sexing system will concentrate in two areas: 1) developing a temperature sensitive lethality (TSL) mutation in screwworms, preferably with lethality occurring very early in development, and 2) developing transgenic techniques useful in screwworms. On successful development of TSL, research will continue toward developing translocations of the responsible gene(s) to the Y-chromosome, as well as cytognetic characterization of the mutation and/or translocation, and characterizing the resultant genetic-sexing strain. Concurrently, as transgenic techniques become available work will aim to isolate existing TSL genes, or other lethal genes (perhaps from other species), so that transgenic techniques may be developed whereby these lethal genes are inserted in such a manner that genetic selection can be done

Comparative Efficiency of Six Stable Fly (Diptera: Muscidae) Traps

Five adhesive traps and the Nzi cloth-target trap were compared to determine their trapping efficiency and biases for stable flies, Stomoxys calcitrans (L.) (Diptera: Muscidae). Two configurations of the BiteFree prototype trap, constructed of polyethylene terephthalate, were most efficient for trapping stable flies, whereas the EZ trap was least efficient. The two Alsynite traps, Broce and Olson, were intermediate to the BiteFree prototype and EZ traps. All adhesive traps collected a ratio of approximately two males for each female. Approximately 50% of the flies collected on the adhesive traps, both male and female, were blood fed, and 20% were vitellogenic. The Nzi trap collected an older component of the stable fly population, 81% blood fed and 62% vitellogenic, but it was much less efficient than the adhesive traps. The effectiveness of the BiteFree prototype trap indicates that materials other than Alsynite are attractive to stable flies