Bacterial Volatiles Attract Gravid Secondary Screwworms (Diptera: Calliphoridae).

Bovine blood inoculated and incubated with bacteria was tested to determine if secondary screwworm, Cochliomyia macellaria (F.), would be attracted to the incubated substrate for oviposition. Five species of bacteria, Klebsiella oxytoca (Flugge), Proteus mirabilis Hauser, Proteus vulgaris Hauser, Providencia rettgeri Hadley, Elkins and Caldwell, and Providencia stuartii Ewing, previously isolated from animal wounds infested by primary screwworms, Cochliomyia hominivorax (Coquerel), were used. Incubated substrates were tested in a two-choice cage bioassay to study landing response and oviposition by gravid C. macellaria. Significantly more flies landed on substrates containing P. mirabilis than on substrates with other species of bacteria. Klebsiella oxytoca-treated substrates attracted the least flies. Substrates containing bacteria incubated for 72 h attracted significantly more flies than those incubated for 24-, 48-, or 96-h period. In 3-h duration oviposition tests, substrates with P. rettgeri attracted significantly more flies to oviposit than the other four species. The most eggs were recorded when substrates treated with all five species of bacteria were offered for oviposition. It is likely that multiple active chemicals present in the volatiles from substrates treated with all five species result in greater response than those in a single species. At least 72-h incubation seems to be necessary to obtain the most active volatile chemicals. Results suggest that C. macellaria uses similar chemical cues as C. hominivorax from bacteria volatiles as oviposition attractant/stimulant.

Response of Lucilia sericata (Diptera: Calliphoridae) to Screwworm Oviposition Attractant.

The sheep blowfly, Lucilia sericata Meigen (Diptera: Calliphoridae), causes sheep myiasis in various parts of the world. Female flies are attracted to sheep following various olfactory cues emanating from the sheep's body, and oviposit on suitable substrates on sheep ultimately causing myiasis. Earlier workers attempted to reduce fly population in the field, with some success, using traps baited with various attractants. This research was conducted to determine if L. sericata would respond to a recently developed synthetic attractant that has attracted gravid screwworms, Cochliomyia hominivorax Coquerel, and stimulated them to oviposit. Results of the laboratory bioassays demonstrated that gravid females L. sericata were attracted to substrates treated with the synthetic screwworm attractant composed of five compounds--dimethyl disulfide, dimethyl trisulfide, phenol, p-cresol, and indole. Tests with various combinations of these compounds suggest that the sulfur compounds and indole are the most important compounds to elicit attraction and stimulate oviposition, while phenol and p-cresol may have minor roles. Semiochemical baits based on these compounds may be useful in the field to trap gravid L. sericata.

Effects of New Dietary Ingredients Used in Artificial Diet for Screwworm Larvae (Diptera: Calliphoridae).

Spray-dried whole bovine blood, dry poultry egg, and a dry milk substitute are the constituents of the artificial diet currently used for mass rearing screwworm larvae, Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae). Due to high cost and uncertainty of the commercial supply of spray-dried blood, research was conducted to identify alternative, locally available, inexpensive, dietary ingredients which could reduce cost of rearing and eliminate concerns of short supply. Experimental diets were prepared without blood component and with various ratios of bovine blood or blood cell product and defatted soy flour. Results indicate that spray-dried bovine blood can be replaced by a readily available and less expensive blood cell product. When the quantity of whole dried blood or blood cell component was reduced or removed completely from the diet, the larvae did not feed adequately, resulting in high mortality. Those larvae that survived produced pupae that were of unacceptable quality. When the milk product was replaced by soy flour, pupae were slightly smaller than those reared using the current diet; however, replacement of egg product with soy flour produced even smaller pupae. Longevity of adult flies that emerged from these small pupae was short and the females deposited few eggs. These results indicate that soy flour cannot replace the blood component from the diet, but can replace the milk product successfully. It is likely that some factor or a combination of factors in the blood act as feeding stimulants, without which larvae are unable to feed normally, resulting in high larval mortality.

Volatiles from waste larval rearing media attract gravid screwworm flies (Diptera: Calliphoridae) to oviposit.

Gravid screwworm flies, Cochliomyia hominivorax (Coquerel), are attracted to the volatiles from waste larval rearing media to deposit eggs. Studies were conducted to identify volatile chemicals from the waste larval media and determine their effectiveness to attract gravid flies to oviposit. Volatiles were collected using solid-phase microextraction method, and five active chemicals, namely, dimethyl disulfide, dimethyl trisulfide, phenol, p-cresol, and indole, were identified using gas chromatography-mass spectrometry. In electroantennography studies, antennae ofgravid screwworm flies, Cochliomyia macellaria (F.), responded positively to each of the identified compounds. A synthetic blend of these five compounds in the ratio of 335:200:57:1:12 was prepared and tested for its effectiveness to attract both C. hominivorax and C. macellaria using laboratory bioassay methods. Significantly more gravid C. macellaria were attracted to and landed on substrates treated with 10-fold diluted blends compared with those landed on substrates treated with ethanol only (as control). Only a few young females and young and old males were attracted to the substrates treated with the synthetic blend. The C. hominivorax females laid significantly more eggs on substrates treated with waste media, 10-fold diluted blend, and 100-fold diluted blend than on substrates with undiluted blend or ethanol. Similarly, C. macellaria deposited significantly more eggs on substrates treated with waste media, 10-fold diluted blend, and 100-fold diluted blend compared with substrates with undiluted blend or ethanol. C. macellaria females deposited significantly less amount of eggs than did C. hominivorax females. These results indicate that the synthetic blend of five compounds identified may serve as an oviposition attractant for C. hominivorax as well as for C. macellaria.

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.

An artificial diet for rearing Cochliomyia macellaria (Diptera: Calliphoridae).

Larvae of the secondary screwworm, Cochliomyia macellaria (F.), feed on carrion and may sometimes cause animal myiasis. They have been reared in the laboratory on various animal tissues to study their growth and development because of their importance in forensic science. We use secondary screwworms in our laboratory for preliminary experiments as a model for the primary screwworm, Cochliomyia hominivorax (Coquerel), which has been eradicated from the United States. C. macellaria larvae reared on animal tissues produced a putrid odor, an unfavorable condition in the laboratory, and variable pupal size and weight, bringing into question the validity of use as a model for C. hominivorax. Therefore, studies were conducted to develop a less odiferous artificial diet with reduced variability in resulting pupae by comparing three diets: 1) an artificial diet prepared from spray-dried blood, spray-dried poultry egg, dry milk substitute, and solidified with a polyacrylate polymer gel; 2) a fresh blood-based diet prepared similarly, except fresh bovine blood was used in place of spray-dried blood; and 3) a beef liver diet. Data from seven life-history parameters of resulting insects were collected and analyzed. Larval and pupal weights of C. macellaria reared on both the dry and fresh blood-based diets were significantly higher than those reared on the liver diet. Numbers of pupae and percentage of adult emergence were also significantly higher from both dry blood and fresh blood-based diets than those reared on the liver diet. Female flies developing from larvae reared on dry and fresh blood-based diets laid significantly more eggs than females developing from larvae reared on the liver diet. Results show that C. macellaria larvae developed and grew normally in the dry and fresh blood-based diets, indicating that an artificial diet can effectively replace the liver diet commonly used for rearing C. macellaria.

Evaluation of artificial larval rearing media waste as oviposition attractant for New World screwworms (Diptera: Calliphoridae).

The waste artificial larval rearing media of New World screwworms, Cochliomyia hominivorax (Coquerel) were evaluated to determine their effectiveness as oviposition attractants. Various concentrations of waste larval media resulting from rearing screwworm larvae in gel and cellulose fiber-based artificial diets tested over a 4-wk period attracted varying number of gravid screwworm flies to oviposit. Three-day-old waste medium with concentrations of 10 and 25% were most attractive to gravid female flies for oviposition and resulted in the most oviposition. One and 7-d-old wastes at all concentrations were less attractive for oviposition than the 3d-old media. The fresh (0-d-old), 14-d- and 28-d-old waste media were the least attractive substrates for oviposition. The waste from the cellulose fiber-based diet resulted in significantly more oviposition compared with waste from the gel-based diet. Microorganisms growing in the waste media probably produce metabolites that attract gravid screwworm flies to oviposit. Use of the waste products of appropriate age and dilution as oviposition substrates would enhance oviposition in mass production colony cages.

Feasibility of using a Caribbean screwworm for SIT campaigns in Brazil.

The screwworm, Cochliomyia hominivorax (Coquerel), remains one of the most damaging parasites of livestock in South America, causing millions of dollars in annual losses to producers. Recently, South American countries demonstrated interest in controlling this pest using the Sterile Insect Technique, and a pilot-project was conducted near the Brazil-Uruguay border in 2009. Since molecular studies have suggested the existence of C. hominivorax regional groups, crossing tests were conducted to evaluate mating competitiveness, mating preference and reproductive compatibility between a C. hominivorax strain from the Caribbean (Jamaica-06) and one from Brazil. Mating rates between Jamaican males and Brazilian females ranged between 82 and 100%, and each male inseminated from 3.3 to 3.95 females. Sterile males, regardless of the strain, competed equally against the fertile males for Brazilian females. Jamaican sterile males and Brazilian fertile males mated randomly with fertile or sterile females. No evidence of genetic incompatibility or hybrid dysgenesis was found in the hybridization crosses. Mating barriers should not compromise the use of Jamaican sterile males for Sterile Insect Technique campaigns in Brazil.

Solidifying agent and processing of blood used for the larval diet affect screwworm (Diptera: Calliphoridae) life-history parameters.

Spray-dried whole bovine blood and a sodium polyacrylate polymer gel as a bulking and solidifying agent are among the constituents of the current larval diet for mass rearing screwworm, Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae). Locally available, inexpensive dietary materials could reduce rearing cost and address an uncertain commercial supply of spray-dried blood. We compared efficacy of diet prepared from fresh bovine blood after decoagulation with sodium citrate or ethylenediaminetetraacetic acid (EDTA) or after mechanical defibrination, with the diet containing spray-dried blood using either gel or cellulose fiber as the bulking and solidifying agent. Several life-history parameters were compared among insects reared on each of the blood and bulking agent diets combination. Diets containing citrated blood yielded the lightest larval and pupal weights and fewest pupae. EDTA-treated blood with the gel also caused reductions. EDTA-treated blood with fiber yielded screwworms that were heavier and more numerous than those from the diet with citrated blood but lighter than those from the control diet using spray-dried blood. A reduction in percentage of adults emerging from pupae occurred from diets with both bulking agents using citrated blood and the diet using EDTA mixed with the gel bulking agent. As a group, the cellulose-fiber diets performed better than the gel diets. Larval diet did not affect adult longevity, weight of the eggs deposited by the females that emerged or subsequent egg hatch. Parameter measurements of insects from both defibrinated blood diets were similar to those from the spray-dried blood diets, indicating that fresh, defibrinated bovine blood can successfully replace the dry blood in the screwworm rearing medium.

Volatiles emitted from eight wound-isolated bacteria differentially attract gravid screwworms (Diptera: Calliphoridae) to oviposit.

Bovine blood inoculated with bacteria isolated from screwworm [Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae)]-infested animal wounds was tested as an attractant for oviposition for gravid screwworms. Eight species of gram-negative coliform (Enterobacteriaceae) bacteria mixed with bovine blood singly or all species combined and incubated for various times produced volatiles that attracted gravid flies in a cage bioassay in varying numbers. In 15-min duration tests, volatiles from five species of bacteria (Klebsiella oxytoca, Proteus mirabilis, Proteus vulgaris, Providencia rettgeri, and Providencia stuartii) attracted more females than volatiles of the three species (Enterobacter cloacae, Enterobacter sakazakii, and Serratia liquefaciens). In 1-h duration oviposition tests, volatiles from the substrate using the same five species of bacteria attracted more females to oviposit than the other three species. Volatiles from 24-h incubation period elicited least attraction and oviposition whereas volatiles from the 48- and 72-h incubation period resulted in significantly more attraction and oviposition. Attraction and oviposition decreased significantly when the substrates were incubated for 96 h. Volatiles from substrate with all species of bacteria combined attracted a significantly higher percentage of flies to land and oviposit than those from substrates prepared with single species. It is possible that multiple active chemicals present in volatiles of the all-species substrate may act as synergists resulting in greater response than those observed with volatiles from single-species substrate. Before oviposition flies took a bloodmeal from the oviposition substrate. It is possible that the oviposition is moderated by two different factors in screwworm-first, by using a chemical cue to land on a potential oviposition site and second, by using a bloodmeal to stimulate oviposition.

Mark-recapture estimates of recruitment, survivorship and population growth rate for the screwworm fly, Cochliomyia hominivorax.

Pradel model mark-release-recapture estimates of survivorship, phi, recruitment, f, and the rate of density-independent population growth, lambda, are presented for eight mark-recapture studies of the screwworm Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae) from Costa Rica, totalling 19 573 released and 4476 recaptured flies. Corroborative estimates of survivorship and the rate of population growth based on an extensive review of the literature are also reported. Weighted-mean +/- standard error of the mean (SEM) mark-release-recapture estimates of survivorship, recruitment and the rate of population growth were phi = 0.798 +/- 0.008, f = 0.193 +/- 0.008 and lambda = 1.005 +/- 0.002, respectively. Population doubling time was estimated from lambda at 139 days. Estimates of phi and lambda from the literature both exceeded those calculated by mark-recapture methods and estimates of population doubling times were consequently shorter.

Development and utilization of transgenic New World screwworm, Cochliomyia hominivorax.

The New World screwworm (NWS), Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae), was the first insect to be effectively controlled using the sterile insect technique (SIT). Recent efforts to improve SIT control of this species have centred on the development of genetically transformed strains using the piggyBac transposon vector system. Eight transgenic strains were produced incorporating an enhanced green fluorescent protein (EGFP) marker gene under polyubiquitin regulation that has the potential for use as a genetic marking system for released males. The transgenic strains were genetically and phenotypically characterized, including for life fitness parameters and mating competitiveness. These characteristics were unique for each strain and thus some strains were deemed suitable for incorporation into SIT eradication programmes. The strain with the best attributes is designated 'CLAY'. Four of the strains, including CLAY, have been successfully cryopreserved so that their original characteristics should be unchanged when further evaluation is required. With the demonstration of efficient germ-line transformation in NWS, allowing production of fit and competitive transformants, it is now possible to consider further transgenic strain development to improve SIT that are currently being tested in other dipteran species. This includes strains that allow genetic marking with fluorescent proteins, genetic sexing by female lethality, male-specific fluorescent sorting and male sterility by testis-specific lethality. The SIT may also be improved upon by new strategies resulting in lethality of offspring of released insects using conditional lethal systems based upon temperature-dependent or dietary tetracycline regulation of lethal gene expression. Both the creation of new NWS transgenic strains and the ecological safety of their release will be enhanced by new vector systems that allow specific genomic targeting of vector constructs and their subsequent immobilization, ensuring transgene and strain stability.

Amplified fragment length polymorphism used for inter- and intraspecific differentiation of screwworms (Diptera: Calliphoridae).

Morphologically, early immature stages of the economically important pest called screwworms, Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae), and non-pest secondary screwworms, Cochliomyia macellaria (Fabricius) (Diptera: Calliphoridae), are nearly indistinguishable. Correct identification is crucial to the ongoing eradication and exclusion program protecting the United States, Mexico and Central America from reinvasion of screwworms persistent in South America and the Caribbean. Amplified fragment length polymorphism (AFLP) polymerase chain reaction was used to differentiate populations of C. hominivorax and to discriminate them from C. macellaria. Ten primer pairs screened for interspecific discrimination of C. hominivorax from C. macellaria showed 52 discrete bands, allowing the two species to be readily distinguished; divergent branches on resulting dendrograms showed 100% bootstrap support. C. macellaria populations grouped at the 92% level; C. hominivorax populations grouped at the 68% level. Of the 52 bands, seven were monomorphic for both species, 22 were specific to C. macellaria, ten were present only in C. hominivorax and the remaining 13 bands differentiated C. hominivorax populations. Separate studies using ten strains of C. hominivorax showed a higher level of genetic similarity within than between populations. Analyses using 72 bands (19 monomorphic bands, 53 bands grouped all ten strains at the 58% similarity level) resolved seven mutant strains from Mexico (85% similarity level); all ten strains were resolved at the 72% similarity level. Diagnostic bands were identified for species and strain identification. We conclude that AFLP can be a valuable tool for studies of interspecific and intraspecific genetic variation in screwworm populations.

Diet pH, and viscosity affect development and survival of screwworm larvae (Diptera: Calliphoridae).

The effects of dietary pH and viscosity on larval development of the New World screwworm, Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae), were studied in the laboratory using a gel-based and a cellulose fiber-based media. The mean initial pH of the standard gelled diet was lower (6.5 +/- 0.3) than that of the standard cellulose fiber-based diet (6.8 +/- 0.6). As larval development progressed, these values decreased to below 6.0 possibly due to the accumulation of acidic metabolic waste. Diets formulated with higher initial pH (7.5) produced a slightly larger and greater number of pupae compared with those for untreated standard diets. The diets with lower than normal initial pH (4.0) produced significantly smaller and lower numbers of pupae compared with those produced by the untreated standard diets. The effects of viscosity were studied using the cellulose fiber-based diet at six different initial viscosity levels ranging from 2,000 to 7,000 cP. The viscosity level of the diet increased as the larval development progressed due to gradual loss of moisture from the diet. The diet viscosity levels of 4,000 and 5,000 cP proved superior for larval development showing significantly higher yield and larger pupae compared with those obtained from diets with initial viscosities of 2,000-3,000 or 6,000-7,000 cP. The cellulose fiber-based diet used for mass rearing should be formulated to an initial viscosity reading of 4,000-5,000 cP for optimal larval growth and development. Adoption of a diet formulated to provide a higher initial pH such as 7.5 may produce better quality insects.

Screwworms, Cochliomyia hominivorax, reared for mass release do not carry and spread foot-and-mouth disease virus and classical swine fever virus.

Experiments were done to determine if transporting live screwworms Cochliomyia hominivorax Coquerel (Diptera: Calliphoridae) for developing new strains from countries where foot-and-mouth disease and classical swine fever are endemic, to the mass rearing facilities in Mexico and Panama, may introduce these exotic diseases into these countries. Are screwworms capable of harboring and spreading foot-and-mouth disease virus (FMDV) and classical swine fever virus (CSFV) when they are grown in virus-inoculated larval rearing medium? In one experiment, screwworm larvae were reared in a FMDV-inoculated artificial medium containing either 0.1 % formaldehyde or antibiotics as an antimicrobial agent. In another experiment, larvae were similarly reared in a CSFV-inoculated artificial medium containing 0.1% formaldehyde. In each experiment, samples of larvae and the rearing media were collected daily until pupation occurred. The presence of FMDV was assayed by observing cytopathic effects on cell cultures and a conventional reverse transcription-polymerase chain reaction (RT-PCR); CSFV was assayed using an avidin-biotin complex assay and a conventional RT-PCR. For media containing antibiotics, FMDV was detected in a larval sample collected on day 1 and in media samples on days 1, 2 and 3. No FMDV was detected from larval and media samples collected on all other days. For media containing formaldehyde, FMDV and CSFV were not detectable in larval or media samples collected on all sampling days. These results indicate that FMDV and CSFV cannot survive in rearing medium containing formaldehyde as an antimicrobial agent. Therefore, insects collected in endemic regions and reared using formaldehyde-containing medium for at least one generation at the collection site should be free of FMDV and CSFV and can be transported safely to a strain development/mass rearing facility.

A cellulose fiber-based diet for screwworm (Diptera: Calliphoridae) larvae.

A highly absorbent cellulose fiber from recycled paper was tested and compared with a polyacrylate gelling agent, Aquatain, normally used for bulking and solidifying larval rearing medium of screwworm, Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae). The absorbent fiber, when mixed with water and dietary ingredients, produced a diet medium of homogeneous texture that supported larval growth and development comparable with the standard gelled diet. Larval and pupal weights from two concentrations of cellulose fiber-based diet were significantly higher than those obtained using gelled diet. The number of pupae per tray, percentage of adult emergence, oviposition, percentage of egg hatch, and adult longevity obtained from the insects reared in the cellulose fiber-based diet were comparable or slightly better than the biological parameters recorded from flies reared in the gelled diet. Moreover, results indicate that a lesser amount of the cellulose fiber-based diet than the normal amount of gelled diet per tray would support normal larval growth. Physical properties and texture of the new diet seem to allow the larvae to move and feed more freely than they do on the semisolid gelled diet, resulting in less wasted diet. The cellulose fiber is biodegradable and inexpensive, whereas the polyacrylate gel polymer is not biodegradable and is relatively expensive. Replacing gel with cellulose fiber in the screwworm larval diet for mass rearing should result in substantial cost savings in material and labor as well as eliminating concern of environmental pollution due to diet waste disposal.

Physical and Physiological Factors Influence Behavioral Responses of Cochliomyia macellaria (Diptera: Calliphoridae) to Synthetic Attractants.

Volatile chemicals from waste artificial larval media as well as from bovine blood inoculated with bacteria isolated from screwworm-infested wounds attract gravid females of Cochliomyia hominivorax Coquerel and Cochliomyia macellaria (F.). Chemicals identified from volatiles are dimethyl disulfide, dimethyl trisulfide, phenol, p-cresol, and indole; a blend of these attracted females to oviposit. Present studies investigated the effectiveness of these compounds, either in a blend or individually as potential oviposition attractants. Tests were conducted to determine the effects of gender, ovarian age, and the color and type of substrates on attraction response and oviposition of C. macellaria adults. Results showed that substrates treated with dimethyl trisulfide (DMTS) alone or the five-compound blend alone attracted significantly more gravid females than other chemicals. Black substrates treated with DMTS attracted more gravid flies than did the yellow substrates. Yellow substrates treated with indole attracted more males and nongravid females. In oviposition tests, females deposited significantly more eggs on meat-based substrates than those without meat. These findings suggest that several factors have to be considered for developing an effective oviposition attractant that should include effectiveness of individual chemicals used, the ratio of the chemicals in a blend, and their concentrations. Also, an effective trap design will need to consider using suitable color which will selectively attract gravid females.

Susceptibility of biological stages of the horn fly, Haematobia irritans, to entomopathogenic fungi (Hyphomycetes).

The susceptibility of the egg, pupa, and adult of Haematobia irritans (L.) (Diptera: Muscidae) to isolates of the fungi Metarhizium anisopliae (Metsch.) Sor., Beauveria bassiana (Bals.) Vuill., and Paecilomyces fumosoroseus (Wize) Brown and Smith, was evaluated under laboratory conditions. Groups of 20 eggs than 4 h old, pupae less than 48h old and adults were sprayed with a conidial suspension of each isolate. Eggs, pupae and adults of horn fly were susceptible to these entomopathogenic fungi. For treated eggs, the isolates Ma3, Ma 15, Ma25, Pfr1, and Pfr8 reduced adult emergence to 3.8% to 6.3% in comparison with the control (72%). The mortality of pupae infected by the isolates Ma2, Ma25, and Pfr10 ranged between 50% and 71.3%. Mortality of adults after treatment with the isolates Ma6, Ma 10, Ma 14, Ma 15, Pfr 1, Pfr 9, Pfr 10, Pfr 11, and Pfr12 were higher than 90%. The isolate Ma6 produced the lowest LC(50) against adult horn flies (8.08 × 10(2)conidia/ml). These findings supported the hypotheses that isolates of M. anisopliae, and P. fumosoroseus are pathogenic against the different biological stages of horn flies by reducing adult emergence when applied on groups of eggs and pupae, and producing mortality when applied to adults.

Identification of screwworms, Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae), with a monoclonal antibody-based enzyme-linked immunosorbent assay (MAb-ELISA).

Myiasis caused by screwworms, Cochliomyia hominivorax (Coquerel), is devastating to warm-blooded animals and economically important to livestock producers. It is difficult to distinguish these pests, immature screwworms, from immatures of other non-pest fly species that often occur in animal wounds; it would be helpful to have tools available that do not rely on morphological characteristics. We developed two monoclonal antibodies (MAbs), highly specific for the screwworm, and used them in an enzyme-linked immunosorbent assay (MAb-ELISA), that differentiated screwworm eggs, larvae, pupae, and adults from those of the closely related secondary screwworm, C. macellaria (Fabricius) as well as Phormia regina (Meigen), Phaenicia sericata (Meigen), Calliphora vicina Robineau-Desvoidy, and Chrysomya rufifacies (Macquart). In a blind study, the microplate MAb-ELISA, which took about 4h to complete, displayed high specificity (99%), sensitivity (92%) and overall accuracy (97%) in distinguishing all life stages of the screwworm. Electrophoresis results suggested that the two monoclonal antibodies recognized identical conformational epitopes present in all screwworm life stages. The screwworm eradication program, successful in eradicating this pest from the US, Mexico, most of Central America and Libya (after an accidental introduction), could benefit in future eradication, surveillance, and exclusion efforts by developing a reliable field identification kit based on MAb-ELISA that accurately and quickly distinguished cases of screwworm myiasis.

Magnetic Rotation in the A = 80 Region: M1 Bands in Heavy Rb Isotopes.

We have studied the isotopes (82)Rb45, (83)Rb46, and (84)Rb47 to search for magnetic rotation which is predicted in the tilted-axis cranking model for a certain mass region around A = 80. Excited states in these nuclei were populated via the reaction (11)B + (76)Ge with E = 50 MeV at the XTU tandem accelerator of the LNL Legnaro. Based on a γ-coincidence experiment using the spectrometer GASP we have found magnetic dipole bands in each studied nuclide. The regular M1 bands observed in the odd-odd nuclei (82)Rb and (84)Rb include B(M1)/B(E2) ratios decreasing smoothly with increasing spin in a range of 13(-) ≤ J(π) ≤ 16(-). These bands are interpreted in the tilted-axis cranking model on the basis of four-quasiparticle configurations of the type [Formula: see text]. This is the first evidence of magnetic rotation in the A ≈ 80 region. In contrast, the M1 sequences in the odd-even nucleus (83)Rb are not regular, and the B(M1)/B(E2) ratios show a pronounced staggering.