Behavioural responses of dairy cattle to the stable fly, Stomoxys calcitrans, in an open field environment

Individual cows (25 in each of four herds) were monitored 8-10 times weekly for 12 weeks (stable fly season) on a southern California dairy, with 100 observations per cow. The numbers of biting stable flies, Stomoxys calcitrans (L.) (Diptera: Muscidae) on the front legs and the frequencies of four fly-repelling behaviours per 2-min observation period [head throws, front leg stamps, skin twitches (panniculus reflex) and tail flicks] were recorded. Fly numbers varied, peaking at 3.0-3.5 flies per leg in week 9 (late May). Weekly herd mean frequencies of fly-repelling behaviours were highly dependent on fly numbers, with a linear regression r(2) > 0.8. Head throws and stamps were less frequent than skin twitches and tail flicks. Individual cows differed in numbers of stable flies and behaviours. Behaviours were correlated with flies for individual cows, but at a lower level than were herd means (r = 0.3-0.7). Cows that stamped more within a herd tended to have lower fly counts; other fly-repelling behaviours were less effective. Cows maintained ranks within a herd with regard to fly numbers (r = 0.47), head throws (0.48), leg stamps (0.64), skin twitches (0.69) and tail flicks (0.64). Older cows tended to harbour higher fly numbers and to stamp less relative to younger adult cows. Ratios of leg stamps and head throws to fly numbers dropped significantly through time, suggesting habituation to pain associated with fly biting. Tail flicks were not effective for repelling Stomoxys, but were easiest to quantify and may help in monitoring pest intensity. At this low-moderate fly pressure, no consistent impacts on milk yield were detected, but methods incorporating cow behaviour are recommended for future studies of economic impact.     

Gravity reception in the walking fly, Calliphora erythrocephala: Tonic and modulatory influences of leg afferents on the head position

The proprioceptive gravity receptor system of the fly, Calliphora erythrocephala, is functionally organized in a manner similar to the statocyst system in vertebrates, molluscs and crustaceans. It includes one system in which excitation is modulated by the gravitational stimulus, and another which exerts a tonic excitation on the neurones of the reflex arc between the leg receptors and the neck muscles. While the modulating system for the compensatory head movement of the walking flies is located only in the forelegs and the middle legs, the tonic excitation is mediated by receptors of all legs.     

Haltere activity in a flightless hippoboscid fly, Crataerina pallida

The halteres of the subapterous fly parasite of swifts, Crataerina pallida, retain a full complement of sensilla. They beat during and for many minutes after wing extension, leg movements and other forms of activity. They can also be caused to beat by a variety of visual and mechanical stimuli, including sound pulses at up to 2 kHz, for several minutes in the absence of other movements. Fed flies show markedly reduced locomotory responsiveness compared to unfed flies, but the halteres of both groups appear to be equally responsive. Haltere extirpation or inactivation does not appear to reduce ocomotory responsiveness. The possibility that haltere activity depresses responsiveness is discussed.     

Social context-dependent modification of courtship behaviour in Drosophila prolongata

Induction of alternative mating tactics by surrounding conditions, such as the presence of conspecific males, is observed in many animal species. Satellite behaviour is a remarkable example in which parasitic males exploit the reproductive investment by other males. Despite the abundance of parasitic mating tactics, however, few examples are known in which males alter courtship behaviour as a counter tactic against parasitic rivals. The fruit fly Drosophila prolongata shows prominent sexual dimorphism in the forelegs. When courting females, males of D. prolongata perform ‘leg vibration’, in which a male vibrates the female''s body with his enlarged forelegs. In this study, we found that leg vibration increased female receptivity, but it also raised a risk of interception of the female by rival males. Consequently, in the presence of rivals, males of D. prolongata shifted their courtship behaviour from leg vibration to ‘rubbing’, which was less vulnerable to interference by rival males. These results demonstrated that the males of D. prolongata adjust their courtship behaviour to circumvent the social context-dependent risk of leg vibration.     

Suitability of a leaf-mining fly,Hydrellia sp., for biological control of the invasive aquatic weed,Hydrilla verticillata in South Africa

South Africa developed its first biological control programme for a submerged aquatic weed following the discovery of Hydrilla verticillata (L.f.) Royle (Hydrocharitaceae) in a major tourism dam in 2006. A leaf-mining fly, Hydrellia sp. (Diptera: Ephydridae) from Singapore, originating on a closely related biotype of the weed invading South Africa, was considered a priority candidate agent. Host range was investigated through no-choice and paired-choice larval development trials. “Host suitability” trials (multiple generations and performance) were used to further evaluate the potential for non-target host use by the fly. Hydrellia sp. developed on a few closely related species in the Hydrocharitaceae and one species in the Potamogetonaceae. However, paired-choice tests demonstrated a strong preference for its host plant and the host suitability trials indicated that Hydrellia sp. has very limited potential to establish permanent populations on native aquatic plant species. Hydrellia sp. should therefore be considered safe for release in South Africa.     

A new species of mite (Acari: Histiostomatidae) phoretic on Gymnomus caesius (Diptera: Heleomyzidae) from Vlčie Diery cave

A new species of histiostomatid mite — Myianoetus sovat sp. n., based on the deutonymph, is described from the fly Gymnomus caesius. It differs from other species of Myianoetus by more characters of idiosomal morphometry, body and leg chaetotaxy, solenidiotaxy and shape of the adhering disc and its structures.     

Dependence of transdetermination frequency on the developmental stage of cultured imaginal discs of Drosophila melanogaster

Male foreleg tissue from prepupal stages of Drosophila melanogaster was tested for its capacity to grow when cultured in the adult fly hemocoel and for its capacity, after culture, to produce adult cuticular structures when differentiated in a metamorphosing larva. Evaginated, segmented leg tissue from 8-hr-old prepupae (at 25°C), still retained the capacity to grow well in culture. Growth was, however, restricted to cells of the proximal half of the leg. Tissue from 11- and 24-hr stages (pupal ecdysis at 11 hr) was not successfully cultured. Cultured proximal halves of 8 hr prepupal legs frequently differentiated not only proximal structures, but also distal structures, such as sex combs and claws, indicating regeneration of missing leg structures during the culture period. Transdetermination to wing tissue occurred only rarely (once in 90 implants) whereas third-instar leg tissue in culture transdetermined frequently (50% of the implants) to wing, even though growth of tissue of the two stages was equivalent. Identical results were obtained with third-instar foreleg discs evaginated in vitro with β-ecdysone. This is the first in vitro treatment reported to reduce transdetermination frequency, without affecting growth proportionately. These results indicate that cell proliferation in culture, while probably a necessary condition for transdetermination, is not a sufficient condition. The developmental stage of the cultured tissue strongly affects the frequency of transdetermination.     

Combination of Hypomorphic Mutations of the Drosophila Homologues of Aryl Hydrocarbon Receptor and Nucleosome Assembly Protein Family Genes Disrupts Morphogenesis,Memory and Detoxification

Aryl hydrocarbon receptor is essential for biological responses to endogenous and exogenous toxins in mammals. Its Drosophila homolog spineless plays an important role in fly morphogenesis. We have previously shown that during morphogenesis spineless genetically interacts with CG5017 gene, which encodes a nucleosome assembly factor and may affect cognitive function of the fly. We now demonstrate synergistic interactions of spineless and CG5017 in pathways controlling oxidative stress response and long-term memory formation in Drosophila melanogaster. Oxidative stress was induced by low doses of X-ray irradiation of flies carrying hypomorphic mutation of spineless, mutation of CG5017, and their combination. To determine the sensitivity of these mutants to pharmacological modifiers of the irradiation effect, we irradiated flies growing on standard medium supplemented by radiosensitizer furazidin and radioprotector serotonin. The effects of irradiation were investigated by analyzing leg and antenna morphological structures and by using real-time PCR to measure mRNA expression levels for spineless, Cyp6g1 and Gst-theta genes. We also examined long-term memory in these mutants using conditioned courtship suppression paradigm. Our results show that the interaction of spineless and CG5017 is important for regulation of morphogenesis, long-term memory formation, and detoxification during oxidative stress. Since spineless and CG5017 are evolutionary conserved, these results must be considered when evaluating the risk of combining similar mutations in other organisms, including humans.     

Environmental Factors Associated with High Fly Densities and Diarrhea in Vellore,India

Diarrhea causes significant morbidity and mortality in Indian children under 5 years of age. Flies carry enteric pathogens and may mediate foodborne infections. In this study, we characterized fly densities as a determinant of infectious diarrhea in a longitudinal cohort of 160 urban and 80 rural households with 1,274 individuals (27% under 5 years of age) in Vellore, India. Household questionnaires on living conditions were completed at enrollment. Fly abundance was measured during the wet and dry seasons using fly ribbons placed in kitchens. PCRs for enteric bacteria, viruses, and protozoa were performed on 60 fly samples. Forty-three (72%) fly samples were positive for the following pathogens: norovirus (50%), Salmonella spp. (46.7%), rotavirus (6.7%), and Escherichia coli (6.7%). Ninety-one episodes of diarrhea occurred (89% in children under 5 years of age). Stool pathogens isolated in 24 of 77 (31%) samples included E. coli, Shigella spp., Vibrio spp., Giardia, Cryptosporidium, and rotavirus. Multivariate log-linear models were used to explore the relationships between diarrhea and fly densities, controlling for demographics, hygiene, and human-animal interactions. Fly abundance was 6 times higher in rural than urban sites (P < 0.0001). Disposal of garbage close to homes and rural living were significant risk factors for high fly densities. The presence of latrines was protective against high fly densities and diarrhea. The adjusted relative risks of diarrheal episodes and duration of diarrhea, associated with fly density at the 75th percentile, were 1.18 (95% confidence interval [CI], 1.03 to 1.34) and 1.15 (95% CI, 1.02 to 1.29), respectively. Flies harbored enteric pathogens, including norovirus, a poorly documented pathogen on flies.     

Length of productive life of crossbred sows is affected by farm management, leg conformation, sow's own prolificacy, sow's origin parity and genetics

The purpose of the current study was to determine if the parity of the litter in which a female was born and the number of pigs within that same litter are associated with future length of productive life (LPL). An additional objective of the study was to examine the associations of leg conformation (evaluated at approx. 100 kg of live weight), age at first farrowing, litter size at first farrowing, and age and backfat thickness at 100 kg on LPL in the Finnish crossbred (Landrace × Large White or Large White × Landrace) population. The data analysed contained information on 11 761 sows, and proportional hazard model (Weibull) was fitted on the data using the Survival Kit. Log likelihood tests were utilised to determine if the individual effects have a significant impact on LPL. Farm conditions and management were identified as major factors impacting on LPL ( P < 0.001). Other factors significantly ( P < 0.001) associated with LPL were leg soundness score, age at first farrowing, and litter size at first farrowing. The better the leg score, the younger age at first farrowing, and the larger litter at first farrowing, the longer sows tended to remain in the herd from the present. Although sows born in litters first, second, and sixth parities had slightly greater risk of being culled when compared with sows born in litters from the other parities, the effect was not statistically significant. Sufficient genetic variation exists in the population evaluated in this study for LPL (h² = 0.25), such that it will be possible to improve LPL through traditional selection methods in an efficient breeding programme. Thus, there are many factors which impact on LPL, and possibilities to improve all of them should be considered in order to improve the economics and animal welfare of modern pork production operations.     

New Components of Drosophila Leg Development Identified through Genome Wide Association Studies

The adult Drosophila melanogaster body develops from imaginal discs, groups of cells set-aside during embryogenesis and expanded in number during larval stages. Specification and development of Drosophila imaginal discs have been studied for many years as models of morphogenesis. These studies are often based on mutations with large developmental effects, mutations that are often lethal in embryos when homozygous. Such forward genetic screens can be limited by factors such as early lethality and genetic redundancy. To identify additional genes and genetic pathways involved in leg imaginal disc development, we employed a Genome Wide Association Study utilizing the natural genetic variation in leg proportionality found in the Drosophila Genetic Reference Panel fly lines. In addition to identifying genes already known to be involved in leg development, we identified several genes involved in pathways that had not previously been linked with leg development. Several of the genes appear to be involved in signaling activities, while others have no known roles at this time. Many of these uncharacterized genes are conserved in mammals, so we can now begin to place these genes into developmental contexts. Interestingly, we identified five genes which, when their function is reduced by RNAi, cause an antenna-to-leg transformation. Our results demonstrate the utility of this approach, integrating the tools of quantitative and molecular genetics to study developmental processes, and provide new insights into the pathways and networks involved in Drosophila leg development.     

The seasonal response of Italian and hybrid ryegrasses to the control of frit fly, Oscinella frit

In years of relatively high frit fly activity the control of all generations produced increases averaging 0×44 t d.m. ha^-1 in annual yield of Italian and hybrid ryegrass. A cutting programme designed to make the sward especially vulnerable to frit fly attack did not increase the total annual effect of pesticide treatment but accentuated the periods at which damage occurred. The annual yield increase was almost entirely obtainable by controlling the second and third frit fly generations, but even one treatment for this purpose was of doubtful economic justification. The prospect of augmenting the response to control of later-occurring pests, such as leatherjackets or eriophyid mites, by including the part of the frit fly response which is recoverable by the same treatment, was a more probable justification for pesticide usage. There was some evidence that a Westerwold and a hybrid cultivar suffered more damage than an Italian ryegrass cultivar, but pesticide treatment did not improve the persistence of any cultivar.     

Suppression of melon fly (Diptera: Tephritidae) populations with releases of Fopius arisanus and Psyttalia fletcheri (Hymenoptera: Braconidae) in North Shore Oahu, HI, USA

Field experiments and surveys were conducted to evaluate the efficacy of releasing Fopius arisanus (Sonan) and Psyttalia fletcheri (Silvestri) parasitoids for suppression of Bactrocera cucurbitae (Coquillett) infesting wild Coccinia grandis L. In 2003 and 2004, P. fletcheri releases combined with natural emergence from wild fly populations resulted in better fly suppression, compared to the control site. While P. fletcheri developed freely on melon fly, F. arisanus was less successful at producing its own progeny, yet causing mortality and a twofold decrease in pupae recovered from ivy gourds. Concurrent releases of both parasitoids exerted a compounded suppressive effect on the melon fly population 2–3 times higher than during the pre-release phase. A similar, less obvious, pattern occurred in 2004, due to reduction of the ivy gourd fruit canopy. In 2005, only P. fletcheri was released, with greatly reduced impact, due to ivy gourd destruction and by growers leaving crop culls in fields, producing large numbers of melon flies unaffected by parasitoid releases.     

Genetic diversity of populations of Old World screwworm fly, Chrysomya bezziana, causing traumatic myiasis of livestock in the Gulf region and implications for control by sterile insect technique

Abstract.  Fly larvae were collected from 181 cases of traumatic myiasis in livestock in 10 regions of four countries in the Middle East Gulf region: Iran, Iraq, Saudi Arabia and Oman. The predominant fly species responsible for cases was the Old World screwworm (OWS) fly, Chrysomya bezziana Villeneuve (Diptera: Calliphoridae). In cases from Iran and Oman, which included non-OWS fly species, OWS fly was found solely responsible for 67.6% of cases and jointly with other fly species for a further 12.7% of cases. The major hosts were sheep and goats, together comprising 84.6% of the total, which reflects their predominance among the livestock of these Gulf countries. The major site of wounding on sheep and goats was the tail (40.3%), followed by female genitalia (14.0%). The 3' terminal 715 nucleotides of the mitochondrial cytochrome b gene were sequenced for 178 larvae of OWS. Five haplotypes were identified: three had been recorded previously in the region (two were common throughout and one was unique to Oman), and two were newly identified, one from southern Iraq and the other from Saudi Arabia, both in regions sampled for the first time. The haplotypes varied from one another only at one or two nucleotide sites, equivalent to an intraspecific difference of 0.14–0.28% across the entire 715-bp fragment. There was a single statistically significant association between host species and haplotype in Saudi Arabia, a first such record for OWS fly. The small degree of genetic diversity between geographical populations of OWS fly within the Gulf region suggests that a single Gulf colony could be used to implement the sterile insect technique within an integrated control programme.     

Classical Olfactory Conditioning in the Oriental Fruit Fly,Bactrocera dorsalis

The oriental fruit fly, Bactrocera dorsalis, is a serious pest of fruits and vegetables. Methyl eugenol (ME), a male attractant, is used to against this fly by mass trapping. Control effect may be influenced by learning, which could modify the olfactory response of the fly to this attractant. To collect the behavioral evidence, studies on the capability of this fly for olfactory learning are necessary. We investigated olfactory learning in male flies with a classical olfactory conditioning procedure using restrained individuals under laboratory conditions. The acquisition of the proboscis extension reflex was used as the criterion for conditioning. A high conditioned response level was found in oriental fruit flies when an odor was presented in paired association with a sucrose reward but not when the odor and sucrose were presented unpaired. We also found that the conditioning performance was influenced by the odor concentration, intertrial interval, and starvation time. A slight sensitization elicited by imbibing sucrose was observed. These results indicate that oriental fruit flies have a high capacity to form an olfactory memory as a result of classical conditioning.     

Leaf surface chemistry of sorghum seedlings influencing expression of resistance to sorghum shoot fly, Atherigona soccata

Sorghum shoot fly, Atherigona soccata is one of the serious constraints to sorghum production, and host plant resistance is an important component for controlling this pest. We studied the expression of resistance to A. soccata in a diverse array of sorghum genotypes in relation to composition of leaf surface chemicals during the seedling stage. The sorghum genotypes IS 1054, IS 1057, IS 2146, IS 4664, IS 2312, IS 2205, SFCR 125, SFCR 151, ICSV 700, and IS 18551 exhibited antixenosis for oviposition, and suffered less deadhearts due to sorghum shoot fly, A. soccata. Compounds undecane 5- methyl, decane 4- methyl, hexane 2, 4- methyl, pentadecane 8- hexyl, and dodecane 2, 6, 11- trimethyl, present on the leaf surface of sorghum seedlings, were associated with susceptibility to shoot fly; while 4, 4- dimethyl cyclooctene was associated with resistance to shoot fly. The compounds associated with resistance/susceptibility to shoot fly, can be used as marker traits to select for resistance as well as for diversifying and increasing the levels of resistance to this pest. The role of biochemical compounds for developing sorghum varieties with resistance to shoot fly, A. soccata has been discussed.     

Identification of a novel gene, H34, in wheat using recombinant inbred lines and single nucleotide polymorphism markers

Hessian fly (HF), Mayetiola destructor, is an important pest of wheat (Triticum aestivum L.) worldwide. Because it has multiple biotypes that are virulent to different wheat HF resistance genes, pyramiding multiple resistance genes in a cultivar can improve resistance durability, and finding DNA markers tightly linked to these genes is essential to this process. This study identified quantitative trait loci (QTLs) for Hessian fly resistance (HFR) in the wheat cultivar ‘Clark’ and tightly linked DNA markers for the QTLs. A linkage map was constructed with single nucleotide polymorphism and simple sequence repeat markers using a population of recombinant inbred lines (RILs) derived from the cross ‘Ning7840’ × ‘Clark’ by single-seed descent. Two QTLs associated with resistance to fly biotype GP were identified on chromosomes 6B and 1A, with the resistance alleles contributed from ‘Clark’. The QTL on 6B flanked by loci Xsnp921 and Xsnp2745 explained about 37.2 % of the phenotypic variation, and the QTL on 1A was flanked by Xgwm33 and Xsnp5150 and accounted for 13.3 % of phenotypic variation for HFR. The QTL on 6B has not been reported before and represents a novel wheat gene with resistance to HF, thus, it is designated H34. A significant positive epistasis was detected between the two QTLs that accounted for about 9.5 % of the mean phenotypic variation and increased HFR by 0.16. Our results indicated that different QTLs may contribute different degrees of resistance in a cultivar and that epistasis may play an important role in HFR.     

Pattern formation and determination in the antenna of the homoeotic mutant Antennapedia of Drosophila melanogaster

The development of the antenna in the antennal-leg homoeotic mutant Antennapedia (Antp^R) was investigated using somatic crossing-over to mark clones of cells in Antp^R antennal appendages. Antp^R antennae ranged from a nearly normal antenna to a nearly normal leg. The arrangement of clones of marked bristles and cuticle in the more antennalike antennae was similar to the wild type antenna, and that of the leglike antennae was similar to the wild-type leg. The contiguity of clones argued against extensive individual cell migration. The regions occupied by homoeotic leg varied considerably between different Antp^R antennae. Observation of Antp^R antennae in these phenotypic mosaics showed that specific leg parts replaced specific antennal parts. Even small groups of leg sensilla appeared only at precise locations in the antenna. These results suggest that homoeotic leg cells and antennal cells can both respond to the same positional information or prepattern. An analysis of clone size provided estimates for cell number in the Antp^R antenna. It was found that cell numbers in the wild-type and Antp^R antennae are about the same until the third instar, when the Antp^R cells start dividing more rapidly than wild type. Previous work had shown that clonal inheritance of a commitment for homoeotic leg also did not occur prior to the early third instar. It is suggested that determination for homoeotic leg occurs in the early third instar, and that thereafter this commitment is inherited by the progeny of the determined cells. The increase in growth rate is probably due to a faster growth rate in cells with a leg commitment than in cells with an antennal commitment. The results suggest that, once initiated, determination may be of two types—a clonally inherited determination (for example, to be homoeotic leg) and an environmental determination (for example, to be a specific part of a homoeotic leg). Clonal inheritance of determination in normal embryonic development and in sex determination in intersexes is discussed.