Hormonal regulation of disaggregation of cellular fragments in the haemolymph of Lucilia cuprina

In the haemolymph of newly emerged adult blowfly (Lucilia cuprina) there is a transient change in the number of circulating, filamentous cellular fragments during the first hours after eclosion. Approximately 1 hr after the fly emerges from its puparium there is a rapid rise in the number of fragments from an undetectable quantity to a maximum of 1·3 × 10⁷ fragments per ml 75 min after eclosion. The number of fragments drops to about 5 × 10⁵ fragments per ml 1 hr later.Release of the fragments from their aggregation site can be inhibited by ligaturing flies between head and thorax as they emerge from their puparia. An injection of blood taken from older flies reverses this inhibition. Appreciable fragment disaggregating hormonal activity (FDH) can be detected in the haemolymph 5 min after eclosion.FDH and the tanning hormone, bursicon, could be the same chemical entity. Their release into the haemolymph is synchronous and both are proteins. The two hormonal activities cannot be separated from each other by ammonium sulphate fractionation or sieving through Sephadex G-50.     

The thoracic mechanism for eclosion and digging during the extrication behaviour of Diptera

ABSTRACT. Dipteran flies escape from the puparium by coordinated contractions of all segments of the body. Whereas special eclosion muscles have been identified in the abdomen and head, none has previously been described in the thorax. Three pairs of large thoracic muscles are described in this paper which are involved solely with eclosion. They have ultrastructures consistent with an ability to supercontract and all three degenerate within 48 h following escape from the puparium. Recordings of electrical activity show them to be rythmically active, coincident with thoracic contractions during eclosion. Many of the non-fibrillar flight muscles are also incorporated in the eclosion motor pattern and have a precise sequence of activity. Following escape there is a rapid switch from eclosion to flight motor and this is discussed with reference to afferent mediation and changing inputs to the muscles.     

Metabolic reserves associated with pupal diapause in the flesh fly, Sarcophaga crassipalpis

Larvae of Sarcophaga crassipalpis destined for pupal diapause (light:dark 12:12, 20°C) contain nearly twice as much lipid and twice the haemolymph protein concentration as larvae that will not enter diapause (light:dark 15:9, 20°C). This conspicuous difference in metabolic reserves provides the earliest indication of the developmental fate of the larva. Lipid reserves are utilized rapidly during the first half of diapause and then remain stable until adult eclosion. In contrast, residual dry weight changes very little early in diapause but drops sharply late in diapause, thus implying a transition from lipid utilization to protein or carbohydrate utilization in mid-diapause. We suggest that this metabolic transition marks the end of the “fixed latency period”: pupae readily respond to environmental or hormonal stimulation after this point. Diapause-destined larvae did not accumulate more glycogen than nondiapause-destined larvae, but an 80% decrease in glycogen at the onset of diapause and its elevation at the end of diapause suggests the utilization of glycerol or related compounds as cryoprotectants during diapause. Profiles of water content are very similar in short-day and long-day flies, thus suggesting that dehydration is not a mechanism exploited by the flesh fly to achieve cold hardiness. Adult flies that have experienced pupal diapause emerge from the puparium with lipid, glycogen, and water content nearly identical to flies that have not experienced diapause, but the residual dry weight is much lower. The severe depletion of protein may account for the reduced fecundity of flies that have experienced diapause.     

Posteclosion behavior of the flesh fly,Sarcophaga crassipalpis: A comparison of wild-type and unicorn mutants

Newly emerged flies go through a stereotypic behavioral pattern of walking, grooming, abdomen contraction (pulsing), and active uptake of air (pumping). These behavioral activities can be readily distinguished on the basis of hemolymph pressure changes. Wild-type flies and a unicorn mutant that fails to properly retract its ptilinum show identical patterns of posteclosion activity. However, a portion of the unicorns do not fully expand their wings and abdomen. Such flies are missing only the pumping component of the normal behavioral repertory, thus implying that pulsing and pumping are independently controlled.     

Characterisation of Predator‐Directed Displays in Tephritid Flies

Flies of the family Tephritidae are known to perform a display in front of their salticid spider predators. This display involves extending the wings while the fly moves from side to side. The wings of many of fly species are banded, and in some species, these bands are thought to deter their predators by mimicking the leg patterns of salticids. However, as this display is also seen in non‐mimicking flies, there is some uncertainty over the functional significance of these displays. In this study, we explored the efficacy of displays by the lightly banded but non‐mimicking Mexican fruit fly (Anastrepha ludens) in deterring attacks by the salticids Paraphidippus aurantius and Phidippus bidentatus. We tested the effect of band visibility and the fly's physiological condition on the production of these displays and the probability of attack by salticids. We filmed the interactions of flies and spiders and analysed fly displays in the presence of the salticid. We show that the fly's display deters salticids and promotes the fly's chances of survival and that the presence or absence of bands does not alter the possibility of attack. Flies fed on different quality diets showed similar rates of display. Our results suggest that tephritid flies deter attacks because of their display and not their appearance.     

Extrication,the primary event in eclosion,and its relationship to digging,pumping and tanning in Sarcophaga bullata

The cyclorrhaphous fly, Sarcophaga bullata (Diptera: Sarcophagidae), normally pupates within a semi-solid medium. Upon eclosion, it digs its way to an environment in which it is free of constraint and only then expands its body and wings and hardens (“tans”) its cuticle.The behaviour pattern is identical for both eclosion and digging, and is described here as a seven-phase continuum. The phases, each of which is a specific element in a series of peristaltic waves of muscular contractions and relaxations, are arranged in a deterministic sequence, for which the term “extrication behaviour” is proposed. The ability of flies to perform this sequential pattern decreases as they get older (time being measured in terms of minutes), the diminution being a depression in both the frequency and amplitude of peristaltic activity. The pattern eventually disappears at about 50 minutes of age. A study of the relationship between the onset of the post-eclosion events (i.e. expansion and hardening) which takes place after digging ends, and the decrease in intensity and, finally, termination of the extrication pattern, reveals that neither expansion nor hardening provides the feedback leading to pattern cessation.     

Aggressive behaviours of female Drosophila melanogaster are influenced by their social experience and food resources

Abstract Aggressive behaviours of female Drosophila melanogaster (Meigen) (Diptera: Drosophilidae) were studied in the laboratory. These behaviours included 'approach', a seemingly intentional movement of a fly to another fly, 'lunge', a dash at another fly, and 'wings erect', a brief erection of wings toward another fly. These behaviours were influenced by social experience and food resources. First, event frequencies of aggressive behaviours were higher in flies that had been held in isolation than in those that had been held in crowded conditions. This difference was the result of the social experience of attacking flies and not that of attacked flies. Second, flies showed aggressive behaviours more frequently when they were on food containing yeast colonies than when they were on food without yeast colonies. Third, flies conditioned to a food solution containing live yeast prior to observation showed lower frequency of aggressive behaviours than flies conditioned to a boiled food solution. Development of aggressive behaviours became apparent one day after eclosion.     

Neural control in the immunocytotoxic destruction of muscles in Diptera

Following successful escape from the puparium (eclosion), sets of muscles in all three segments of dipteran flies degenerate. Whereas the head and abdominal muscles degenerate in response to hormonal triggers released before, and immediately after eclosion, the thoracic muscles require a specific neural trigger encountered following eclosion. Evidence is presented for the role of neural activity in the activation of immunocytes that destroy the thoracic muscles. Removal of the neural input by severing the nerve to any particular muscle results in survival of the muscle and inactivation of the immunocyte. The destruction process can be stopped at any time by severing the nerve and the muscle fibres that remain continue to show normal physiology and response to stimulation. Elcctrophysiological recordings of the response to lethal attack are presented together with ultrastructural evidence demonstrating the invasion of muscle fibres by processes of the immunocyte.     

Post eclosion age predicts the prevalence of midgut trypanosome infections in Glossina

The teneral phenomenon, as observed in Glossina sp., refers to the increased susceptibility of the fly to trypanosome infection when the first bloodmeal taken is trypanosome-infected. In recent years, the term teneral has gradually become synonymous with unfed, and thus fails to consider the age of the newly emerged fly at the time the first bloodmeal is taken. Furthermore, conflicting evidence exists of the effect of the age of the teneral fly post eclosion when it is given the infected first bloodmeal in determining the infection prevalence. This study demonstrates that it is not the feeding history of the fly but rather the age (hours after eclosion of the fly from the puparium) of the fly when it takes the first (infective) bloodmeal that determines the level of fly susceptibility to trypanosome infection. We examine this phenomenon in male and female flies from two distinct tsetse clades (Glossina morsitans morsitans and Glossina palpalis palpalis) infected with two salivarian trypanosome species, Trypanosoma (Trypanozoon) brucei brucei and Trypanosoma (Nannomonas) congolense using Fisher's exact test to examine differences in infection rates. Teneral tsetse aged less than 24 hours post-eclosion (h.p.e.) are twice as susceptible to trypanosome infection as flies aged 48 h.p.e. This trend is conserved across sex, vector clade and parasite species. The life cycle stage of the parasite fed to the fly (mammalian versus insect form trypanosomes) does not alter this age-related bias in infection. Reducing the numbers of parasites fed to 48 h.p.e., but not to 24 h.p.e. flies, increases teneral refractoriness. The importance of this phenomenon in disease biology in the field as well as the necessity of employing flies of consistent age in laboratory-based infection studies is discussed.     

Physiological state influences the antennal response of Anastrepha obliqua to male and host volatiles

The sexual and host‐related behaviours of the fruit fly Anastrepha obliqua Macquart (Diptera: Tephritidae) are mediated by volatile compounds. However, whether the physiological state of this species affects its antennal and behavioural responses to semiochemicals is unknown. The effects of age, mating status, diet and the topical application of methoprene, a Juvenile hormone analogue (JHA), on the antennal sensitivity of this tephritid fruit fly species to selected male [(Z)‐3‐nonenol] and host fruit volatiles (ethyl benzoate, ethyl hexanoate, ethyl butyrate and trans‐β‐ocimene) are investigated using electroantennography (EAG). Overall, (Z)‐3‐nonenol and ethyl benzoate elicit the highest EAG responses in both sexes. Flies of both sexes aged 1, 5 and 10 days old show higher EAG responses to the tested compounds compared with flies aged 20 days old. Virgin females and males show higher EAG responses to volatile compounds than mated flies. Females and males fed with sugar plus protein show higher antennal responses to volatiles compared with flies fed sugar or protein alone. Flies of both sexes treated with methoprene show higher antennal responses than flies treated with acetone (control). These results suggest that the peripheral olfactory system in A. obliqua is modulated by the physiological state of the flies.     

Studying the “fly factor” phenomenon and its underlying mechanisms in house flies Musca domestica

The “fly factor” was first discovered >60 years ago and describes the phenomenon that food currently or previously fed on by flies attracts more foraging flies than the same type and amount of food kept inaccessible to flies. Since then, there has been little progress made to understanding this phenomenon. Our objectives were (i) to demonstrate the existence of the fly factor in house flies, Musca domestica and (ii) to study underlying mechanisms that may cause or contribute to the fly factor. In 2‐choice laboratory bioassays, we obtained unambiguous evidence for a fly factor phenomenon in house flies, in that we demonstrated that feeding flies are more attractive to foraging flies than are nonfeeding flies, and that fed‐on food is more attractive to foraging flies than is “clean” food. Of the potential mechanisms (fly excreta, metabolic output parameters [elevated temperature, relative humidity, carbon dioxide]), causing the fly factor, fly feces, and regurgitate do attract foraging flies but none of the metabolic output parameters of feeding flies does. Even though feeding flies produce significantly more CO₂ than nonfeeding flies, elevated levels of CO₂ have no behavior‐modifying effect on flies. Preferential attraction of house flies to fly feces and regurgitate indicates that the flies sense airborne semiochemicals emanating from these sources. Hypothesizing that these semiochemicals are microbe‐produced, future studies will aim at isolating and mass producing these microbes to accumulate semiochemicals for identification.     

Survival, ovarian development and bloodmeal size for the horn fly Haematobia irritans irritans reared in vitro

Horn flies, Haematobia irritans irritans (Linneaus) (Diptera: Muscidae) were reared in vitro using cattle, pig, horse, rabbit, sheep, goat or chicken blood. The highest survival, bloodmeal size and rate of ovarian development were recorded for both female and male flies fed cattle blood. Flies fed pig, rabbit, sheep and goat blood showed intermediate survival. Flies fed chicken blood showed the lowest survival rates, ingested the smallest bloodmeals and did not develop ovaries. The relationship between dietary factors and host specificity of the horn fly, and the efficiency of vertebrate blood source of several animals for laboratory colonization of horn fly are discussed.     

The role of eclosion hormone in the larval ecdyses of Manduca sexta

Each larval moult in Manduca sexta consists of an identical series of developmental and behavioural events leading up to ecdysis. Injections of eclosion hormone into staged larvae in any instar resulted in the premature elicitation of the larval pre-ecdysis behaviour, comprising a rhythmic sequence of muscle contractions, followed by the larval ecdysis behaviour.A marked depletion of eclosion hormone stores form the ventral chain of ganglia coincided with each larval ecdysis and in the moult to the fifth instar, eclosion hormone activity appeared in the blood at the onset of the pre-ecdysis behaviour.Responsiveness to eclosion hormone for pre-ecdysis and ecdysis behaviour developed about 12 and 6 hr before normal ecdysis, respectively. Elicitation of ecdysis behaviour by exogenous hormone inhibited both subsequent behavioural responses to eclosion hormone and endogenous hormonal release.In conclusion, the behavioural programme involved in each larval ecdysis appears to be controlled by the eclosion hormone.     

家蝇卵巢摄取卵黄蛋白的机理

在家蝇Ｍｕｓｃａ　ｄｏｍｅｓｔｉｃａ　ｖｉａｉｎａ的印黄发生过程中,卵母细胞摄取卵黄原蛋白与滤沟开放是相关的。观察不同发育时期的家蝇滤泡结果表明,在摄取活动最旺盛的时期也就是卵黄发生的顶盛时期,其滤泡开放程度最大,而在卵黄发生前期和后期基本上没有摄取活动,此时的滤泡上皮细胞间不开放。卵巢体外培养的激素处理表明,ＪＨ可以促进滤泡开放。家蝇卵巢微粒体制备物的Ｎａ＋－Ｋ＋ＡＴＰ酶活力在卵巢发育过程中存在着动态变化。羽化后２４小时时有一定的酶活性,随着卵黄发生的进行,酶活力逐渐增加,到现化４８小时时酶活力最高,然后又开始下降,到弱化７２小时时已经很小。羽化３２小时的家蝇点滴或注射ＪＨ之后,测得的卵巢微粒体制备物的Ｎａ＋－Ｋ＋ＡＴＰ酶活力比正常羽化３６小时的高,羽化率４４小时的家蝇点滴和注射ＪＨ之后,测得酶活力比正常羽化４８小时的低．羽化３６小时和４８小时的家蝇卵巢微粒体制备物与ＪＨ共同作用后,其Ｎａ＋－Ｋ＋ＡＴＰ酶的活力分别增加２．９５倍和３．５０倍,羽化４８小时的家蝇卵巢在含有ＪＨ的培养液中培养后,其匀浆液的酶活性为对照组的１．２６倍。由此我们可以推测在家蝇的卵黄发生过程中,ＪＨ通过促进滤泡开放和增加卵巢微粒体制     

The 28th Conference of the International Society for Chronobiology (ISC) will be held in Bucharest (Romania), at Ramada Parc Hotel on 4–8 June 2014

The eclosion rhythm of a laboratory population of Drosophila melanogaster was studied under 12h light, 12h dark (LD 12:12) cycles. Although most of the flies were found to eclose just after “lights on” in LD 12:12, termed within gate (WG) flies, a few flies were found to eclose nearly 10h after peak eclosion, termed outside gate (OG) flies. The circadian parameters of the clocks controlling oviposition rhythms in the WG and the OG flies were estimated to understand the cause of such differences in the timing of eclosion. The distribution of the fraction of individual flies exhibiting single, multiple, and no significant period in the WG flies was significantly different from distribution in the OG flies. Compared to the WG flies, more OG flies were found to exhibit oviposition rhythm with multiple periodicity, whereas more WG flies exhibited an oviposition rhythm with a single significant period. The fraction of flies with arrhythmic oviposition was similar in both the WG and the OG flies. Free-running period τ in constant darkness (DD) and the phase angle difference ψ in LD 12:12 for the oviposition rhythm of WG and OG flies were significantly different. These results suggest that the differences in the time of eclosion between the flies eclosing within the gate and outside the gate of eclosion are probably due to differences in the circadian system controlling eclosion, which is reflected by the differences in their oviposition rhythm. (Chronobiology International, 18(4), 601–612, 2001)     

家蝇卵巢摄取卵黄蛋白的机理

在家蝇Musca domestica viaina 的卵黄发生过程中,卵母细胞摄取卵黄原蛋白与滤泡开放是相关的。观察不同发育时期的家蝇滤泡结果表明,在摄取活动最旺盛的时期也就是卵黄发生的顶盛时期,其滤泡开放程度最大,而在卵黄发生前期和后期基本上没有摄取活动,此时的滤泡上皮细胞间不开放。卵巢体外培养的激素处理表明,JH可以促进滤泡开放。家蝇卵巢微粒体制备物的Na⁺-K⁺ATP酶活力在卵巢发育过程中存在着动态变化。羽化后24小时时有一定的酶活性,随着卵黄发生的进行,酶活力逐渐增加,到羽化48小时时酶活力最高,然后又开始下降,到羽化72小时时已经很小。羽化32小时的家蝇点滴或注躬 JH之后,测得的卵巢微粒体制备物的Na⁺-K⁺ATP酶活力比正常羽化36小时的高,羽化44小时的家蝇点滴和注射JH之后,测得酶活力比正常羽化48小时的低。羽化36小时和48小时的家蝇卵巢微粒体制备物与JH共同作用后,其Na⁺-K⁺ATP酶的活力分别增加2.95倍和3.50倍,羽化48小时的家蝇卵巢在含有JH的培养液中培养启,其匀浆液的酶活性为对照组的1.26倍。 由此我们可以推测在家蝇的卵黄发生过程中,JH通过促进滤泡开放和增加卵巢微粒体制备物Na⁺-K⁺ATP酶的活力,从而调控卵母细胞对卵黄蛋白的摄取。     

Effects of host age, host density and parent age on reproduction of the filth fly parasite Urolepis rufipes (Hymenoptera: Pteromalidae)

Urolepis rufipes Ashmead, a pteromalid wasp, was recently discovered parasitizing house fly and stable fly pupae in eastern Nebraska dairies. Studies have been conducted on the biology of this parasite to evaluate its potential as a biological control agent of stable flies (Stomoxys calcitrans (L.] and house flies (Musca domestica L.). House fly pupae were suitable as hosts for U.rufipes at all ages; however, significantly higher parasitism occurred on host pupae aged 96-120 h. Parasite-induced mortality (host mortality without progeny production) was higher than for other pteromalid parasites of filth flies under similar conditions. Parasitism increased with parasite--host ratio at 20 degrees C; however, the opposite was noted at 30 degrees C for parasite--host ratios ranging from 5:50 to 50:50. Fly eclosion decreased as parasite--host ratio increased at 20 degrees C, and no host eclosion occurred at the highest parasite--host ratios (20:50 and 50:50) at 30 degrees C. Females produced an average of 18.6 female and 7.6 male progeny. 88% of the progeny were produced during the first 6 days post parental eclosion. The short life span, low progeny emergence rate and high per cent host eclosion, in comparison with other parasite species, suggests that the Nebraska strain of U.rufipes may not an effective biological control agent of house flies.     

Differential posteclosion housing experiences and reproduction in Drosophila

Differential housing following eclosion was found to affect the mating behaviour of both sexes of Drosophila melanogaster. Flies housed in isolation showed higher mating frequencies and shorter latencies than did group-housed flies. Given a choice of an isolated or group-housed male, females tended to mate with males with similar housing experiences as themselves. Given a choice of an isolated or group-housed female, males strongly preferred the former. The possibility is advanced that these effects are mediated by olfactory stimuli.     

SEXUAL SELECTION,VIABILITY SELECTION,AND DEVELOPMENTAL STABILITY IN THE DOMESTIC FLY MUSCA DOMESTICA

Associations between developmental stability, sexual selection, and viability selection were studied in the domestic fly Musca domestica (Diptera, Muscidae). Developmental stability of the wings and tibia of flies of both sexes, measured in terms of their level of fluctuating asymmetry, was positively associated with mating success in free ranging populations and in sexual selection experiments. Mated individuals may have obtained indirect fitness benefits from sexual selection of two different kinds. First, the entomopathogenic fungus Enthomophthora muscae (Zygomycetes, Entomophthorales) infects and kills adult domestic flies, and flies dead from fungus infections had more asymmetric wings than flies dead for other reasons. Experimental deposition of fungus spores on uninfected flies demonstrated that flies with asymmetric wings were more susceptible to fungus infections than flies with symmetric wings. Second, domestic flies were frequently eaten by insectivorous barn swallows Hirundo rustica, and flies depredated by birds had more asymmetric wings and tibia than surviving flies.     

Ovipositional behaviour of Simulium argyreatum and S. variegatum and its relationship to infection by the fungus Erynia conica (Entomophthoraceae)

SUMMARY. 1. At two sites in Devon S. argyreatum and S. variegatum only oviposited on water-splashed boulders. The oviposition season was from 15 March to 9 November at Steps Bridge and from 28 March to 7 December at Fingle Bridge. Flies laid eggs only during a brief period after sunset.
2. Flies infected with the fungus E. conica returned to the oviposition sites at the same times as healthy flies, but infected flies appeared to be unable to lay eggs.
3. At least 10.9% of healthy flies were found to have infective conidia of E. conica on their wings after laying eggs.