Egg developmental status and the complexity of synthetic kairomones combine to influence attraction behaviour in the blowfly Calliphora vicina

The flight responses of 750 female Calliphora vicina Robineau‐Desvoidy, 1830 (Diptera: Calliphoridae) are investigated in a wind tunnel bioassay. The attraction of C. vicina towards dead mice and seven different synthetic lures made from dimethyl trisulphide, mercaptoethanol and O‐cresol is compared. Responses towards natural odours and the three‐component synthetic kairomones depend on the flies' ovarian egg developmental status. The natural and three‐component lures also induce similar age‐dependent responses, although the dead mice lure yields a significantly higher attraction. Oriented flight increases with the number of chemicals in the synthetic kairomone; one‐, two‐ and three‐compound lures induce 13–25%, 32–43% and 62% attraction, respectively. Responses to one‐component lures are not significantly influenced by egg developmental status, whereas blends of two or three components are. Attraction levels increase in a stepwise manner both across egg developmental categories and with the number of compounds. The results suggest that the attractiveness of synthetic kairomones is influenced not only by the blowflies' physiological state, but also by the complexity of the lure.     

Delayed egg production and a possible group effect in the blowfly Calliphora vicina

Abstract .Protein-fed Calliphora vicina , F₁ offspring of wild flies in two cages with lower and higher fly densities showed variable delay in starting oocyte vitellogenesis at ambient semi-natural temperatures in warm July–August weather in 1996 and 1997 at Durham in northern England (54°45' N). The high-density flies in 1996 showed no delay, in that the thermal sum (degree-days) experienced was 133, comparable to 18°C constant, assuming the lower threshold for egg maturation to be 5°C. Low-density cages and flies in a large outdoor cage (2 m³) in both years showed delays in production of first eggs of 34 days (thermal sum 293 degree-days) in 1996 and 32 days (396 degree-days) in 1997, and longer delays for other individuals. Delays in egg production at low densities relative to high densities seem to be a group effect of unknown mechanism.     

Effects of constant light on the rhythm of adult locomotor activity in the blowfly, Calliphora vicina

Abstract. Females of the blowfly, Calliphora vicina , showed an increase in the free-running period (γ) of their locomotor activity rhythm when transferred from continuous darkness (DD) to continuous 'dim' light (LL) at an irradiance below about 0.03 Wm^-2. Transfer to LL of this intensity also caused a reduction in the duration of the active phase (α) of the cycle. Transfer to 'bright' light (>0.03 Wm²), however, lead to arrhythmicity. Data suggest that constant light of this intensity does not 'stop' the circadian pacemaker but imposes behavioural arrhythmicity at a more superficial level.     

Larval growth rates of the blowfly, Calliphora vicina, over a range of temperatures

Blowfly larvae (Diptera: Calliphoridae) fulfil an important ecological function in the decomposition of animal remains. They are also used extensively in forensic entomology, predominantly to establish a minimum time since death, or a minimum post-mortem interval, using the larval length as a 'biological clock'. This study examined the larval growth rate of a forensically important fly species, Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae) at temperatures of between 4 degrees C and 30 degrees C, under controlled laboratory conditions. The laboratory flies had been trapped initially in London, U.K. The minimum developmental temperature was estimated to be 1 degrees C and 4700 accumulated degree hours (ADH) were required for development from egg hatch to the point of pupariation. Lines fitted to the laboratory larval growth data were found to adequately explain the growth of larvae in the field. The nature of variation in growth rates from geographically isolated populations is discussed.     

Precocious egg development in the blowfly Calliphora vicina: implications for developmental studies and post-mortem interval estimation

The occurrence of precocious egg development in forensically important calliphorid species has previously been reported; however, the frequency of occurrence in both wild and captive colonies, and the consequent effects on developmental studies and post-mortem interval (PMI) estimates, are largely unknown. A PMI estimate based on samples developed from precocious eggs could be extended by the entire period of embryogenesis, which at 22 °C would result in a significant error of around 24 h. This study examined the occurrence of precocious egg development in Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae) wild-caught and captive-bred adults by investigating the presence of larvae in the adult female genital chamber and by monitoring hatching times of entire batches of eggs throughout embryogenesis, respectively. A total of 8.82% of gravid wild-caught females contained a larva in the genital tract (i.e. a precocious egg). This indicates that all specimens collected should be considered potentially precocious for the purpose of PMI estimation. Less than 2.55% of a batch of eggs laid by captive females were precocious; protocols for minimizing the effect of precocious eggs on developmental studies are suggested.     

Proline-specific dipeptidyl peptidase from the blue blowfly Calliphora vicina hydrolyzes in vitro the ecdysiostatic peptide trypsin-modulating oostatic factor (Neb-TMOF)

To elucidate the mechanisms of inactivation of the ecdysiostatic peptide trypsin-modulating oostatic factor (Neb-TMOF) in the blue blowfly Calliphora vicina, we investigated its proteolytic degradation. In homogenates and membrane and soluble fractions, this hexapeptide (sequence: NPTNLH) was hydrolyzed into two fragments, NP and TNLH, suggesting the involvement of a proline-specific dipeptidyl peptidase. The dipeptidyl peptidase activity was highest in the late larval stage. It was purified 240-fold from soluble fractions of pupae of mixed age and classified on the basis of several catalytic properties as an invertebrate homologue of mammalian dipeptidyl peptidase IV (EC 3.4.14.5). Fly dipeptidyl peptidase IV has a molecular mass of 200 kDa, showed a pH optimum of 7.5–8.0 with the chromogenic substrate Gly-Pro-4-nitroanilide, and cleaved other chromogenic substrates with penultimate Pro or, with lower activity, Ala. It liberated Xaa-Pro dipeptides from the N-terminus of several bioactive peptides including substance P, neuropeptide Y, and peptide YY but not from bradykinin, indicating that the peptide bond between the two proline residues was resistant to cleavage. Fly dipeptidyl peptidase belongs to the serine class of proteases as the mammalian enzyme does; the fly enzyme, however, is not inhibited by several selective or nonselective inhibitors of its mammalian counterpart. It is suggested that dipeptidyl peptidases exert a regulatory role for the clearance not only of TMOF in flies but for other bioactive peptides in various invertebrates. Arch. Insect Biochem. Physiol. 37:146–157, 1998. © 1998 Wiley-Liss, Inc.     

The effect of larval temperature and photoperiod on the incidence of larval diapause in the blowfly, Calliphora vicina

ABSTRACT. The blowfly, Calliphora vicina Meigen (Diptera: Calliphoridae), displays a maternally induced larval diapause. Progeny of adults exposed to short days enter diapause if the larval temperature is 15C or below; exposing adults to long days, or larvae to temperatures above 15C, results in non-diapause. By keeping progeny from short-day parents at the parental temperature of 23.5C for various lengths of time before transfer to 11C, it could be shown that the diapause-averting effect of high temperature operates in the late wandering stage of larva, possibly at the moment of the decision for the brain-ring gland complex to release PTTH/ecdysone at the diapause/non-diapause stage.
Although photoperiodic induction in the blowfly is maternal, previous work had shown that the larvae were also slightly sensitive to photoperiod. From the present study it is evident that also the eggs are photo-sensitive.     

Maternal influence on the incidence and duration of larval diapause in Calliphora vicina

ABSTRACT. The photoperiodic mechanism governing larval diapause in the blowfly Calliphora vicina R.-D. (Diptera: Calliphoridac) is largely maternal. The critical daylength for adult flies at 20C, and larvae derived from day 12 eggs and maintained in darkness at 11C, is about 14.5 h/24. At short daylength (LD 12:12 h) and a range of temperatures, eggs laid on or before day 9 gave rise to a low incidence of diapause, whereas those laid on day 10 and later gave rise to a high incidence; the photoperiodic 'counter' therefore shows a temperature-compensated mechanism for 'accumulating' successive short days. The rate of switching from non-diapause to diapause progeny is hardly affected by the timing of protein meals, although an early supply of meat accelerates egg development and leads to an increasing proportion of early, non-diapausing progeny. There is no evidence for a maternal effect preventing diapause induction in the first post-diapause ('spring') generation of flies. Diapausing larvae terminate diapause spontaneously in darkness at 11C after a variable period which is positively correlated with the incidence of diapause in the group. Diapause incidence and duration therefore are both determined maternally.     

Incorporation of calliphorin into the cuticle of the developing blowfly,Calliphora vicina

Summary The stage-specific appearance of calliphorin in cuticles of Calliphora vicina was analysed by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. The fate of the protein, injected into last instar larvae, was pursued by autoradiography of histological sections. Fractionation of sclerotized pupal cuticle in buffer-soluble, urea-soluble and NaOH-soluble fractions shows that calliphorin forms covalent and non-covalent links with other cuticle components. Calliphorin traverses the epidermal cells and enters the cuticle in an undegraded state and appears to be an important constituent of the sclerotizing system.     

Serotonin modulates a photic response in circadian locomotor rhythmicity of adults of the blow fly, Calliphora vicina

Abstract. The present experiments were undertaken to explore a role for serotonin (5-hydroxytryptamine, 5-HT) in modulating photic signal transduction in photoreceptors of the blow fly, Calliphora vicina. Injection of p-chlorophenylalanine (pCPA) into the haemolymph appeared to reduce sensitivity to the photic effects of constant ‘bright’ light (LL hyperactivity and circadian arrhythmicity). After drug injection in bright LL, flies continued with a free-running rhythm as in constant darkness (DD) or with a lengthened period τ as in ‘dim’ LL. When 5-HT was injected into flies kept in dim LL, they became hyperactive and arrhythmic as in bright LL. This finding suggests a potential role for serotonin as mediator of circadian changes in the insect visual system including extraretinal photoreceptors.     

Phenology and life history of the blowfly Calliphora vicina in stockfish production areas

Calliphora vicina Robineau‐Desvoidy (Diptera: Calliphoridae) causes yearly losses of 1–2 million Euros to the stockfish industry in Lofoten, Norway. To develop an efficient management program, knowledge of its life cycle and phenology in production areas is needed. Cohort studies in a simulated Lofoten climate showed that field abundance peaks of adults in early spring and midsummer can be explained by a cohort originating from stockfish and its subsequent generations. Laboratory simulations with normal, increased, and decreased Lofoten temperatures indicate that C. vicina overwinter as a mix of larvae, pupae, and adults, and a temperature change of ± 2 °C significantly influences reproductive timing, reproductive output, and female mortality. Flies originating from stockfish reproduced during the first summer when temperatures were increased 2 °C above normal. At lower temperatures, the reproductive investment was low or absent during the first summer and the adult flies entered the winter in a diapausing state. Most offspring produced during the first summer and autumn developed continuously without maternally induced diapause, pupated during the winter, and hatched in the early spring to co‐occur with their parent generation during stockfish production. Calliphora vicina showed flexibility in reproductive efforts and overwintering strategies. The high proportion of adults overwintering compared with the commonly used larval diapause strategy might be interpreted as an adaptation to exploit the stockfish resource. The majority of female C. vicina that cause damage to stockfish likely developed on fish dried the previous year, and a continuous year‐long trapping is recommended to decimate the population.     

Immunocytochemical demonstration of S-antigen (arrestin) in the brain of the blowfly Calliphora vicina

S-Antigen (arrestin)-immunoreaction can be considered as a marker for retinal and extraretinal photoreceptors in both vertebrate and invertebrate species. The present immunocytochemical study with the blowfly Calliphora vicina revealed S-antigen immunoreaction in retinal photoreceptors and various groups of neurons bilaterally distributed in the optic lobes and in the proto-, deuto- and tritocerebrum. S-Antigen-immunoreactive processes and terminal formations were found in the lower division of the central body complex and in the neuropil of the mushroom body. Also neuropil regions of the optic lobe, the lamina, medulla and lobula displayed S-antigen-immunoreactive fibers which were arranged in different patterns. These immunocytochemical data suggest that extraocular photoreceptors may be located in various parts of the blowfly brain. They provide a structural basis for further experiments which are needed to identify definitely these elements as extraretinal photoreceptors.     

The effect of in vivo heat treatments on blowfly flight muscle mitochondrial function: Effects on partial reactions of the respiratory chain

1. 1. The development of thermotolerance has been shown to protect blowfly flight muscle mitochondrial function from damage resulting from an LD₅₀ in vivo heat dose.

2. 2. The principal sites of the damage have been studied using specific inhibitors of the respiratory chain, rotenone and antimycin A, together with substrates that stimulate respiration through the different complexes.

3. 3. Complex I was identified as the primary site for heat damage. State III respiration was inhibited following the LD₅₀ in vivo heat dose, and uncoupling with FCCP did not restore respiration to control levels, indicating that the respiratory enzymes were inactivated. The development of thermotolerance protected this site from heat damage.

4. 4. In contrast, G3-P stimulated respiration was the same in control, LD₅₀ in vivo treated controls and LD₅₀, in vivo treated thermotolerant mitochondria, and significantly higher than state III respiration of LD₅₀ in vivo treated controls. This suggested that respiration through G3-P dehydrogenase, Co enzyme Q and Complex III is not damaged. However, as G3-P stimulated respiration of coupled mitochondria from LD₅₀ in-vivo treated flies was markedly reduced (El-Wadawi and Bowler, 1995. J. exp. Biol. 198: 2413–2421), phosphorylation at complex III may be inhibited also.

5. 5. Ferrocyanide stimulated respiration through cytochrome c-Complex IV was also inhibited in LD₅₀ in vivo treated flies, as compared with unheated control mitochondria. However, thermotolerance protected this site also from heat damage.

     

风洞技术在昆虫化学通讯研究中的应用

综述了昆虫化学生态学中所使用的风洞技术。内容包括风洞的构造 ,风洞的工作条件 ,风洞操作中的技巧和数据采集 ,昆虫在风洞中表现出的典型行为特征以及一些需要注意的问题     

Maternal temperature has different effects on the photoperiodic response and duration of larval diapause in blow fly ( Calliphora vicina ) strains collected at two latitudes

Abstract .The blow fly Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae) has a wide distribution across northern and temperate Europe. It has a facultative, maternally-induced larval diapause in response to short days. The photoperiodic response, measured at 15 and 20°C, of two populations was compared. A southern population (originating at 51° N) was sensitive to temperature at all daylengths; the incidence of diapause was greatly reduced at 20°C compared with 15°C. The photoperiodic response of a northern population (from 65° N) was sensitive to temperature only in long days; in short days (< 14 h of light) the response of this strain was identical at each temperature.
Variation in parental photoperiod and temperature were found to affect the duration of larval diapause, indicating a role for maternal effects in diapause intensity as well as incidence. However, the between-strain variation was greater than that within strains, indicating qualitative differences in diapause response. These differences may arise from the ecological conditions at the points of origin of the two strains. The northern strain from the harsher climate has a more intense diapause that follows a relatively temperature-insensitive photoperiodic response. In contrast, the southern strain has a shallow diapause and its photoperiodic response may be overridden by the experience of concurrent high temperature.     

Morphology of the first instar of Calliphora vicina, Phormia regina and Lucilia illustris (Diptera, Calliphoridae)

Scanning electron microscopy documentation of first instar Calliphora vicina Robineau-Desvoidy, Phormia regina (Meigen) and Lucilia illustris (Meigen) (Diptera: Calliphoridae) is presented for the first time, and the following morphological structures are documented: pseudocephalon; antenna; maxillary palpus; facial mask; labial lobe; thoracic and abdominal spinulation; spiracular field; posterior spiracles, and anal pad. Light microscopy documentation and illustrations are provided for the cephaloskeleton in lateral and ventral views. New diagnostic features are revealed in the configuration of the facial mask, cephaloskeleton and posterior spiracles. The first instar morphology of C. vicina, Ph. regina and L. illustris is discussed in the light of existing knowledge about early instars of blowflies.     

The use of carrion as breeding sites by the blowfly Lucilia sericata and other Calliphoridae

Abstract. To examine the species composition of flies breeding in carrion in the field, the carcasses of mice and quail were exposed on sheep farms in the South West of England. Calliphora vicina was the dominant species of Diptera; 19,294 individuals emerged from 175 of the 241 infested carcasses recovered. Lucilia sericata emerged from only 39 of the infested carcasses, at a median of 10 adults per infested carcass. Other species of Lucilia present were L.ampullacea, L.caesar and L.illustris. The highest number of L.sericata emerged from carcasses placed in open pasture, the highest number of C.vicina emerged from carcasses in hedgerow, whereas the highest numbers of L.caesar, L.ampullacea and L.illustris emerged from carcasses in woodland. The duration of exposure of carcasses in the field was negatively related to the size of the adult L.sericata which emerged and, in woodland and hedgerow habitats, to the number of L.sericata which emerged. These data indicate that the larvae of L.sericata in carcasses experience significant levels of competition and that the intensity of this competition may be sufficient to reduce the numbers of L.sericata able to emerge successfully. The size distributions of female L. sericata which emerged from carcasses or which were caught as adults in the field showed only a small degree of overlap, suggesting that only a relatively small proportion of the wild L.sericata population emerge from carcass breeding sites. The results are discussed in relation to the development of new approaches to the control of blowfly strike of sheep.     

The control of wing kinematics by two steering muscles of the blowfly (Calliphora vicina)

We used a combination of high speed video and electrophysiological recordings to investigate the relationship between wing kinematics and the firing patterns of the first (b1) and second (b2) basalar muscles of tethered flying blowflies (Calliphora vicina). The b1 typically fires once during every wing stroke near the time of the dorsal stroke reversal. The b2 fires either intermittently or in bursts that may be elicited by a visual turning stimulus. Sustained activation of the b1 at rates near wing beat frequency appears necessary for the tonic maintenance of stroke amplitude. In addition, advances in the phase of b1 activation were correlated with both increased wing protraction during the down-stroke and increased stroke amplitude. Similar kinematic alterations were correlated with b2 spikes, and consequently, both muscles may function in the control of turns toward the contralateral side. The effects of the two muscles were evident within a single stroke period and decayed quickly. Kinematic changes correlated with b1 phase shifts were graded, suggesting a role in compensatory course stabilization. In contrast, b2 spikes were correlated with all-or-none changes in the wing stroke, a characteristic consistent with a role in mediating rapid turns towards or away from objects.Abbreviations b1 first basalar muscle - b2 second basalar muscle - PWP pleural wing process - RS radial stop - S wing span · - angle between the stroke plane and the longitudinal body axis - stroke amplitude - stroke elevation - L wing length - b1 phase of b1 activation - b2 phase of b2 activation - stroke deviation     

Sex differences in olfaction‐mediated visual acuity in blowflies and its consequences for gender‐specific trapping

The behaviour of 650 female Calliphora vicina Robineau‐Desvoidy (Diptera: Calliphoridae) was examined in a wind tunnel using odour, in combination with six artificial visual stimuli, ranging from a simple black square to a three‐dimensional model of a dead mouse. The carcasses of laboratory mice were used to provide a natural odour and visual source, and a blend consisting of dimethyl trisulphide, mercaptoethanol, and o‐cresol was used to provide a synthetic lure. Significant differences were found in attraction to these odour sources: 90% of the flies oriented upwind to the natural source and 62% to the synthetic lure. No significant differences were found in upwind orientation towards different visual stimuli, but flies showed significantly more landings if the visual cues provided a vertical contrast against the background. A horizontal contrast gave no difference in landing rate compared to treatments without visual cues. In a field study, the blowfly genera Pollenia, Calliphora, and Lucilia were caught. The overall blowfly catch was significantly higher when an odour lure was present (Pollenia: 3×, Calliphora: 15×, Lucilia: >79×). A significant three‐way interaction between visual cue, genus, and gender was found. The saprophagous Lucilia and Calliphora showed a gender‐specific response to visual stimuli, whereas the parasitic Pollenia did not. A 2:1 female:male sex ratio was found for Calliphora spp. and a 12:1 sex ratio for Lucilia spp. The data suggest that landing responses of male and female saprophagous blowflies, and consequently trap catches, result from olfaction, but also from gender‐specific visual responses when under the influence of odour.