摘要:

Abstract.The spontaneous activity and locomotor responses to liver odour of females of the blowflyLucilia sericataMeigen (Diptera: Calliphoridae) were examined in the laboratory using a rocking‐box olfactometer. Spontaneous activity levels depended on fly age, previous exposure to protein and recent oviposition history; 1‐day‐old females, 3‐day‐old protein‐fed females, and females that had recently oviposited exhibited lower levels of spontaneous activity than protein‐deprived or fully gravid individuals. Changes in locomotor activity in response to liver odour also depended on previous exposure to protein. In protein‐fed flies, activity decreased in response to liver odour and then increased on termination of an odour pulse. This response became more pronounced with age, broadly in line with the expected state of oocyte maturation. This pattern of change was not evident in protein‐deprived females. The results are discussed in relation to the relative importance of protein and oviposition‐site resources toL. sericataand the resultant age and ovarian development‐stage biases evi

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1995.tb00816.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Abstract.Key characteristics of airflow were measured in the African bush in a study of host odour plume structure. Wind speed, speed variance, direction, and directional variance were measured by conventional cup anemometers plus wind‐vanes and by a solid state ultrasonic anemometer, on time scales from seconds to minutes. The two technologies gave opposite relationships between wind speed and turbulence measured as rate of angular direction change in the wind (° s‐1). A positive correlation between turbulence and wind speed was observed with mechanical anemometers and wind‐vanes, evidently caused by their inherent hysteresis (stalling in weak wind, overswinging after gusts). The same correlation wasnegativewith the solid‐state anemometer which, being hysteresis free, should have measured the true directional turbulence more accurately. Such fine‐scale turbulence at a fixed point in space (on a scale of about ∼15 cm diam.) decreased with wind speed up to ∼1.5 m s‐1, as does large‐scale (∼1m diam.) turbulence of air movingthroughspace (Bradyet al., 1989). This decrease occurred both within vegetation and out in the open, but the slope and intercepts of the relationship depended on vegetation and topography. Variables for describing wind speed and turbulence are considered in the context of o

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1995.tb00817.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Abstract.Tsetse flies (mainlyGlossina pallidipesAust.) were captured by various means at sources of artificial host odour in Zimbabwe and Kenya. Their rates of arrival and flight directions were compared with simultaneous data on the wind's speed and direction, on time‐scales ranging from 1 s to 30 min. It was predicted that because increasing wind speed up to 1 m s‐1straightens out the airflow (Bradyet al., 1989) it will straighten out odour plumes, make them easier to navigate, and should therefore increase the rate of arrival of flies at an odour source. In the event, the relationship proved to be more complex, with both positive and negative correlations of arrival rate on wind speed. It seems there is a bimodal relationship: odour source finding is positively related to increasing wind speed in weak winds up to ∼0.5 m s‐1(presumably as the odour plume straightens out), but is negatively related to increasing wind speed in strong winds above ∼1.0 m s‐1(presumably due to increasing turbulence breaking up the o

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1995.tb00818.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Abstract.The artificially selected ‘non‐diapause’ strain ofPyrrhocoris apterus(L.) (Heteroptera) showed no diapause response to photoperiod at 26°C (Socha&Hodkova, 1994). However, the diapause response to short‐day photoperiod (LD 12:12 h) became apparent at lower temperatures of 17°C (70% diapause) or 20°C (41% diapause). Diapause was induced in 60% females by short‐day photoperiod combined with thermoperiod of 26/16°C, whereas only 20% diapause was induced by the same thermoperiod under continuous darkness. Thus the time‐measuring system was not removed by artificial selection but the diapause response was shifted to lower temperatures. The diapause response to short days seems to be favoured rather by low temperature during scotophase than by low temperature throughout the whole light/dark cycle. If the percentage of diapause at 26°C is compared in F1hybrids and in wild and selected parental strains the diapause appears to be dominant at LD 13:11 h but recessive at LD 11:13 h and LD 10:14 h. A hypothesis is proposed that the inheritance of the percentage of diapause in F1 hybrids is determined by interactions of genes controlling the temperature dependence of photop

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1995.tb00819.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Abstract.The influence of age, temperature and host plant on pheromone release was investigated in females of two forms ofCallosobruchus maculatus(Coleoptera: Bruchidae), referred to as the flightless form and the flight form. The emission of pheromone seemed to be correlated with reproductive status: the flightless‐form females which were sexually mature at emergence began to release pheromone on the first day following emergence. The flight‐form females which exhibited no reproductive activity at emergence also showed a delayed emission of pheromone. The temperature conditions and the availability of host plant seeds had no apparent effect on pheromone release by the flightless form. In flight‐form females pheromone release was stimulated by the presence of host plant seeds. Temperature seemed to affect the age at which females initiated pheromone release for the first time after emergence, pheromonal emission being brought forward slightly by higher temperature. All these results are discussed relative to the specific environment of each

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1995.tb00820.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Abstract.The patterns of changes in cuticle weight, its chitin content and chitinase activity have been studied during postembryonic development of the housefly,Musca domesticaL. During pupariation the larval cuticle loses weight. During the early part of this weight‐loss the decline in chitin content parallels the overall change in cuticle weight. A simultaneous elevation in chitinase activity suggests that at this time the larval cuticle is being enzymatically degraded. Later weight loss may be due to sclerotization. No significant changes in cuticle weight or its chitin content occur in pharate cuticle until one day before eclosion. However, a peak of chitinase activity found at mid‐late pupal stage suggests the timing of pupal cuticle breakd

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1995.tb00821.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Abstract.The postpharyngeal gland ofCataglyphis niger(André, 1881) workers is characterized, at the ultrastructural level, by a well‐developed smooth endoplasmic reticulum, Golgi apparatus, and numerous mitochondria and lamellar inclusions suggesting an involvement in lipid metabolism. In addition, the microvillar differentiation of the apical membrane and basal invaginations of the cell imply a transportation process.The gland shows a clear structural as well as chemical age‐dependent development. Epithelial thickness increases with age, reaching its maximum within the first week after emergence. Concurrently there is a progressive development of microvilli and appearance of the lamellar inclusions. The gland's secretion consists mainly of hydrocarbons, with a predominance of monomethyl and dimethyl alkanes. Congruency was found between the hydrocarbon composition of glandular exudates and those of the epicuticular washes. An age‐dependent increase in the total amount of hydrocarbons was found to correlate with the ultrastructural development and gross morphology (thickness of epicuticular lining) of the

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1995.tb00822.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Abstract.Sesamia nonagrioidesLefebvre diapauses as mature larvae. Once diapause is induced, larvae continue to grow and moult with no apparent changes, so distinction between non‐diapausing and diapausing larvae is difficult. In the present work two physiological markers of diapause induction are obtained and their efficacy in detecting diapause onset and in monitoring diapause development in field populations is evaluated. The first marker is based on the differential capacity of two photoregimes, LD 0:24 h and LD 16:8 h, to reverse diapause induction. When larvae of the first and second stadia were subjected to the diapause‐inducing LD 12:12 h light cycle and then transferred to LD 0:24 h, larvae pupated after a development duration significantly higher than that of the larvae transferred to LD 168 h. This criterion was used to monitor diapause development in overwintering larvae until field‐collected larvae submitted to LD 0:24 h pupated synchronously with those submitted to LD 16:8 h. This occurred between late January and early March. The second marker refers to development of imaginal wing discs. A relative index of the tracheal mass area divided by the total disc area diminishes steadily during development in non‐diapausing sixth‐instar larvae until it becomes zero just before pupation, whereas it remains constant in diapausing larvae. Though wing disc development was blocked in diapausing sixth‐instar larvae, the disc continued to grow and, consequently, the total area of the disc was not a suitable marker of diapause induction. When the constancy of the relative area index was used to monitor diapause development and termination in overwintering larvae, the results agreed with those obtained using the first criterion and with previous field o

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1995.tb00823.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Abstract.Components of the wandering phase of mature stable fly (Stomoxys calcitransL. (Diptera: Muscidae)) larvae were examined. The mean length of the wandering phase was estimated to be 10.6 ± 3.5 h. In a factorial experiment in which wandering larvae were allowed to pupate in media with three levels each of moisture, temperature and light, the mean time to 50% pupariation was delayed and the rate of pupariation was lowest at high moisture levels, but this latter effect was seen only at the moderate light level. Pupae in media with higher moisture contents had significantly higher fresh weights. However, none of the three factors affected dry weight of pupae. A significant interaction was observed between the effects of moisture and temperature on survival; only at highest moisture content and at the highest temperature did a significant decrease in survival occur. In a separate experiment, density was found to have no effect on mean time to 50% pupariation or the rate of pupariation. Puparium formation appeared to be random under a LD 169 h photocycle, showing no apparent circadian rhythm

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1995.tb00824.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Abstract.The abdominal colour pattern ofEristalis arbustorum(L.) shows seasonal variation, with animals emerging in spring being darker than those emerging during summer. One of the most important environmental cues influencing the abdominal colour pattern is developmental temperature. An experiment was carried out to establish which period during the immature stages was important in determining final adult colour pattern. The results indicate a good relationship between the length of the pupal period and both the extent of the paler markings on the abdomen and the grey score of these markings. The length of the larval period did not have any effect on adult colour pattern.

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1995.tb00825.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY