摘要:

Abstract.Responses ofRhagoletis pomonella(Wash) (Diptera: Tephritidae) to synthetic host fruit violates were studied in the field. Individually marked females were released in the centre of a 25 m2patch containing twenty‐five host trees (Crataegus mollis var, toba) and followed as they moved within and between trees. Fly response to three experimental conditions was studied: (1) ‘clean’ air; (2) synthetic host fruit violates (apple) permeating the patch; and (3) a single point source of odour placedc1m away from the edge of the patch. Files in a patch permeated with host odour moved faster, exhibited more straightened‐out moves, and reached the edges of the patch more quickly than those exposed to clean air. Flies exposed to a point source of odour exhibited clear orientation responses, arriving consistently at the tree harbouring the source of odour. Odour exposure was intermittent and usually brief (c. 20s‐1exposure) with intervals between exposure periods averaging 103s. Wind speed and direction were highly variable. Flies moved during wind ranging in speed form 0.5 to 4.4 m s‐1, with their activity being greatest at winds below 2m s‐1. Strong winds (>3.5 ms‐1) either arrested movement or enhanced downwind displacement. Our observations tend to support the ‘series‐of‐steps’ hypothesis reviewed by Gibson&Brandy (1985) as a mechanism of close‐range host location (1‐5m from odour source). Our findings are discussed with respect to theoretical and practical implications of insect orientation mechanisms to odours, disper

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1992.tb00983.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.The effect of the stage of ovarian development on the volumes of meals of the protein‐rich material, liver exudate, taken by females of the blowfly,L. cuprina(Wiedemann), was examined using an experimental regime which was designed to isolate the effects of ovarian development from any other more direct effects of protein feeding or deprivation. It was found that volumes of meals taken by females with developing ovaries were little, if any, smaller than the volumes taken by protein‐deprived females until quite late in vitellogenesis, at which stage meal size fell abruptly to that of meals taken by gravid females. A direct effect of protein‐feeding was also demonstrated, with females that had consumed exudate during the previous few hours taking substantially smaller meals than those that had not done so. This effect was, however, shown to be non‐specific in that the recent consumption of an equal volume of concentrated sucrose solution caused a similar reduction in the volume of exudat

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1992.tb00984.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.Extracellular single cell recordings of CO2‐sensitive receptors in tsetse flies revealed a steep dose response over a range of stimuli of two to three orders of magnitude and a maximum response of approximately 70 impulses/s after exposure to a high, but naturally feasible, C02concentration of 5%. These receptor neurones are slightly sensitive to C02levels occurring in air (‐0.03%); the sensitivity to CO2above that level may be used to locate potential hosts. The C02‐sensitive neurones did not respond to some other biologically relevant odours such as octenol, butanone or p‐cresol; however, other receptor cells, some in the same sensillum, are sensitive to some of these odours.A striking feature of the C02receptors is that they appear not to adapt in their response frequencies. The spike numbers of the phasic‐tonic response remain constant in the tonic portion during continuous (or repetitively pulsed) long‐term stimulation (1 min). This unusual physiological ability would allow continuous monitoring of C02values as well as detecting potential hosts that exhale CO2. These electrophysiological results are compared to the behavioural findings in tsetse flies and to the physiological data on C02receptors of other, non‐bloodsu

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1992.tb00985.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.The tropical belostomatidDiplonychus indicusVenk.&Rao (Heter‐optera: Belostomatidae) forages both actively and from ambush, changing frequently from one predatory mode to the other. Analyses presented here of the influence of feeding and of developmental stage on several locomotory and predatory parameters show that the fact that a bug was eating did not prevent it from reacting to and from seizing prey items, but it did influence the mode of predatory attempts. Feeding bugs were less active and they foraged actively less frequently, but feeding did not affect the frequency of predatory attempts from ambush. No important variations during development were found and first stadium larvae behaved similarly to adults. Capture success rates were higher at all developmental stages during a meal than when a bug was not eating and rejection rates were lower during a meal. These results suggest that, when eating,Diplonychus indicusbugs aim more successfully at prey items they are more likely to capture and to ea

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1992.tb00986.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.Action potentials from individual cells and receptor potentials were recorded from antennae (funiculi) of living tsetse flies,Glossina m.morsitansWestwood, using a ‘surface‐contact’ recording technique. Stimuli were pressure of the electrode, changes in temperature and the vapours of l‐octen‐3–ol, acetone, 3–methylphenol, dichloromethane and CO2. Two types of mechano‐receptive cells were found. One type only fired action potentials when pressure was increased, the other type continued firing when pressure was maintained. Of the 182 cells tested for their sensitivity to temperature change and the odour stimuli, 19% did not respond to any of the stimuli, suggesting that we are still unaware of cues which may be of import to the flies, and 4% responded to temperature only, increasing and decreasing their activity with a decrement and increment in temperature, respectively. Of the 141 cells which were olfactory receptors, 52% responded to 1‐octen‐3–ol and 40% were exclusively sensitive to this substance. For 3–methylphenol these percentages were 23 and 18, for acetone 13 and 11, for dichloromethane 12 and 7, for CO213 and 13. No clustering of cell types in certain areas of the funiculi was found, nor was a difference apparent between the sexes. The majority of the olfactory cells responded by increasing their activities on odour stimulation. Inhibition was found in three cells only, in which spontaneous activity was suppressed on stimulation with 3–methylphenol. Spike responses were phasic‐tonic and varied between two extremes: Cells showing relatively rapid cessation of spike activity after the end of stimulation, and cells which continued firing for several seconds or minutes after stimulation. Possible behavioural effects of the activities of the vario

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1992.tb00987.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.The behaviour of queen and worker honeybees(Apis melliferaL.) was observed using small colonies in observation hives. Workers paid more attention to queens which had been mated for 2 months or more than to those which were newly mated; virgin queens received least attention. Queens received most attention when they were stationary and least when they were walking over the comb; virgin queens were most active. Queen cells had as many attendants as virgin queens and queen larvae were inspected almost continuously. The queen pheromone component 9–oxo‐trans‐2–decenoic acid stimulated ‘court’ behaviour when presented on small polyethylene blocks, but workers responded aggressively to complete extracts of queens' heads. Both the heads and abdomens of mated queens received much attention from court workers but the abdomens were palpated by more workers for longer and were licked much more. The queens' thoraces were least attended. Abdominal tergites posterior to tergite glands were licked for longer than those anterior to the glands. Only worker bees very near to the queen reacted to her and joined her ‘court’.No evidence was found of a diel periodicity in the behaviour of a queen or her ‘court’. During the winter the queen's court was smaller than in summer and she walked less and laid fewer eggs. When colonies were fed with sucrose syrup in winter, their queens laid more eggs and workers reared more brood but there was no change in the attention received by the queens.The implications of these findings for the secretion and distribution of queen phero

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1992.tb00988.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.Penultimate (fifth) and last (sixth) stadium larvae ofSpodoptera mauritiaBoisd. (Lepidoptera: Noctuidae) of various ages were injected with 0.5 μg, 1 μg or 2 μg azadirachtin and the effects on moulting and larval‐pupal transformation were analysed. Higher doses (1 μg and 2 μg) of azadirachtin induced a prolongation of the fifth stadium in larvae treated on day 0 and day 1. The resulting sixth stadium larvae failed to pupate. Sixth stadium larvae injected with 0.5 μg, 1 μg or 2 μg azadirachtin showed prolongation of sixth larval period. Azadirachtin treatments completely prevented normal pupation in ‘day 0’ and ‘day 1’ larvae even though the percentage of pupation increased in treated larvae of other age groups. Injection of 2 fig azadirachtin prevented normal pupation in larvae of all age groups. Injection of 4 μg ecdysterone to sixth stadium larvae pre‐treated with 1 fig azadirachtin (on day 0) promoted normal pupation in the

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1992.tb00989.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.Plasticity in in‐flight orientation to odours from the plant‐host complex (PHC: plant infested by the host) was investigated inCotesia rubecula, a specialist larval parasitoid ofPieris rapaewhich feeds almost exclusively upon cruciferous plants. A wind tunnel was used to study effects of both concentration of volatile emissions and females' experience. A low proportion of naive wasps located weak odourant sources, i.e. either a single cabbage leaf or a leaf with two first stadiumP.rapaelarvae. This rate could be elevated by increasing the odour concentration or by providing the wasps with either a previous oviposition experience on the PHC or an exposure to the PHC odour. Previous oviposition on washed larvae (diet‐fed, starved and then rinsed with distilled water) in an odourless environment had no effect, which suggested that increased sensitivity to the PHC odour resulted from olfactory experience. The number of mature eggs in a female was affected by oviposition on the PHC or washed larvae but not by exposure to the PHC odour. Therefore the number of mature eggs available was not correlated to the observed differences in orientation behaviour. Possible mechanisms of the behavioural changes described are discussed in the light of the host specificities ofC.rubeculaandP.

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1992.tb00990.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.During oviposition, femalePotamarcha congener(Rambur) (Libel‐lulidae: Odonata) hover over water and face towards the margins of temporary pools. They repeatedly scoop up drops of water with the posterior end of the abdomen and flick them together with eggs towards the bank. Embryonic development is complete in 7–8 days at 28d̀C but hatching can be delayed for up to 80 days if the eggs are kept in air at 100% r.h. Hatching is triggered by oxygen lack. In the laboratory, perfusion with gases containing oxygen at partial pressures below 5.3kPa causes hatching without submergence in water. Eggs exhibit considerable variability of hatching threshold: this is partly due to age but it also occurs regardless of age among the eggs of a single clutch and probably has adaptive value. The eggs of two other species tested,Pantala flavescensandOrthetrum pruinosum, show no hatching response to oxygen

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1992.tb00991.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.The auditory system of three closely related bushcrickets was investigated with respect to morphological and physiological differences. The size of the acoustic vesicle in the prothorax cavity and the size of the acoustic spiracle were compared to differences in auditory tuning of the tympanic nerve and differences in the directionality. The results indicate that a small auditory vesicle and auditory spiracle provide reduced sensitivity in the high frequency range (above 10—15 kHz), but increase sensitivity at low frequencies (below 10 kHz). The directionality of the hearing system deteriorates at frequencies between 10 and 25 kHz in species with a small spiracle and trachea. The evolutionary implications of these differences of the auditory systems are discussed. They are considered to be influenced more by ecological factors than bioacoustical one

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1992.tb00992.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY