摘要:

ABSTRACT.The behaviour of the circadian locomotor rhythm of the New Zealand weta,Hemideina thoracica(White), supports the model that the underlying pacemaker consists of a population of weakly coupled oscillators. Certain patterns of locomotor activity, previously demonstrated almost exclusively in vertebrates, are presented here as evidence for the above hypothesis. They include after‐effects of various pre‐treatments, rhythm‐splitting and spontaneous changes in the rhythm. After‐effects, which describe the unstable behaviour of free‐running circadian rhythms following particular experimental perturbations, have been observed inHemideinafollowing single light pulses, constant dim light, and laboratory and natural entrainment. Period changes occurred in the activity rhythm after single light pulses of 8‐h and 12‐h duration (25 lx). Constant dim light (0.1 lx) increased the free‐running period (τ) of the activity rhythm, but the after‐effect of constant dim light was either an increase or a decrease in τ. After‐effects upon both τ and the active phase length of the activity rhythm were found following non‐24‐h light entrainment cycles with 8‐h and 12‐h light phases of 25 lx. Qualitative measurements of these after‐effects upon τ are presented which reveal a relationship between both the direction and amount of change in τ, and the difference between entrainment cycle length (T) and pre‐entrainment free‐running period. The after‐effect of natural entrainment was an initial short‐period free‐run (τ<24h) lasting 5–10 days, generally followed by a rapid period lengthening to τ= 25–26 h. Support for the population model was provided by spontaneous dampening, recovery, and period changes of the rhythm, together with the disruption of the active phase following critical light perturbations, and rhythm‐splitting. TheseHemideinaresults are compared with the simulation

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1982.tb00661.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACT.Selected sugars, amino acids and allelochemicals were tested over a range of concentrations to determine their effect on the ingestion rates of adult tarnished plant bugs. Experiments were performed with a two‐choice bioassay technique utilizing artificial membranes. Sucrose was the most effective feeding stimulant of all the compounds tested. Glucose was an effective stimulant but was 8 times less potent than sucrose. Fructose was 50 times less potent than sucrose. Methionine and phenylalanine were the only amino acids of seven tested which stimulated feeding. Leucine produced a deterrent effect. Cotton tannin was the most effective deterrent of all allelochemicals tested and was 10 times more potent than gossypol. The quinone, 1, 4‐napthoquinone, and the alkaloid, tomatine, were also effective feeding deterrents. Sinigrin and its aglycone, ethyl isothiocyanate, were among the weakest deterrents of all the allelochemicals tested. Hydroquinone was the least potent deterrent of all compounds tested. The results indicate a strong chemosensory component regulating the feeding response of the tarnished plant bug. It is suggested that this response is mediated by epipharyngeal chemosensitive sensi

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1982.tb00662.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACT.The horizontal motion‐detecting system controlling optomotor head‐turning behaviour in honeybees,Apis mellifera, was found to be partitioned into two separate subsystems. Each subsystem is direction‐specific such that visual stimulation in the preferred direction elicited a high level of responses that correcly followed the movement, whereas stimulation in the non‐preferred direction resulted in response levels comparable to or lower than those for blinded controls. The results indicate that medial eye regions are specialized for the detection of posterior‐to‐anterior movements and lateral regions are specialized for detecting anterior‐to‐posterior motion. A model suggesting possible neural correlates for this functional subdivision of the optomotor respo

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1982.tb00663.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACT.Photoperiod significantly affected size‐related aspects of metamorphosis in the milkweed leaf beetleLabidomera clivicollis(Kirby) (Chrysomelidae). Larvae reared under short‐day photoperiod successfully pupated at lower weights than larvae reared under long‐day photoperiods. This short‐day effect was observed to an equivalent extent in both males and females; but within photoperiod treatments, males consistently pupated at lower weights than females. It is likely that the short‐day effect on metamorphosis is associated with photo‐periodically induced changes in larval corpora allata activity or juvenile hormone titre. Ecologically, the short‐day effect on metamorphosis may enhance the moulting success of larvae which encounter food shortages

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1982.tb00664.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACT.The course and projection areas of the tympanal receptor fibres in the thoracic ventral cord were revealed by iontophoresis in the last three larval instars. There were no significant differences between the arrangement in larvae and that in adults. The threshold curves of the auditory organ of the last three instars were measured by recording summed potentials in the tympanal nerve. In the frequency range tested (1–20 kHz), larvae and adults differed only in sensitivity. More detailed information was obtained by single‐cell recordings from receptor neurones in the tympanal nerve of last instar larvae. No differences could be shown between the threshold curves, or the suprathreshold activity, of low frequency receptors of last instars and adults. However, the high frequency receptors of the last instars are far less sensitive in the frequency range above 12 kHz. This seems to depend on the different mechanical properties of the tympanum in larvae. The response patterns of some typical ventralcord neurones (G‐, K‐, B‐type) were identified by extracellular single‐cell recordings in last instar larvae. Convergence of auditory and vibratory inputs onto the G‐neurone and the B‐neurone (as is known to exist in the adult) was found in larvae in the final and penultimate instars to be causing similar re

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1982.tb00665.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACT.The oocytes of 3‐day‐old unfedAedes aegyptimosquitoes are in a state of oogenic arrest, but microgram doses of ecdysterone stimulate their accumulation of a variable amount of yolk. We now find that these doses also induce the deposition of plaques of vitelline envelope by the follicle cells, and with transmission electron microscopy we have compared their formation with that in normal blood‐fed females. Plaques in the experimental animals were abnormally large and irregular in shape and distribution. In part, these abnormalities were attributable to the fact that the follicle cells remain in close contact with the oocyte, whereas the space between follicle cells and oocyte increase significantly in the blood‐fed female. Deposition of the plaques occurred earliest after the injection of 5 μg ecdysterone, but even at this high dose the amount of plaque material deposited was less than in the blood‐fed controls. Induction of the deposition of abnormal vitelline envelope in unfed females was most clearly demonstrated after two injections, 1 μg ecdysterone each, 14h apart; 24h after the second injection, the plaques had prematurely fused into a thin disorganized envelope. When females were injected with ecdysterone immediately after a blood‐meal, vitelline envelope plaques formed prematurely, and their structure became increasingly abnormal with time. This early onset of activity was characteristic of follicle cells adjacent both to the oocyte and to nurse cells. Thus, the factors that normally control the formation and organization of the vitelline envelope are absent in the unfed female stimulated with high doses of ecdysterone, while in the blood‐fed females, excessive ecdysterone apparently interferes with the timing and orderly sequence of env

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1982.tb00666.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACT.Daily rhythms controlling oviposition, egg‐hatching and adult eclosion in the sorghum shootfly,Atherigona soccataRondani, were investigated. Eggs were laid only during the photophase of a LD 12:12 cycle, in two peaks. Under continuous light, this oviposition was considerably attenuated but not made immediately arrhythmic. Egg‐hatching and adult eclosion both commenced just before dawn. Some feature of the scotophase during or immediately after black‐head formation apparently acts as a signal for hatching. Eclosion was controlled by light but its timing in the field was modified by temperature. The last 2–3 days of the pupal period constituted the most sensitive stage, and light signals received during this period determined the time of eclosion. Ecological advantages of these rhythms to the shootfly are di

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1982.tb00667.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACT.A circular humidity gradient apparatus with a porous cellulose substrate was used to compare the humidity responses of pseudoworkers (immature wood‐feeding forms) of five species of dry‐wood termites. Four of these species are widely distributed pests of buildings:Cryptotermes brevis(Walker),C. cynocephalusLight,C. dudleyiBanks andC. havilandi(Sjöstedt). The fifth species,C. naudeiCoaton, has not been recorded from buildings.C. havilandi, C. cynocephalusandC. naudeiwere found to tend to group and feed at humidites above 90% r.h., whileC. dudleyipseudoworkers avoided humidities above 90% r.h. and below 70% r.h. These results accord with the results of studies on the effects of relative humidity on feeding and reproduction of these species. The behaviour of the most widespread species,C. brevis, seems to be closely associated with its ability to undergo acclimatization and to feed efficiently at either medium (c.60%) or high (c.90%) relative humidity.C. breviskept at 89% r.h. showed an increased tendency to group at humidities above 90%, with a lower temperature preference, changes in faecal pellet formation and, for one population at least, an increased tolerance of exposure to saturated air. The humidity preferences at constant temperature were compared with the temperature preferences of the same individuals examined in uniform humidity. The value of behavioural responses as indicators of physiological differences between species and populations is consid

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1982.tb00668.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACT.The ability ofTelenomus heliothidisAshmead (Hymenoptera; Scelionidae) to recognize its host, the eggs ofHeliothis virescens(F.) (Lepidoptera; Noctuidae), was determined in laboratory studies. The material present in the accessory gland of femaleH. virescensadults acted as an egg recognition kairomone forT. heliothidis.Host eggs which lacked the kairomone were not attacked, while glass beads the size ofH. virescenseggs and coated with the accessory gland material were. The parasitoid failed to respond to the kairomone unless it was associated with a target the size and shape of normal hosts. The kairomone is heat stable, but was deactivated by proteolytic enzymes. The accessory gland contained 200 mg/ml protein which suggests that the kairomone is proteinaceous.

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1982.tb00669.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACT.Use of small microcomputers to collect and record from the outputs of activity detectors is described in simple terms for the uninitiated. Provided simple external latches are used, the microcomputer may be programmed in a high level language, such as BASIC, and the system can be used to control light or temperature cycles. Data are acquired and control effected through an 8‐bit parallel ‘user’ port, as fitted to most microcomputers, and details are given of the installation of such a

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1982.tb00670.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY