摘要:

Abstract.A recently developed framework was applied to investigate the responses of newborn pea aphids,Acyrthosiphon pisum(Harris) (Homoptera: Aphididae), to simultaneous variations in dietary suerose and amino acid levels. The location of functional ‘targets’ for intake and growth were determined experimentally using performance criteria. Behavioural rules employed by insects to approach these targets were investigated by reference to the geometry of arrays of intake and growth across a range of diets. First‐instar aphids were fed one of thirty‐one chemically‐defined diets ranging in sucrose concentration from 200 to 1000 mM and amino acid concentration from 25 to 250 mM. Insect survivorship, dry weight, protein‐ and carbohydrate‐derived growth were high for all diets except those with the lowest nutrient levels. Peaks in final dry weight and protein content identified the intake target as the point reached by larvae fed the 600 mM sucrose, 75 mM amino acid diet. Aphids regulated sucrose primarily by consumption (i.e. behaviourally), whereas amino acids were regulated post‐ingestively (i.e. by physiologi

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1994.tb01081.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.The ability of two sphecid wasps,Bembix rostrataandB.zonata(Hymenoptera: Sphecidae), to warm up endothermically is demonstrated under laboratory conditions. Mean warm‐up rates ofB.rostrataare comparable to bees of similar weight. Despite endothermic ability, field observations reveal thatB.rostrataare not active below 22d̀C. From observations at the nectar‐foraging site (clumps ofThymus vulgarisflowers) it is calculated that the energy resources available to wasps are sufficient to power endothermic warm‐up at low temperatures. Alternative explanations for the absence of wasp activity at low temperatures, such as the risk of parasitism, are suggested. Endothermy may be used periodically to increase flight efficiency in response to added load, such as prey carried by females, and mates by

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1994.tb01082.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.Rates of desiccation, rehydration and survival, under conditions of 0 and 100% relative humidity, were investigated in the high arctic collembolanOnychiurus arcticus(Tullberg) over a range of temperatures from ‐3 to 10d̀C. Desiccation, measured over 4h in a dry environment, was rapid and highly significantly correlated with saturated vapour pressure deficit (SVPD). At 10d̀C animals lost over 60% of body moisture in under 1h. Under moist conditions body weight remained constant. Survival, measured over 4h under dry conditions, showed a highly significant negative correlation with SVPD across the range of temperatures. Survival in moist controls was 100%. Partially desiccated animals were able to rehydrate using free water or moisture from a saturated atmosphere, but uptake of the former was faster. Rates of water uptake were around 30 times slower than rates of loss through desiccation. Animals given free water regained initial weights in 24‐144h, dependent on temperature. Uptake rates of free water, measured over the time necessary fully to rehydrate, were highly significantly correlated with temperature, whereas those for atmospheric moisture were not. Over the time scales used in the experiments, three linear regression equations accurately predict rates of desiccation, rehydration and survival from SVPD or temperature. Ecological adaptation byO.arcticusto the highly contrasting climatic environments of the arctic summer and winter seasons is discussed in the context of climate c

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1994.tb01083.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.There is a close correspondence in composition between the hydrocarbons of the Dufour gland and the cuticular hydrocarbons of workers of some bumblebee species. This correspondence is characteristic of the species, and independent of the place and time of collection.

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1994.tb01084.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.In studies conducted on potted host trees in field cages and in the laboratory, we examined the influence of egg load on the finding and acceptance of high‐ranking (kumquat) and lower‐ranking (grapefruit) hosts for oviposition by wild‐origin Mediterranean fruit fly females,Ceratitis capitata(Wiedemann). By prescribing the periods during which females had access to protein prior to testing, we generated four classes of females having progressively increasing egg loads but not differing in population origin, age, degree of protein hunger at testing, or amount of prior experience with host fruit (none). Egg load had no discernible effect on behaviour associated with finding either type of fruit but did have a significant effect on several behaviours associated with oviposition after alighting on fruit. Increasing egg load led to increasing propensity to engage in ovipositional‐type behaviour on both kumquats and grapefruits. There was no evidence, however, to support a hypothesis that medflies would become less discriminating against grapefruits relative to kumquats as egg load increased. Relative to kumquats, grapefruits were accepted for oviposition by intermediate and high egg load females to a substantially greater degree in laboratory cages than on trees, suggesting that results of laboratory cage experiments on host discrimination by tephritid flies may poorly reflect differences in behavioural responses expressed under less constrained con

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1994.tb01085.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.Larval holometabolous insects show changes in behaviour (e.g. start of wandering and spinning) in specific periods of the moulting cycle in relation to definite ratios of juvenile hormone and moulting hormone (ecdysone). In hemimetabolous insects no such changes in behaviour are known. It should be investigated whether the cockroachPeriplaneta americanashows changes in locomotor activity and in food and water consumption in relation to periods of ecdysone production during the last larval stage. Within a mean duration of the last larval stage of 30 days there were two periods of reduced locomotor activity: on day 9 and between days 13 and 17. From days 12–13 food consumption decreased byc. 40% up to the day 18. Water consumption decreased between days 9 and 18 by about 55%. Peaks of ecdysone production appeared after these changes of behaviour in each case. Therefore in larvalPeriplanetaecdysone seems not to trigger these behavioural change

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1994.tb01086.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.The European cherry fruit fly (Rhagoletis cerasiL.; Diptera, Tephritidae) marks cherries (Prunus aviumL.) after oviposition with a host marking pheromone (HMP). The marking trail prevents additional oviposition by the same or other females into the same fruit. On the ventral side of the tarsi of both sexes, contact‐chemoreceptor sensilla were identified which contain a receptor cell selectively sensitive to HMP. The HMP receptors of males were slightly more sensitive than those of females, suggesting that the more general term ‘host‐marking pheromone’ is more appropriate than the previously used ‘oviposition deterring pheromone (ODP)’.The four structural isomers of the HMP, N(15R, S(β‐glucopyranosyl)‐oxy‐8RS‐hydroxypalmitoyl)‐taurine, and various derivatives were synthesized and tested in an electrophysiological bioassay. Both the 8R,15Rand the 8S,15RSisomers of the HMP were equally active with a threshold of about 2 times 10‐10M, and were shown to be present in the female faeces in similar proportions. The two 15SHMP isomers were about 13 times less active.Testing synthetic derivatives of the HMP molecule revealed that the presence of the four moieties of the molecule are important for the activity: taurine, palmitic acid, C(8)hydroxyl group, and glucose (C(15)). The chain length of the fatty acid, the hydroxyl group at C(8)and the position of glucose at C(15)also influenced the activity. Only minor loss of activity (factor 2) relative to the natural molecule was observed when the methyl group in the C(15)position was removed. The removal of the β‐glycosidically linked glucose (replaced by a hydroxyl group) resulted in about a 4‐fold loss of activity. The cation of the HMP molecule seemed to have no effect on its activity, whereas both low and high pH reduced it significantly.Based on these results, field experiments have been initiated to control oviposition by cherry fruit flies on cherries applying th

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1994.tb01087.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.Anoxia induced by nitrogen or carbon dioxide, or hypoxic/hypobaric conditions generated by a partial vacuum sensitizes red‐eye pharate adults ofSarcophaga crassipalpisMacquart to a high temperature exposure that is normally nonlethal (40d̀C for 2–3 h). Thermotolerance induced by a2h exposure to 40d̀C (under aerobic conditions) doubles the pharate adults' tolerance to 45d̀C but provides no protection against a combined exposure to 45d̀C and anoxia, and only modest protection against a combined exposure to 40d̀C and anoxia. Under aerobic conditions, exposing pharate adults to 0d̀C for 2 h increases their tolerance to ‐10d̀C (rapid cold hardening). Rapid cold hardening at 0d̀C is not induced under anoxia. These results imply that tolerance to high temperatures and rapid cold hardening are dependent on aerobic processes and suggest that certain forms of temperature stress can be further exacerbate

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1994.tb01088.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.We present in this study data which indicate that there is a diel periodicity in the pheromone production of the pink bollworm mothPectinophora gossypiella(Sanders) (Lepidoptera: Gelechiidae) but that it is not well defined. Moreover the control mechanism of pheromone production differs somewhat from that reported for other moths. No pheromonotropic response was obtained when photophase females were injected with syntheticHelicoverpa zeapheromone biosynthesis activating neuropeptide (Hez‐PBAN). After decapitation for 24 h, Hez‐PBAN did not induce pheromonotropic activity above control levels, which themselves remained relatively high. No effect on pheromone production was observed after treatment with the non‐steroidal ecdysone agonist (RH5999). Decapitation for 72 h resulted in a significant drop in the control levels of pheromone titres. After decapitation for 72 h, stimulation by injections of Hez‐PBAN and pink bollworm head extracts was observed. In addition, an enhancement of the PBAN stimulation was observed when combined with severance of the ventral nerve cord before injection. On the other hand, pink bollworm head extracts did not cross‐react with Hez‐PBAN antiserum in a radioimmunoassay, indicating that the pheromonotropic factor present is sufficiently different from Hez‐PBAN and does not recognize the antigenic binding sites. In studies using isolated abdomen and pheromone gland culturesin vitro, no stimulation ofde novopheromone biosynthesis was observed but a 3‐fold increase in thede novofatty acid biosynthesis was detected in pheromone

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1994.tb01089.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY