摘要:

Abstract.The mutualistic fungus of leaf‐cutting ants produces both ordinary hyphae and specialized ant rewards: the staphylae. Workers ofAtta sexdens(L.) lived longer on diets which included nutritive staphylae than on those which provided only hyphae. However, hyphae were a better diet than sucrose solution or water alone. Small workers lived longer than large workers when receiving fungus garden, whether or not staphylae were available, probably because they are specialized to care for the garden and can exploit it. Large workers lived longer than small ones when only water was available. This may be a consequence of scale, larger workers containing proportionately more nutritional reserves in their bodies.When starved workers were exposed to fungus for 3h, they gained weight. This weight gain represented the amount of food ingested during the test period. Workers gained 7.3 times more weight on natural fungus garden bearing staphylae than on garden with only hyphae. They gained only 1.5 times as much weight when the fungus was artificially cultured on agar. The results suggested that workers found hyphae attractive, but difficult to obtain in natural fungus gardens.Material from hyphae and staphylae stained with a fluorescent dye was detected in worker crop contents using fluorescence microscopy. The crop contents of workers fed on staphylae fluoresced 1.14 times more than those of workers fed on hyphae.Hyphae may provide a small source of food for workers, and the fungus as a whole may provide up to 9.0% of the respiratory energy requirements of workers, the remainder presumably being provided by plant sa

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1995.tb00793.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Abstract.Parasitoid host range may proceed from traits affecting host suitability, traits affecting parasitoid foraging behaviour, or both. We tested the hypothesis that encapsulation can be used as a reliable indicator of parasitoid host range in two closely related larval endoparasitoids of Lepidoptera.Cotesia glomerata(L.) (Hymenoptera: Braconidae) is gregarious and a generalist on several species of Pieridae, whereas C. rubecula (Marshall) is solitary and specific to Pieris rapae (L.). We determined the effects of host species (Pieris brassicae(L.),P. napi(L.) andP. rapae) (Lepidoptera: Pieridae) and host developmental stage (early first, second and third instar) on encapsulation of parasitoid eggs. Host species and parasitoid species, as well as the resulting interaction between these two factors had significant effects on encapsulation of Cotesia eggs. Encapsulation in Pieris hosts was much lower forC. glomerata(32%), even when the latter was parasitizingP. rapae.Encapsulation increased with the age of the larvae, although the only significant difference was forC. glomerata.Overall,P. rapaeshowed a stronger encapsulation reaction thanP. brassicaeandP. napi.Encapsulation levels ofC. glomeratacorresponded well to patterns of female host species and host age preference for oviposition and parasitoid larval performance. In contrast, percentages of encapsulation ofC. rubeculawere not consistent with host preference and host suitability. We argue that encapsulation alone is unlikely to provide a sufficient explanation forC. glomerataandC. rubeculahost range.

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1995.tb00794.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Abstract.Embryonic diapause induction in the Senegalese grasshopper,Oedaleus senegalensisKrauss (Orthoptera: Acrididae), is influenced both by the photoperiod and the temperature experienced by females. High temperatures (40°C) and long photoperiods (LD 14:10h), which characterize the beginning of the rainy season in the Sahel, cause non‐diapausing eggs to be laid. Lower temperatures (25°C) and shorter photoperiods (LD 12:12h), which occur at the end of the rains, result in the production of diapausing eggs. At 30°C and constant photoperiods,O. senegalensisexhibited a long‐day‐short‐day response with critical photoperiods of c. 13 h andc.20 h, only the former value being of ecological significance. The photoperiodically sensitive stages to diapause induction in females occurred from the fifth stadium onwards. Temperature also affected the coloration of both nymphs and adults. Dark‐black and pale‐white individuals were produced by low (25°C) and high (40°C) temperatures respectively, whereas an intermediate temperature (30°C) produced individuals which were greyish brown. These results are discussed in relation to the ecology

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1995.tb00795.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Abstract.Agelena labyrinthicaClerck spiders were raised in the laboratory at three diet levels. Growth, reproduction and the pattern of nutrient extraction of each spider were monitored. The extraction of proteins, carbohydrates and lipids by each spider was analysed on three occasions, covering the immature and mature stages. More nutrients were extracted the less well‐fed the spider, and females extracted more nutrients than did males. Nutrients were extracted most completely during early growth and, especially protein, by females in the reproductive phase. Protein was extracted more completely than lipids or carbohydrates. The relative amounts of the three nutrients extracted changed significantly with time, indicating that spiders are able to adjust their detailed feeding behaviour to their immediate needs. Field collections over the season showed that most spiders in the field grew approximately as those on the medium laboratory ration for most of the tim

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1995.tb00796.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Abstract.Extracts of volatiles from rabbit and chicken faeces preferentially attracted gravid sandflies,Lutzomyia longipalpis(Lutz and Neiva), in an oviposition bioassay. In electrophysiology experiments, the same extracts selectively stimulated two olfactory cells while inhibiting another in ascoid sensilla on the antennae of these flies. Analysis of faeces volatiles by gas chromatography linked to ascoid sensillum recording revealed two early eluting electrophysiologically active components of rabbit faeces. These active compounds were identified in both rabbit and chicken faeces volatile extracts by gas chromatography ‐mass spectrometry as hexanal and 2‐methyl‐2‐butanol. Hexanal stimulated one cell type and inhibited another, whereas 2‐methyl‐2‐butanol stimulated a third cell type. A 1:l mixture of synthetic hexanal and 2‐methyl‐2‐butanol elicited the same targeted oviposition response from gravid females on the treatment septum of the bioassay as did the total volatile extract of rabbit or chicken faeces.The monoterpenes α(+)‐pinene (plus some optical and positional isomers) and a‐terpinene activated a separate cell type, whereas benzaldehyde stimulated the same receptor as hexanal, but with a higher threshold. Furthermore, an olfactory cell selectively tuned to the perception of the male sex pheromone of this species was also found

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1995.tb00797.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Abstract.The innervation of the gut of the cockroachLeucophaea madera(F.) has been studied by means of wholemount immunocytochemistry with antisera raised against Leu‐callatostatin, a cockroach allatostatin homologue identified from neuropeptide isolation and gene studies in the blowflyCalliphora vomitoria.Leu‐callatostatin‐imunoreactive neurones in the brain, with axon trajectories in the stomatogastric nervous system, innervate the foregut and midgut. Neurones in the last abdominal ganglion supply the hindgut and the midgut via the proctodeal nerve. In addition to a rich callatostatin‐immunoreactive nerve supply, the midgut, including the midgut caeca, contain numerous callatostatin‐immunoreactive endocrine cells. Physiological studies show that the spontaneous contractile activities of the foregut, but not the hindgut, are inhibited by callatostatin neuropeptides. Leu‐callatostatin 3 was the most potent of the range of Leu‐and Met‐callatostatins tested, with a dose‐dependent response between 10‐13and 10‐7M. This is similar to the results obtained with the previously identified myoinhibitory peptide ofL. maderae, leucomyosuppressin. However, this peptide, with a different type of structure to the allatostatins, inhibits both foregut and hindgut motility equally. Experiments with a series of analogues of the Met‐callatostatins showed that the free acid (as opposed to the carboxyamidated peptide) and N‐terminally truncated peptides were inactive. These morphological and physiological results are thought to be representative of the, as yet unidentified, naturally occurring allatostatin homologues ofL. maderae.This family of peptides should be added to the increasing list of insect gut

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1995.tb00798.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Abstract.Two peptides were isolated from methanolic extracts of corpora cardiaca of the blister beetle,Decupotoma lunata, by a single‐step purification procedure, utilizing C‐18 reversed‐phase high‐performance liquid chromatography (RP‐HPLC) for separation, and the increase of haemolymph lipids inLocusta migratoriafor bioassay. The native peptides were analysed by matrix‐assisted laser‐desorption ionization mass spectrometry revealing main ions at m/z 1180 and 1009 respectively which were attributed to the [M + Na]+form of the respective peptides. After deblocking of the N‐terminal pyroglutamate residue of each peptide, the structures of the deblocked peptides were determined by pulsed‐liquid phase sequencing employing Edman chemistry. The sequences of the two peptides, (1) pGlu‐Leu‐Asn‐Phe‐Ser‐Pro‐Am‐Trp‐Gly‐AsnNH2and (2) pGlu‐Leu‐Asn‐Phe‐Ser‐Pro‐Asn‐TrpNH2, characterize them as deca‐ and octapeptide members of the AKH/RPCH family. Whereas the decapeptide is a novel member of this family and is given the acronym Del‐CC (Decupotoma lunatacorpus cardiacum peptide), the octapeptide has previously been found in tenebrionid beetles and has the acronym Tem‐HrTH. The corpora cardiaca of two other species of blister beetles (Cyaneolytta pectoralisandMylabris coeca) contain the same two peptides asD. lunata, as judged by RP‐HPLC and biological activity. Neither a corpus cardiacum extract ofDecupotoma lunatanor the synthetic peptides Del‐CC and Tem‐HrTH were activ

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1995.tb00799.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Abstract.Face flies overwinter as adults in reproductive diapause. Administration of 20‐hyroxyecdysone and/or methoprene induced reproductive development in diapausing flies which were maintained in a diapause‐inducing environment. Hormone effects were additive and female flies were more sensitive than males. Release of vitellogenin from cultured fat body was stimulated by 20‐hydroxyecdysone or methoprene. Transfer of flies from diapause to diapause‐breaking environments induced some to break diapause, but this decreased with the time flies had been in a diapause‐inducing environment. In contrast, topical application of methoprene to diapausing flies induced reproductive development irrespective of their ages even when they were kept in the diapause‐inducing environment for 80 day degrees above a 12°C base temperature (14.5 days). Therefore diapause induction must depend on hormone levels less than some threshold level. The putative threshold varied according to diapause propensities of different genetic lines. Lines showing high frequencies of diapause required greater amounts of methoprene for reproductive development in diapause conditions than did lines showing low frequencies

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1995.tb00800.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Abstract.The concentrations of fat body and haemolymph vitellogenin and ovarian vitellin during the first gonadotropic cycle of the cockroachBlattella germanica(L.) (Dictyoptera, Blattellidae) have been studied. For these purposes, a polyclonal antibody againstB. germanicavitellogenin and vitellin has been obtained, and an ELISA to quantify these proteins has been developed. Ovarian vitellin levels follow a pattern which parallels those of basal oocyte growth and Juvenile Hormone production by the corpora allata. This suggests that Juvenile Hormone regulates vitellogenin uptake into oocytes. Fat body and haemolymph vitellogenin levels give cyclic and parallel patterns. However, the cycle of Juvenile Hormone appears delayed with respect to that of vitellogenin. We suggest that the production of Juvenile Hormone, although cyclic in profile, does not modulate alone the cycle of vitellogenin. At least a supplementary mechanism, apparently independent of Juvenile Hormone, may be involved in the decline of vitellogenin production at the end of the vitellogenic cycle.

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1995.tb00801.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Abstract.Males of the caddis flyAthripsodes cinereus(Curtis) (Trichoptera: Leptoceridae) swarm above the water surface of lakes and streams. Females enter swarms and are pursued until grasped by a male. The pair couple their genitalia in the air, and then the male alone flies the pair to the shore where they settle and complete the copulation. About 8% of the pairs (totaln= 384 pairs) dipped in the water soon after the coupling manoeuvre and about 25% of those then separated. Males in dipping pairs (n= 13) were on average smaller and relatively older than the males that successfully carried their mate to the shore (n= 54). No differences were found for flight muscle ratio (weight of flight muscles/total body weight) or relative load (total load/flight muscle weight). Males were larger than females (wing length), though typically female Trichoptera are the larger sex. Large male body size inA. cinereusmay be an adaptation for flight during pairing; i.e. larger males are more likely to be able to carry larger loads.

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1995.tb00802.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY