摘要:

Abstract.1. Relative to Nepenthes species in West Malaysia near the evolutionary centre of the genus, outlying species of Nepenthes in the Seychelles, Sri Lanka and Madagascar have fewer species of both prey and predator living in them, fewer and smaller guilds of species, much apparently empty niche space, less complex food webs, and a greater connectance. The ratios of prey to predators, and of connectance (C1) to the total number of trophic types present remain approximately constant.2. Differences between the food webs appear to be related in a complex way to the size of the country and its degree of spatial and temporal isolation, the size of the local species pool capable of colonizing the pitchers, and the number of Nepenthes species present. However, the maximal length of food chains in the richest and most complex food webs is probably limited by energetic constraints or environmental predictability.3. The data may illustrate how food webs change to become more complex, both by the addition of new guilds of species and the addition of species to existing guilds, while at the same time certain properties of the food web are kept approximately constant.

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1985.tb00720.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.1. The seasonal changes in abundance of macropterous N. lugens (Stal) and S. furcifera (Horvath) (Homoptera: Delphacidae) are described based on observed numbers of adults and presumptive macroptery in fifth‐instar nymphs occurring in rice crops in the Philippines.2. Percentage presumptive macroptery in fifth‐instar nymphs was correlated with nymphal density over the range of 0–20 nymphs per hill for females of both species and 5–20 nymphs per hill for male N. lugens.3. Lunar phase had no effect on wingmorph expression in either species.4. Comparison of the percentage macroptery in fifth‐instar nymphs with subsequent percentage macroptery in N. lugens adults for one season showed net emigration occurred from 60 DAT (days after transplanting) to harvest except for a period of net immigration lasting 7–10 days at approximately 95 DAT for

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1985.tb00721.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.1. Radar observations of insects migrating at night over central‐western New South Wales have detected an instance of migration in a low‐level wind jet.2. From the characteristics of the radar echoes, and from the catches obtained in traps at ground level and at the altitude of migration, the migrants can be identified as noctuid and pyralid moths of a number of different species.3. The migration, which was in a downwind direction, started at dusk and ended at about dawn. During the period immediately before first light, a large proportion of the migrants were concentrated into a 100m deep layer at an altitude of about 250m; this layer had not been present during the first half of the night.4. The boundary layer wind profile at dawn exhibited a clear low‐level jet structure, with a wind maximum between 100 and 300m, and strong shear in the wind direction below 300m. A strong surface temperature inversion, but not a wind‐speed maximum, had been present the previous evening.5. The formation of the layer concentration in the upper part of the jet may be accounted for in terms of previously described responses of nocturnally migrating insects to a surface temperature inversion. It is not therefore necessary to assume that the migrants were responding specifically to the presence of a wind‐spee

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1985.tb00722.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.1. We studied the fecundity of Epirrita autumnata Bkh. (Lepidoptera) in relation to pupal weight of females and males.2. There was no clear correlation between male size and the success in fertilization over a considerable range of weights (from 50 mg to over 100 mg) although in one experiment only large males were successful in multiple fertilizations.3. In the three experiments where small males (<50 mg) were used they showed reduced performance, and a large proportion of them was sterile.4. Unlike in males, the number of eggs laid by females correlated linearly with pupal weight over the whole range of female weights.

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1985.tb00723.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.1. The causes and reproductive consequences of body size variation of Brachinus lateralis Dejean, a parasitic carabid beetle, were investigated.2. Body size variation occurs within and between sites. Host size has a major influence on body size of the adult.3. Fecundity is positively correlated with body size. Egg size is not correlated with body size.4. Mating males tend to be larger than non‐mating males. There is a positive correlation of body sizes in mating pairs.5. Limited opportunity for host choice may maintain size variation despite the advantages of large size.6. The non‐random patterns of mating for a species without obvious intrasexual aggression suggest that subtle means of male‐male competition or female choice may be impo

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1985.tb00724.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.1. Flower thrips could feed on pollen of a wide range of sizes and were unaffected by exine spines. One species of thrips was unable to feed on very adhesive grains.2. The proportion of time spent feeding on each species of pollen (in seconds per minute of exposure) reflected the known host specificities. Host‐specific thrips could distinguish their host pollen, apparently without probing.3. Kakothrips pisivorus (Westwood) appeared to have a higher rate of ingestion of a host pollen than of four non‐host pollens.4. In cages in the laboratory, Thrips fuscipennis Haliday laid significantly more eggs over 48h when given pollen than when given other floral tissues or no food. K. pisivonis and Ceratothrips ericae (Haliday) also laid significantly more eggs over 48h in the presence of pollen than in its absence.5. In comparisons between pollen diets, T. fuscipennis, a generalist, laid similar numbers of eggs with each species of pollen, but K. pisivorus and C. ericae laid significantly more eggs with their respective host pollens. The differences in oviposition rate between pollen diets reflected the differences in the proportion of time spent feed

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1985.tb00725.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.1. Host plant choice of the seed bug, Neacoryphus bicrucis Say (Hemiritera, Lygaeidae), was evaluated in four different Georgia habitats. N. bicrucis utilized only species of Senecio as host plants at a granite outcrop and at old fields on the coastal plain, in the piedmont, and in the Blue Ridge Mountains.2. In laboratory tests N. bicrucis is distasteful to the green anole lizard, Anolis carolinensis Voight. Only six of ninety field‐collected bugs were eaten in palatability trials while eighty‐four of the remaining ninety attacked bugs were rejected by lizards without apparent harm. However, the bugs were palatable to Fowler's toads, Bufo woodhousei fowleri Hinckley, which ate all thirty‐six bugs offered to them.3. N. bicrucis selectively sequesters pyrrolizidine alkaloids from Senecio spp. These may cause the insects' distastefulness to green anoles. In palatability trials, lizards ate all twenty insects reared on sunflower seeds, Helianthus annus, but rejected all twenty reared on Senecio sm

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1985.tb00726.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.1. About 166,000 African armyworm moths, Spodoptera exempta (Walk.), were marked at an emergence site near Nairobi when they fed at night on trees baited with dyed molasses.2. Six marked moths were captured in pheromone traps, including one at 90 km after flying for only one night, and another at 147 km.3. Moth flight trajectories deduced from radar and from marking showed that migration was downwind.4. During migration, moths become dispersed; hence the high densities that lead to outbreaks must be produced by concentration.5. Some moths were ready to mate on the same night they completed their long‐distance fligh

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1985.tb00727.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.1. Activity patterns, diets and interspecific interactions of two coexisting carabid beetles, Carabus yaconinus B. and Leptocarabus kumagaii K. et K., were studied in a lowland habitat in Japan.2. Larvae of C. yaconinus appeared from May to October and fed on earthworms. Those of L. kumagaii appeared from October to the next May and fed on dipteran and lepidopteran larvae.3. In the adult stages, feeding habits and daily activities of the two species were similar. The beetles fed mainly on earthworms and other animal materials, but various plant materials were also utilized.4. Direct competition for food items was observed both intra‐ and interspecifically. Interspecific interactions occurred only in early summer, however, because of the difference in breeding seasons (i.e. spring for C. yaconinus and autumn for L. kumagaii).5. The difference in seasonal life history patterns between these carabids is a possible mechanism of coexistenc

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1985.tb00728.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.1. The polyphagous butterfly, Plebejus argus L., was found to have specialized requirements: eggs are laid along vegetation/bare ground margins, larvae specialize on tender meristematic and reproductive growth, larvae and pupae are tended by Lasius ants, and warm microclimates are favoured.2. These requirements are met in early successional habitats within several bio topes. These habitats are locally distributed, as is P. argus.3. Populations on limestone, heathland and mossland biotopes did not differ greatly in ecologies. Given a choice of foodplants in captivity, larvae from heathland and limestone did show slight differences in preference, selecting some of the hostplants they normally encounter in the wild. Regardless of biotope, all these larvae were plant taxa generalists (on three plant families), but specialists on plant parts.4. The decline of P. argus in Britain is attributed to loss of biotopes and to declining traditional management of them. Fewer habitats are available, and the distances between them are greater than formerly. As some of these habitats are short lived, and P. argus rarely flies far, the butterfly's decline is a compound effect of reduced areas of habitat and inability to colonize them.

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1985.tb00729.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY