摘要:

Abstract.1. We determined mortality and distributional patterns of leaf miners on three oak host species (Quercus falcata, Q.nigra and Q.hemisphaerica) in northern Florida, U.S.A.2. Patterns of intra‐ and interspecific occurrence within leaves, and mortality of five most abundant leaf miner species were analysed as a test of competition.3. Miners co‐occurred on leaves more often that expected by chance (P<0.05) in six of ten possible species combinations and log‐linear model analysis showed no negative higher‐order interactions.4. All five miner species had highly clumped distributions between leaves (P<0.01).5. Leaf miner survival was less than expected for four of five species when co‐occurring on leaves with conspecifics than when mining with heterospecifics or alone (P<0.05).6. We conclude that interspecific competition is unapparent within this leaf miner guild and that intraspecific competition occurs in four of the five major leaf miner species. We discuss leaf miner selection of common leaves, perhaps based on chemical/physical leaf characters, as a cause of intra‐ and interspecific

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1985.tb00541.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.1. The army ant Eciton rapax (F. Smith) produces longer raid systems than any other member of its genus and it is a specialist predator of forest floor and understory ants such as species of Camponotus, Odontomachus and Pachycondyla.2. Allometrical analysis confirms that E. rapax is the only member of its genus without distinct physical castes among its workers: its foraging population is entirely monomorphic and there are no majors.3. The workers of E. rapax are distributed over a considerable size range, and there are distinct divisions of labour within these colonies: small workers tend to stay in the nests and among the larger foraging workers those retrieving prey items are significantly bigger than the rest.4. An analysis of foraging efficiency and worker performance in E. rapax suggests that transport costs, resulting from the great distances that workers travel during raids and emigrations, are one of the selection pressures that have favoured the evolution of large monomorphic workers in this species.

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1985.tb00542.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.1. Changes in the chemosensory responses and physiological host tolerance of phytophagous insects and parasitoids may result in new host associations. This paper considers the origin of those changes in ecological and evolutionary time.2. The chemical legacy hypothesis postulates that effects of larval chemosensory environment on adult chemosensory responsiveness depend not (or not only) on persistent neural changes (‘memory’), but on traces of chemical cues, inside or outside the insect's body, which influence adult behaviour, perhaps particularly during a ‘sensitive period’ associated with adult emergence or hatching of the egg.3. Chemical cues bequeathed by earlier stages may affect adults or larvae by reducing peripheral sensitivity. Depending on the form of the dose–response curve, this change could decrease aversion or increase a positive response to a previously deterrent stimulus.4. Attention is drawn to a possible link between this behavioural induction and the induction of detoxification enzymes. This link might be of practical importance if exposure to host allelochemicals were to influence insects' responses to insecticides, and vice versa.5. An influence on the chemosensory responsiveness of an individual by chemical cues derived from its parents would be hard to distinguish from a genetic effect.6. Some testable postulates of the chemical legacy hypothesis are i

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1985.tb00543.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.1. Leaves of tomato (cv. Moneymaker) were artificially damaged and offered to Spodoptera larvae at a range of intervals following damage. Grazing levels on these leaves were compared with those on undamaged leaves on the same or different plants.2. In separate experiments, three leaves in a middle position on the main stem were clipped and after 48 h grazing levels on undamaged leaves above and below those damaged were compared with similar leaves from control plants.3. Within 8 h, grazing levels on damaged leaves were significantly lower than those on control leaves, and within 24 h, leaves adjacent to damaged ones were similarly affected. These effects persisted for at least 7 days and leaves above and below those damaged were affected. There was up to nine‐fold reduction in area consumed.4. The possible ecological consequences of reduced palatability at these levels are discusse

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1985.tb00544.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.1. Data are presented on the species richness and faunal composition of herbivorous insects on birch seedlings, saplings and trees at one site in Northern England.2. Species richness of insect herbivores in equal‐sized samples from birch seedlings and trees was similar through most of the season.3. Effects of plant architecture were confined to the first sampling date, when seedling faunas were species poor compared with trees – possibly due to safe overwintering sites on the extensive bark, twigs and buds of trees.4. The faunal composition of birch seedlings, saplings and trees was also similar. Out of a total of 112 recorded species of herbivores, only one aphid species was confined to seedlings.5. Similarly, no evidence for clear‐cut vertical stratification of insects within trees was found.6. Species turnover as host plants mature (‘horizontal’ stratification) and vertical stratification within trees add little to the high overall species richness of birch‐feeding insects in Britain, contrary to the predictions of La

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1985.tb00545.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.1. A study of searching behaviour on wheat and host preference of Aphidius rhopalosiphi (DeStefani‐Perez) is described.2. Parasitoids divided their time equally between the leaves but spent very little time on the ear.3. After contact with honeydew or an aphid host, parasitoids were arrested in a particular area and increased the time spent searching.4. Aphids feeding on the ear were parasitized less successfully, since their position between the grains protected them from parasitoid attacks.5. A.rhopalosiphi exhibited no preference for Metopolophium dirhodum (Walker) or Sitobion avenae (Fabricius), although the handling time for the latter was significantly longer; this resulted in fewer S.avenae being parasitized when it was abundant. Parasitoids did not switch between hosts in these experiments.6. As a result of its searching behaviour, A.rhopalosiphi will encounter and parasitize M.dirhodum feeding on the leaves more frequently than S.avenae, which feeds on the ear. This will limit the parasitoid's ability to regulate populations of the cereal aphid S. avena

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1985.tb00546.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.1. Small arenas in the field were used for observing adult Agonum dorsale (Pont.) foraging in a wheat crop.2. The carabid showed no significant change in behaviour between low and high aphid density arenas.3. Individuals foraged nocturnally and spent most of their time on the ground searching for prey. They climbed infrequently and then not high enough to reach aphid aggregations on the ears and flag leaves of wheat.4. Gut dissection showed that more individuals had eaten aphids in the high aphid density arena than the low. Recording of aphid distribution within the arenas showed that this increase in aphid consumption could be explained by A.dorsale capturing aphids on the ground. Prey availability per unit area was in fact higher on the ground than on the wheat.5. The contribution of ground‐zone predators such as A.dorsale to the control of cereal aphids will be determined by the frequency with which aphids arrive on the ground and the proportion of these which reclimb the wheat and reproduce in the absence of predatio

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1985.tb00547.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.1. Ants, parasitoids and flies are about equally frequent at foliar nectaries of Byttneria aculeata (Sterculiaceae) in lowland Costa Rica during the dry season, a pattern previously unreported but also observed at other plants in the area.2. Species of Ectatomma, Crematogaster and Camponotus were the most frequent of twenty‐four ant species on Byttneria, eight of which nested in the hollow stems. Ants spent most time at nectaries and little in patrolling.3. Collections at nectaries yielded large numbers of species of parasitoid Hymenoptera with few individuals of each. Rearing studies of leaf‐feeding herbivores yielded several species of parasitoids, including one species taken at a nectary and two others congeneric or closely related.4. Flies appear to be nectar thieves, in the same sense as non‐pollinating floral visitors, despite close association with Byttneria.5. Ant‐plants may be poor models for the larger number of species of less specialized plants with extrafloral nectaries. Plants which have only extrafloral nectaries may better suit the needs of parasitoids than ants, and plants such as Byttneria may benefit as much from parasitoids as fr

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1985.tb00548.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.1. Egg weights decrease over the oviposition period in all of the five satyrid butterflies that have been studied, viz Parage aegeria L., Lasiommata petropolitana F., L.maera L., L.megera L. and Lopingaachine Scop. However, within each species, no correlation was found between variation in egg weight and egg mortality in 30% relative humidity or the ability of newly hatched larvae to survive without food for 1–4 days.2. Although egg weights of Papilio machaon L. were similar to the highest satyrid egg weights, newly hatched larvae of P.machaon showed significantly higher mortality after 1 day of starvation when compared to all of the satyrid larvae. This indicates that the capability of newly hatched larvae to endure starvation is not necessarily correlated with egg weight, and consequently that this character trait of satyrid larvae has been selected for (i.e. should be regarded as an adaptation). It is noteworthy that this ability of satyrid larvae to endure starvation is coupled with the habit of many satyrid butterflies not to deposit their eggs directly on the larval host plants.3. In 30% relative humidity, egg mortality of L.achine was 100% and that of P.aegeria 29.2%, whereas that of the three Lasiommata spp. was significantly lower. At 100% relative humidity egg mortality in L.achine dropped to 8%. Since egg weights are higher in L.achine than in the other four satyrids this indicates that egg resistance to desiccation is not necessarily correlated with egg size (as might be expected due to the area to volume ratio which is negatively correlated with egg size). Thus the resistance to desiccation which is found in the three Lasiommata spp. should be regarded as an adaptation to the habit of these three butterflies to deposit their eggs in relatively dry microhabitats. This resistance to desiccation is not found in eggs of the two forest‐dwelling satyrids P.aegeria and L.achine which lay their eggs in microhabitats where the relative humidity is h

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1985.tb00549.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.1. Adult female pine beauty moths, Panolis flammea (D&S), when given a choice of whole plants or needle pairs of four provenances of Lodgepole pine, Pinus contorta (Douglas), laid most eggs on that provenance on which the larvae attained their greatest growth rates.2. When presented with a greater number of Lodgepole pine provenances and Pinus sylvestris L, P.flammea oviposition preferences reflected the trade‐off between growth rate and survival.3. There is some evidence to suggest that the moths are responding to the monoterpene composition of the plants.4. Adult moths showed no preference for Lodgepole pine needles of a range of ages (1–4 years), ovipositing uniformly on all age clas

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1985.tb00550.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY