摘要:

The abundance and diversity of insects was the subject of the joint commemorative meeting between the Linnean Society and the Royal Entomological Society of London. This paper gives a brief outline of the foundation and early history of the Entomological Society and its forerunners, and its relations with the Linnean Society at the time. It also shows how the contributions of the founding fellows of the Society, whose interests originated in collecting and insect natural history, laid the foundations of many of the present day fields of entomological research.

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1988.tb00473.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Biologists are still trying to grasp the global dimensions of the phylum Arthropoda and its major class the Insecta, in spite of the fact that over a million species of arthropods have been described. The canopy of rain forest trees is believed by many to hold the key to the immense diversity of insects. In recent years the use of knock‐down insecticides to sample insects from rain forest canopy has revealed information on the canopy's arthropod inhabitants and community structure. The sampling techniques involved are outlined and data reviewed on taxonomic and guild structure, species abundance, body size and biomass of insects, and the faunal similarity of trees. Calculations by Erwin (1982), based on knock‐down insecticide studies of the beetle fauna of one species of Central American tree, suggest there may be 30 million species of tropical forest arthropods. Reanalysis of these calculations, using additional data, produces a range of possible estimates from about 10 to 80 million. The unknown range of plant host‐specificities of tropical insects is the main weakness of this method of calculation. Assessment of the faunal importance of the canopy in relation to that of other rain forest biotopes requires comparative quantitative studies. The preliminary results of one such simple study suggest that over 42 million arthropods may be found in a hectare of Seram rain forest (at the time of study), and that 70% occur in the soil and leaf litter and 14% in the canopy. They also suggest that Collembola and Acarina are the dominant groups in this hectare, and that there are as many ants as all the other insects (excluding Collem

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1988.tb00474.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Evidence that chemical changes in plants following insect feeding can lead to reduced grazing levels, enhanced insect movement and selective leaf avoidance is briefly reviewed. A simple model is constructed in which changes in damaged and/or adjacent leaves lead to effects on herbivore performance. The model reveals that as the density of herbivore larvae/plant increases from one to twenty‐four, wound‐induced changes in the leaves reduce larval survival by up to 40%, treble the number of movements of the larvae and increase their development time byc.10%. The distribution of grazing between leaves changes in the direction of more leaves with lower grazing levels but overall grazing levels are not greatly affected by the above changes in larval performance. The model's output is discussed in relation to recent views concerning the relative roles of intra‐specific competition and predation in regulating insect herbivore nu

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1988.tb00475.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The four major biological strategies of ichneumonoid parasitoids, koinobiont and idiobiont, ecto‐and endoparasitism, are discussed and the evolutionary radiations of the two families Ichneumonidae and Braconidae compared in an attempt to relate differences in patterns of host utilization to differences in evolutionary history. The most primitive members of both families are idiobiont ectoparasitoids of hosts concealed in plant tissue. Idiobiont ectoparasitic braconids are all still primarily associated with such hosts, but idiobiont ectoparasitic ichneumonids have radiated to attack hosts in other situations, such as in aculeate nests or in cocoons. A shift in emphasis between the behavioural steps, host habitat location and host location, is envisaged as being important in such evolutionary change. Idiobiont endoparasitism is postulated as having arisen amongst ectoparasitoids attacking cocooned hosts, as an adaptation that allows them to exploit pupae and puparia in relatively exposed positions; it is a fairly common strategy in the Ichneumonidae, but virtually unknown in the Braconidae. Koinobiosis is perceived as having evolved in association with hosts which feed in a relatively weakly concealed position, but pupate in a more secluded and safe location. The strategy is advantageous as it allows a parasitoid to oviposit on an easily discoverable host, but to use the host's pupation concealment to complete its own development. The evolution of koinobiosis has allowed parasitoids to exploit hosts that feed in exposed positions, and to attack hosts at a younger and numerically more common stage in the host's life cycle. Koinobiont ectoparasitism is envisaged, in some braconid and ichneumonid groups, to occupy an evolutionary transitional position between idiobiosis and endoparasitic koinobiosis; only in the Ichneumonidae have large radiations of koinobiont ectoparasitoids occurred. Endoparasitic koinobiosis is hypothesized as having arisen in the Braconidae in association with lepidopterous/coleopterous hosts, whilst in the major lineage of endoparasitic koinobiont ichneumonids, this habit is hypothesized as having arisen in association with symphytan hosts. The great majority of braconids are koinobiont endoparasitoids, but only about 50% of the Ichneumonidae have this habit. Very few koinobiont braconids develop as endoparasitoids of hymenopterous hosts, although many endoparasitic ichneumonids attack Hymenoptera. However, lineages of the Braconidae have radiated to exploit adult insects and exopterygote nymphs; ichneumonids do not utilize such host

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1988.tb00476.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

A survey of 35 species indicates that monitor lizards(Varanus)typically hunt over large areas, search in particular microhabitats, and feed frequently on a wide variety of prey, many of which are relatively small. There is ontogenetic, seasonal, and geographic variation in diet. With some exceptions, invertebrates are the predominant prey, but rare predation on vertebrates is often energetically significant. A few monitors specialize on prey types that occur as occasional items in the diet of species with more generalized diets; these include crabs, snails, orthopterans, lizards, and large mammals. For most species, prey specialization occurs via habitat selection and a variety of prey types and sizes are eaten, as expected for widely searching predators. Comparisons with other anguimorphans suggest that derived features ofVaranusare associated with high body temperature and activity levels; specialized chemoreception; and rapid, skillful capture of hidden and/or potentially hard to catch prey. Occasional ingestion of moderately large prey is primitive for Varanoidca (Helodermatidae +Varanidae), accentuating a trend that is perhaps primitive for anguimorphan lizards. Reduction of very large prey prior to ingestion is a derived attribute withinVaranus, seen infrequently in several larger species and commonly inV. komodoensis.This study illustrates the synthesis of comparative natural history in a phylogenetic context, a method that addresses the history of organismal change.

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1988.tb00477.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY