In an earlier study (Holling, 1959) the basic and subsidiary components of predation were demonstrated in a predator-prey situation involving the predation of sawfly cocoons by small mammals. One of the basic components, termed the functional response, was a response of the consumption of prey by individual predators to changes of prey density, and it appeared to be at least theoretically important in population regulation: Because of this importance the functional response has been further examined in an attempt to explain its characteristics.

The fluctuation of an animal's numbers between restricted limits is determined by a balance between that animal's capacity to increase and the environmenta1 cheks to this increase. Many authors have indulged in the calculating the propressive increase of a population when no checks nrerc operating. Thus Huxley calculated that the progeny of a single Aphis in the course of 10 generations, supposing all survived,would “contain more ponderable substance than five hundred millions of stout men; that is, more than the whole population of China”, (in Thompson, 1929). Checks, however, do occur and it has been the subject of much controversy to determine how these checks operate. Certain general principles—the density-dependence concept of Smith ( 1955) , the competition theory of Nicholson (1933)—have been proposed both verbally and mathematically, but because they have been based in part upon untested and restrictive assumptions they have been severelv criticized (e.g. Andrewartha and Birch 1954). These problems could be considerably clarified if we knew the mode of operation of each process that affects numbers, if we knew its basic and subsidiary components. predation, one such process, forms the subject of the present paper.

The multiple funnel trap, an efficient, collapsible, non-sticky trap for scolytid beetles, consists of a series of vertically aligned funnels with a collecting jar at the bottom. The trap compared favorably with sticky traps and Scandinavian drainpipe traps for three species of ambrosia beetles and the mountain pine beetle. Minimum maintenance required for this trap allows for high efficiency in pheromone-based research, survey, and mass trapping of scolytid beetles.

We describe a litter-washing technique for collecting quantitative samples of ground-beetles (Carabidae), and compare the results with those from liner extraction by Tullgren funnels and pitfall (rapping. We also compare performance of four types of pitfall traps across five habitats. Carabid species composition from litter washing and funnel extraction was similar but washing revealed higher densities. Large-bodied species predominated in pitfall samples and small-bodied species predominated in litter samples. Uncovered, round pitfall traps yielded generally higher catches than rectangular or covered, round traps but the pattern was not consistent over all species or the five habitats. Ecological studies of carabid populations and assemblages using pitfall traps may be improved if they are both designed and interpreted in light of the biology of the group and with regard to the deficiencies of pitfall trapping as discussed here and elsewhere.

The potential for mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae: Scolytinae), to expand its historical range in North America from west of the continental divide into the eastern boreal forest was assessed on the basis of analyses of the effects of climate and weather on brood development and survival, and key aspects of the interaction of mountain pine beetle with its hosts and associated organisms. Variation in climate suitability and high host susceptibility in the boreal forest create a finite risk of establishment and local persistence of low-level mountain pine beetle populations outside their historical range. Eventually, these populations could become widespread and cause epidemic infestations, creating an ecological pathway eastward through the boreal forest. Such infestations would reduce the commercial value of forests and impose an additional disturbance on native ecological systems.

The spruce budworm, Choristoneura fumiferana (Clemens), was reared on a synthetic diet. Comparison of two successive laboratory generations reared on synthetic diet and on frozen balsam fir buds showed that diet-fed insects had a higher survival, developed faster, were heavier, mated more successfully, and were more fecund.

The Diptera are the second most important order among flower-visiting (anthophilous) and flower-pollinating insects worldwide. Their taxonomic diversity ranges from Nematocera to Brachycera, including most families within the suborders. Especially important are Syrphidae, Bombyliidae, and Muscoidea. Other families, especially of small flies, are less appreciated and often overlooked for their associations with flowers. We have compiled records of their flower visitations to show that they may be more prevalent than usually thought. Our knowledge of anthophilous Diptera needs to be enhanced by future research concerning (i) the significance of nocturnal Nematocera and acalypterate muscoids as pollinators, (ii) the extent to which the relatively ineffective pollen-carrying ability of some taxa can be compensated by the abundance of individuals, and (iii) the role of Diptera as pollinators of the first flowering plants (Angiospermae) by using phylogenetic and palaeontological evidence. Specializations in floral relationships involve the morphology of Diptera, especially of their mouthparts, nutritional requirements, and behaviour, as well as concomitant floral attributes. The South African flora has the most highly specialized relations with dipterous pollinators, but in arctic and alpine generalist fly–flower relations are important in pollination and fly nutrition.

The chaetotactic nomenclature proposed by Lindquist and Evans (1965) for the Gamasina, using the family Ascidae as examplar, is adopted for use in the family Phytoseiidae. Probable setal homologies were determined by: examining and comparing ontogenetic relationships in both the Phytoseiidae and Ascidae; standardizing the shape and size of the dorsal shield of exemplars from 7 genera of Phytoseiidae and one of Ascidae in order to compare standardized, transformed setal positions; examining the spatial relationships between setal and pore positions. The technique used to standardize the shape and size of the dorsal shield is described. The setal nomenclature adopted for each of the genera of Phytoseiidae is discussed and presented in diagrammatic form. Ventral chaetotaxy in the Ascidae and Phytoseiidae is also discussed.

A suspected chemical means of habitat selection by Diaeretiella rapae, a primary parasite of aphids on crucifer plants, was investigated in the laboratory with the aid of an olfactometer. Females (and, to a lesser extent, males) were found to be attracted by odor to leaves and leaf juices of a crucifer host plant and to dilute solutions of the mustard oil allyl isothiocyanate. Given a choice of aphid colonies (Myzus persicae) on leaves of beet (Chenopodiaceae — mustard oils not present) and collard (Cruciferae — mustard oils present), female D. rapae displayed a marked preference to oviposit in aphids feeding on collard. It is concluded that female D. rapae parasites locate their hosts initially by a response to an odor emanating from the aphid host-plant, followed by visual searching. Male D. rapae were attracted by odor from female D. rapae, suggesting the existence of a sex pheromone in this species.Neither males nor females of Charips brassicae, a hyperparasite of D. rapae, were attracted to collard leaves, though females showed apparent attraction to female D. rapae. As with D. rapae, males of C. brassicae are attracted by odor to females of the same species.The host finding behavior of D. rapae is discussed in relation to that of other insect species belonging to the fauna associated with the plant family Cruciferae.

Insects are selected for slow development (but relatively fast growth) in spring, but for fast development in summer. These contrasting selection pressures explain five puzzling effects of temperature on insects: growth and development rates increase almost linearly with temperature; genetic variability in development rate is reduced at high (27°C) temperatures; genetic variability in growth rate is reduced at low (15°C) temperatures; development is very slow at the time of emergence after diapause, regardless of the temperature threshold for emergence; and growth is slow at low temperatures, but development is even slower.

Insects use temperature to indicate time-of-season. Different species are geared differently to rising temperatures. Insect predators and parasitoids become more effective at high temperatures; and insect population dynamics are not stable in the conventional sense.

A survey is made of the major features of the venation, articulation, and folding in the hind wings of Coleoptera. The documentation is based upon examination of 108 Coleoptera families and 200 specimens, and shown in 101 published figures. Wing veins and articular sclerites are homologized with elements of the neopteran wing groundplan, resulting in wing vein terminology that differs substantially from that generally used by coleopterists. We tabulate the differences between currently used venational nomenclature and the all-pterygote homologous symbols. The use of the neopteran groundplan, combined with the knowledge of the way in which veins evolved, provides many strong characters linked to the early evolutionary radiation of Coleoptera. The order originated with the development of the apical folding of the hind wings under the elytra executed by the radial and medial loop. The loops, which are very complex venational structures, further diversified in four distinctly different ways which mark the highest (suborder) taxa. The remaining venation and the wing articulation have changed with the loops, which formed additional synapomorphies and autapomorphies at the suborder, superfamily, and sometimes even family and tribe levels. Relationships among the four currently recognized suborders of Coleoptera are reexamined using hind wing characters. The number of wing-related apomorphies are 16 in Coleoptera, seven in Archostemata + Adephaga–Myxophaga, four in Adephaga–Myxophaga, seven in Myxophaga, nine in Archostemata, and five in Polyphaga. The following phylogenetic scheme is suggested: Polyphaga [Archostemata (Adephaga + Myxophaga)]. Venational evidence is given to define two major lineages (the hydrophiloid and the eucinetoid) within the suborder Polyphaga. The unique apical wing folding mechanism of beetles is described. Derived types of wing folding are discussed, based mainly on a survey of recent literature. A sister group relationship between Coleoptera and Strepsiptera is supported by hind wing evidence.

Among the attributes of the parasitic Hymenoptera that contribute to the ability of certain species to maintain host populations at low densities is the power to restrict egg deposition to sites suitable for the continued development of the offspring, and to regulate, regardless of host density, the number of eggs deposited per host (Flanders 1947). High searching capacity is, in part, a function of female longevity correlated with the conservation of reproductive material. It is self evident that time used in wasteful oviposition means less time for searching and consequently less effective control of the host.

With the current advances in insect population modelling, the need for more accurate simulation of temperature-dependent growth rates has become vital. The day-degree concept, with its linear temperature–rate relationship, has not been adequate for simulation of field populations under highly variable temperature conditions. Similarly, several of the non-linear relationships proposed in the past (Janisch’s catenary, parabola) have also been inadequate. All of these relationships produce large errors at temperature extremes.

This paper presents a comparison of various functions which have been used for developmental time estimation and an algorithm for a sigmoid function which can be used in simulations having either a calendar or a physiological time base. Validation of the algorithm is presented for three insect species.

The many components of seasonal adaptations in insects are reviewed, especially from the viewpoint of aspects that must be studied in order to understand the structure and purposes of the adaptations. Component responses include dispersal, habitat selection, habitat modification, resistance to cold, dryness, and food limitation, trade-offs, diapause, modifications of developmental rate, sensitivity to environmental signals, life-cycle patterns including multiple alternatives in one species, and types of variation in phenology and development. Spatial, temporal, and resource elements of the environment are also reviewed, as are environmental signals, supporting the conclusion that further understanding of all of these seasonal responses requires detailed simultaneous study of the natural environments that drive the patterns of response.

The new association approach for selecting biological control agents has been reanalyzed in the light of recent data. The results support the conclusion that the new association approach is ecologically and statistically sound. One of the major advantages of this approach is its capacity to control native pests, which make up 60–80% of all pests. The specificity of biocontrol agents newly associated with the target hosts is similar to other biocontrol agents. In addition, the new association approach is as safe as the old association approach in terms of environmental risks. Recent trials in the use of new associations have been most encouraging, and suggest that this approach should contribute to the future success of biological pest control worldwide.

Temperature-dependent development of the egg, larval, and pupal life-stages of the mountain pine beetle (Dendroctonus ponderosae Hopkins) was described using data from constant-temperature laboratory experiments. A phenology model describing the effect of temperature on the temporal distribution of the life-stages was developed using these data. Phloem temperatures recorded in a beetle-infested lodgepole pine (Pinus contorta Douglas) were used as input to run the model. Results from model simulations suggest that inherent temperature thresholds in each life-stage help to synchronize population dynamics with seasonal climatic changes. This basic phenological information and the developed model will facilitate both research and management endeavors aimed at reducing losses in lodgepole pine stands caused by mountain pine beetle infestations.

Comparative gas chromatographic analyses of volatiles generated by Ips indicate the presence of cis- and trans-verbenol in hindguts of the 12 species investigated. The biosynthesis of verbenol does not require feeding, but instead results from the insect’s contact with oleoresin. Ipsdienol is the most frequently occurring pheromone in Ips species after feeding. Aggregation of these bark beetles appears to be regulated by two distinct functional types of pheromones, i.e. contact pheromones, produced and/or released upon contact with new host material, and frass pheromones, which require actual feeding in the new host’s tissues. The aggregation of aggressive bark beetle species seems to be largely dependent on contact pheromones, whereas the host’s susceptibility to feeding is indicated by the release of frass pheromones.

A new classification of dormancy in insects is proposed on the basis of the evolutionary nature of dormancy, its synchronization with the aetiology of the species for their phenological advantage, the nature of ecological adversity, and the consequent physiological and biochemical adjustments. The roles of the above factors in the induction and termination of dormancies are discussed. The inadequacies of all the previous systems of describing various conditions of dormancy are pointed out.All instances of dormancy are divided into three major groups: hibernation, aestivation, and athermopause. Each of these classes is further subdivided into three categories representing a sequence of evolutionary adaptations: quiescence, oligopause, and diapause, in that order of evolutionary development. Depending upon the physiological condition of diapausing individuals or populations, two diapause states are recognized: teleodiapause and ateleodiapause. Each term is defined and discussed with examples.

Factors affecting the winter survival of temperate-zone insects are reviewed. Certain species suffer high winter mortality especially in cold years, or in years with below normal amounts of insulating snow.

Survival depends on the choice of winter microhabitat and on cold-hardiness, but also on biological features that have not previously been emphasized. These include behaviour that results in placement of overwintering eggs in less severe sites and manufacture of cocoons or other structures that retard inoculation by ice, or desiccation. The possible role of habitat heterogeneity in facilitating population survival is stressed.

Microhabitats are characterized mainly with respect to temperature. They differ markedly among geographic areas and not only in midwinter conditions (including the extent of variation), but also in the time at which entry to the microhabitat in fall is necessary to avoid the risk of frost. The cues that govern entry into these microhabitats include negative phototaxis in many species but have not been subjected to quantitative analysis. Deeper layers are warmer in winter but warm up more slowly in spring and therefore some species, especially in arctic habitats where rapid vernal development is advantageous because the season is short, overwinter in superficial or insolated sites.

Supposed mechanisms of cold- and freezing-injury and its avoidance are reviewed. There are several theories of freezing-injury: many modem theories focus on damage to the cell membrane, apparently caused by changes in cell volume induced during freezing. Injury is avoided by suppression of haemolymph nucleators (enhancing supercooling); or by a variety of methods, especially those involving solutes, minimising damage to frozen tissues. Among these solutes, the prevalence of glycerol in overwintering insects is not unexpected since glycerol is a normal metabolite in animals and can play several possible roles in cryoprotection.

Cold-hardiness is metabolically costly because of these solute adjustments. The cold-hardiness of a taxon depends partly on climatic history during its evolution. Faunal composition at the highest latitudes reflects this dependence.

The winter survival of many high-latitude insects varies rather widely from year to year; but the many detailed studies on cold-hardiness that have been made in the laboratory have seldom been related to natural mortality.

The overwintering stage depends partly on the taxon. It is often fixed within a genus, but less closely within higher taxa. Proportionately more species overwinter as larvae at higher latitudes, especially when the life cycle lasts more than one year. Habitat also influences the overwintering stage: aquatic species generally overwinter as larvae, although species of temporary pools frequently overwinter as eggs. Overwintering in more than one stage is not common.

This review suggests that winter survival of a group depends on latitude (or its climatic equivalent), habitat, and evolutionary history. It might therefore be especially useful to compare cold-hardiness, developmental rates, control of the life cycle and other features among species at the same latitude from each extreme of a series, that contrasts cold-hardy groups in stable habitats (such as Chironomidae) with aerial or vegetation dwelling groups that are not cold-hardy (such as Orthoptera). Future study of winter survival also demands more ecological data (overwintering stage, microhabitat, and conditions experienced there) for a larger sample of the fauna, and the simultaneous measurement of cold-hardiness.

Fitness, defined as the per capita rate of increase of a genotype with reference to the population carrying the associated genes, is a concept used by biologists to describe how well an individual performs in a population. Fitness is rarely measured directly and biologists resort to proxies more easily measured but with varying connection to fitness. Size, progeny survival, and developmental rate are the most common proxies used in the literature to describe parasitoid fitness. The importance of the proxies varies between papers looking at evolutionary theories and those assessing ecological applications. The most direct measures of fitness for parasitoids are realised fecundity for females and mating ability for males, although these proxies are more difficult to measure under natural conditions. For practical purposes, measure of size, through body size or mass, is the proxy easiest to use while providing good comparative values; however, care must be taken when using a single proxy, as proxies can be affected differently by rearing conditions of the parasitoid.