A provisional cladistic analysis of the species groups of Gonatocerus Nees is presented, based on 24 characters. Six species groups are defined, but only the four Nearctic ones are described. The species groups proposed are the ater, deficiens, litoralis, membraciphagus, straeleni, and sulphuripes groups. The ater group is divided into the morrilli, ater (s.s.), and bucculentus subgroups. Keys are provided to distinguish the species groups, and females of the sulphuripes- and ater-group species. Twenty-four species are recognized in the sulphuripes and ater groups for America north of Mexico. Eight species are recognized in the sulphuripes group, of which californicus, koebelei, maga, mexicanus, rivalis, and utahensis are redescribed. Two species, floridensis and lissonotus, are described as new. One new synonymy is proposed: titillatus is considered a junior synonym of utahensis. Sixteen species are recognized in the ater group, of which ashmeadi, capitatus, dolichocerus, fasciatus, latipennis, morrilli, novifasciatus, ovicenatus, and triguttatus are redescribed. Seven species, bucculentus, enicmophilus, flagellatus, impar, incomptus, inexpectatus, and inflatiscapus, are described as new. Two new synonymies are proposed: maximus is considered a junior synonym of latipennis, and marilandicus a junior synonym of dolichocerus. Lectotypes are designated for ashmeadi, capitatus, koebelei, mexicanus, morrilli, ovicenatus, triguttatus, and utahensis.

The complex origins of the North American Ephemeroptera fauna extended from the Lower Permian to the Recent. This paper discusses origins of North American genera of the cosmopolitan family Leptophlebiidae with a few examples from other mayfly families. The two extant subfamilies, Leptophlebiinae and Atalophlebiinae, probably evolved at least by the mid-Cretaceous, or about 100 million years before present. The primitive Leptophlebiinae are distributed throughout most of the Northern Hemisphere and the ancestors of the Leptophlebia–Paraleptophlebia complex within this subfamily dispersed widely by the North Atlantic route as early as the mid-Cretaceous and later probably by northern trans-Pacific dispersals through Beringia. The ancestors of Habrophlebia dispersed through the North Atlantic route at an early time, but the vicariant distribution of Habrophlebiodes in several areas of the Oriental Region and eastern North America correlates with the Arcto-Tertiary forest that covered most of the Northern Hemisphere including Beringia from the Early Tertiary into the Pleistocene. Within the nearly cosmopolitan Atalophlebiinae, Traverella is austral in origin and probably dispersed north through the Mexican Transition Zone during the mid-Tertiary as an ancient dispersal and then dispersed to its northern and eastern limits following the last Pleistocene deglaciation by way of the Missouri River tributaries. Thraulodes and Farrodes are both austral in origin and probably dispersed north through the Mexican Transition Zone during the Early Pleistocene as a relatively recent dispersal. The origins of Choroterpes sensu stricto and Neochoroterpes in North America are unknown. The mayfly fauna of the West Indies is Neotropical in origins, and no affinities between the West Indies and North America through Florida have ever been confirmed.

To improve management of resources, such as agricultural crops or forests, scientists attempt to analyse the resource systems and to predict the consequences or outcomes of interventions. They construct models of interactions of components of the systems, drawing on knowledge and experience. In agriculture, five types of models have become common — empirical, crop–weather, crop–growth, crop–system, and crop–process. The models aim mainly to predict crop yields when a series of actions are taken. They differ markedly in complexity, from a simple regression to a series of mechanistic relations aimed at simulating the crop system. The uses to which a model is to be put, and by whom it will be used, are major determinants of the nature of the model so modellers must work with the potential users. In fact, modelling is an exercise in human relations as much as in science. All things being equal, the simpler the model is that meets the objectives of the users, the better are the chances of its being used.

Concerns are frequently expressed within the resource management community that many of the tools or models being developed to help people manage resources aren't being used. Less clear are the reasons, but a look at the contrasts between resource management and resource science provides some clues. The disciplinary organization of scientific knowledge, compared with the general nature of management problems, contributes to the gap between science and management. Many of the difficulties that resource scientists are experiencing are shared by management scientists attempting to provide problem-solving support to managers. In fact, management scientists who are developing tools for use by managers are sometimes said to be doing research on "toy" problems because of their tendency to oversimplify the "messes" or complex systems with which managers are trying to deal. To derive tools of use in solving real problems, some resource scientists will have to be willing to study and work with resource managers in the context where problems are faced.

Ecosystems that are managed for resource production are under continual structural change. Changes imposed by local management aggregate to produce regional patterns and new regionwide responses. Anthropogenic influences on hemispheric and global processes add another level of change. The result is a bewildering variety of real or anticipated changes unique to experience. For example, in the spruce/fir and budworm interaction of eastern North America, a syndrome of causes affects the vulnerability of renewable resources, and the triggers of change can never be predicted. Yet, it is possible to identify key features that affect resilience of ecosystems and robustness of regulation and to reject other possibilities. This approach provides a way to assign priorities for research and for contingency planning to adapt to change.

Mecoptera of the Nearctic Region are, in general, more like those of the eastern Palaearctic than of any other faunal region. But the fossil record shows that our major extant genera have been in the northern continents since Early Cenozoic. Panorpidae and Panorpodidae probably entered North America by way of Beringia in the Eocene or Oligocene. Nearctic Bittacidae probably came from the Neotropical Region, but a few exhibit peculiar affinities with some eastern Asiatic species, suggesting migration out of the Nearctic into the Palaearctic. Boreidae appear to have been of North American origin but are now Holarctic; they are unknown as fossils. The Meropeidae were probably widespread in mid–Mesozoic but now are found only in eastern North America and western Australia.

Two research programs in support of the wheat industry provide insights into mechanisms that can be used in research planning and in technology transfer. Modelling was pivotal in both: in Australia since 1973 in efforts against rice weevil, Sitophilus oryzae L., infestations of stored wheat and in Canada since 1970 against grasshopper infestations of wheat fields. The research studies, described in published papers, were designed by the scientists within broad research objectives defined by the employing organizations. A mixture of technical and human considerations determined the direction of the research: the talents of scientific staff combined to capitalize on fortuitous events or situations. Serendipity improved the response to uncertainty in both research and industrial environments. The nature and amount of effort needed to get scientific insights applied varied with the specifics of the scientific insight. A general analysis of technology transfer suggests that, in some cases, application requires the involvement of a variety of nonscientific specialists and that research managers are well positioned to coordinate the efforts. Taken together, the conclusions show that satisfying a need or solving a problem is a task within which research is only one part. Success requires effective communication and compromises among very different people.

The present distributions of stonefly genera in North America, their occurrence as endemics, or as shared with the Far East, Europe and South America, are considered in conjunction with geological history. It is concluded that the Plecoptera of North America have four sources of origin.There was an ancient eastern fauna shared with Europe before the formation of the North Atlantic Ocean. A second group moved in from the west during the formation of the western mountains. After formation of the isthmus one genus moved northward from South America. After the Pleistocene period several species migrated from the Bering Strait region, possibly from an Alaskan refugium. Some of these have clearly moved eastward, but a few may have moved westward.

New technology allows the rapid mapping of point or polygon variables, the correlation of maps, and the use of maps as variables in computer models. An illustration is the use of map correlation to investigate how changes in abundance of adult grasshoppers relate to rainfall in Alberta: maps of monthly rainfall, monthly hours of sunlight and annual grasshopper counts (8391 survey records) from a 5-year period were contoured and correlated. The methods of smoothing are described. Correlograms of Moran's I over distance show spatial autocorrelation of grasshopper abundance on a geographic scale. The grasshopper counts were autocorrelated to 20–30 km on most maps, and the relationship of correlograms to contour mapping is discussed. Quotient maps were produced: each population–abundance map was divided by the map from the previous year, and the results were correlated with monthly rainfall maps. There was significant association between areas of increase and levels of rainfall. Population tended to decline in areas of above-average rainfall. A simple model enabled a forecast of grasshopper distribution from the previous year's grasshopper population, monthly rainfall maps, and sunlight hours during the previous August.

Three populations of the pea aphid, Acyrthosiphon pisum (Harris), from locations between 27 and 36°S in eastern Australia were studied at five constant temperatures from 10 to 28 °C. A three-parameter, nonlinear equation accurately described developmental rate as a function of temperature for each of the five lines from each population. Maximum adult weight was attained at 20 °C. Wingless aphids developed faster and were heavier than winged aphids. There were no significant differences in developmental times among populations, and adult weights among populations differed only at 25 °C. These weight differences and other nonsignificant differences among populations showed no trends with the long-term average temperatures at the collection sites. This finding indicates that developmental rate and adult weight have not been adapted to temperature in the 5 years since the aphids were introduced. The maximum rate of development, optimum temperature for rapid development, developmental threshold, and optimum temperature for high adult weight were higher for the Australian populations than for North American populations, but these differences do not reflect adaptation to different environmental temperatures. We conclude that Australian populations of A. pisum did not originate in North America.

Fusarium attacking the roots of Douglas-firs in a forestry nursery was the focus of a computer simulation model that was tested against several years of nursery disease observations. Soil temperature, seedling growth, disease spread, and inoculum density and distribution were studied and their effects on measures to control Fusarium root rot were simulated. Interactions of these factors in space and time were examined from seedling germination to end of the growing season. The results from the model indicated that low soil temperature at the beginning of the growing season, rapid seedling growth, and reduction of disease inoculum levels in the upper soil horizons were the optimum prescription for disease reduction.