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More than 25 years ago, Donald Stokes argued that we must move beyond the false dichotomy of basic or applied research and suggested that when considering a program of scientific research it is important to ask whether (i) the work is motivated by use and (ii) if there is a search for fundamental understanding. Giving yes/no answers to these questions allows us to characterize research more fully, replacing the "or" of "basic or applied" by a richer understanding of the process of science. Stokes proposed that research that was motivated by a consideration of use and sought fundamental understanding be called research in Pasteur's Quadrant. One advantage of such work is that the search for fundamental understanding means that the problem-solving tools are more likely to be transferrable. After reviewing Stokes's formulation of research, I illustrate it with examples from the control of tephritid flies and the use of insect parasitoids for biological control. Thinking about one's work within Stokes's framework has many advantages for individual scientists, including guidance for journal selection, how to organize and conclude papers and seminars, and the "elevator speech." Furthermore, since research in Pasteur's Quadrant has the characteristic of simultaneously increasing our understanding of how the world works and improving applications, it will more likely benefit the community of pest scientists. [ABSTRACT FROM AUTHOR]

In the last decade, the influence of microbial symbionts on ecological and physiological traits of their hosts has been increasingly recognized. However, most of these effects have been revealed under laboratory conditions, which oversimplifies the complexity of the factors involved in the dynamics of symbiotic associations in nature. The pea aphid, Acyrthosiphon pisum, forms a complex of plant-adapted biotypes, which strongly differ in the prevalence of their facultative endosymbionts. Some of the facultative endosymbionts of A. pisum have been shown to confer protection against natural enemies, among which Hamiltonella defensa is known to protect its host from parasitoid wasps. Here, we tested under natural conditions whether the endosymbiont communities of different A. pisum biotypes had a protective effect on their hosts and whether endosymbiotic associations and parasitoid communities associated with the pea aphid complex were linked. A space-time monitoring of symbiotic associations, parasitoid pressure and parasitoid communities was carried out in three A. pisum biotypes respectively specialized on Medicago sativa (alfalfa), Pisum sativum (pea), and Trifolium sp. (clover) throughout the whole cropping season. While symbiotic associations, and to a lesser extent, parasitoid communities were stable over time and structured mainly by the A. pisum biotypes, the parasitoid pressure strongly varied during the season and differed among the three biotypes. This suggests a limited influence of parasitoid pressure on the dynamics of facultative endosymbionts at a seasonal scale. However, we found a positive correlation between the α and β diversities of the endosymbiont and parasitoid communities, indicating interactions between these two guilds. Also, we revealed a negative correlation between the prevalence of H. defensa and Fukatsuia symbiotica in co-infection and the intensity of parasitoid pressure in the alfalfa biotype, confirming in field conditions the protective effect of this symbiotic combination.

Parasitoids are a key component of most terrestrial ecosystems due to their numbers and ecological significance due to the nature of their life cycle which partly depend on other insects for their survival. They are vitally important for the maintenance of biodiversity being involved in a vast number of trophic interactions including regulatory effect on insect pest populations. There are four insect orders that are particularly prominent for this type of life history. These are Hymenoptera, Diptera, Coleoptera and Neuroptera. The greatest number is found in the order Hymenoptera, which account for nearly 75% of the estimated number of parasitoid species. There are considerable variations in parasitism of insect parasitoids. These may be I diobionts, whose hosts stop development, when they are parasitized and Koinobionts which allow the hosts to continue their development until the parasitoid's offspring matures. Reports have shown that species richness of koinobionts parasitoids tends to decrease toward the tropics while idiobionts richness does it less severely. Such pattern was however intrinsically related to the host feeding niche. In hymenopteran parasitoid complexes however the richness of both idiobionts and koinobionts falls toward the tropics in exophytic hosts, while on endophytic hosts, there are no changes in species richness for both types of parasitoids. Biological control is the central stone of integrated pest management (IPM) paradigm and natural enemies are becoming an increasingly desirable prospect in lieu of chemical insecticides. Although hymenopteran parasitoids are widely used in the control of insect pest due to their Diversity and species richness, Coleopterans parasitoids could be useful in suppressing pest due to the pattern of their parasitism. Host selection strategies of insect parasitoids are largely influenced by chemical signals from plants attacked by insect pest. Their competitive fitness and reproductive success will therefore depend extensively on the ability to employ such signals more efficiently. [ABSTRACT FROM AUTHOR]

Abstract: Life‐history traits within ecological communities can be influenced by regional environmental conditions (external filters) and community‐wide density‐dependent processes (internal filters). While traits in a regional context may converge to a narrow range of values because of environmental filtering, species belonging to a guild may present contrasting traits as a means of niche differentiation, allowing coexistence whilst exploiting the same resources. To disentangle the role of external and internal filters on phenotypic diversity within ecological communities, we examined the patterns of life‐history trait variation within a guild of insect parasitoids during two successive years across three contrasted regions in relation to several ecological factors. By combining a mean‐field approach and an analysis of phenotypic variance across organizational levels (from individual to guild), we showed that the patterns of life‐history trait variation across regions are consistent with local adaptation or adaptive phenotypic plasticity while the patterns of phenotypic variation within regions suggested how coexistence modulates life‐history traits expression through niche differentiation. Within a given region, phenotypic pattern of parasitoid life‐history traits may also arise from bottom‐up effects of trophic webs: insect host species could also control parasitoid life‐history traits in nature. Our results also showed that parasitoid life‐history traits presented contrasting variation patterns according to the sampling year, suggesting temporal variations in evolutionary and ecological dynamics of parasitoid species. The application of such trait‐based studies to insect parasitoids has the potential to provide further insight on how agricultural environments contribute to differential diversification among natural enemies guilds, highlighting the main role of agricultural landscape management for organisms'responses. A plain language summary is available for this article. [ABSTRACT FROM AUTHOR]

We conducted a 14-yr intensive study of spruce budworm ( Choristoneura fumiferana (Clem.)) survivorship at three study plots in largely balsam fir ( Abies balsamea (L.) Mill.) stands in New Brunswick, Canada, to elucidate certain key mechanisms underlying spruce budworm outbreak cycles. The study covered a peak-to-declining phase (from 1981 and 1994) of the budworm outbreak cycle that had started in the early 1960s. Frequent sampling was carried out in each plot-year to construct a practically continuous survivorship curve, and the annual variation in population density was estimated. We found a high level of correlation between the studied phase of the outbreak cycle and annual variations in the survivorship over the postdiapause period, suggesting that postdiapause survivorship was the chief determinant of the cycle. We found the annual changes in population density in the present study to be closely similar in pattern to those from the provincial budworm surveys conducted in much larger areas. This implies that the mechanism underlying the population process found in the few study plots in largely balsam fir stands also applies to the process in much larger areas of diverse stand types. The main source of postdiapause mortality is found to be natural enemies. The impacts of parasitoids and disease are evaluated by rearing budworm samples in the laboratory. Hymenopteran and dipteran parasitoids are by far the major sources of mortality, and microsporidians are the most prevalent pathogen. Occurrences of other entomopathogenic fungi and viruses were insignificant throughout the study. Seasonal changes in laboratory survivorship are compared with the corresponding field survivorship to estimate the effect of predation. No major mortality factor is found to singly play a predominant role in determining the outbreak cycle. Conversely, some minor factors are shown to have played significant roles. Thus, the importance of recognizing the action of natural enemies as a complex is emphasized for understanding the budworm outbreak cycle. Finally, centered on the roles played by the chronological succession of natural enemies in the present study, the results of budworm research in New Brunswick since the mid-1940s are synthesized to outline basic mechanisms underlying the outbreak processes as a guide for further studies. [ABSTRACT FROM AUTHOR]