Beginning with Emlen (1966) and MacArthur and Pianka (1966) and extending through the last ten years, several authors have sought to predict the foraging behavior of animals by means of mathematical models. These models are very similar,in that they all assume that the fitness of a foraging animal is a function of the efficiency of foraging measured in terms of some "currency" (Schoener, 1971) -usually energy- and that natural selection has resulted in animals that forage so as to maximize this fitness. As a result of these similarities, the models have become known as "optimal foraging models"; and the theory that embodies them, "optimal foraging theory." The situations to which optimal foraging theory has been applied, with the exception of a few recent studies, can be divided into the following four categories: (1) choice by an animal of which food types to eat (i.e., optimal diet); (2) choice of which patch type to feed in (i.e., optimal patch choice); (3) optimal allocation of time to different patches; and (4) optimal patterns and speed of movements. In this review we discuss each of these categories separately, dealing with both the theoretical developments and the data that permit tests of the predictions. The review is selective in the sense that we emphasize studies that either develop testable predictions or that attempt to test predictions in a precise quantitative manner. We also discuss what we see to be some of the future developments in the area of optimal foraging theory and how this theory can be related to other areas of biology. Our general conclusion is that the simple models so far formulated are supported are supported reasonably well by available data and that we are optimistic about the value both now and in the future of optimal foraging theory. We argue, however, that these simple models will requre much modification, espicially to deal with situations that either cannot easily be put into one or another of the above four categories or entail currencies more complicated that just energy.

Citation classic - optimal foraging - a selective review of theory and tests

▪ Abstract Many agroecosystems are unfavorable environments for natural enemies due to high levels of disturbance. Habitat management, a form of conservation biological control, is an ecologically based approach aimed at favoring natural enemies and enhancing biological control in agricultural systems. The goal of habitat management is to create a suitable ecological infrastructure within the agricultural landscape to provide resources such as food for adult natural enemies, alternative prey or hosts, and shelter from adverse conditions. These resources must be integrated into the landscape in a way that is spatially and temporally favorable to natural enemies and practical for producers to implement. The rapidly expanding literature on habitat management is reviewed with attention to practices for favoring predators and parasitoids, implementation of habitat management, and the contributions of modeling and ecological theory to this developing area of conservation biological control. The potential to int...

Habitat Management to Conserve Natural Enemies of Arthropod Pests in Agriculture

1. Ecologists concerned with life-history strategies of parasitoid wasps have recently focused on interspecific variation in the fraction of the maximum potential lifetime egg complement that is mature when the female emerges into the environment. Species that have all of this complement mature upon emergence are termed 'pro-ovigenic', while those that do not are termed 'synovigenic'. We document and quantify the diversity of egg maturation patterns among 638 species of parasitoid wasps from 28 families. 2. We test a series of hypotheses concerning variation in 'ovigeny' and likely life- history correlates by devising a quantitative index - the proportion of the maximum potential lifetime complement that is mature upon female emergence. 3. Synovigeny, which we define as emerging with at least some immature eggs, was found to be by far the predominant egg maturation pattern (98.12% of species). Even allowing for some taxonomic bias in our sample of species, pro-ovigeny is rare among parasitoid wasps. 4. There is strong evidence for a predicted continuum in ovigeny index among parasitoid wasps, from pro-ovigenic (ovigeny index = 1) to extremely synovigenic species (ovigeny index = 0). 5. As predicted, synovigenic species are longer-lived than pro- ovigenic ones, and ovigeny index and life span are negatively correlated across parasitoid taxa, suggesting a life span cost of concentrating reproductive effort early in adult life. 6. There is equivocal evidence that host feeding (i.e, consumption of host haemolymph and/or tissues by adult wasps) is confined to synovigenic parasitoid wasps. It is also not certain from our analyses whether host feeding is associated with a relatively low ovigeny index. 7. As predicted, egg resorption capability is concentrated among producers of yolk-rich eggs. Also, the hypothesis that it is associated with a tendency towards a low ovigeny index is supported. Parasitoid species that produce yolk-rich eggs also exhibit a lower ovigeny index than species that produce yolk-deficient eggs. 8. Ovigeny index appears to be linked to parasitoid development mode (koinobiosis-idiobiosis). 9. We conclude that 'ovigeny' is a concept applicable to insects generally. [KEYWORDS: feeding strategies; pro-ovigeny; synovigeny; timing of reproduction Leptopilina-boulardi hymenoptera; host-feeding strategies; egg limitation; reproductive-biology; clutch size; independent contrasts; functional-response; asobara-tabida; drosophila-melanogaster; evolutionary argument]

https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1046/j.1365-2656.2001.00507.x

Life-history strategies in parasitoid wasps: a comparative analysis of ‘ovigeny’

The inflorescences of 53 plant species in a variety of habitats were examined for the presence of adult hymenopteran parasitoids (‘Parasitica’ only), and the wasps observed for feeding behaviour. At inflorescences of 32 of the plant species examined, over 1000 parasitoid individuals were observed displaying feeding behaviour (either feeding at nectaries or displaying behaviour associated with searching for food). Over 900 individuals were collected. Around 250 species belonging to 15 families of Hymenoptera were represented. The taxonomic, behavioural and ecological significance of known parasitoid-food plant associations are discussed, and the literature reviewed.

Flower-visiting by hymenopteran parasitoids

The diminutive size of most parasitoids undoubtedly has limited their choice as subjects for behavioral study, despite their great diversity in lifestyles and reproductive strategies The present chapter addresses their foraging behavior as influenced by learning Most of their adult life female parasitoids search for host insects which, in turn, are under selection to avoid being found and devoured This scenario sets the stage for the evolution of diverse hide-and-seek games played by parasitoids and their victims, most often herbivores That parasitoids are successful in their quest for hosts is evidenced by the vast number of parasitoid species and their importance in insect management

N. A. C. Kidd

Papers

Host‐feeding strategies in hymenopteran parasitoids