Dr. Phil.nat., Frankfurt
Room B8278, (778) 782-4808
mackauer@sfu.ca
Current Research Program
The focus of my research is on insect parasitoids and biological control of agricultural pests. I use aphids and their hymenopteran parasitoids as model systems to quantify parasitoid attributes and control potential.
Current research is mainly concerned with two areas: host choice and nutritional ecology. Most species of parasitoids discriminate between unparasitized and previously parasitized hosts and avoid depositing eggs in the latter. Aphid parasitoids use an external pheromone-like substance to mark parasitized hosts. We have shown that oviposition restraint varies with the probability of offspring survival, which is influenced by oviposition sequence and interval length between ovipositions. A wasp's reproductive strategy is also important. Females with a high number of mature eggs are less likely to reject previously parasitized aphids. Some wasp species respond to host scarcity by resorbing mature eggs and by varying the rate of egg maturation.
The second area of research is concerned with the nutritional ecology of aphid parasitoids and the effects of host size on parasitoid fitness attributes. Wasp size is constrained by aphid size at parasitization and by the aphid's ability to satisfy the nutritional requirements of the growing parasitoid larva. We have developed a model of parasitoid growth within a conceptual framework of competing resource acquisition and utilization strategies. Wasps optimize adult size by varying the rate of development in different-sized hosts; the functional relationship between host size and parasitoid growth is sex-specific.
Other research is on patterns and mechanisms of offspring sex allocation, sexual size dimorphism, and the role of biological control in sustainable agricultural systems.
Selected Publications
Growth and devlopment in parasitoid wasps: adaptation to variable host resources. (M. Mackauer, R. Sequeira and M. Otto in "Vertical Food Web Interactions" (K. Dettner et al., eds.). Springer-Verlag, Berlin. Ecological Studies, 130: 191-203, 1977).
Host choice by aphidiid parasitoids (Hymenoptera: Aphidiidae): host recognition, host quality, and host value. (M. Mackauer, J.P. Michaud and W. Volkl, The Canadian Entomologist, 128: 959-980, 1996).
Sequential allocation of offspring sexes in the hyperparasitoid wasp, Dendrocerus carpenteri. (A. Chow and M. Mackauer, Animal Behaviour, 51: 859-870, 1996).
The use of visual cues in host evaluation by aphidiid wasps. I. Comparison between three Aphidius parasitoids of the pea aphid; II. Comparison between Ephedrus californicus, Monoctonus paulensis, and Praon pequodorum. (J.P. Michaud and M. Mackauer, Entomologia experimentalis et applicata, 70: 273-283, 1994; 74: 267-275, 1995).
Sex-ratio bias in an aphid parasitoid-hyperparasitoid association: a test of two hypotheses. (M. Mackauer and R.M. Lardner, Ecological Entomology, 20: 118-124, 1995).
Regulation of aphid populations by aphidiid wasps: Does parasitoid foraging behaviour or hyperparasitism limit impact? (M. Mackauer and W. Volkl, Oecologia, 94: 339-350, 1993).
Patterns of development in insect parasites. (M. Mackauer and R. Sequeira in "Parasites and Pathogens of Insects, Vol 1" (N.E. Beckage, S.N. Thompson and B.A. Federici, eds.). Academic Press, Orlando, Fl. pp. 1-23 (1993).
Model of host discrimination. Parasitoid females generally avoid oviposition in previously parasitized hosts which are being marked by a volatile external marking pheromone (short-term marker, shaded area). A change in host physiology (=internal mark) associated with a developing parasitoid egg or larva can also result in host rejection (long-term marker, indicated by curves).
This page last updated March 1998.