Nicholas J. Mills
Associate Professor and Associate Entomolgist
212 Wellman Hall
Phone #: (510) 642-1711
FAX #: (510) 642-7428
nmills@nature.berkeley.edu
Research Interests
The focus of my research group is the biological control of insect pests
and the ecology of insect parasitoids. Classical biological control has
an outstanding history of success in the sustained regional control of invading
pests and provides exciting opportunities for both lab and field-based ecological
research. However, not all biological control introductions result in spectacular
reductions of pest damage and so a major emphasis in our work is to address
arguably one of the most challenging questions in biological control research:
what are the determinants of success in classical biological control? In
addition to classical biological control, the augmentation of naturally-occurring
parasitoid populations is an aspect of biological control that is rapidly
gaining attention. The use of parasitoids as biological pesticides raises
some very interesting questions that we have recently begun to explore on
performance characteristics of parasitoids, strategies for parasitoid release
and the optimization of parasitoid impact.
It is also important to realize that parasitoids, as macroparasites of phytophagous
insect hosts, represent a very significant component of the terrestrial
fauna, known not only for their importance in biological control and population
ecology, but also because of their fascinating and diverse lifestyles and
their value in the analysis of biodiversity and community ecology. As a
result, our research interests span the general biology of parasitoids,
the population ecology of parasitoids and structure and function in parasitoid
communities as well as biological control. One of the most satisfying aspects
of our work is the knowledge that we are pursuing an environmentally-sound
program which has the potential to reduce pesticide pollution and to restore
the natural balance of ecological systems.
Current Projects
One of the major research programs in our laboratory is directed toward
the biological control of the codling moth, Cydia pomonella, a notorious
fruit-borer that is the key pest of apple, pear and walnut production in
California and worldwide. As an exotic pest, codling moth has no specialized
parasitoids in the US and we are conducting foreign exploration for parasitoids
in Central Asia, evaluating the potential performance of individual parasitoid
species, and selecting the best combination for field release. However,
as the codling moth is a fruit-boring pest, classical parasitoid introductions
alone are unlikely to achieve the degree of control required for commercial
fruit production and so we are also investigating the potential to augment
populations of Trichogramma platneri, a naturally-occurring egg parasitoid.
We have recently been able to demonstrate a significant impact of Trichogramma
augmentation on codling moth in all three commodities and are currently
examining this tritrophic (tree-moth-parasitoid) system in detail to identify
the limiting characteristics of the parasitoid and the influence of release
strategy on parasitoid impact. The population dynamics and community ecology
of parasitoids is another underlying theme of our research. We have recently
used a prospective population model to question whether heteronomous hyperparasitism
is compatible with biological control of whiteflies and are currently developing
a model to select the best combination of parasitoids for introduction against
the codling moth. We have also developed the concept of parasitoid guilds,
a functional classification of parasitoid lifestyles, that facilitates the
analysis of structure, diversity and function in parasitoid communities.
We are currently using this approach to analyze the parasitoid communities
associated with oak gall wasps in California and other phytophagous insect
taxa.
Selected Publications
Riddick, E.W. and Mills, J.N. 1994. Potential of adult carabids (Coleoptera:
Carabidae) as predators of fifth-instar codling moth (Lepidoptera: Tortricidae)
in apple orchards in California. Environ. Entomol. 23:1338-1345.
Kenis, M., Hulme, M.A., and Mills, N.J. 1996. Comparative developmental
biology of populations of three European and one North American Eubazus
spp. (Hymenoptera: Braconidae), parasitoids of Pissodes spp. weeviles (Coleoptera:
Curculionidae). Bulletin of Entomol. Res. 86:143-153.
Getz, W.M. and Mills, N.J. 1996. Host-parasitoid coexistence and egg-limited
encounter rates. American Naturalist 148:301-315.
Hawkins, B.A. and Mills, N.J. 1996. Variability in parasitoid community
structure. J. Animal Ecol. 65:501-516.
Mills, N.J. and Gutierrez, A.P. 1966. Prospective modelling in biological
control: an analysis of the dynamics of heteronomous hyperparasitism in
a cotton-whitefly-parasitoid system. J. Applied Ecol. In Press
Current Graduate students:
- Greg Fanslow
- Jan Hirabayashi
- Sarah Mansfield
- Diane Stark
- Tania Zaviezo
Names of Post-docs/Researchers/Specialists/SRAs, etc.:
- Ulrich Kuhlman, Postdoctoral Fellow
- Lou Dixon, Staff Research Associate