Pests population dynamics

There is a wealth of literature on pest population dynamics (e.g., 13-14). Only some rudimentary concepts can be given here. 

As a taxonomic precaution, the identity of this Cordyceps sp. (Fig. 1) is still left open to doubt, since limacodid hosts are variously deposited in both Herb. IMI and Herb. K under the names C. coccinea Penz. Sacc., C. militaris (Fr.) Link, C. pruinosa Petch, and C. typhulaeformis (Petch, 1942 Evans, 1987). Clearly, there is a need for a taxonomic reevaluation of the pathogens associated with limacodid hosts and of the actual role that they play in pest population dynamics, as well as of their potential value as biological control agents of these pest species in Asia. 

These examples serve to Illustrate the Indirect role that plant chemicals may play In the population dynamics of Insect pests. Work In this area has been very limited, but the potential utilization of an Insect s own spacing mechanism may offer a new approach to pest management, and a good understanding of the plant/lnsect relationship will be essential. 

Figure 2 depicts just some of the known response-stimulus relationships for plant pests. Collection of the fundamental data and description of the responses with mathematical models can lead to a better understanding of pests in the field. If one knew the current environmental conditions, one could predict whether or not the potato leafhopper would increase during the next week. Final decisions would also be based on the known population dynamics of the pests of interest (see below), as well as the known interaction between the plant host and pest. 

Such subde effects of the trichome barrier might explain our recent finding that feeding is a much smaller portion of the activity budget of Colorado potato beetle larvae on S. berthaultii than on non-glandular susceptible cultivars (Table V) (34) and thus provide an explanation for several of the major impacts of resistance on this pest, i.e. decreased food consumption leads to the reduced growth rates, retarded development, and their cumulative suppressive effects on survival, fecundity, and population dynamics. 

Southwood, T. R. E. (1977) The relevance of population dynamic theory to pest status. In Origins of Pest, Parasite, Disease, and Weed Problems (Chcrrett, J. M. and Sagan, G. R., eds) pp. 35-54. Blackwell Scientific, Oxford. 

McNeil, J. N. and Turgeon, J. J. (1982) Pheromone biology in the population dynamics of Pseudaletia unipuncta (Haw) (Lepidoptera Noctuidae), a sporadic pest. Les m diateurs chimiques agissant sur le comportement des insects. INRA Coll., 7, 215-24. 

Ewing, B., P. Rauch, and J. F. Barbieri. Simulating the Dynamics and Structure of Populations. Presented at the Third Annual Integrated Pest Management Modellers Conference, Berkeley, California, January 1975. CONF-7S0101-2 or UCRL-76046 (rev. 1). 61 pp. 

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