DISTRIBUTED EGG-PRODUCTION FUNCTIONS FOR MELOIDOGYNE-ARENARIA IN GRAPE VARIETIES AND CONSIDERATION OF THE MECHANISTIC RELATIONSHIP BETWEEN PLANT AND PARASITE

Abstract

Nematode egg production rates, as mediated by environmental conditions and host status, are important determinants of population development. Rates of egg production by M. arenaria varied from 0.48 to 1.0 egg/female per DD10 (degree days above 10.degree. C) in different grape varieties. The length of the egg production period ranged 550-855 DD10 where measurable, and was generally longer in those varieties where the production rate was slow. If a successful infection site is established, a constant number of eggs is produced if favorable environmental conditions prevail. Mechanistic coupling structures between plant growth and nematode population models were formulated. The nematode population influences metabolite supply through its effect on physiological efficiency and also acts a metabolic sink; the degree of plant physiological stress influences nematode population development by affecting the sex ratio and egg production rates.