Measuring development of Heliothis species

Abstract

The "life history" approach to population ecology uses the interactions of biological factors with each other and components of the environment of the subject organism to explain population performance (Kitching, 1977, and Chapter 14). In insects, as in all poikilotherms, the interactions are complicated by a temperature-mediated "time scale". This time scale is the fundamental driving variable in the population dynamics of insects. It features prominently in all population dynamics models of Heliothis spp., for example, MOTHZV-2 (Hartstack, Witz, Hollingsworth, Ridgeway, and Hunt, 1976), and in models used to aid in Heliothis management, for example, SIRATAC (Hearn, Ives, Room, Thompson, and Wilson, 1981) (see Chapter 14). In this chapter we deal with the influence of temperature on development and ways of measuring and modelling these effects. Differences in microhabitat temperature, behavioral thermoregulation and temperature fluctuation, host plant effects and intraspecific variability are discussed. Previous temperature-related studies with Australian Heliothis spp. are reviewed.