Influence of Temperature on Population Growth of the Pink Bollworm, Pectinophora gossypiella (Lepidoptera: Gelechiidae)1,2

Abstract

Population increase of the pink bollworm, Pectinophora gossypiella (Saunders), was studied in relation to various simulated field conditions. The intrinsic rate of increase (rm), net reproduction rate (R), and mean generation time (T) were the basic population parameters calculated to assess the influence of fluctuating as well as constant temperatures on the insect. Temperature influenced population increase by affecting immature mortality, developmental time, and fecundity. The lower temperatures in this study were shown to be least detrimental and the higher temperatures most detrimental for surivival. In general, the females that lived the longest had the longest oviposition period. Agespecific fecundity rates and percent hatch were significantly reduced at the higher temperatures. The 90°F temperature proved to be the most detrimental for oviposition and hatch. A constant 83°F and a truncated 82°–98°F (10 and 14 hr, respectively) were least detrimental. The incubation and oviposition periods were longest at the lower constant and fluctuating temperatures. The preoviposition period was longest at a fluctuating temperature of 58°–91°F and was shorter and more constant at the other temperatures. The high temperature of each fluctuating temperature had virtually no effect on mating and oviposition since the higher temperature occurred under photophase; mating and oviposition activities occurred during scotophase. Temperature influenced immature development in various ways. Larval developmental time was greatly reduced at higher temperatures. As a result of high temperatures, desiccation proved to be detrimental to newlyhatched larvae. The highest incidence of larvae entering diapause occurred at a constant 75°F. Percent moth emergence was reduced at the low temperatures. The intrinsic rate of increase and net reproduction rate were greatest and mean generation time shortest at a constant 83°F. A constant 90°F regime was the most detrimental for population increase; results from the lowest constant temperature treatment of 75° were intermediate.