Temperature Effects on Infection and Mortality of Pectinophora gossypiella (Lepidoptera: Gelechiidae) Larvae by Two Entomopathogenic Nematode Species

Steinernema riobravis Cabanillas, Poinar & Raulston infected pink bollworm, Pectinophora gossypiella (Saunders), larvae over a temperature range of 15.6–38.0°C. At temperatures >21.0°C, mortality occurred in 24–72 h, but substantial mortality at 15.6°C did not occur until 2–6 d later. In some cases, temperatures of 35.6 and 38.0°C pink bollworm larval mortality by S. riobravis and S. carpocapsae (Weiser) was lower than temperatures ranging from 21.0 to 32.2°C. The adverse effects on efficacy were greater for S. carpocapsae than for S. riobravis . Temperatures of 32.2°C and higher and exposure for 48 h or more often resulted in decreased numbers of nematode killed larvae with living nematodes and increased numbers of dead larvae with dead or no nematodes.