High-Temperature Controlled Atmosphere and Air Treatments to Control Obscure Mealybug (Hemiptera: Pseudococcidae) on Apples

Abstract

Obscure mealybug, Pseudococcus affinis (Maskell), life stages infested on apples were exposed to various concentrations of O2 (0.4-20.9%) at high temperatures (35-45°C) and mortality was determined. Results showed that the time for 99% mortality (LT99) reduced with increasing temperature and decreasing O2 concentration (35 and 40°C only). Life stage differences at these temperatures (female adults more tolerant than all instars) were distinguishable only in air (20.9% O2). Exposure to the lowest O2 concentration tested (0.4% O2) at 35 and 40°C resulted in the lowest mean LT99s (12.4-14.8 and 8.3-9.7 h, respectively). At 45°C, the effect of reducing O2 concentration was diminished, and no life stage differences were evident. At this temperature, maximum mean LT99s ranged from 4.9 (0.4% O2) to 8.2 (20.9% O2) h.