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 (35-45ºC) and mortality was determined. Results showed that the time for 99% mortality (LT99) reduced with increasing temperature and decreasing O2 concentration (35and 40ºC 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 40ºC resulted in the lowest mean LT99s (12.4-14.8 and 8.3-9.7 h, respectively).At 45ºC, 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.