Water Loss and Desiccation Tolerance of the Two Yearly Generations of Adult and Nymphal Kudzu Bugs, Megacopta cribraria (Hemiptera: Plataspidae)

Abstract

Water loss rate, percentage total body water content (%TBW), cuticular permeability (CP), and desiccation tolerance were investigated in adult and immature stages of the invasive kudzu bug, Megacopta cribraria (Fab.) (Hemiptera: Plataspidae), a serious soybean pest and an urban nuisance. Adults and all five nymphal instars were weighed prior to and 2, 4, 6, 8, 10, and 24 h after desiccated at 30 ± 1°C and 0-2% RH. Both % initial mass and %TBW loss increased linearly with time of desiccation. Rates of loss ranged from approximately 1-7%/h. Mortality occurred at 10 h after desiccation. Desiccation tolerance (%TBW lost at death) ranged between 25.6% for first-generation adult females and 75% for first-generation fifth-instar nymphs. First-generation first-instar nymphs had significantly greater %TBW (88.9%) than the other generations and instars, whereas second-generation fifth instars had the lowest %TBW (62.4%). The CP value of first-generation adult females (12.3 ± 1.6 µg cm-1 h-1 mmHg-1) was the greatest across generations. First-generation first instars had the greatest mass loss (111.11 mg/g) among all instars and generations, whereas overwintered second-generation adult females had the lowest mass loss (18.39) across generations. This study demonstrated that desiccation stress differentially affected the survival of adult and nymphal kudzu bugs and may imply that environmental stress can affect the relative abundance of this species in the fields and around homes.

Keywords: Plataspidae; cuticular permeability; desiccation; percentage of total body water.