Effects of temperature and dietary sucrose concentration on respiration inthe silverleaf whitefly, Bemisia argentifolii

A system consisting of a flow-through chamber connected to a commercial inf rared gas analysis system was developed to measure homopteran respiration d uring feeding. Using this system, respiration rates of 202 and 206 mu mol C O2 h(-1) g(-1) (4.96 and 5.04 ml CO2 h(-1) g(-1)) were determined for white flies and cotton aphids, respectively, at 25 degrees C on diets containing 15% sucrose. These rates were considerably higher than those of other stati onary insects, indicating that whiteflies and aphids maintain a relatively high metabolic rate when feeding. Whitefly respiration increased with tempe rature from 25 to 46 degrees C with a Q(10) of about 2 on diets containing 10, 15 and 20% sucrose, but less than 2 on diets containing 2.5 and 5% sucr ose. Respiration rates were similar on the diets containing >10% sucrose, b ut were generally lower on the diets containing <10% sucrose. Respiration r ates decreased upon extended exposure to 47 degrees C; the rate of decrease was inversely related to the dietary sucrose concentration up to 15%. The results indicate that whiteflies require a sucrose concentration of between 5 and 10% (i.e. 0.15 and 0.3 M) for maximum rates of metabolism while feed ing. Higher concentrations of sucrose in the diet delayed high-temperature mortality, possibly a reflection of the high sucrose requirement for sorbit ol synthesis in whiteflies. Published by Elsevier Science Ltd.