COMPENSATORY FEEDING IN RESPONSE TO VARIABLE FOOD QUALITY BY MELANOPLUS-DIFFERENTIALIS

The behavioural mechanisms driving compensatory food consumption in re sponse to dietary dilution as well as the relationship between feeding time and food residence time (i.e. digesta retention time in the gut) were studied using the non-diapausing strain of the grasshopper Melan oplus differentialis (Thomas) (Orthoptera: Acrididae). 3-day-old, sixt h-instar nymphs and 3-day-old adults were fed artificial diets contain ing 1%, 3% and 5% total nitrogen (N) at 30 degrees C, LD 14:10 h; the feeding behaviour was recorded using electronic monitoring devices con nected to microcomputers for 24h. The percentage of time spent feeding increased linearly as diets were diluted using non-digestible cellulo se from 5% to 1% N. This response was due to an increase in the number of meals while the meal duration of a feeding bout was unaltered. Six th-instar nymphs spent about 40% more time feeding than the larger adu lts. The increased feeding time in nymphs resulted from both more freq uent feeding bouts and longer meal duration. Feeding time and food res idence time were highly negatively related.