Jg. Kingsolver et Ha. Woods, Interactions of temperature and dietary protein concentration in growth and feeding of Manduca sexta caterpillars, PHYSL ENTOM, 23(4), 1998, pp. 354-359
Temperature and the protein content of food affect rates of consumption and
growth in herbivorous insects in different ways: reduced temperature typic
ally reduces both consumption and growth rates, whereas reduced dietary pro
tein typically increases consumption rate but either reduces or has no effe
ct an growth rate. The: interactions between temperature and dietary protei
n concentration in affecting consumption, growth and efficiency in fifth-in
star caterpillars of Manduca sexta were studied, using both short-term (4h)
and long-term (duration of fifth stadium) experiments. The short-term expe
riments examined constant temperatures between 14 and 42 degrees C, whereas
the long-term experiments examined constant temperatures between 18 and 34
degrees C; both experiments considered two levels of dietary protein. In b
oth expects, caterpillars had significantly higher consumption and Erase pr
oduction rates on low-protein compared with high-protein diets at each test
temperature between 18 and 34 degrees C, thereby compensating for the lowe
r diet quality. In contrast, at more extreme temperatures (14 and 42 degree
s C) in the short-term studies, consumption and frass production rates were
lower on low-protein compared with high-protein diets. As a result, there
were substantial interactions between temperature and dietary protein for c
onsumption and frass production rates in the short-term experiments, but no
t in the long-term experiments. These results suggest that interactions bet
ween temperature and dietary protein may emerge because of.,the failure of
compensatory feeding responses at low and high temperatures. It is hypothes
ized that the failure of compensatory responses is more Likely to occur und
er diurnally fluctuating temperatures than under a constant temperature wit
h the same mean, and it is proposed that interactions between temperature a
nd dietary protein for consumption are relevant to M. sexta and other cater
pillars that experience wide diurnal fluctuations in temperature in the hel
d.