Ts. Sahota et al., WEEVIL PHYSIOLOGY CONTROLS THE FEEDING RATES OF PISSODES STROBI ON PICEA-SITCHENSIS, Canadian Entomologist, 130(3), 1998, pp. 305-314
The number and volume of feeding and oviposition holes made by female
white pine weevils, Pissodes strobi (Peck), on lateral branches of res
istant and susceptible Sitka spruce, Picea sitchensis (Bong.) Carr., w
ere determined. When all possible effects of weevil reproduction on fe
eding rates were eliminated, by using reproductively noncompetent weev
ils, there was no significant difference in the number of feeding hole
s made on the two host types. In addition, the volume of feeding holes
was unaffected by host type on day 1. In contrast, when differential
reproductive activity was induced by treating weevils with juvenile ho
rmone, and the host factor was eliminated, by using only the susceptib
le host, higher reproductive activity was accompanied by a significant
ly larger number of feeding holes. Hormone treatment also led to an in
crease in the volume of feeding holes in the absence of any influence
of host factors. Results are interpreted in relation to the direct eff
ects of host resistance on feeding rates (which determine host accepta
bility); and the indirect effects of host resistance on feeding rates
mediated through the physiology of the weevils (which determine host s
uitability). Our results show that both the number of feeding holes an
d their volume are determined primarily through weevil metabolism.