Sf. Matter, INTERPATCH MOVEMENT ED THE RED MILKWEED BEETLE, TETRAOPES TETRAOPHTHALMUS - INDIVIDUAL-RESPONSES TO PATCH SIZE AND ISOLATION, Oecologia, 105(4), 1996, pp. 447-453
Individual movement patterns and the effects of host plant patch size
and isolation on patch occupancy were examined for red milkweed beetle
s, Tetraopes tetraophthalmus, residing in a heterogeneous landscape. M
ale beetles were found to move both more often and farther between hos
t plant patches than female beetles, and this difference affected the
patterns of patch occupancy observed. Overall, unoccupied milkweed pat
ches were smaller and more isolated than patches occupied by beetles.
Patches uninhabited by females tended to be more isolated, but not nec
essarily smaller, than patches with female beetles, indicating that fe
males may be affected more by patch isolation than patch size. Presenc
e of male beetles on patches showed a stronger response to patch size
than to patch isolation. Differences in movement between males and fem
ales illustrate the need for demographically based dispersal data. Com
parisons of Tetraopes interpatch movement patterns between landscapes
composed of patches of different size revealed that landscapes with ov
erall smaller patches may have greater rates of interpatch movement.