Do granivorous insects invade fallen acorns of Pasania edulis (Makino) Makino through exit holes of curculio weevil larvae?

Pasania edulis (Fagacea) is a dominant tree species in evergreen broad-leaved forests in southern Japan. Predation by insects is harmful to seedling establishment. The larvae of the acorn weevil, likely Curculio hilgendorfi, feed on the acorns of P. edulis and exit the fallen acorns to overwinter in the ground. The fallen acorns are used for invasion by other insects, we buried the acorns in the ground in April 2015 and compared the germination ratio, the condition of the cotyledons, and the invasion of the acorn borer, Coccotrypes graniceps, and the Bell moth, Cryptaspasma trigonata, in acorns in November 2015. The germination ratio was significantly higher in acorns without holes (S-acorns) and acorns with artificial holes mimicking the exit hole of weevil larvae (H-acorns) than for acorns with an exit hole (W-acorns). The acorn borer did invade S-and H-acorns, but not through the exit holes or the artificial holes. The Bell moth attacked some H-acorns through the artificial holes. The percentage of ungerminated acorns with intact cotyledons was significantly higher in S-acorns than in H- or W-acorns. These results show that the exit holes of the curculio weevil larvae may contribute only slightly to invasion by other granivorous insects, but may significantly facilitate the invasion of fungal and arthropod decomposers into the fallen acorns