2020/12/05 by Balmaceda, Nicolette, Durovic, Jovana, Montes, Sierra +1
#acorn predation #filbert weevils #filbertworms #insect infestation #oak recruitment
paper · doi:10.21973/n3166z
Oak woodlands are in decline due to failed oak recruitment in California. Oak recruitment is heavily impacted by vertebrate herbivory and insect infestation of acorns. Oaks have developed chemical defenses such as tannins to protect acorns from attack. Studies have explored infestation differences in red oaks but have not compared infestation between red oaks and white oaks. We explored how Cydia latiferreana (filbertworm) infestation, Curculio occidentalis (filbert weevil) infestation, and Sciurus griseus nigripes (western gray squirrel) seed predation differed among two white oaks, Quercus douglasii (blue oak), Q. lobata (valley oak), and a red oak, Q. agrifolia (live oak) in a Central California oak woodland. We collected 1352 acorns and recorded the presence and abundance of both boring insects. Additionally, we performed an experiment to determine which acorns squirrels preferred to eat. We found that live oak acorns had the highest presence of boring insects. Filbertworms were more commonly found in live oak, while filbert weevils were found equally in all three species. In live oaks when filbertworms were present, weevils were less likely to be present. Insects overall infested larger acorns within each species. Squirrels preferred blue and valley acorns over live oak acorns. Our findings can provide insight into how the preferences of herbivorous vertebrates may be impacting oak recruitment as well as indirectly influencing acorn infesting insects.