Bottom-up effects of host plant bud sizes on the emerging strawberry blossom weevil and their associated parasitoids

Monday, November 14, 2022

10:42 AM – 10:54 AM PT

Location: Vancouver Convention Centre, Meeting Room 215/216

Presenting Author(s)

JS

Jade Sherwood

Graduate Student
Agriculture and Agri-Food Canada
Burnaby, British Columbia, Canada

Co-Author(s)

Warren Hung Leuk Wong

Graduate Student
The University of British Columbia
Burnaby, British Columbia, Canada
Tim Haye

Head Arthropod Biological Control
Centre for Agriculture and Bioscience International (CABI)
Delémont, Jura, Switzerland
HB

Hannes Baur

Natural History Museum of Bern
Bern, Bern, Switzerland
GG

Gary Gibson

Agriculture and Agri-Food Canada
Ottawa, Ontario, Canada
JC

Juli Carrillo

Assistant Professor
The University of British Columbia
Vancouver, British Columbia, Canada
Michelle T. Franklin

Entomologist
Agriculture and Agri-Food Canada
Agassiz, British Columbia, Canada

Strawberry blossom weevil, Anthonomus rubi (Herbst) is an invasive species in British Columbia Canada, commonly associated with plants from the family Rosaceae. It successfully reproduces on strawberries (Fragaria x ananassa) and Himalayan blackberries (Rubus armeniacus), laying eggs in developing buds and clipping the peduncle haulting further bud development thus reducing yields. There are limited control options for A. rubi and an action threshold has yet to be determined in Canada. Foreign survey work began in 2021 to explore the possibility of introduction of a biological control agent from its native range in Europe. From these foreign surveys, eight species of parasitoids have been detected. Through surveys conducted in 2020 and 2021 in A. rubi’s newly invaded range of BC, Canada two species of parasitoids have been found to be associated with A. rubi. One Pteromalus species has shown considerable body size variation, which could have implications for parasitoid fitness. Two hypotheses could explain this difference: (i) parasitism of different host stages that vary with bud size could impact the size of emerging parasitoids and; (ii) phenological differences between plant hosts and plant quality for host larvae could have a bottom-up cascading effect on parasitoid size. We collected clipped buds from strawberry and Himalayan blackberry at several locations in the Fraser Valley, BC, Canada. We evaluated indices of host plant quality (bud measurements), emerging host size and parasitoid size alongside laboratory experiments to determine the importance of these factors and their potential implications for biological control.