Evaluating the impact of cultivar selection on carrot weevil (Coleoptera: Curculionidae) damage and foliar insect pest assemblages in carrot.

Knowledge of specialty crop cultivars with resistance against insect pests is limited, and this may serve as a barrier to implementing host-plant resistance as part of an integrated pest management strategy. Carrot (Daucus carota L.) (Apiaels: Apiaceae)is a valuable specialty crop with a diversity of insect pests and cultivars that differ in physical and chemical qualities that influence insect pest preferences. To investigate the role of cultivar as a tool to reduce insect pest damage, we evaluated 7 carrot cultivars in replicated laboratory and field trials in IN and OH, USA in 2021. During June and July, we documented oviposition and feeding damage by the carrot weevil (Listronotus oregonenesis LeConte) (Coleoptera: Curculionidae) and used faunistic analysis to measure the abundance and diversity of foliar insect assemblages on each cultivar. We found no significant differences in oviposition and root damage across cultivars in the field, with mean cumulative egg scars ranging from 1.83 ± 1.40 in "Red Core Chantenay" to 5.17 ± 2.62 in "Cosmic Purple". However, there was a positive correlation between the cumulative number of egg scars and number of trichomes on petioles. Similarly, no-choice laboratory bioassays revealed no significant differences in mean cumulative egg scars, ranging from 5.00 ± 1.15 in "Red Core Chantenay" to 10.63 ± 1.02 in "Danvers 126". Predominant insect pests differed across cultivars, but Cicadellidae was common across all cultivars. Interestingly, only 1 beneficial insect family, Pteromalidae, was predominant across cultivars. This research highlights the impact of cultivar selection on the diversity and damage potential of insect pests in carrot production.