Differential susceptibility of local and introduced chestnuts to a chestnut weevil Curculio davidi (Coleoptera: Curculionidae) in the Qinling Mountains.

Abstract

The chestnut weevil, Curculio davidi Fairmaire (Coleoptera: Curculionidae) is a major pest of chestnuts. Damage caused by C. davidi has increased as beetle populations have expanded. To promote effective C. davidi management practices based on its host plant, we compared the susceptibility of local chestnut cultivar 'Qinli 2'(QL2) and introduced chestnut cultivar 'Hongli' (HL) in Qinling Mountains to this weevil. Number of eggs laid by C. davidi females in HL was significantly higher than that of QL2. Chestnut weevil females laid 6.25-fold and 3-fold more eggs in HL than QL2 in the choice tests and no-choice tests, respectively. From 2021 to 2023, C. davidi infestation rates of HL were significantly higher than that of QL2 in the field. HL was smaller, softer, and have lower cellulose content as compared with QL2. HL contained 4.61%, 13.76%, 10.09%, 26.53%, 9.24%, 18.4%, 6.28%, and 23.26% higher amounts of N, K, Ca, Mg, S, Na, Mn, and Cu respectively, than QL2. In contrast, QL2 contained 25.28%, 19.80%, and 16.83% higher amounts of Al, B, and Fe, than HL. Our results revealed that the introduced chestnut cultivar is more susceptible to C. davidi compared to the local chestnut cultivar in Qinling Mountain, which was associated with several physico-chemical changes in chestnuts. These findings may contribute to the future efforts for breeding of C. davidi-resistant chestnut cultivars.