Abstract
The polyphagous shot hole borer (PSHB), Euwallacea nr. fornicatus (Coleoptera; Scolytinae) has become a serious threat to the avocado industry and several shade tree species in Israel. Branch wilting and tree mortality is the outcome of PSHB galleries. Understanding the relationship between avocado trees and the PSHB is required for considering management strategies. In Israel, 52 tree species from 26 botanical families were attacked by the PSHB, but only 12 species were suitable for beetle reproduction. All examined avocado cultivars were attacked, but ‘Hass’ most severely. Large and medium diameter avocado branches were more resistant to PSHB, compared to thin branches. Effectively, gallery density increased as branch diameter decreased. Concomitantly, in large and medium diameter branches, extensive sugar exudation occurred and beetle attack rarely progressed to the formation of natal galleries, whereas minimal sugar exudation was observed in thin branches. This was more evident in those that were weakened by repeated attacks followed by successful beetle colonization. PSHB prefers and successfully colonized branches that had been previously attacked by its conspecifics, and reproduction was much higher in these branches, as opposed to initial attacks. Lesion frequencies increased from late spring (April) until late summer (September). Avocado branches at the early stages of beetle colonization may be identified by sugar exudation at the base of the thin branches. The main approach for reducing damage caused by the PSHB is sanitation, achieved by the removal of colonized branches and intact infested pruned slash.
| Original language | English |
|---|---|
| Pages (from-to) | 341-359 |
| Number of pages | 19 |
| Journal | Phytoparasitica |
| Volume | 45 |
| Issue number | 3 |
| DOIs | |
| State | Published - 1 Jul 2017 |
| Externally published | Yes |
Bibliographical note
Publisher Copyright:© 2017, Springer Science+Business Media B.V.
Funding
The authors are grateful to Dr. Hillary Voet, from the Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, for assistance with statistical analyses of the data. We express our appreciation to many avocado growers, in particular Roni Israeli from Nochsholim and Ofri Yongerman and Roni Bucksboim from Eyal, gardeners and landscape managers who shared valuable information of infested hosts on their properties and allowed us to remove plant materials for this study. We thank Randy C. Ploetz and Akif Eskalen for their important comments on an early draft. We also thank two anonymous reviewers for the valuable suggestions. This research was partially funded by grants No. 131-1679 and 131- 1834 from the Chief Scientist of the Ministry of Agriculture and the Israeli avocado growers’ association.
| Funders | Funder number |
|---|---|
| Ministry of Agriculture of the People's Republic of China |
Keywords
- Ambrosia beetle
- Avocado
- Colonization
- Damage
- Euwallacea