Host range, host preference and geographical distribution of five Cuscuta species growing in Salah -Adin Governorate - North-Central Iraq

Abstract

       a large scale survey was conducted in natural areas of Salah -Adin Governorate -north central Iraq during  march 2023-  august 2024 to report Cuscuta species and their host range , host  preference and geographical distribution. Host preference based on the ability of the parasite to maintain its growth up to fruiting ,  number of haustoria  and intensity of the parasite on the host . In this study , five Cuscuta  species were identified based on morphological and molecular characteristics , namely :     C. approximate Bab., C. australis R.Br.,  C. campestris Yun., Lam., C.monogyna Vahl., and C. pedicellata Ledeb. Results of the field survey and  regardless of the dodder species, showed that the genus Cuscuta had a host range of 27wild species from 26 genera and 15 plant families(25 dicots, 2 monocots) among them 23 herbaceous species, 2 shrub species and 2 tree species. This study revealed  that C. australis  had the largest host range of  20 wild  host species from 19 genera and 12 plant families (2 monocots and 18 dicots). This host range includes 17 herbs, 1 shrub, and 2 trees and 11 prefered species. This Cuscuta species was recorded in the districts of Samarra and Sharqat.C. campestris was found to occur on 18 wild species from 18 genera and 13 families (2 monocots and 16 dicots) including 15 herbs, 1 shrub, and 2 trees and 10 prefered species. Distribution of this dodder was  confined  to the districts of  Dujail and Tikrit. C. pedicellata was recorded on 6 wild herbaceous species from 6 genera and 6 families (all dicots, including 5 prefered species) distributed in  districts of  Dijayl, Samarra and Tikrit . while C. approximata was reported on 5 wild herbaceous species from 5 genera and 4 families (all dicots) including 3 prefered species and all these hosts were distributed in 4 districts( Balad, Samarra, Ad-Dur and Tikrit ) . C.monogyna was  found on Populus euphratica  in Tiktit district only .Compared to other studied  families , Asteraceae was found to include the most  prefered  host species for the  studied dodders. The current results indicated that both C. australis and C.campestris are  a generalist parasite due to their broad host range while C.approximata and C.pedicellata are  narrow host range parasites . C.monogyna in this study is the only specialized  dodder species and the poplar plant is the only host for this parasite in the study area.