Antixenosis resistance of different willow species to willow and poplar lace-bug,
Monosteira unicostata (Mulsant & Rey) (Hemiptera: Tingidae)

Willow and poplar lace-bug, Monosteira unicostata, is considered as an important pest of willow and causes serious damages directly on leaves and indirectly on timbers quality and quantity of willow and poplar species and clones in Iran. Antixenosis resistance of 11 willow species including Salix acmophylla, S. aegyptiaca, S. alba, S. elbursensis, S. rodini, S. excelsa, S. fragilis, S. triandra, S. wilhelmsiana, S. zygostemon and S. matsudana to willow and poplar lace-bug was evaluated under laboratory condition during 2008 at Research Institute of Forests and Rangelands, Tehran. Willow 3-6-leaf cuts of each species were taken and exposed to adult bugs developed on two willow species, S. acmophylla and S. alba, then collected and released in a designed olfactometer at normal room conditions. The experiment was carried out with eight replications. Number of male and female bugs attracted to each willow species were recorded after 1 hours. Statistical analysis revealed a significant difference (P < 0.01) in number of attracted lace-bugs to willow species. The most lace-bug numbers were attracted to S. acmophylla, S. matsudana, S. alba and S. excelsa, respectively and they were considered as the most susceptible species to the lace-bug. The lowest attraction of lace-bugs was observed in S. aegyptiaca, S. elbursensis, S. fragilis, S. rodini, S. wilhelmsiana and S. zygostemon, and they could be considered as the most or relatively resistant species.