ANTIXENOSIS COMPONENT OF RESISTANCE IN POPLAR SPECIES AND CLONES (POPULUS SPP.) TO THE WILLOW AND POPLAR LACE-BUG, MONOSTEIRA UNICOSTATA (MULSANT & REY) (HEMIPTERA: TINGIDAE)

During the year 2007, antixenosis resistance mechanism of 4 poplar species, including Populus alba, P. deltoides, P. euramericana and P. nigra, and 15 related clones was evaluated against the willow and poplar lace-bug, Monosteira unicostata, one of the most important pests of these trees. Poplar cuts, bearing 3-5 uniform and similar leaves, of each species were taken. The adult bugs previously developed under natural conditions on one poplar species, P. alba, were collected and released in a designed olfactometer while placing in a germinator (at temperature 24±0.1 oC, 50 % relative humidity, and a photoperiod of 16L:8D). The experiment was carried out with 10 replications. The numbers of male and female bugs attracted to each poplar clones were counted and recorded after 24 hours. Statistical analysis revealed a significant difference (P<0.01) in numbers of attracted lace-bugs to the poplar species and clones. The most lace-bug numbers were attracted to P. nigra and P. alba respectively, and the lowest attraction of lace-bugs was observed in P. euramericana and P. deltoides. Among the poplar clones, the comparison of means showed that P. n. 42.78, P. n. 56.53 and P. n. betulifolia attracted the most adult bugs and were considered as the most susceptible clones, while P. d. missouriensis, P. e. vernirubensis and P. e. triplo were the most resistant clones.