مرکز منطقه ای اطلاع رساني علوم و فناوري - مقاومت آنتي زنوزي در ارقام نيشكر به ساقه خوار

چكيده لاتين :

Antixenosis is the resistance mechanism exhibited by a plant to deter settlement and colonization of an insect. Plants that exhibit antixenotic resistance could be expected to under go reduced initial infestation than the susceptible ones. This mechanism is a host plantʹs characteristic that affects oviposition preference of the pest as well as its stay. In this study, antixenotic experiments were designed in three categories including: oviposition preference of adults, alighting and settlement of neonate larvae on different sugarcane varieties. Cuts of twelve sugarcane varieties were planted in plastic pots (20%<20 diamxh.). The experiment was so designed as to compare the oviposition response of adults on a range of varieties in a choice test. This experiment was carried out by placing pots from each variety inside a cage (2x2x 1.5 m), which was covered by net cloth. Egg deposition was assessed 72 h. after which adults had been released inside the center of the cage. In the experiment involving larvae, 50 neonate larvae were placed with the aid of a fine camelʹs brush in plant collar of to be infested plants in each pot. The larvae were confined to the plant by placing a ventilated plastic cage on them. In the other experiment, preference of neonate larvae was evaluated in no choice (comparison of each variety with CP69-1062) and choice-tests. Oviposition preference in adults, settlement and alighting of neonate larvae were conducted in 4, 4, 10 replications respectively. Comparison of means by non-parametric method revealed that it could be possible to group varieties into three categories. The most egg deposition was observed in susceptible variety (L60-40), while the minimum was observed in resistant (CP73-21 and N51-539) and commercial (NCO-310 and SP-70) varieties. In the experiment assaying neonate settlement, no significant differences were observed among varieties. Moreover, there was not any significant preference by neonate larvae to varieties in choice and no - choice experiments. Based on the results one, is led to the conclusion that mechanisms of antixenosis might play a major role in sugarcane resistance to S. nonagrioides. This study is the first demonstration regarding the existence of ovipositional preference by the insectʹs adults in sugarcane varieties.