The synchronism between infestation period of Oryzophagus oryzae (Costa Lima) larvae and tillering period, was evaluated in four cultivars of irrigated rice (Bluebelle, BR-IRGA 410, BR-IRGA 414 e Dawn), which differ on degree of resistance to the insect and duration of development cycle. The experiments were carried out in the field, during 1994 and 1995 rice seasons. The number of larvae and tillers were registered weekly from 10 to 85 days after rice plants inundation (DAI). The first larvae were found 10 DAI, while the peak of larval population occurred 31 DAI, regardless the cultivars. The cultivars BR-IRGA 414 and Bluebelle (early cycle) produced tillers up to 45 DAI, while the cultivars BR-IRGA 410 and Dawn (medium cycle) produced tillers up to 68 DAI. The tillering period of early and semi-early cultivars lasted respectively 14 and 37 days, after the populational peak of larvae occurred. Medium cycle cultivars have shown higher capacity of recovering damaged roots after larval attack, thus becoming potentially more tolerant to insect damage.
Insecta; Oryza sativa; rice water weevil
