Abstract
Mechanisms of varietal resistance to the whitebacked planthopper, Sogatella furcifera, in a Chinese japonica rice "Chengjiang 06 (CJ-06)" were investigated in comparison with a susceptible hybrid rice "Shanyou 63 (SY-63)". Field experiments revealed definite field resistance of CJ-06 to S. furcifera. The immigrants exhibited non-preference to CJ-06 and failed to establish progeny, whereas they preferred to settle and reproduced CT-06 well on SY-63. Under a free-choice condition, significantly fewer individuals alighted on CJ-06 than did on SY-63. Significantly less honeydew exeretion by S. furcifera females on CJ-06 than on SY-63 indicated suppressed sucking on CJ-06. Both fecundity and egg hatchability were greatly reduced on CJ-06 as compared with those on SY-63, when newly emerged females were fed on CJ-06. The fertility of S. furcifera on CJ-06 was only about one tenth of that on SY-63. S. furcifera eggs suffered high mortality in watery lesions at oviposition sites on CJ-06. The watery lesions rapidly led to the formation of conspicuous necrotic symptoms before the eggs hatched. The egg mortality in the watery lesions occurred within 1-2 days after oviposition. Such watery lesions seldom occurred in SY-63, where the egg mortality was very low. It is concluded that sucking suppression and ovicidal reaction are the critical components for the Sa furcifera resistance of CJ-06, which is expressed as not only antixenosis against S. furcifera immigrants, but also antibiosis to reduce fecundity and egg hatchability of inhabitants, respectively.
