Paddy grains with a slight gap between the lemma and palea are vulnerable to rice leaf bugs, Stenotus rubrovittatus（Matsumura）and Trigonotylus caelestialium（Kirkaldy）（Hemiptera: Miridae）. This study aimed to determine the vulnerable paddy rate that can reduce pecky rice damage. Field data were collected from 2021 to 2023 in Joetsu City, Japan. Logistic models were constructed using data from 76 fields to estimate the probability of damage incidence; a relatively good model was selected. The selected model was used to assess the probability of ＞0.7% damaged grain incidence with two explanatory variables: percentage of vulnerable paddies and total number of rice leaf bug adults and larvae collected by sweeping at the full-heading stage. Using data from 113 fields, the selected model was evaluated and was reproducible for the ＜10% and 10–50% grades but not for the 50–90% and ＞90% grades. The model indicated that low vulnerable paddy incidence（＜13.3%）reduces the probability to ＜10% damage incidence under low bug density conditions（≤3.4 rice leaf bugs/20 sweepings）. Although moderately effective（reducing damage to ≤0.7%）, the low incidence of vulnerable paddy may help control damage, especially in late-heading rice fields.
Hiroaki Takeuchi (Thu,) studied this question.