<scp> <i>Leptocorisa chinensis</i> </scp> Management in Paddy Fields Employing a Synthetic Form of ( <scp> <i>E</i> </scp> )‐2‐Octenal, the Major Compound of Its Alarm Pheromone

ABSTRACT Leptocorisa chinensis Dallas (Hemiptera: Alydidae) is a serious pest responsible for causing pecky rice grains in paddy fields. When disturbed, an adult L. chinensis emit a pungent odour—an alarm pheromone—that induces escape behaviour in conspecifics. ( E )‐2‐Octenal ( E ‐2‐OAL) is a major component of this odour and is responsible for triggering the escape response. We hypothesized that the synthetic form of E ‐2‐OAL could be used to control L. chinensis adults. This study aimed to reduce the incidence of pecky rice grains in paddy fields by deploying E ‐2‐OAL dispensers. To determine an effective concentration for field application, outdoor experiments were conducted. A 1% emulsified E ‐2‐OAL solution placed 30 cm upwind of caged adults L. chinensis effectively elicited escape behaviour. Field trials were conducted during the milk‐ripe stage of rice plants in paddy fields in two regions in Japan. In a paddy field, a plot treated with 1% emulsified E ‐2‐OAL was established, with a control plot of the same size located 30 m away in the same field. In both regions, the E ‐2‐OAL‐treated plots showed a significant reduction in pecky rice grains attributed to L. chinensis compared to the control plots. The total number of rice grains harvested did not differ significantly between treated and control plots. These results suggest that applying E ‐2‐OAL in paddy fields can effectively alter L. chinensis behaviour, reducing pecky rice grain damage without negatively impacting rice yield.