DOI: 10.5061/dryad.wstqjq2x6
title: Use of (E)-2-octenal, a major alarm pheromone of Leptocorisa chinensis, to manage conspecifics in paddy fields

description:  (E)-2-Octenal (E-2-OAL) is a major component of alarm pheromones
 in the rice-ear bug, Leptocorisa chinensis. Cage experiments
 revealed that 1 % emulsified E-2-OAL effectively induced escape behavior
 in adult L. chinensis. In the commercial paddy fields, a treated
 plot (5 × 5 m) was established with 16 rods (1 m high, spaced 1.5 m apart
 in 4 × 4 formations), each topped with a glass Petri dish containing a 1 %
 E-2-OAL solution. A control plot of similar size was established 30 m from
 the treated plot in the same field. Experiments were carried out in six
 paddy fields during the milk-ripe stage of rice plants. We observed a
 significant reduction in pecky rice grains likely caused by L. chinensis
 in the E-2-OAL-treated plots compared with that in the control plots,
 successfully maintaining damage levels below the economic injury level.
description: <strong>Cage bioassay</strong>
 <em>E</em>-2-OAL was purchased from Wako Pure
 Chemical Industries, Ltd. (Osaka, Japan). The compound was dissolved in
 methanol (10 % v/v) and subsequently diluted with distilled water to
 obtain 1, 0.1, and 0.01 % emulsified solutions. To
 determine the effective concentration of emulsified
 <em>E</em>-2-OAL solution, we conducted a nylon mesh cage
 bioassay in the fields. Five undisturbed female <em>L.
 chinensis</em> were placed in a mesh cage (30 × 30 × 50 cm, covered
 with a 2 mm nylon mesh). A small Petri dish (diameter: 10 cm, height: 3
 cm) containing 50 mL of 1, 0.1, or 0.01 % solution was positioned 30 cm
 upwind from the cage. We observed the behavior of females (standing still,
 grooming, wandering, and flying downwind) for 5 min. The experiments were
 repeated six times for the 0.01 and 0.1 % solutions and 14 times for the 1
 % solution over three experimental days.
 <strong>Paddy field experiments</strong>
 We used emulsified <em>E</em>-2-OAL solution-filled
 Petri dishes of the same size as the cage bioassay. Each Petri dish
 containing 50 mL of 1% <em>E</em>-2-OAL solution was placed on
 a plastic board (26 × 26 cm) with a roof of similar dimensions to protect
 it from rain and direct sunlight. The board was placed on a 1-meter-long
 plastic rod called a dispenser. Experiments were
 conducted in three commercial paddy fields in the Sayoh (var. Koshihikari)
 and Aogaki (var. Hinohikari), Hyogo Prefecture, Japan. The experiments
 were initiated before the rice plants reached the milk-ripe stage. In this
 study, <em>L. chinensis</em> was the predominant bug species
 in paddy fields. Pecky rice grains infested with <em>L.
 chinensis</em> had distinctive brownish margins surrounding the
 damaged site. A treated plot (5 × 5 m) was established
 in each paddy field with 16 dispensers arranged in a 4 × 4 square
 formation spaced approximately 1.5 m apart. A control plot of similar
 size, without dispensers, was established 30 m from the treated plot.
 Approximately 49 rice bunches were planted in each plot. The
 <em>E</em>-2-OAL solution in the Petri dishes was replaced
 daily. No insecticides were used in the field until harvest. Following
 harvest, we counted the pecky rice grains exhibiting characteristic
 brownish margin damage, likely caused by <em>L.
 chinensis</em>. In the first, second, and third trials, 16, 12, and
 21 rice bunches were selected, respectively. For statistical analysis,
 since the arcsine transformation of the data did not achieve
 homoscedasticity, a <em>t</em>-test was conducted after
 applying the Box-Cox transformation, with the total grain count used as
 weighting in JMP version 14.2.0 (SAS Institute, 2018).
description: # Use of (E)-2-octenal, a major alarm pheromone of Leptocorisa chinensis,
 to manage conspecifics in paddy fields
 [https://doi.org/10.5061/dryad.wstqjq2x6](https://doi.org/10.5061/dryad.wstqjq2x6) This study aimed to assess whether (*E*)-2-octenal (*E*-2-OAL) can effectively reduce damage caused by *Leptocorisa chinensis* in commercial paddy fields. *L. chinensis* is a significant pest in rice crops, causing pecky rice grains, but effective field-based repellents are lacking, justifying the exploration of *E*-2-OAL as a potential solution. The study revealed that *E*-2-OAL-treated plots had significantly fewer pecky rice grains compared to those of the control plots, indicating *E*-2-OAL as a promising tool for managing *L. chinensis* damage in rice fields and maintaining pest damage below the economic injury threshold. ## Description of the data and file structure These data are used to create all of the figures and carry out the analyses presented in the manuscript. * Data_for_Figure_1.csv: This file contains the cage bioassay data of the bioassay in the laboratory. The cage bioassay data show three concentrations of E-2-OAL in emulsified solution.  - Data_for_Figure_2_and_3MU.csv: This file contains the data used to evaluate the effects of (*E*)-2-octenal set in paddy fields in Sayoh region and Aigaki region on the number of pecky rice grains. (Figures 2 and 3).