Risk Odors Deriving from Predator Abdominal Gland Secretions Mediate Non-Consumptive Effects on Prey

Abstract

Prey can detect the presence of predators by predator-released cues and then flexibly alter their phenotypical traits to mitigate the risk, thus non-consumptive effects emerge. Non-consumptive effects have been widely studied in many ecosystems, however, the mechanisms underlying these effects are poorly understood, leaving questions as to the nature of the risk cues and how prey detect the predator. Here, we used a Y-tube olfactometer to examine whether small brown planthoppers, Laodelphax striatellus (Fallén), could detect the presence of rove beetles (Paederus fuscipes Curtis) via odor from rove beetle abdominal gland secretion. We further identified the chemicals of abdominal gland secretion by gas chromatography-mass spectrometry. Chemicals identified were exposed to a planthopper to test their effects on planthopper behavior. Female or male planthoppers could distinguish the predation risk odors of rove beetle or rove beetle abdominal gland secretion from odor without predation risks. Through gas chromatography-mass spectrometry, sixteen of the most abundant chemicals were found in female and male abdominal gland secretion. Five of them (n-undecane, n-pentadecane, n-hexadecane, n-eicosane, and n-heneicosane) individually or collectively reduced the activity level of planthoppers. These findings enhance our understanding of the role of abdominal gland secretion in mediating non-consumptive predator effects, with significant implications for pest management, and the evolution of chemical signals.

Field spray abdominal gland secretions of rove beetles: Effects on the pest abundance and arthropod community

“…Here, 390 uL of n‐undecane, 1230 uL of n‐tridecane, 1590 uL of n‐pentadecane, 1050 uL of n‐hexadecane, 1410 mg of n‐eicosane, and 660 mg of n‐heneicosane were mixed to form a solution, which was mixed with distilled water at 40°C to form a 6‐L unstable water emulsion. Thus, their proportions in the emulsion were 1.28, 4.12, 5.32, 3.50, 4.72, and 2.22%, respectively, which resembled the relative percentages in natural AGS examined by GC–MS (Wen & Ueno, 2022). Notably, the AGS solution is not soluble in water, but by adding warm water (i.e., 40°C) and shaking vigorously, an unstable water emulsion can be formed.…”

“…The rove beetle P. fuscipes has an abdominal gland located at the front margin of the fourth sternite (Kellner & Dettner, 1992). P. fuscipes elicits AGS when attacked by predators or conspecifics (allomones) and it has also been reported as a sex pheromone (Peschke, 1983, 1986; Peschke & Metzler, 1982) and kairomone (Wen & Ueno, 2022). The chemical profiles of these secretions were identified by gas chromatography–mass spectrometry (GC–MS) in our previous study (Wen & Ueno, 2022).…”

“…P. fuscipes elicits AGS when attacked by predators or conspecifics (allomones) and it has also been reported as a sex pheromone (Peschke, 1983, 1986; Peschke & Metzler, 1982) and kairomone (Wen & Ueno, 2022). The chemical profiles of these secretions were identified by gas chromatography–mass spectrometry (GC–MS) in our previous study (Wen & Ueno, 2022). We prepared an artificial solution of rove beetle AGS using the method described previously (Wen & Ueno, 2022).…”

“…The chemical profiles of these secretions were identified by gas chromatography–mass spectrometry (GC–MS) in our previous study (Wen & Ueno, 2022). We prepared an artificial solution of rove beetle AGS using the method described previously (Wen & Ueno, 2022). Here, 390 uL of n‐undecane, 1230 uL of n‐tridecane, 1590 uL of n‐pentadecane, 1050 uL of n‐hexadecane, 1410 mg of n‐eicosane, and 660 mg of n‐heneicosane were mixed to form a solution, which was mixed with distilled water at 40°C to form a 6‐L unstable water emulsion.…”

“…In our previous studies, we found that AGS from the rove beetle can alter the behaviour and morphology of a rice pest, the small brown planthopper, in the laboratory (Wen & Ueno, 2021b; Wen & Ueno, 2022), lowering its fitness (shorter life span and lower fecundity, Wen & Ueno, 2021a), acting as a kairomone (predator‐associated cues) and mediating NCEs. However, research remains limited into how these secretions affect the population of L. striatellus or other arthropods and if they have synergistic, cumulative, or interference effects on the suppression of pest populations in the field; thus, whether these secretions are environmentally friendly and can be used in real‐world applications remains poorly understood.…”