A Computational Analysis Based on Automatic Digitization of Movement Tracks Reveals the Altered Diurnal Behavior of the Western Flower Thrips, <i>Frankliniella occidentalis</i>, Suppressed in <i>PKG</i> Expression

The western flower thrips, <i>Frankliniella occidentalis</i>, a worldwide insect pest with its polyphagous feeding behavior and capacity to transmit viruses, follows a diurnal rhythmicity driven by expression of the circadian clock genes. However, it remained unclear how the clock signal...

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Main Authors: Chunlei Xia, Gahyeon Jin, Falguni Khan, Hye-Won Kim, Yong-Hyeok Jang, Nam Jung, Yonggyun Kim, Tae-Soo Chon
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Language:English
Published: MDPI AG 2025-03-01
Series:Insects
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Online Access:https://www.mdpi.com/2075-4450/16/3/320
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author Chunlei Xia
Gahyeon Jin
Falguni Khan
Hye-Won Kim
Yong-Hyeok Jang
Nam Jung
Yonggyun Kim
Tae-Soo Chon
author_facet Chunlei Xia
Gahyeon Jin
Falguni Khan
Hye-Won Kim
Yong-Hyeok Jang
Nam Jung
Yonggyun Kim
Tae-Soo Chon
author_sort Chunlei Xia
collection DOAJ
description The western flower thrips, <i>Frankliniella occidentalis</i>, a worldwide insect pest with its polyphagous feeding behavior and capacity to transmit viruses, follows a diurnal rhythmicity driven by expression of the circadian clock genes. However, it remained unclear how the clock signal triggers the thrips behaviors. This study posed a hypothesis that the clock signal modulates cGMP-dependent protein kinase (<i>PKG</i>) activity to mediate the diurnal behaviors. A <i>PKG</i> gene is encoded in <i>F. occidentalis</i> and exhibits high sequence homologies with those of honeybee and fruit fly. Interestingly, its expression followed a diel pattern with high expression during photophase in larvae and adults of <i>F. occidentalis</i>. It is noteworthy that <i>PKG</i> expression was clearly observed in the midgut during photophase but not in scotophase from our fluorescence in situ hybridization analysis. A prediction of protein–protein interaction suggested its functional association with clock genes. To test this functional link, RNA interference (RNAi) of the PKG gene expression was performed by feeding a gene-specific double-stranded RNA, which led to significant alteration of the two clock genes (<i>Clock</i> and <i>Period</i>) in their expression levels. The RNAi treatment caused adverse effects on early-life development and adult fecundity. To further analyze the role of PKG in affecting diurnal behavior, the adult females were continuously observed for a 24 h period with an automatic digitization device to obtain movement parameters and durations (%) in different micro-areas in the observation arena. Diel difference was observed with speed in RNAi-control females at 0.16 mm/s and 0.08 mm/s, in photo- and scotophase, respectively, whereas diel difference was not observed for the <i>PKG</i>-specific RNAi-treated females, which showed 0.07 mm/s and 0.06 mm/s, respectively. The diel difference was also observed in durations (%) in the control females, more strongly in the intermediate area in the observation arena. Speed and durations in the different micro-areas in mid-scotophase were significantly different from most photophase in the control females, while speed was significantly different mainly during late photophase when comparing effects of control and RNAi treatments in each light phase. Three sequential stages consisting of high activity followed by feeding and visiting of micro-areas were observed for the control females. For RNAi-treated females, the three phases were disturbed with irregular speed and visits to micro-areas. These results suggest that PKG is associated with implementing the diurnal behavior of <i>F. occidentalis</i> by interacting with expressions of the circadian clock genes.
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spelling doaj-art-03864edab9b44fddb1f66770530c1f9c2025-08-20T03:43:31ZengMDPI AGInsects2075-44502025-03-0116332010.3390/insects16030320A Computational Analysis Based on Automatic Digitization of Movement Tracks Reveals the Altered Diurnal Behavior of the Western Flower Thrips, <i>Frankliniella occidentalis</i>, Suppressed in <i>PKG</i> ExpressionChunlei Xia0Gahyeon Jin1Falguni Khan2Hye-Won Kim3Yong-Hyeok Jang4Nam Jung5Yonggyun Kim6Tae-Soo Chon7Research and Development, Ecology and Future Research Institute (EnFRI), Busan 46241, Republic of KoreaDepartment of Plant Medicals, Andong National University, Andong 36729, Republic of KoreaDepartment of Plant Medicals, Andong National University, Andong 36729, Republic of KoreaResearch and Development, Ecology and Future Research Institute (EnFRI), Busan 46241, Republic of KoreaResearch and Development, Ecology and Future Research Institute (EnFRI), Busan 46241, Republic of KoreaResearch and Development, Ecology and Future Research Institute (EnFRI), Busan 46241, Republic of KoreaDepartment of Plant Medicals, Andong National University, Andong 36729, Republic of KoreaResearch and Development, Ecology and Future Research Institute (EnFRI), Busan 46241, Republic of KoreaThe western flower thrips, <i>Frankliniella occidentalis</i>, a worldwide insect pest with its polyphagous feeding behavior and capacity to transmit viruses, follows a diurnal rhythmicity driven by expression of the circadian clock genes. However, it remained unclear how the clock signal triggers the thrips behaviors. This study posed a hypothesis that the clock signal modulates cGMP-dependent protein kinase (<i>PKG</i>) activity to mediate the diurnal behaviors. A <i>PKG</i> gene is encoded in <i>F. occidentalis</i> and exhibits high sequence homologies with those of honeybee and fruit fly. Interestingly, its expression followed a diel pattern with high expression during photophase in larvae and adults of <i>F. occidentalis</i>. It is noteworthy that <i>PKG</i> expression was clearly observed in the midgut during photophase but not in scotophase from our fluorescence in situ hybridization analysis. A prediction of protein–protein interaction suggested its functional association with clock genes. To test this functional link, RNA interference (RNAi) of the PKG gene expression was performed by feeding a gene-specific double-stranded RNA, which led to significant alteration of the two clock genes (<i>Clock</i> and <i>Period</i>) in their expression levels. The RNAi treatment caused adverse effects on early-life development and adult fecundity. To further analyze the role of PKG in affecting diurnal behavior, the adult females were continuously observed for a 24 h period with an automatic digitization device to obtain movement parameters and durations (%) in different micro-areas in the observation arena. Diel difference was observed with speed in RNAi-control females at 0.16 mm/s and 0.08 mm/s, in photo- and scotophase, respectively, whereas diel difference was not observed for the <i>PKG</i>-specific RNAi-treated females, which showed 0.07 mm/s and 0.06 mm/s, respectively. The diel difference was also observed in durations (%) in the control females, more strongly in the intermediate area in the observation arena. Speed and durations in the different micro-areas in mid-scotophase were significantly different from most photophase in the control females, while speed was significantly different mainly during late photophase when comparing effects of control and RNAi treatments in each light phase. Three sequential stages consisting of high activity followed by feeding and visiting of micro-areas were observed for the control females. For RNAi-treated females, the three phases were disturbed with irregular speed and visits to micro-areas. These results suggest that PKG is associated with implementing the diurnal behavior of <i>F. occidentalis</i> by interacting with expressions of the circadian clock genes.https://www.mdpi.com/2075-4450/16/3/320diurnal behaviorneural networkthripsPKGRNA interference
spellingShingle Chunlei Xia
Gahyeon Jin
Falguni Khan
Hye-Won Kim
Yong-Hyeok Jang
Nam Jung
Yonggyun Kim
Tae-Soo Chon
A Computational Analysis Based on Automatic Digitization of Movement Tracks Reveals the Altered Diurnal Behavior of the Western Flower Thrips, <i>Frankliniella occidentalis</i>, Suppressed in <i>PKG</i> Expression
Insects
diurnal behavior
neural network
thrips
PKG
RNA interference
title A Computational Analysis Based on Automatic Digitization of Movement Tracks Reveals the Altered Diurnal Behavior of the Western Flower Thrips, <i>Frankliniella occidentalis</i>, Suppressed in <i>PKG</i> Expression
title_full A Computational Analysis Based on Automatic Digitization of Movement Tracks Reveals the Altered Diurnal Behavior of the Western Flower Thrips, <i>Frankliniella occidentalis</i>, Suppressed in <i>PKG</i> Expression
title_fullStr A Computational Analysis Based on Automatic Digitization of Movement Tracks Reveals the Altered Diurnal Behavior of the Western Flower Thrips, <i>Frankliniella occidentalis</i>, Suppressed in <i>PKG</i> Expression
title_full_unstemmed A Computational Analysis Based on Automatic Digitization of Movement Tracks Reveals the Altered Diurnal Behavior of the Western Flower Thrips, <i>Frankliniella occidentalis</i>, Suppressed in <i>PKG</i> Expression
title_short A Computational Analysis Based on Automatic Digitization of Movement Tracks Reveals the Altered Diurnal Behavior of the Western Flower Thrips, <i>Frankliniella occidentalis</i>, Suppressed in <i>PKG</i> Expression
title_sort computational analysis based on automatic digitization of movement tracks reveals the altered diurnal behavior of the western flower thrips i frankliniella occidentalis i suppressed in i pkg i expression
topic diurnal behavior
neural network
thrips
PKG
RNA interference
url https://www.mdpi.com/2075-4450/16/3/320
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