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Violet LED light enhances the recruitment of a thrip predator in open fields

View Article: PubMed Central - PubMed

ABSTRACT

The predatory bug Orius sauteri is an indigenous natural enemy of thrips and whiteflies in Asian countries. To put these bugs to practical use in pest management, methods to attract and retain the bugs in agricultural fields are needed. We previously showed that violet light (405 nm) attracts O. sauteri selectively. Many thrips and whiteflies are attracted to UV or green light. In this study, we examined the effect of violet-LED illumination on O. sauteri in pesticide-free eggplant (Solanum melongena L.) cultivation. In three cultivation trials, the density of O. sauteri on eggplant leaves was consistently higher in the illuminated plots; at least twice that of the non-illuminated plots. Simultaneously, the density of thrips declined markedly to less than half that of the non-illuminated plots. We identified three positive effects of violet light including an “immediate-effect” on predator attraction, a “persistent-effect” on predator reproduction, and a “secondary-effect” on the food web structure. Our results showed that illumination with violet light provides a powerful tool for integrated pest management. This is the first report on the use of illumination to manipulate the behavior of natural enemies.

No MeSH data available.


Plot design and locations of experimental plots in the eggplant field.(A) The experimental field had six plots which included three illuminated plots and three non-illuminated plots. Sorghum fence approximately 3 m in width were planted to separate each experimental plot to minimize inter-plot interference. (B) There were three rows of eggplant per plot. Four eggplant trees were planted in a row. Banker plants were planted surrounding eggplant rows. Space between eggplants was 0.9 m in the row, and one plot consisted of three rows 2.5 m apart.
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f1: Plot design and locations of experimental plots in the eggplant field.(A) The experimental field had six plots which included three illuminated plots and three non-illuminated plots. Sorghum fence approximately 3 m in width were planted to separate each experimental plot to minimize inter-plot interference. (B) There were three rows of eggplant per plot. Four eggplant trees were planted in a row. Banker plants were planted surrounding eggplant rows. Space between eggplants was 0.9 m in the row, and one plot consisted of three rows 2.5 m apart.

Mentions: We divided an eggplant field into two plots; violet illuminated and non-illuminated (Fig. 1), then observed the occurrence of O. sauteri and thrips in these plots. A rope-type LED light source (3 m long) was used. O. sauteri and thrips on ten eggplant leaves were captured using square sticky paper. The numbers of catches in both plots were compared to verify whether O. sauteri was attracted to illuminated plants and whether the population density of thrips was suppressed. We conducted three trials: In Trial 1, three ropes of LEDs were lit, from June 29 to July 30. In Trial 2, three ropes of LEDs were lit from August 4 to October 9. In Trial 3, one rope of LEDs was lit from August 19 to October 10. In all trials and throughout the experimental period, O. sauteri and thrips species that were captured were identified to be O. sauteri and Mycterothrips glycines (Okamoto), respectively, based on their morphologies. Mean temperatures and precipitation in Tsukuba City during the experimental period were measured at the Aerological Observatory which is located 2.8 km from the experimental field with an elevation difference of 3.2 m.


Violet LED light enhances the recruitment of a thrip predator in open fields
Plot design and locations of experimental plots in the eggplant field.(A) The experimental field had six plots which included three illuminated plots and three non-illuminated plots. Sorghum fence approximately 3 m in width were planted to separate each experimental plot to minimize inter-plot interference. (B) There were three rows of eggplant per plot. Four eggplant trees were planted in a row. Banker plants were planted surrounding eggplant rows. Space between eggplants was 0.9 m in the row, and one plot consisted of three rows 2.5 m apart.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5015028&req=5

f1: Plot design and locations of experimental plots in the eggplant field.(A) The experimental field had six plots which included three illuminated plots and three non-illuminated plots. Sorghum fence approximately 3 m in width were planted to separate each experimental plot to minimize inter-plot interference. (B) There were three rows of eggplant per plot. Four eggplant trees were planted in a row. Banker plants were planted surrounding eggplant rows. Space between eggplants was 0.9 m in the row, and one plot consisted of three rows 2.5 m apart.
Mentions: We divided an eggplant field into two plots; violet illuminated and non-illuminated (Fig. 1), then observed the occurrence of O. sauteri and thrips in these plots. A rope-type LED light source (3 m long) was used. O. sauteri and thrips on ten eggplant leaves were captured using square sticky paper. The numbers of catches in both plots were compared to verify whether O. sauteri was attracted to illuminated plants and whether the population density of thrips was suppressed. We conducted three trials: In Trial 1, three ropes of LEDs were lit, from June 29 to July 30. In Trial 2, three ropes of LEDs were lit from August 4 to October 9. In Trial 3, one rope of LEDs was lit from August 19 to October 10. In all trials and throughout the experimental period, O. sauteri and thrips species that were captured were identified to be O. sauteri and Mycterothrips glycines (Okamoto), respectively, based on their morphologies. Mean temperatures and precipitation in Tsukuba City during the experimental period were measured at the Aerological Observatory which is located 2.8 km from the experimental field with an elevation difference of 3.2 m.

View Article: PubMed Central - PubMed

ABSTRACT

The predatory bug Orius sauteri is an indigenous natural enemy of thrips and whiteflies in Asian countries. To put these bugs to practical use in pest management, methods to attract and retain the bugs in agricultural fields are needed. We previously showed that violet light (405 nm) attracts O. sauteri selectively. Many thrips and whiteflies are attracted to UV or green light. In this study, we examined the effect of violet-LED illumination on O. sauteri in pesticide-free eggplant (Solanum melongena L.) cultivation. In three cultivation trials, the density of O. sauteri on eggplant leaves was consistently higher in the illuminated plots; at least twice that of the non-illuminated plots. Simultaneously, the density of thrips declined markedly to less than half that of the non-illuminated plots. We identified three positive effects of violet light including an “immediate-effect” on predator attraction, a “persistent-effect” on predator reproduction, and a “secondary-effect” on the food web structure. Our results showed that illumination with violet light provides a powerful tool for integrated pest management. This is the first report on the use of illumination to manipulate the behavior of natural enemies.

No MeSH data available.