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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.


Population trends for Orius sauteri and thrips.Total number of O. sauteri (upper panel) and thrips (middle panel) captured in Trial 3. The mean temperature and precipitation in Tsukuba City during the experimental period (lower panel). LED light was turned on beginning August 26.
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f5: Population trends for Orius sauteri and thrips.Total number of O. sauteri (upper panel) and thrips (middle panel) captured in Trial 3. The mean temperature and precipitation in Tsukuba City during the experimental period (lower panel). LED light was turned on beginning August 26.

Mentions: Next, we investigated temporal variation in the numbers of captured O. sauteri and thrips (Fig. 5). After three days from the start of lighting, the numbers of O. sauteri captured in the illuminated and the non-illuminated plots were 9 and 2, respectively. In contrast, the numbers of thrips captured in the illuminated and non-illuminated plots were 1 and 9, respectively, confirming that the effects of violet illumination had already begun after three days from the start of lighting, as was the case for Trial 1. Except for September 15 and 24, the density of O. sauteri in the illuminated plots was higher than in the non-illuminated plots until October 3. As with Trial 2, no O. sauteri were captured at that time, since the mean temperature was lower than 20 °C. The changes in the densities of O. sauteri and thrips were concurrent with decreases in atmospheric temperature. On September 6, the thrip density in the illuminated plots increased temporally greater than that in the non-illuminated plots (Fig. 5, middle panel). Except for that day, the density of thrips remained lower than in the non-illuminated plots after the first peak, until September 24.


Violet LED light enhances the recruitment of a thrip predator in open fields
Population trends for Orius sauteri and thrips.Total number of O. sauteri (upper panel) and thrips (middle panel) captured in Trial 3. The mean temperature and precipitation in Tsukuba City during the experimental period (lower panel). LED light was turned on beginning August 26.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f5: Population trends for Orius sauteri and thrips.Total number of O. sauteri (upper panel) and thrips (middle panel) captured in Trial 3. The mean temperature and precipitation in Tsukuba City during the experimental period (lower panel). LED light was turned on beginning August 26.
Mentions: Next, we investigated temporal variation in the numbers of captured O. sauteri and thrips (Fig. 5). After three days from the start of lighting, the numbers of O. sauteri captured in the illuminated and the non-illuminated plots were 9 and 2, respectively. In contrast, the numbers of thrips captured in the illuminated and non-illuminated plots were 1 and 9, respectively, confirming that the effects of violet illumination had already begun after three days from the start of lighting, as was the case for Trial 1. Except for September 15 and 24, the density of O. sauteri in the illuminated plots was higher than in the non-illuminated plots until October 3. As with Trial 2, no O. sauteri were captured at that time, since the mean temperature was lower than 20 °C. The changes in the densities of O. sauteri and thrips were concurrent with decreases in atmospheric temperature. On September 6, the thrip density in the illuminated plots increased temporally greater than that in the non-illuminated plots (Fig. 5, middle panel). Except for that day, the density of thrips remained lower than in the non-illuminated plots after the first peak, until September 24.

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.