Manipulation of Ultraviolet Light Affects Immigration Behavior of <I>Ceratothripoides claratris</I> (Thysanoptera: Thripidae)

Abstract

Studies were conducted in tropical greenhouses to elucidate the role of UV light (UV) for the orientation and flight behavior of the thrips Ceratothripoides claratris (Shumsher) (Thysanoptera: Thripidae), an important pest on tomato (Lycopersicum spp.), in the hot and humid tropics of South-East Asia. Four greenhouse types characterized by different combinations of UV-absorbing or -transmitting plastic films and nets on the roof and sidewalls, respectively, were used in these studies. In choice experiments C. claratris always preferred the environment with higher UV intensity. Furthermore, natural thrips populations around the greenhouses were captured during the majority of control dates in lower numbers on sticky traps on the outer sidewalls of greenhouses clad with UV-absorbing materials compared with UV-transmitting materials. The immigration of thrips into the UV-absorbing greenhouses also was impeded, as measured by sticky traps on the inner side walls. UV-absorbing plastic roofs showed the most pronounced deterrent effect for thrips movement toward greenhouses, and the UV-absorbing net effectively reduced thrips numbers crossing the net barrier into the greenhouse. A simple extension of UV-absorbing plastic roof around conventional greenhouses clad with UV-transmitting plastic and net reduced thrips capture rates inside the greenhouse up to 77% when thrips was released at 1 m distance from the net walls. These results are discussed in the context of wavelength dependent insect vision and the dilemma of tropical greenhouse constructions, i.e., physical pest exclusion versus appropriate ventilation to ensure a conducive microclimate for plant growth.

Insect reactions to light and its applications to pest management

“…For insects given access to a space with UV radiation and a space from which near-UV radiation was eliminated, many species avoid the latter. Studies have shown reduced incidence of insects such as aphids, whiteflies, and thrips in facilities covered with UVabsorbing film (Costa et al 2002;Nguyen et al 2009;Nonaka and Nagai 1985;Ohta and Kitamura 2006). In addition to vinyl chloride films, products made of highly durable polyolefin films have recently been developed to block near-UV radiation, to prevent infestation inside greenhouses.…”

Management of Air-Borne Viruses by “Optical Barriers” in Protected Agriculture and Open-Field Crops

“…Initially, insects are excluded from the greenhouse wall due to the lack of UV emission from the inner space of the greenhouse. This effect was well demonstrated by Antignus et al (2001) and Nguyen et al (2009) who monitored lower numbers of whiteflies and thrips, respectively, on sticky traps placed on the outer sidewalls of greenhouses covered with UV-absorbing cladding materials. Hypothetically, a "two-compartment effect" is formed by the photoselective cladding materials: the greenhouse ambient environment has a normal level of UV irradiation, thus representing a UV-rich compartment, while a second UV-deficient compartment is formed within the greenhouse due to UV filtration.…”

“…Many insects have two rhodopsins, one with maximum absorption in ultraviolet wavelengths (365 nm) and one with maximum absorption in the green part of the spectrum (540 nm) (Borst, 2009;Matteson, Terry, Ascoli, & Gilbert, 1992). UV component of the light spectrum plays an important role in aspects of insect behavior, including orientation, navigation, feeding, and interaction between the sexes (Mazokhin-Porshnykov, 1969;Nguyen, Borgemeister, Max, & Poehling, 2009;Seliger, Lall, & Biggley, 1994). The involvement of UV rays in the flight behavior of some economically important insect pests has been studied by several workers (Coombe, 1982;Issacs, Willis, & Byrne, 1999;Kring, 1972;Matteson et al, 1992;Moericke, 1955;Mound, 1962;Vaishampayan, Kogan, Waldbauer, & Wooley, 1975;.…”

“…Moller (2002) assumed that UV reflection from plant surfaces plays an important role in making plants visible to herbivorous insects, thus directing their take off and initial orientation. It was assumed that stimulation of UV receptors by incoming UV mainly controls initiation of take off and directs the route of dispersion flight of the thrips C. claratris (Nguyen et al, 2009). However, high reflectance of UV rays seems to disrupt the host-finding behavior of insect pests.…”

Manipulation of light spectral quality disrupts host location and attachment by parasitic plants in the genus Cuscuta

“…Spectral manipulation techniques have previously been employed effectively for the control of other classes of pests and pathogens in greenhouses (Raviv & Antignus ; Nguyen et al . ) and to control plant growth without the use of growth regulators (Decoteau et al . ; Rajapakse et al .…”