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United States Department of Agriculture

Agricultural Research Service

Research Project: BIOLOGICALLY BASED MANAGEMENT OF INVASIVE INSECT PESTS AND WEEDS

Location: Insect Behavior and Biocontrol Research Unit

Title: Management strategies for western flower thrips and the role of insecticides

Authors
item Reitz, Stuart
item Funderburk, Joe -

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: July 27, 2011
Publication Date: February 15, 2012
Citation: Reitz, S.R., Funderburk, J. 2012. Management strategies for western flower thrips and the role of insecticides. In: Perveen, F., editor. Insecticides-Pest Engineering. Rijeka, Croatia: InTech. p. 355-385.

Interpretive Summary: Today, the western flower thrips, is one of the most significant agricultural pests globally because of the damage it is able to inflict on a wide range of crops. Adults and larvae feed by piercing plant tissues with their needle-shaped mandible and draining the contents of punctured cells. Most importantly, western flower thrips is the major vector of Tomato spotted wilt virus and Impatiens necrotic spot virus worldwide. Historically, growers have relied on insecticides in attempts to manage western flower thrips. Despite the limited success with insecticides as a stand-alone tactic, only recently has the sole reliance on insecticides for western flower thrips management been challenged. Scientists with the USDA-ARS, Center for Medical, Agricultural and Veterinary Entomology, Gainesville, Florida, and the University of Florida have developed successful management programs for western flower thrips and thrips-vectored viruses,and these programs are reviewed in this chapter. These strategies involve: an emphasis on scouting and the identification of thrips species present in a crop; the optimal nitrogen fertilization to reduce the attractiveness of crops without adversely affecting yields; the use of ultraviolet reflective mulches to deter thrips entrance into crop fields; the use of systemic "antibiotics" to suppress development of tomato spotted wilt symptoms in fruit of susceptible varieties; and the use of economic thresholds to determine the need and timing of insecticide applications; and the use of select insecticides to help suppress reproduction of thrips in the field, and thus manage secondary spread of tomato spotted wilt from within fields. This low input approach helps to avoid other pest problems as well.

Technical Abstract: Today, the western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) is one of the most significant agricultural pests globally because of the damage it is able to inflict on a wide range of crops. Adults and larvae feed by piercing plant tissues with their needle-shaped mandible and draining the contents of punctured cells. Feeding by adults and larvae produces scarring on foliage, flowers and fruits, which results in aesthetic crop damage and disrupts plant growth and physiology. Also, oviposition can produce a wound response in fruiting structures, which reduces the marketability of certain horticultural produce. Most importantly, western flower thrips is able to transmit several species of destructive plant viruses in the genus Tospovirus (Bunyaviridae). It is the most important vector of Tomato spotted wilt virus and Impatiens necrotic spot virus worldwide, and it is also known to vector Chrysanthemum stem necrosis virus, Groundnut ringspot virus and Tomato chlorotic spot virus. Historically, growers have relied on insecticides in attempts to manage western flower thrips. Despite the limited success with insecticides as a stand-alone tactic, only recently has the sole reliance on insecticides for western flower thrips management been challenged. Scientists with the Agricultural Research Service and the University of Florida have developed successful management programs for western flower thrips and thrips-vectored viruses in solanaceous crops, and these programs are reviewed in this chapter. These programs are on an understanding of thrips ecology and how different species interact with different crops. These strategies involve: an emphasis on scouting and the identification of thrips species present in a crop; the optimal nitrogen fertilization inputs to reduce the attractiveness of crops to western flower thrips without adversely affecting yields; the use of ultraviolet reflective mulches to deter thrips entrance into crop fields; the use of acibenzolar-S-methyl to suppress development of tomato spotted wilt symptoms in fruit of susceptible varieties; and the use of economic thresholds to determine the need and timing of insecticide applications; and the use of select insecticides to help suppress reproduction of thrips in the field, and thus manage secondary spread of tomato spotted wilt from within fields. The understanding of the importance of biotic resistance against western flower thrips provided by competing species of native thrips and natural enemies, such as O. insidiosus, has been of fundamental importance to improving western flower thrips management. This low input approach helps to avoid other pest problems as well. For example, the conservation biological control program for western flower thrips and Tomato spotted wilt virus in peppers has been used by growers in north Florida since the late 1990's, and growers have experienced far fewer problems from whiteflies, aphids, and other pests than when they were following a prophylactic, calendar-based spray program that included frequent use of broad-spectrum insecticides to control pests. Even with these successes, the management of western flower thrips will continue to be an ongoing challenge. Management programs cannot be static as they will need to be continually refined and updated with the advent of new invasive pests or as other conditions change. For example, Scirtothrips dorsalis Hood invaded Florida within the past five years and poses a threat to crops including pepper and eggplant. Recently, a new form of Tospovirus, a genetic reassortant of Groundnut ringspot virus and Tomato chlorotic spot virus has been found in Florida. Although western flower thrips can transmit this virus, it is not yet known if it or another thrips species is the most important vector. Despite these challenges, we believe that western flower thrips can be successfully managed, given a thorough understanding of its ecology and pest status.

Last Modified: 10/21/2014
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