Evaluating an Action Threshold-Based Insecticide Program on Onion Cultivars Varying in Resistance to Onion Thrips (Thysanoptera: Thripidae)

Abstract

Onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), is a highly destructive pest of onion, Allium cepa L., and its management relies on multiple applications of foliar insecticides. Development of insecticide resistance is common in T. tabaci populations, and new strategies are needed to relax existing levels of insecticide use, but still provide protection against T. tabaci without compromising marketable onion yield. An action threshold-based insecticide program combined with or without a thrips-resistant onion cultivar was investigated as an improved approach for managing T. tabaci infestations in commercial onion fields. Regardless of cultivar type, the average number of insecticide applications needed to manage T. tabaci infestations in the action-threshold based program was 4.3, while the average number of sprays in the standard weekly program was 7.2 (a 40% reduction). The mean percent reduction in numbers of applications following the action threshold treatment in the thrips-resistant onion cultivar, 'Advantage', was 46.7% (range 40-50%) compared with the standard program, whereas the percentage reduction in applications in action threshold treatments in the thrips-susceptible onion cultivar, 'Santana', was 34.3% (range 13-50%) compared with the standard program, suggesting a benefit of the thrips-resistant cultivar. Marketable bulb yields for both 'Advantage' and 'Santana' in the action threshold-based program were nearly identical to those in the standard program, indicating that commercially acceptable bulb yields will be generated with fewer insecticide sprays following an action threshold-based program, saving money, time and benefiting the environment.

Soil conservation practices for insect pest management in highly disturbed agroecosystems – a review

“…Onion thrips populations also have been shown to develop resistance to insecticides in New York, USA (Shelton et al, 2003), Canada (MacIntyre Allen et al, 2005), and New Zealand (Martin et al, 2003). Although insecticides continue to be relied upon for onion thrips control, efforts to reduce insecticide use have been encouraged through the adoption of action thresholds and thrips-resistant cultivars (Nault & Huseth, 2016;Leach et al, 2017). In New York, onion growers have substantially increased their adoption of action thresholds and rotation of insecticide classes with the primary goal of mitigating insecticide resistance development in onion thrips populations (Leach et al, 2018b).…”

Grower adoption of insecticide resistance management practices increase with extension‐based program

“…Onion thrips has developed resistance to pyrethroids, organophosphates, and carbamates . Previous research has identified two pest management practices that should mitigate insecticide resistance and control onion thrips populations; using an action threshold and following an insecticide sequence that rotates insecticide classes . The use of thresholds is an important component to insecticide resistance management programs .…”

“…The use of thresholds is an important component to insecticide resistance management programs . In onion production in the Great Lakes region, an action threshold of one thrips per leaf has been effective in controlling thrips populations without reducing yield . Implementing an action threshold to control thrips in onion production can reduce the frequency of insecticide applications between 30% and 50%, thereby reducing exposure of insecticides to onion thrips populations .…”

“…In onion production in the Great Lakes region, an action threshold of one thrips per leaf has been effective in controlling thrips populations without reducing yield . Implementing an action threshold to control thrips in onion production can reduce the frequency of insecticide applications between 30% and 50%, thereby reducing exposure of insecticides to onion thrips populations . Recent research also has identified effective thrips management using season‐long rotation sequences of insecticides belonging to different classes .…”

Onion thrips colonization of onion fields bordering crop and non‐crop habitats in muck cropping systems

“…Thrips tabaci infestations in onion are typically managed using multiple applications of insecticides (Gill et al. ), and the recent development of action thresholds encourages fields to be sampled weekly to determine control decisions (Nault and Shelton ; Nault and Huseth ). Currently, a decision to control T. tabaci is based on sampling only a few onion fields on the entire farm.…”