Biology, Ecology and Management of Onion Thrips in Onion Updated March 2007 Brian A. Nault Department of Entomology Cornell University NYSAES Geneva, NY
Onion Production in New York Dry bulb onions, Allium cepa L. Value of crop $45 to 55 million 13,600 acres Gross value per acre is $3,700 Among fresh-market vegetable crops in NY, onion crop value ranks between 2 nd and 5 th
Major Onion Producing Regions in New York Orleans Co. Oswego Co. Wayne Co. Geneva Yates Co. Ithaca Orange Co.
Elba, NY (Orleans Co.)
Potter, NY (Yates Co.)
Prattsburg, NY (Steuben Co.)
Onion Thrips, Thrips tabaci Lindeman Adult Larva
Onion Thrips Damage Sodus, NY 2005 Protected with insecticides Not protected
Onion Thrips Damage Reduces Yield Untreated Treated 30 to 50% yield loss at harvest
Iris Yellow Spot Virus Transmitted by onion thrips First detection in NY occurred in June 2006 (onion cull pile in Elba) Onion fields sampled using DAS ELISA in 2006 (37 of 41 fields tested positive!) IYSV detected in the following hosts: onion, burdock, dandelion, goldenrod, pigweed, purslane, ragweed, and red raspberry C. Hoepting 2006
Onion Thrips Life Cycle Adult - All female populations - Mating is not necessary for reproduction! PARTHENOGENESIS - In NY, all female AND male + female populations in NY - Live for 13 to 47 d
Onion Thrips Life Cycle Adult Egg - 60 to 200 eggs/female - Deposited singly in leaves - Hatch in 4-10 days
Onion Thrips Life Cycle Adult Egg Hatch in 4-10 days Larva (2 instars) Lasts 7-14 days
Onion Thrips Life Cycle Adult Prepupa + Pupa Do NOT feed In soil for 5-7 days Egg Hatch in 4-10 days Larva (2 instars) Lasts 7-14 days
Onion Thrips Life Cycle * Adult *17-30 days total Prepupa + Pupa In soil for 5-7 days Egg Hatch in 4-10 days Larva (2 instars) Lasts 7-14 days
Onion Thrips Survival, Fecundity and Generation Times (Days) at Various Temperatures Days Factor 68 0 F 77 0 F 86 0 F Survival 47 25 13 Eggs laid/ female 210 165 63 Generation time 48 30 17 Murai (2000)
Onion Thrips Population Growth Date 68 0 F July 1 1 July 8 July 15 July 22 July 29 August 5 August 12 August 19 210 August 26 September 2 Number generations 1 Number of Females
Onion Thrips Population Growth Number of Females Date 68 0 F 77 0 F July 1 1 1 July 8 July 15 July 22 July 29 165 August 5 August 12 August 19 210 August 26 September 2 27,225 Number generations 1 2
Onion Thrips Population Growth Number of Females Date 68 0 F 77 0 F 86 0 F July 1 1 1 1 July 8 July 15 63 July 22 July 29 165 3,969 August 5 August 12 250,047 August 19 210 August 26 15,752,961 September 2 27,225 Number generations 1 2 4
Onion Thrips Ecology Adults overwinter on culls and in soil within onion and other crop fields onion cull pile volunteer onion
Onion Thrips Ecology Overwintering thrips emerge from soil in May and June Mean number of adults/emergence trap Potter, NY Onions planted 2005 Date E. Larentzaki Cornell Univ.
Onion Thrips Ecology Colonize onion in late June to July Four to six generations per season Mean number adults/trap 20000 16000 12000 8000 4000 0 Potter, NY 2005 5/22 6/5 6/19 7/3 7/17 7/31 8/14 8/28 9/11 Date E. Larentzaki Cornell Univ.
Onion Thrips Ecology Thrips migrate into onion fields in spring from soil, culls, weeds, other crops, imported transplants Thrips migrate into onion fields in summer from transplanted fields and early-maturing fields onion onion Imported plants alfalfa
Onion Thrips Resistance Detection Using Thrips Insecticide Bioassay System (TIBS) Expose thrips to insecticides in the lab to avoid issues such as (1) inadequate spray coverage (2) environmental conditions that could affect control insecticide 20 larvae water + sugar
Onion Thrips Resistance to λ-cyhalothrin (Warrior) in New York - 2001 1100 1000 900 LC 50 (ppm) 800 700 600 500 400 300 200 3.2 fl oz/a 100 0 Shelton et al. (2003) OR1 OR3 OR4 WA1 WA2 PO1 PO3 PO4 EL1 EL2 EL4 OS1 OS2 ST1 ST2 ST6 Population
Onion Thrips Resistance to λ-cyhalothrin (Warrior) in New York - 2002 % Mortality 100 90 80 70 60 50 40 30 20 10 0 Shelton et al. (2003) *3.2 fl oz/acre OR2 OR3 EL3 EL6 OS1 PO5 Population Mid Season Late Season Late Season PO6 PR1 WA3 WA4 Mid Season
Biological Attributes that make Onion Thrips a Pest of Onion Short developmental time Parthenogenic (do not need to find a mate) Mobile Wide host range Overwinter where onions are grown Capable of developing resistance to insecticides Transmit Iris Yellow Spot Virus
Plant Resistance Chemical Control Onion Thrips Management Cultural Control Biological Control
Objectives To determine efficacy of: 1) insecticide seed treatments 2) foliar-applied insecticides 3) action thresholds
Insecticide Seed Treatments Evaluated for Onion Thrips Control Trade Name Active Ingredient Class Regent fipronil Phenylpyrazole Entrust spinosad Spinosyn Poncho clothianidin Neonicotinoid Note: None of these products are labeled on onion.
Insecticide Seed Treatments Evaluated for Onion Thrips Control - Sodus, NY - Variety Millennium - Planted April 15, 2005
Onion Thrips Control Using Insecticide Seed Treatments Sodus, NY 2005 Mean number larvae/plant 6 5 4 3 2 1 0 Untreated Entrust Poncho Regent Planting Plants have 7-8 leaves on July 9th 4/15 4/29 5/13 5/27 6/10 6/24 7/8 Date ns a a ns ab b
Summary Seed Treatments Insecticide seed treatments had a minimal to no impact on onion thrips control in NY Bulb onion production - thrips often colonize > 2 months after planting - populations build quickly at time seed treatments have run out of gas Onion seed production - onion seeds planted in late summer/fall could be protected by seed treatments (e.g., fipronil)
Foliar-Applied Insecticides Evaluated in New York in 2006 Product Active Ingredient Rate (amnt/acre) Warrior lambda-cyhalothrin 3.8 fl oz Lannate LV methomyl 48 fl oz SpinTor 2SC spinosad 6 fl oz *Carzol SP formetanate hydrocloride 0.5, 0.75 and 1.0 lb Radiant SC spinetoram 7 fl oz Agri-Mek 0.15EC abamectin 10 fl oz Note: Products highlighted in yellow are labeled on onion in NY; *In 2006, Carzol was permitted for use in NY under a Crisis Exemption; Products in white are not labeled on onion.
Foliar-Applied Insecticides for Onion Thrips Control Potter, NY Variety Barrage Planted 3 April 2006 First spray July 18 3 applications total 90 GPA; 40 psi Visual estimates of thrips damage (0= high; 11=none) Rating= 2 Rating= 10
Foliar-Applied Insecticides for Onion Thrips Control 100 90 80 70 60 50 40 30 20 10 0 a a b Potter, NY August 5, 2006 c bc Mean number of larvae/plant Untreated Warrior Lannate SpinTor Agri-Mek Radiant Carzol (low) Carzol (medium) Carzol (high) Plots sprayed on 7/18, 7/24 and 7/31. Treatment d d d d
Foliar-Applied Insecticides for Onion Thrips Control 10 9 8 7 6 5 4 3 2 1 0 *Plots sprayed on 7/18, 7/24 and 7/31. Potter, NY August 7, 2006 ab acceptable e e d cd b-d a a Average Leaf Damage Rating Untreated Warrior Lannate SpinTor Agri-Mek Radiant Carzol (low) Carzol (medium) Carzol (high) Treatment a-c
Summary Foliar-Applied Insecticides Onions were best protected from onion thrips damage using Carzol and Radiant SpinTor, Agri-Mek and Lannate provided adequate to nearly adequate levels of protection Warrior failed to control thrips
What action threshold should be used to time sprays for thrips?
Action Thresholds Evaluated in 2006 Product Action Threshold Rate (amnt/acre) Warrior 1 larva/leaf 3.8 fl oz Warrior 3 larvae/leaf Warrior 5 larvae/leaf Lannate LV 1 larva/leaf 48 fl oz Lannate LV 3 larvae/leaf Lannate LV 5 larvae/leaf Carzol SP 1 larva/leaf 0.75 lb Carzol SP 3 larvae/leaf Carzol SP 5 larvae/leaf
Criteria for Identifying a Successful Action Threshold Season average thrips density is equal to or below the action threshold evaluated Visual damage rating near harvest should be an 8 or above
Action Thresholds in 2006 Potter, NY Variety Barrage Planted 3 April 2006 Thrips density in plots determined visually by counting all larvae per plant Action thresholds of 1, 3 and 5 larvae/leaf met on 7/18, 7/24 and 7/31, respectively
Onion Thrips Control Using Warrior @ and an Action Threshold of 1 larva/leaf Mean number larvae/plant 30 25 Untreated 20 1 larva/leaf 15 10 5 0 harvest action threshold 7/18 7/25 8/1 8/8 8/15 Date
Onion Thrips Control Using Warrior @ and an Action Threshold of 3 larvae/leaf Mean number larvae/plant 30 25 Untreated 20 3 larvae/leaf 15 10 5 0 harvest action threshold 7/18 7/25 8/1 8/8 8/15 Date
Onion Thrips Control Using Warrior @ and an Action Threshold of 5 larvae/leaf Mean number larvae/plant 30 25 Untreated 20 5 larvae/leaf 15 10 5 0 harvest action threshold 7/18 7/25 8/1 8/8 8/15 Date
Onion Thrips Control Using Lannate LV @ and an Action Threshold of 1 larva/leaf Mean number larvae/plant 25 20 Untreated 15 1 larva/leaf 10 5 0 harvest action threshold 7/18 7/25 8/1 8/8 8/15 Date
Onion Thrips Control Using Lannate LV @ and an Action Threshold of 3 larvae/leaf Mean number larvae/plant 30 25 Untreated 20 3 larvae/leaf 15 10 5 0 action threshold harvest 7/18 7/25 8/1 8/8 8/15 Date
Onion Thrips Control Using Lannate LV @ and an Action Threshold of 5 larvae/leaf Mean number larvae/plant 30 25 Untreated 20 5 larvae/leaf 15 10 5 0 harvest action threshold 7/18 7/25 8/1 8/8 8/15 Date
Onion Thrips Control Using Carzol SP @ and an Action Threshold of 1 larva/leaf Mean number larvae/plant 25 20 Untreated 15 1 larva/leaf 10 5 0 harvest action threshold 7/18 7/25 8/1 8/8 8/15 Date
Onion Thrips Control Using Carzol SP @ and an Action Threshold of 3 larvae/leaf Mean number larvae/plant 30 25 20 15 10 5 0 Untreated 3 larvae/leaf 7/18 7/25 8/1 8/8 8/15 Date action threshold harvest
Onion Thrips Control Using Carzol SP @ and an Action Threshold of 5 larvae/leaf Mean number larvae/plant 30 25 Untreated 20 5 larvae/leaf 15 10 5 0 harvest action threshold 7/18 7/25 8/1 8/8 8/15 Date
Action Thresholds in 2006 Action No. of Season Avg. No. Mean Damage Product Threshold Sprays Larvae/Leaf Rating on 7 Aug Untreated - 0 8.1 ab 2.8 e Warrior 1 larva/leaf 4 6.6 ab 3.0 e Warrior 3 larvae/leaf 3 6.1 b 3.8 de Warrior 5 larvae/leaf 2 9.5 a 2.5 e Lannate LV 1 larva/leaf 3 1.5 e 6.3 c Lannate LV 3 larvae/leaf 2 4.1c 5.3 cd Lannate LV 5 larvae/leaf 1 2.8 cd 3.5 de Carzol SP 1 larva/leaf 2 0.6 f 10.0 a Carzol SP 3 larvae/leaf 1 1.4 e 8.3 b Carzol SP 5 larvae/leaf 1 2.0 de 6.3 c
Summary Action Thresholds Action threshold is highly dependent on efficacy of product Warrior failed, regardless of the action threshold Lannate sprayed at 1 and 3 thrips/leaf reduced infestation, but not to an acceptable level Carzol sprayed at 1 and 3 thrips/leaf provided excellent control; *only 1 spray required at the 3 thrips/leaf threshold Spraying at 5 thrips/leaf allowed too much damage
Reasons why insecticides may work better for controlling onion thrips in eastern US compared with western US Shorter duration of onion thrips pressure Thrips do not attack onions until late June/early July, which occurs > 1 to 1.5 months later than out west Lower thrips pressure Often more rain and cooler temperatures, which may suppress populations Better insecticide coverage Sprays using ground rigs provide better coverage than sprays made by airplane
Guidelines for Managing Onion Thrips in Onion (1 of 3) Scout fields before making a control decision largest plants will be infested first (e.g., transplanted fields, early-maturing varieties) field edges are often first colonized (consider nearby crops) spray hot spots rather than entire field Use most appropriate action threshold 0.5 to 1 thrips per leaf for Lannate, SpinTor and pyrethroids 3 thrips per leaf for Carzol
Guidelines for Managing Onion Thrips in Onion (2 of 3) Rotate insecticides (insecticide classes if possible) Two successive applications of one product (targets a single generation) Avoid tank mixing insecticides when possible Don t use your best product too early
Guidelines for Managing Onion Thrips in Onion (3 of 3) Maximize insecticide deposition on leaves use high volume of water use relatively low pressure use flat fan, twin cap or twin jet nozzles rather than hollow cone Make sure sprayer is calibrated properly