pheromone traps

7/28/2019 Pheromone Traps

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Integrated Pest Management

www.nysipm.cornell.edu/factsheets/vegetables/swcorn/pheromone_traps.pdf

1995

102GFS795.00VEGETABLES

Pheromone TrapsEffectiveTools for MonitoringLepidopterous Insect Pestsof Sweet CornJanet J. Knodel and Curtis H. Petzoldt,IPM Support Group, NYS Agricultural Experiment Station at

Geneva, and Michael P. Hoffmann, Department o

Entomolgy, Cornell University

IntroductionTraps baited with sex pheromones, the chemicals usuallyemitted by emale insects to attract males o the same speciesor mating, have become a valuable tool or monitoring pest

populations in survey and integrated pest management (IPM)programs. Many insect sex pheromones can now be chemicallysynthesized or use in pest monitoring and control.

Pheromone traps can be used to: 1) detect early pestinestations, such as the rst occurrence o migratory pests,2) dene areas o pest inestations, 3) track the buildup oa pest population, and 4) help in decision making or pestmanagement. In some instances traps have been successulin estimating pest population densities and the potential risko crop damage. Since pheromone traps are relatively easyto use and inexpensive, species specic, and environmentallybenign, they make ideal tools or IPM programs. An eective

pheromone trapping system, however, requires careulpreparation, handling, and selection o pheromone traps andlures, as well as proper trap placement.

Pheromone Traps in Sweet Corn IPMPheromone traps have demonstrated value in monitoring popu-lations o Lepidopterous (moth) insect pests in sweet corn,

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Fig. 1. Adult male European corn borer. Fig. 2. Adult male corn earworm. Fig. 3. Adult male all armyworm.

Fig. 4. Proper placement o

ScentryTMHeliothis net trap or

monitoring European corn borer and

corn earworm.

Fig. 5. Bucket-style universal moth

trap (unitrap) or monitoring all

armyworm.

Fig. 6. Using the lure package to avoid cross-

contamination.


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particularly to indicate when a pest is present and what is theproper window or eld scouting. With degree-day modelsor orecasting insect development, an increasing pheromonetrap catch can be used to predict when the various pest liestages will occur in a eld or area. By timing controls with themost susceptible lie stages o the pest and crop growth, theecacy o spray applications can be optimized. Other benetso pheromone trapping include identication o pest problemhot spots and timely inormation about pest fight patterns

Insect Pests and Their Trapping ProtocolsIn the northeastern United States, the primary Lepidopterousinsect pests o sweet corn are the endemic European cornborer (ECB), Ostrinia nubilalis (Hubner) and two migratorypests-corn earworm (CEW),Helicoverpa zea (Boddie), and allarmyworm (FAW), Spodoptera frugiperda (Smith).

The male ECB moth (g. 1) is identied by reddish-brown toyellow coloring and the two dark serrated lines that run acrossthe outer third o the orewings. When resting, the wings o ECBorm a characteristic triangular shape. The male CEW moth(g. 2) varies rom a yellowish tan to brown, and each orewinghas two dark spots. The main identication eature o CEW isthe bu hindwing with a wide dark band at the outer margin.

The male FAW moth (g. 3), is distinguished by two whitish

markings on the brown orewings: a small white marking at thewings apex (tip), and a larger diagonal white line that runs romthe outer margin to the center o the wing. A yellowish orbicularspot is also located on this line The wingspan o ECB is about1.25 inches (3.18 ern), whereas the wingspans o CEW andFAW are about 1.5 inches (3.81 cm). Identication may bedicult i the moths are damaged in the traps.

The migratory CEW and FAW usually arrive late June to lateJuly, depending on location, and can inest mid-late plantedsweet corn. ECB occurs throughout the growing season.

There are three races o ECB in the Northeast: a univoltine Z-race, a bivoltine Z-race, and a bivoltine E-race. The univoltinerace has one generation per season (one fight in July) while thebivoltine races have two or more generations per season (one

fight each in June and August). Although not all races o ECBare present in all sweet corn growing regions, traps or both

Z-and E-races are recommended at each eld site. The Z-raceo ECB is also known as the Iowa strain and the E-race as theNew York strain.

Throughout the eld season, pheromone traps should beset out near sweet corn as each eld reaches the phenologicalstaqe o devetopment preerred by the pest(s). Pheromone-traps should continually be relocated to new elds as they enterthis critical growth stage. For example, the CEW trap shouldbe installed when green silks begin to appear, then moved toanother eld when silks become brown. The Scentry Heliothisnet trap (g. 4), or a comparable trap design, is used or ECBand CEW, and the bucket-style universal moth trap (or unitrap)(g. 5) or FAW. Generally, the ScentryTM Heliothis net trap

is attached to a stake 6 t. (2 m) above the ground, and theuniversal moth trap (unitrap) is suspended rom a stake 4 t.(1.3 m) above the ground. At the beginning o the trappingperiod, a killing (vapona) strip should be placed in the bucket othe unitrap to kill captured FAW moths. For FAW, three dierentlures (2-,3-, and 4-component) are available. The 2-componentlure is generally more selective and used when trap contamina-tion rom nontarget armyworm moths (i.e., wheathead or com-mon armyworm) is a problem. The specic trap and lure proto-cols and critical crop growth stage(s) or pest monitoring aresummarized in Table 1.

Trap PlacementSince ECB eed, rest, and mate in grassy vegetation called

action sites, the pheromone traps are placed on grassyedges o sweet corn elds out o the path o equipment (g.4). They are usually installed beore the mid-May emergenceo rst-generation ECBs. For the migratory CEW and FAW,pheromone traps are installed well beore their expected arrivalin the edges o the eld, as with ECB, or 16-24 rows in romthe elds edge. The expected arrival date or these pests inNew York, or example, is late June or late July. The bottom onet traps in the eld should be at least 3 t. (1 m) high and thebottom o universal moth traps (unitraps) should be above thecorn canopy. Traps in the eld should be marked with a fag tomake it easier to locate them.

All traps should be spaced at least 60-120 t. (20-40 m)apart to avoid possible pheromone intererence, and placed

on the windward side o a eld so that the pheromone will beblown into the eld. Wooded edges are not good trap sitesbecause the pheromone will not dissipate over the eld. Trapopenings should be ree o any vegetation that might impedemoth entry.

Pest Trap design Lure Lure feld lie(Long-termstorage lie)

Growth stage o corn

European corn borer ScentryTM

Heliothis net TreceTM

E-race (ECB II)Z-race (ECB I)

2 weeks(3 years) Mid-whorl to silk

Corn earworm Scentry TM Heliothis net HerconTM 2 weeks(1 years)

Green silks present

Fall armyworm IPSTM Universal moth trap orunitrap (all green trap)

ScentryTM

(4-component) or(2-component),

TreceTM

(3-component)

3 weeks(2 years)

Late whorl to green silk

Table 1. Trap and lure protocols or monitoring insect pests o sweet corn.


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0

20

40

60

80

100

120

140

Date

ECB-EECB-Z

Bivoltine

Univoltine

Starting point

for accumulating

Degree Days

uncontaminated set o orceps is needed or each dierentpheromone. Do not leave contaminated gloves, lure wrappers,or other pheromone-contaminated material near trap sitesbecause this could attract the target insect away rom yourtrap! Forceps should be cleaned with acetone or nail polishremover between uses. Forceps can be stored in labeledglass jars lled with acetone. Avoid contaminating traps by nothandling them with gloves used to handle pheromone lures.

Checking Traps and Recording Trap Data

Traps should be serviced requently to prevent overloading andmake identication o trapped specimens easier. It is suggestedthat traps be checked at least weekly, preerably twice a week.

When moth numbers begin to increase, checking at least twoto three times a week is desirable. Once CEW captures start,or example, inestations can occur very quickly. Eggs o CEWmay hatch in as little as 48 hours when temperatures are high.Inormation to record during each visit is shown in the sampledata sheet or pheromone trapping. Trap catches can also begraphed over time to easily show seasonal trends (g. 7).

Storing and Changing LuresSince most pheromones degrade rapidly i exposed to brightlight or high temperatures, lures should be stored in tightlysealed glass containers or oil pouches and preerably kept ina reezer or rerigerator to ensure their longevity. To avoid crosscontamination, do not place dierent moth lures in the samecontainer.

Because volatility and degradation rates vary amongpheromone components or various insect species, and releasecharacteristics are dierent or the various dispensers, no

generalization can be made about the eld l ie o lures. Expectedeld lie and recommended intervals o lure replacement andlong-term storage lie or each individual species are providedby pheromone manuacturers (table 1). Rubber septumdispensers should be placed in the lure holders with the wideend pointing out (g. 6).

Since the pheromones are impregnated onto a luredispenser, it is very important that each species lure ishandled with vinyl/latex gloves or orceps (g. 6) to avoidcross contaminationa pheromone lure or one insect maybe a strong repellent or another. A new pair o gloves or

Figure 7. Flights o the E-race and Z-race o European corn borer (ECB) and how to use trap catch data to predict ECB development.

Sample Data Sheet or Pheromone Trapping


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ECB Forecasting Using Growing Degree DaysWeather monitoring equipment is necessary or recordingthe temperature (daily maximum and minimum) at trap sitesor orecasting ECB development. Weather records may alsobe obtained rom your local weather stations, or the New

York State Integrated Pest Management Programs Networkor Environment & Weather Awareness (http://www.nysipm.cornell.edu/newa/deault.asp). Heat units or degree days arethe number o degrees above a given threshold temperaturethat occur each day. A simple ormula or calculating degree

days or one day is:

The threshold temperature or ECB is 50F (10C) Accumulateddegree days are daily degree days summed over time.

Despite the geographic variation in ECB populations anddierent weather conditions, pheromone trap catch data havebeen ound to be a reliable means o predicting ECB lie stages,in the spring, degree days are accumulated starting with therst signicant moth fight (increasing trap catches) (g. 7). Therequired degree day accumulations needed to reach variouslie stages are given in Table 2.

Produced by the New York State Integrated Pest Management Program, which isunded through Cornell University, Cornell Cooperative Extension, the NYS Departmento Agriculture and Markets, the NYS Department o Environmental Conservation, andUSDA-CSREES. Design by Media Services, Cornell University. Layout by Karen English,New York State IPM Program. Cornell Cooperative Extension provides equal programand employment opportunities. 1995 Cornell University and the New York State IPMProgram. Posted 6/07 at www.nysipm.cornell.edu/actsheets/vegetables/swcorn/pheromone_traps.pd

Forecasts or ECB lie stages are made during increasingfight periods o both the bivoltine E-and Z-races, and theunivoltine Z-race. Initial orecasts are based on historical tem-perature data, but these are upgraded weekly using currenttemperature data to rene the predictions as the seasonprogresses. Forecasts made rom the rst fight o the bivoltineraces include all o the lie stages (egg laying, larval instars,pupation) and the second adult fight. When the second fight othe bivoltine races begins to increase, the degree day accumu-lations can be initiated again predicting egg laying, larval instars,

and so orth. The orecast or the univoltine Z-race is madeor only oviposition and larval instars 1-4 since the 5th instarlarvae o this race enters an overwintering condition known asdiapause.

Sources of Pheromone Trapping SuppliesContact your local county Cooperative Extension agent or IPMspecialist or inormation on where to purchase pheromonetrapping supplies.

Degree days rom event (F) Lie stage

0 Increasing moth fight (peak)

100 Peak egg hatch

200+ 1st - 2nd instar larvae

350+ 3rd instar larvae

400+ 4th instar larvae

550+ 5th instar larvae

900+ Pupation1150 - 1700 Adult moths

* rom: European Corn Borer Development and Management,USDA NC Reg. Ext. Pub. No. 327, May 1989. Threshold =50F (10C)

Table 2. Degree day accumulations or predicting ECB activities in the feld.*

Degree days =(Max. temperature + min. temperature) - threshold temperature

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