Chemical Control of the Erythrina (Wiliwili) Gall Wasp (EGW), Quadrastichus erythrinae:

Trials and Tribulations

Arnold H. Hara1, Christopher M. Jacobsen1,

and Dick M. Tsuda2

University of Hawaii at ManoaCollege of Tropical Agriculture and Human Resources

1Beaumont Agricultural Research Center, 875 Komohana St, Hilo, HI 967202Department of Plant and Environmental Protection Sciences, 3050 Maile Way, Honolulu, HI 96822

E-mail=arnold@hawaii.edu

Erythrina = Wiliwili Gall Wasp

• First described in 2004 causing severe damage

in Taiwan and Singapore.• First found on Oahu in

April 2005.• Found in Big Island,

Kona, Kauai, and Maui in July 2005.

Spread was like a wild fireD. Ogata

EGW Life Cycle – Egg to adult in 21 days

1 mm1.5 mm

7 days after egg laying

Adult emergence after21 days

12 day old larva

6 days after oviposition larva is observed

14 day old larvae20 days after egg laying

Yalemar, Nagamine, Heu HDOA

Adult male female

Eggs hatch in < 3 days

Initiates galling

Life cycleegg to adult – 21 days

Ovipositional preference female lays eggs in young terminal growth

Sex ratio7♂ : 1♀, more males emerge first

Adult longevitywithout honey: ♂ and ♀ = about 2-3 dayswith honey (nectar) : ♂ =10 days, ♀=6 days

Fecundityfemale wasp emerges with about 85 mature eggs

Yalemar, Nagamine, Heu and Ramadan HDOA

Summary of the Life Cycle of EGW

HOSTSHealthy Gall Wasp Injury

tiger's claw,Indian coral tree

tall erythrina,tall wiliwili

Erythrinacrista-gallicommon coraltree

Healthy Gall Wasp Injury

Native wiliwili

Erythrina sandwicensis

Most Threaten Speciesin Hawaii

Major Control Strategies

Short Term:Chemical ControlUH-CTAHR

Long Term:Biological ControlHDOA, UH-CTAHR

CHEMICAL CONTROL

Mode of Action Tradename Common name Systemic Drench Merit imidacloprid

Safari dinotefuran Orthene acephate

InjectionMaujet Imicide imidacloprid

Abacide abamectinWedgle Pointer imidacloprid

Sidewinder Imicide imidacloprid

First Study Site in Pearl City, HI Tall wiliwili 5-12” diam 20-30” tall

Injection and Drench Treatment: Aug 03, 2005

Treatments 

Treatment Rate

Imicide 10% injection(imidacloprid)

4 ml per capsule; no. of capsules= in diam/2

Merit 2 F drench(imidaclorpid)

0.2 fl oz per 1 in trunk diam

Delivered in 10 gal drench

Safari 20 SG drench(dinotefuran)

4oz/tree in 10-gal drench

Abacide 1% injection(abamectin)

2 ml per capsule; no. of capsules= in diam/2

InjectingDrilling

DrenchingTrenching

Applying Treaments

Determing Effectiveness

Sampling Selecting galls without emergence

Gall sample weight

Holding galled tissue for complete emergence

Abamectin injection

Imidacloprid injection

Merit drench

Untreated (water drench)

Wasps Emerging from Samples Taken 4 Weeks after Treatment

Wasp numbers were quantified after emergence from samples ceased.

Emerged Wasps per Gram of Gall Tissue

Treatments1 2 2.5 3 4

Untreated 55.4a

64.4a

48.2a

21.9a

17.3a

Imicide (injection)

1.9b

12.7b

15.8a

2.6b

1.1b

Abacide (injection)

52.1a

45.8a

21.7a

18.1ab

18.1a

Merit (drench)

65.1a

52.5a

45.8a

21.8a

9.4a

Safari (drench)

48.7a

52.1a

35.4a

21.7ab

24.3a

Months after Treatment

Means in a column followed by different letters are significantly different.

About 1 Month after Treatment

Imidacloprid injectionAbamectin injection

Untreated (water drench)

Safari drench

Imidacloprid injection,only effective treatment,

drenches failed.

UntreatedUntreated

Approx 2 Months after Treatment

Success with Imidacloprid Drench Application

4 Months after Treatment (West Hawaii)

KukioCalvin PetersonJan 2006

*Trees were irrigated regularly and imidacloprid was applied at point of irrigation.*Merit 2F was applied in conjunction with a liquid fertilizer to optimize uptake and increase plant vigor.

*Merit took >3 weeks to become effective.*Merit drench is still effective 4 months after treatment with no emergence from the few new galls that were found.

Factors Conributing to Successful Merit Drench

4 Months after Merit vs. Safari Drench

Merit Drench

Safari Drench

*Safari (dinotefuran) was applied to regularly irrigated trees at point of irrigation.*Safari was applied together with a liquid fertilizer.*Within 2.5 weeks efficacy was found. From two large samples of galled leaves only 1 male emerged from galls.*Severe damage reoccurred in <4 months.*Safari is much more water soluble than Merit.

Safari DrenchQuick Efficacy-Shorter Residual

as compared with Merit

Experiences with Trunk Injection Systems

Arbor Systems Wedgle Direct-Inject

Mauget Tree Injectors

Sidewinder Precision Injectors

Arborjet System – not yet evaluated

Sidewinder Tree InjectorImicide or other formulations

5ml/ injection site

Pointer (5% Imidacloprid)1ml/ injection site

Mauget Tree InjectorsImicide (10% Imidacloprid)

2-4ml/ capsule

Injection Systems Evaluated

*Each injection system have its advantages and disadvantages.

*Advantage is the needle is much less intrusive than drilling holes.*Disadvantage is that the unit uses a lower %A.I. and smaller volume than other injection systems.

*Injection of common coral trees, E. crista-galli, using Wedgle Direct-Inject by landscapers in West Hawaii appeared effective.

*Experience with the Wedgle has been largely disappointing on Indian coral trees. *E. crista-galli is the only species that has responded to treatment.

E. crista-galli

5.9 wasps/ g gall

E. variegata

22.4 wasps/ g gall

Wedgle Treated Trees 3 Months after Treatment

Bark Thickness and Growth Condition among Wiliwili Species and Affect Effectiveness

E. crista-galli E. variegata

E. sandwicensis

*Trees under water stress and/or no functional leaves will not translocate injected insecticide with “bleeding”.*Bark thickness affects critical depth of injection into the active cambium area of uptake.

Mauget Tree Injectors

*Advantage is the passive system and opaque capsule that allows visual inspection of uptake.*Disadvantages are drilling wound, clogging and the need to return later to retrieve plastic container.

Mauget Tree Injectors*Some positive results.*With native williwilli in natural, dry conditions uptake was extremely slow due probably due to low translocation activity due to drought conditions.*Clogging of injector with drill sawdust is a problem with native wiliwili in the dryland forest of Puuwaawaa.

Native Wiliwili in Irrigated LandscapeSuccessful Mauget treatment by injecting each major limb.

HualalaiRobin Lorenzo

Sidewinder Precision Injector

*Advantages are larger dose 5 ml/hole, up to 2 quart reservoir in backpack to treat many trees, and possible to inject generic formulations.*Disadvantages are wounding by drilling and difficult to insure 5ml is being delivered.

*Additional trials with Merit/Safari drenches and Sidewinder, Maujet and Wedgle injections are in progress in the landscape and dryland forests in West Hawaii.*Chemical analyses of galled and un-galled leaves from treated trees are in progress by UH-CTAHR chemists.*Exploratory searches for natural enemies of the wiliwili gall wasp have been conducted by Hawaii Dept. of Agriculture and UH-CTAHR in Africa and offers the long term control strategy.

What’s Next?

Tanzania & South AfricaHDOA Exploratory Entomologist, Dr. Mohsen Ramadan has discovered and imported promising parasitic wasps the HDOAquarantine lab.

South Africa & KenyaUH - CTAHR Cooperators w/ HDOA Drs. Messing, Wright, Rubinoff recently returned from Africa.

Heu, Nagamine, YalemarHDOA

Search for Natural Enemies of the Gall Wasp in Africa

Derek ArakakiBecky AzamaPete BalleriniMike DonohoRobert Hauff

Hawaii Land Care Guy Hera

Ronald Heu Clyde Hirayama

Anne-Marie LaRosa Robin Lorenzo

Mike Matsukawa Ty McDonald

George NakashimaRuth Niino-Duponte

Ken OgawaKyle Onuma

Calvin PetersonJuliana Yalemar

A BIGA BIG THANK YOU!THANK YOU!

A BIGA BIG THANK YOU!THANK YOU!