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NAVEL ORANGEWORM

 

Amyelois transitella (Walker) -- Lepidoptera, Phycitidae

&

CAROB MOTH

 

Ectomyelois ceratoniae (Zeller) -- Lepidoptera, Pyralidae

 

(Contacts)

 

 

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       One external larval parasitoid, Goniozus emigratus (Rohwer) and one internal egg-larval parasitoid, Copidosomopsis plethorica Caltagirone, which are dominant on navel orangeworm, Amyelois transitella, in south Texas, Mexico, and one imported external larval parasitoid, Goniozus legneri Gordh from Uruguay and Argentina, were successfully established in irrigated and nonirrigated almond orchards in California's Central Valley in 1979-86 (Caltagirone 1966, 1964; Legner & Silveira-Guido 1983).

 

 

       Goniozus legneri was also established on carob  moth, Ectomyelois ceratoniae, infesting plants with seed pods along the southern California coast.  Separate k-value analyses indicated significant regulation of their navel orangeworm host during the warm summer season.  Variable percentages of field-collected larvae of the navel orangeworm and the imported parasitoids have required significantly longer developmental periods to the adult stage than those in laboratory control cultures.  These differences indicate diapause in the host triggered by several seasonally varying factors, and a diapause in the parasitoids triggered by hormonal changes in the host.  Possible latitudinal effects on diapause are also observed.  The ability of the imported parasitoids to diapause with their host enables their permanent establishment and ability to reduce host population densities to economic levels (Legner 1983b).

 

       The relationship between residual almond mummies on densities of the navel orangeworm and parasitism has been demonstrated (Legner 1983a).  The two imported Goniozus parasitoids have also been shown capable of regulating navel orangeworm at low densities (Legner & Silveira-Guido 1983, Legner & Gordh 1992).  Superimposed upon the whole system is a diapausing mechanism in both the navel orangeworm and the parasitoids (Legner 1983b).  Efforts are now required that would tie together all these forces into a sound, reliable integrated management, which would allow growers to make reasonable decisions on whether or not to remove mummied almonds, or to use within season sprays.  Nevertheless, although growers have the capacity to recognize the value of predators in animal populations such as the deer/wolves interactions as demonstrated in Yellowstone National Park, they seem incapable of fathoming similar interactions among insect populations.  This is probably due to the considerably smaller size of the animals in the latter case.

 

       Populations of navel orangeworm have been followed since 1979 in six almond orchards near Paso Robles, Hilmar, Chowchilla, Selma, Westley and Atwater, to determine the impact of the parasitoids.  A clear drop in the average density of navel orangeworm in all orchards is coincident with the establishment of the three parasitoids (Legner & Gordh 1992).  However, the almond reject levels are not always below the economic threshold of 5% in all orchards.  Careful investigations show that invariably such rejects are due to other causes, such as ant activity and fungus infections.  In certain years, the peach twig borer has been found to be the principal cause, which subsequently stimulates oviposition by navel orangeworm moths.  Packing plant appraisals frequently attribute damage incited by twig borer to the navel orangeworm.

 

       In the Atwater almond orchard, the grower has sustained a reject level of 2 ½ percent or less for many years.  Commercial insectaries have begun to harvest Goniozus legneri in this orchard for introductions elsewhere.  However, in 2005 the orchard became under threat of removal by eminent domain from human population expansion in the area.

 

       Copidosomopsis plethoricus and Goniozus legneri, <PHOTO>and to a lesser extent Goniozus emigratus overwinter in release orchards year after year.  However, only Copidosomopsis can consistently be recovered at all times of the year.  The Goniozus species are not recovered in significant numbers until early summer.  However, adults of the latter are frequently observed in large numbers during autumn and early spring months. 

 

       Goniozus legneri has been reared from codling moth and oriental fruit moth in peaches in the Paso Robles area in addition to navel orangeworm from almonds.  Field data suggest that a certain number of old mummied nuts is necessary to maintain a desirable synchrony of these parasitoids with navel orangeworm to produce the lowest average densities (below 4% damage at harvest).  In fact, at Paso Robles mummies often exceed 1,000 per tree through the winter months, and produce navel orangeworm densities at harvest at below 1% on soft-shelled varieties.

 

       Pest management in almond orchards frequently involves periodic releases of Goniozus legneri and/or Copidosomopsis plethoricus to reestablish balances that were disrupted by insecticidal drift or by the absence of overwintering mummied fruit refuges.

 

       Goniozus legneri --The discovery of Goniozus legneri <PHOTO> in South America involved making initial contact with Dr. José Pastrana of the University of Buenos Aires.  Arrangements were made for Dr. Legner to meet with Dr. Pastrana in Punta del Este, Uruguay in 1977.  The navel orangeworm was not a common insect at higher latitudes in South America, and Dr. Pastrana only recalled having studied it in his collections from central Argentina.  He advised Dr. Legner to travel to Concordia, Argentina to inquire there.

 

       In Concordia, Dr. Aquiles Silveira-Guido accompanied Dr. Legner, where both of them searched through collections in a Christian monastery serving also as an experiment station there.  A dusty room, filled to the ceiling with wooden insect collection boxes, was searched intensively.   Several specimens of the navel orangeworm were found from collections made in 1938, and from the host coral tree, Erythrinia crista-galli.  This knowledge enabled a further search in the wild on this host tree. (also see efl-210, efl-258).

 

       Subsequently, collections were continued in Argentina and Uruguay with the aid of Dr. Silveira-Guido.  Goniozus legneri turned out to be the most frequently collected parasitoid from navel orangeworm and the imported carob moth, Ectomyelois ceratoniae, with other parasitoid species of only ca. 5% occurrence being  Temelucha sp, Coccygonimus sp. and Venturia canescens (Graven-Stein), Bracon sp. & Copidosoma sp.  Cultures sent to Riverside, California were attempted, but Goniozus legneri remains the most succssful importation. Cultures of Goniozus legneri were also sent to Dr. Ahmed El-Heneidy in Egypt and Dr. Shmul Gothilf in Israel, and successful establishment on carob moth were recorded (Gothilf 1978 & 1987; Shoeb et al. 2005).  Later, G. legneri also became established on carob moth in Iran (Ehteshami 2010a, 2010b)

 

       Collections were also made from Texas where it was found that Pentalitomastix (Copidosoma) plethorica) parasitized navel orangeworm on Nonpareil almonds as far north as Brownwood (33 deg. N. lat.) and on Texas ebony and western soapberry seeds along the Gulf of Mexico coast and throughout south Texas.  At the latitude of Corpus Christi, another parasitoid, a biparental strain of Goniozus emigratus was found attacking this host at low densities in all seasons on western soapberry and Texas ebony.  Although identified as G. emigratus by Gordh & Hawkins (1981), its biparental behavior and fecundity differed significantly from the uniparental Hawaiian form to indicate its possible sibling status.

 

PEST MANAGEMENT

 

       The control of this pest with parasitic insects depends heavily on the perpetuation of parasitoids in orchards.  This can only be accomplished by a careful understanding of the dynamics involved.  Storing rejected almonds in protective shelters during winter months increases parasitoid abundance.  This will allow the parasitoids to reproduce in large numbers for subsequent spread thru out an orchard in the spring when outdoor temperatures rise.  An almond reject level of 4% is optimum for this system, although lower levels are often achieved.  Surrounding orchards of pistachios that harbor navel orangeworms but where parasitoid populations are not favored may disrupt the balances achieved in almond orchards.  Complete sanitation of an orchard (i.e., removal of rejected almonds) is counter productive to the successful biological suppression of the pest as this also eliminates natural enemies.  [For current status as of 2010 please refer to Legner 2010]. 

 

       Finally, those growers who are unaware of animal population interactions and are habituated to insecticidal controls may be responsive only to yearly natural enemy releases in their orchards.  Although continuous contact and discussion between grower and researcher may mitigate the problem, researchers must be aware that data from such orchards may be lost.

 

RESULTS & CONCLUSIONS

 

       Establishment of Goniozus legneri occurred quickly following liberations in California, Egypt and Israel in almond orchards.  The parasitoid then spread to neighboring countries, such as Iran.  Carob moth populations also descended to low levels.  In California an infestation of carob moth in California date groves was not controlled by G. legneri, however, as relative humidity levels there were  believed to be too low for parasitoid survival.

 

 

REFERENCES:

 

 Abbas, M.S.T., Shidi, R.H., Jumah, S. and Al-Khatry, S.A.  2008.  Utilization of Goniozus sp. (Hym.: Bethylidae) as a bio-control agent

 against the lesser date moth, Batreachedra amydaraula (Meyrick) (lep.: Batrachedridae) in date palm orchards in Sultanate of Oman.

 Egyptian Journal of Biological Pest Control 18:47-50.

 

Abbas, M.S.T., Al-Khatry, S.A., Shidi, R.H.; Al-Ajmi, and Najat, A.  2014.  Natural enemies of the lesser date moth, Batrachedra amydraula Meyrick (Lepidoptera: Batrachedridae) with special reference to its parasitoid Goniozus sp. Egyptian Journal of Biological

Pest Control 24: 293-296.

 

Bellows, T. S. & T. W. Fisher (eds.).  1999. Handbook of Biological Control:  Principles and Applications.  Academic Press, San Diego, New York. 1046 p.

 

 Butler, G.D, Jr., and Schmidt, K.M.  1985.  Goniozus legneri (Hymenoptera: Bethylidae): development, oviposition, and longevity in

 relation to temperature. _ Annals of the Entomological Society of America_ 78: 373–375.

 

Caltagirone, L. E.  1966.  A new Pentalitomastix from Mexico.  The Pan Pacific Entomol. 42:  145-151.

 

Caltagirone, L. E., K. P. Shea and G. L. Finney.  1964.  Parasites to aid control of navel orangeworm.  Calif. Agric. 19(1):  10-12.

 

Conference (Iran):.  2010.  First record of Goniozus legneri Gordh (Hymenoptera: Bethylidae), the larval ectoparasitoid of carob moth, in Iran.  Iranian Plant Protection Congress, July 2010, Tehran:  Vol. 19. July 2010.

 

 Ehteshami, F..,  M  Aleosfoor,  H. Allahyari, M. Alichi, M. A. Akrami  & M. Kiani.  2010a.  First record of Goniozus legneri Gordh

 (Hymenoptera: Bethylidae), the larval ectoparasitoid of carob moth, in Iran.  Proceedings of 19th Iranian Plant Protection Congress,

 31 July-3 August 2010, Iranian Research Institute of Plant Protection, Tehran, 123 pp.

 

 Ehteshami, F..,  M  Aleosfoor,  H. Allahyari, M. Alichi, M. A. Akrami  & M. Kiani.   2010b.  Primary investigation on the biology

 of Goniozus legneri Gordh (Hymenoptera:Bethylidae), a larval ectoparasitoid of carob moth, on Ectomyelois ceratoniae (Zeller).

 Proceedings of 19th Iranian Plant Protection Congress, 31 July-3 August 2010, Iranian; Research Institute of Plant Protection,

 Tehran, 605 pp

 

 El-Basha, N.A. and Mandour, N.S.  2006.  Effect of Goniozus legneri Gordh (Hymenoptera: Bethylidae) on the life table of Palpita unionalis

 Hb. (Lepidoptera: Pyralidae). Egyptian Journal of Biological Pest Control 16: 5-11.

 

Etiam, A. 2001.  Oviposition behavior and development of immature stages of Parasierola swirskiana, a parasitoid of the lesser moth Batrachedra amydraula.  Phytoparasitica 29: 405-412.

 

Garrido, S., Cichon, L., Fernández, D. and Azevedo, C.  2005.  Primera cita de la especie Goniozus legneri (Hymenoptera: Bethylidae) en el Alto Valle de Río Negro, Patagonia Argentina. Revue de Societe Entomologique Argentina 64: 14-16.

 

Gordh, G.  1982.  A new species of Goniozus imported into California for the biological control of navel orangeworm [Hymenoptera: Bethylidae; Lepidoptera: Pyralidae].  Entomol. News 93:  136-138.

 

Gordh, G. and Evans, H. E.  1976.  A new species of  Goniozus imported into California from Ethiopia for the biological control of pink bollworm and some notes on the taxonomic status of Parasierola and Goniozus (Hymenoptera: Bethylidae). Proceedings of the Entomological Society of Washington 78: 479-489.

 

Gordh, G. & B. Hawkins.  1981.  Goniozus emigratus (Rohwer), a primary external parasite of Paramyelois transitella (Walker), and comments  on bethylids attacking Lepidoptera [Hymenoptera: Bethylidae; Lepidoptera: Pyralidae].  J. Kansas Entomol. Soc. 54:  787-803.

 

Gothilf, S.  1978.  Establishment of the imported parasite Pentalitomastix plethoricus [Hym: Encyrtidae] on Ectomyelois ceratoniae [Lep: Phycitidae]  in Israel.  Entomophaga 23:  299-302.

 

 Gothilf, S. and Mazor, M.  1987.  Release and recovery of imported parasites of the carob moth Spectrobates ceratoniae (Lepidoptera:

 Pyralidae) in Israel. Israel Journal of Entomology 21: 19-23.

 

211.  Legner, E. F.  1983a.  Influence of residual Nonpareil almond mummies on densities of the navel orangeworm and parasitization.  J. Econ. Entomol.  76:  473-475.

 

209.   Legner, E. F.  1983b.  Patterns of field diapause in the navel orangeworm (Lepidoptera: Phycitidae) and three imported parasites.  Ann. Entomol. Soc. Amer. 76:  503-506.

 

258.  Legner, E. F. & G. Gordh.  1992.  Lower navel orangeworm (Lepidoptera: Phycitidae) population densities following establishment of Goniozus  legneri (Hymenoptera: Bethylidae) in  California.  J. Econ. Ent. 85(6):  2153-60.

 

210.  Legner, E. F. & A. Silveira-Guido.  1983.  Establishment of Goniozus emigratus and Goniozus legneri [Hym: Bethylidae] on navel orangeworm,  Amyelois transitella [Lep: Phycitidae] in California and biological control potential.  Entomophaga 28:  97-106.

 

 240.  Legner, E. F. and Warkentin, E.F. 1988. Parasitization of Goniozus legneri (Hymenoptera: Bethylidae) at increasing parasite and

  host, Amyelois transitella (Lepidoptera: Phycitidae), densities. Annals of the Entomological Society of America 81: 774–776.

 

205.  Legner, E. F., G. Gordh, A. Silveira-Guido & M. E. Badgley.  1982.  New larvicidal wasp to attempt control of navel orangeworm.  Almond  Facts  47(3):  56-58.

 

203.  Legner, E. F., G. Gordh, A. Silveira-Guido & M. E. Badgley.  1982.  New wasp may help control navel orangeworm.  Calif. Agric. 38(5-6): 1, 3-5.

 

Shoeb, M. A., Abul-Fadl, H .A. and El-Heneidy, A. H.  2005.  Biological aspects of the ecto-larval parasitoid, Goniozus legneri Gordh on different insect hosts under laboratory conditions. Egyptian Journal of Biological Pest Control 15: 5-9