Eurytoma amygdali Enderlein
Taxonomic placing: Insecta, Holometabola, Hymenoptera, Eurytomidae.
Common name: Almond fruit wasp.
Geographical distribution: Southeastern Mediterranean countries, the Middle East and some parts of the former Soviet Union.
Host plants: Almond.
Economic importance: The pest can damage 50% or more of the almond yield of some varieties. The larvae mostly attack fruits of soft shells, or of late-flowering varieties, whereas fruits of bitter varieties do not seem to be preferred. Infested almonds blacken and remain on the trees as “mummies”, not dropping when the trees are shaken during harvest, thus remaining there in the next year. Infested almonds of certain varieties drop shortly after pest attack, and the losses from such drop may exceed losses from mummified fruit.
Morphology: The body of the wasp is dark brown, about 7 mm in length, and the wings are almost transparent with a small dark spot. The larva is white with a very small, sunken brown head, body up to 4 mm long.
Life cycle: The pest is univoltine and requires one or more years to complete development. In autumn it enters winter diapause, induced by falling temperatures, remaining within the seed and pupating there. In spring the emerging and immediately-mated females place one or more eggs on the developing almond, the larger fruits being preferred. A female may oviposit around 25 eggs, mostly during mid-day and live for about 13 days. The calculated thermal threshold for development is 10-12°C, and the thermal units needed for the development of one generation are around 2700 day-degrees.
Management
Monitoring: Adult emergence is monitored with sex pheromone traps, or by placing cages that contain living virgin females. Emergence can also be followed by collecting infested (black) almonds from the previous year off the trees, maintaining them in cages and noting the emerging adults.
Plant Resistance: Certain almond varieties appear to be resistant to the pest.
Chemical control: Chemicals to control the adults should be applied to susceptible varieties about 3-4 weeks after the beginning of male captures in the pheromone traps. A single spray with a pyrethroid resulted in less than 4% infestation in Greece. Neonicotinoids are also in current use.
Biological control: Several hymenopterous and one acarine parasitoids attacked E. amygdali in eastern Turkey, killing up to 30-40% of the pests. In southern Turkey another enemy, Pyemotes amygdali Çobanoğlu and Doğanlar (Pyemotidae) attacks the pest.
References
Athanassiou, C.G., Kavallieratos, N.G. and Mazomenos, B.E. 2008. Almond seed wasp (Hymenoptera: Eurytomidae) sex pheromone: effect of trap type, trap position, blend ratio and time of the day on male attraction. Bulletin of Entomological Research 98: 535-541.
Çobanoğlu, S. and Doğanlar, M. 2006. A new Pyemotes (Acari: Pyemotidae) reared from larvae of the Almond Seed Wasp, Eurytoma amygdali (Hymenoptera: Eurytomidae) from Hatay, Turkey. Zoology in the Middle East 39: 101-106.
Doğanlar, O., Yıldırım, A.E. and Doğanlar, M. 2006. Natural enemy complex of Eurytoma amygdali Enderlein, 1907 (Hymenoptera, Eurytomidae) in Eastern Mediterranean region of Turkey; notes on their interaction and effectiveness. Research Journal of Agriculture and Biological Sciences 2: 282-286.
Ibrahim, M.Y., Al- Fouzoo, T. and Al- Naser, Z. 2008. Biological and ecological studies of almond fruit wasp, Eurytoma amygdali End., (Hymenoptera: Eurytomidae) at Homs Governorate (Syria). Jordan Journal of Agricultural Sciences 4: 139-151 (in Arabic with English Abstract).
Katsoyannos, B.I., Kouloussis, N.A. and Bassiliou, A. 1992. Monitoring populations of the almond seed wasp, Eurytoma amygdali, with sex pheromone traps and other means, and optimal timing of chemical control. Entomologia Experimentalis et Applicata 62: 9-16.
Klapperich, J. 1964. Eurytoma amygdali End. (Chalcididae, Hymenoptera) a pest of almond cultivation in Jordan. Gesunde Pflanzen 16: 73-78.
Kouloussis, N.A. and Katsoyannos, B.I. 1995 Distribution and activities of Eurytoma amygdali (Hymenoptera, Eurytomidae) wasps on almond trees. Annals of the Entomological Society of America 88: 547-553.
Plaut, H.N. 1972. On the biology of the adult of the almond wasp, Eurytoma amygdali End. (Hym., Eurytomidae), in Israel. Bulletin of Entomological Research 61: 275-281.
Reuveny, H. and Farkash, S. 2012. Integrated control of almond pests. Alon Hanotea 66: 30-35 (in Hebrew).
Tzanakakis, M.E., Papadopoulos, N.T., Katsoyannos, B.I., Drakos, G.N. and Manolakis, E. 1997. Premature fruit drop caused by Eurytoma amygdali (Hymenoptera: Eurytomidae) on three almond varieties. Journal of Economic Entomology 90: 1635-1640.
WebsiteS: