Gruber, Françis

Halbert, Susan E.

Kirijak, Ivan

Undetermined

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Section VCereal Crop PestsEXPLORATION FOR NATURAL ENEMIES AND SURVEY OF RUSSIAN WHEAT APHIDIN THE SOUTHERN U.S.S.R.Susan Halbert, Ivan Kirijak1 and Frangis Gruber2University of Idaho, SW Idaho R/E Center, 29603 U of I Lane, Parma, ID 83660IntroductionRussian wheat aphid (RWA) [Diuraphis noxia (Mordvilko)] is indigenous to the middleeast and the southern part of the Soviet Union, where it is not considered a pest. It isthought that natural enemies native to the Soviet Union may play an important part inkeeping this pest under control. The primary purpose of our expedition was to collectnatural enemies of RWA. Parasites and predators which are active in the autumn mayhave particular benefit in the Pacific Northwest where RWA is abundant in fail crops. Asecondary purpose of our expedition was to learn as much as possible about thebiology of RWA in Moldavia and the southern part of the Ukraine.MethodsWe surveyed fields of winter wheat and barley and volunteer grain in southern Moldaviaand the Ukraine (including the Crimean Peninsula) for RWA and its natural enemies inOctober and November, 1989. All mummies (regardless of aphid host), predators anddiseased cereal aphids were collected. The mummies and diseased specimens wereheld in small vials and refrigerated each night. The predators were kept in plastic cagesprovided with RJiopalosiphum spp. for food. All RWA were kept alive on fresh wheatplants in plastic containers for observation to see if mummies developed. As the RWAbecame adults, the numbers of each morph were counted and recorded.Results and DiscussionRWA was not common in Moldavia and the Ukraine. The infestations weobserved were limited to isolated plants or patches up to 2m in diameter. RWA wasmost common in volunteer grain. In winter wheat, infestations were most common nearborders or in places where plants were sparse. Each damaged plant typically had oneor two RWA. Other cereal aphids, especially Rhopalosiphum padi (L), RJiopalosiphummaidis (Fitch) and Sitobion avenae (Fabricius), were common.Of the 161 RWA collected in the Soviet Union, to date 10 have been found to beparasitized. In contrast to this, only three parasitized RWA were found among the morethan 400 similarly collected RWA in the Treasure Valley this season. Mating pairs ofAphidius sp. and Aphelinus sp. from the Soviet Union are in culture at the USDAEuropean Parasite Lab.1 All Union Research Institute for Biological Methods in Agriculture, Kishinev, Moldavia,U.S.S.R.2 USDAEuropean Parasite Lab, Behaust, France22Five species of predators were found including Coccinella septempunatata, Adoniavariegata, Hippodamia 13~punctata, Thea 22-punctata and Propylea 14-punctata. Thesehave been sent to the USDA lab at Newark for rearing.Diseased aphids are at EPLwhere fungi will be identified and propagated by Dr.Tad Poprawski.No alatae or alatoid nymphs were found in the Soviet Union (Table 1). InMoldavia virtually all the D. noxia collected were sexual forms. In the Ukraine manysexual forms were also found, especially in the Crimean collections.Table 1. Morphs oiDiuraphis noxia (Mordvilko) found in the southern Soviet Union.morphs foundLocation Numberof sitesalate1viviparaeapterousviviparaeOviparae Males UndifferentiatednymphsMoldavia 2 . 0 0 26 0 1Crimea 4 0 6 21 3 6Ukraine2 5 0 89 9 0 01 includes alatoid nymphs2 fields near and between Odessa and Kherson23

Exploration for Natural Enemies and Survey of Russian Wheat Aphid in the Southern U.S.S.R.

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Exploration for Natural Enemies and Survey of Russian Wheat Aphid in the Southern U.S.S.R.

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