Biology of the stem sawflies Trachelus tabidus and Cephus pygmaeus in the Negev of southern Israel

Abstract

Wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) stems in the Negev Desert of southern Israel are subject to mass infestations by stem sawflies larvae, primarily Trachelus tabidus F. (Cephidae, Hymenoptera). Infestations up to 55% and 50% in wheat and barley, respectively, were found in 1982/83. In addition, up to 8.6% of wild oat (Avena sp.) stems were cut by sawfly larvae in June 1983. The phenology of the insects was studied in 1981 to 1983 using yellow watertraps to catch adults and by dissecting infested stems to establish the pre‐imaginal stages. Adults emerged at the end of February at Ma‐gen and at the beginning of March at Gilat. Eggs and newly emerged larvae appeared in April. Larvae in diapause were found in cut stubs at the end of April and beginning of May. Pupae were found at the end of January and February. Of the sawfly specimens trapped in 1982 and 1983, the great majority was identified as T. tabidus and less than 5% as Cephus pygmaeus (Cephidae, Hymenoptera). The males of the sawflies appeared 4–6 days before the females, and were less numerous than them. About 12% of the larvae were parasitised by Tetrastichus sp. (Chalcidoidea, Eulophidae) in wheat, barley and wild oat, and about 4% by Collyria sp. (Ichneumoidea, Ichneumonidae) in wheat and barley stubs. Résumé Biologie de Trachelus tabidus et Cephus pygmaeus dans le Négev du Sud d'Israël Les tiges de blé et d'orge subissent des attaques massives de tenthrèdes dans le désert du Négev au Sud d'Israël. Des attaques atteignant 55 et 50,4% ont été observées respectivement sur blé et orge en 1982/83. De plus, jusqu'à 8,6% de tiges d'avoine sauvage ont été coupées par les larves de tenthrèdes en juin 1983. La phénologie des insectes a été étudiée de 1981 à 83 en utilisant des pièges jaunes pleins d'eau pour capturer les adultes et en disséquant les tiges attaquées pour déterminer les stades préimaginaux. Les adultes ont émergé à fin de février et au début mars. Les oeufs et les larves sont apparus en avril. Les larves en diapause ont été trouvées dans les souches coupées à la fin d'avril et au début mai, et les nymphes à la fin de janvier et en février. La grande majorité de Cephidae adultes piégés en 1982 et 1983 a été identifiée Trachelus tabidus F., Cephus pygmaeus L. correspondait à moins de 5%. Les mâles de tenthrèdes sont apparus 4 à 6 jours avant les femelles qui étaient plus nombreuses. Environ 12% des larves étaient parasitées par un eulophide (Tetrastichus sp.) sur blé, orge et avoine sauvage, tandis que 3,6% l'étaient par un ichneumonide (Collyria sp.) dans les souches de blé et d'orge.

Plant density and wheat stem sawfly (Hymenoptera: Cephidae) resistance in Syrian wheats

“…In Syria the heaviest infestations occur in the northern provinces of Idlib, Hama, and Aleppo (Rashwani, 1983). The European wheat stem sawfly, C. pygmeus, is the most serious, but is not the only sawfly that attacks cereals in the region (Gol'berg, 1986;El Bouhssini et al, 1987). In Syria wheat, barley, oats, rye, timothy and a number of wild grasses are commonly infested by stem sawflies (Miller, 1987a).…”

Distribution and density of wheat stem sawflies (Hymenoptera: Cephidae) at wheat fields in Yozgat province, Turkey

“…ve Brom otu başaklarında bulunduğunu, Mutlu (2019) ise erginlerin doğaya çıkmasından sonra dişilerin çoğunlukla yabani hardal bitkilerinin (S. arvensis L.) çiçeklerinin nektarları ile beslendiklerini bildirmiştir. Bu konuda Udine (1941) saparısı erginlerin sarıçiçekli yabancı otlar ile beslendiğini, (Ries, 1926;Gol'berg, 1986) Buğday sapları içinde erken dönem larva 2020 yılı mayıs ayı sonunda belirlenmiştir. Cephus pygmeus'un yumurta açılma sürelerinin 8-10 gün arasında değişebildiği (Bonnemaison, 1962;Altınayar, 1975), T. tabidus'un ise 4-7 gün arasında alabileceği bildirilmiştir (Udine, 1941).…”

“…Çünkü Konya ilinde diyapoz dönemine geçen olgun larvalar yıllara göre değişmekle beraber haziran ayı ortası ile temmuz ayı başında tespit edilmiştir. Ülkemizden daha sıcak iklime sahip İsrail'de C. pygmeus ve T. tabidus'un diyapoz başlangıcı nisan sonu ve mayıs başı olduğu kayıt edilmiştir (Gol'berg, 1986). Sıcaklığın böceklerin gelişme dönemleri üzerine etkileri temel bir faktör olduğundan (Taylor, 1981)…”

Resistance to insect pests in wheat—rye and Aegilops speltoides Tausch translocation and substitution lines

“…There are several species of the Cephus genus that attack wheat, the most common in North America is Cephus cinctus Norton (Beres et al 2011). However, the predominant species in North Africa and West Asia is Cephus pygmaeus L. (Golberg 1986;El Bouhssini et al 1987). This species, C. pygmaeus, is also reported to be present in Europe and Central Asia (Leach and Hobbs 2013;CABI-EPPO 2018).…”

“…As the plant reaches maturity, the larvae move to the basal part of the plant to build an hibernaculum, above of which the plant weakens and breaks. Then the larvae go into diapause during the winter (Golberg 1986;Shanower 2008).…”