scholarly journals Molecular identification of Trichogramma egg parasitoids of Ostrinia nubilalis in northeastern Serbia

2018 ◽  
Vol 70 (3) ◽  
pp. 425-432 ◽  
Author(s):  
Aleksandar Ivezic ◽  
Paul Rugman-Jones ◽  
Richard Stouthamer ◽  
Aleksandra Ignjatovic-Cupina

The European corn borer Ostrinia nubilalis (Hubner, 1796) (Lepidoptera: Pyralidae) is a major pest of corn (Zea mays Linnaeus, 1753) in Serbia. Regular monitoring of O. nubilalis in the region of Kikinda (province of Vojvodina, Serbia) demonstrated a high percentage of parasitized eggs of this pest. Preliminary identification of the egg parasitoids based on morphological traits revealed that they belong to the genus Trichogramma Westwood, 1833 (Hymenoptera, Trichogrammatidae). The objective of this study was to identify the autochthonous Trichogramma species present in the region of Kikinda by using sequences of ribosomal DNA. Specimens of Trichogramma were reared from parasitized eggs of O. nubilalis collected at different localities in the region of Kikinda. The ITS2 gene was sequenced and subjected to BLAST searches of GenBank NCBI (National Center for Biotechnology Information). The majority of collected specimens were identified as Trichogramma brassicae Bezdenko, 1968, and a single specimen as T. evanescens Westwood, 1833. Intraspecific variation of T. brassicae was assessed by amplifying the mitochondrial cytochrome oxidase I (COI) gene. Wasps were also tested for the presence of the endosymbiotic bacteria Wolbachia Hertig, 1936 using Wolbachia-specific 16S and wsp primers as a preliminary test for evidence of thelytoky. Understanding of the diversity and biology of autochthonous Trichogramma species is a key step in the potential commercial implementation of these egg parasitoid wasps in the protection of corn fields in Serbia.

1997 ◽  
Vol 75 (3) ◽  
pp. 484-489 ◽  
Author(s):  
J. Chihrane ◽  
G. Laugé

Trichogramma brassicae, a parasitoid used in the biological control of the European corn borer, Ostrinia nubilalis, becomes less effective if certain thermal conditions prevail at the time of its release. A laboratory study demonstrated that the generation liberated in the field had reduced fecundity and that the proportion of females was lower in the following generation. These results prompted us to examine the germ lines of the parasitoid. Exposure to a temperature of 35 °C at the white nymph stage does not affect ovarian function, but exposure to 44 °C does: the number of mature ovocytes at emergence is lower than that observed in controls; certain ovaries are abnormal or remain juvenile. At the time of emergence, the seminal vesicles of male controls contain large numbers of typical sperm and a few atypical sperm, the latter becoming more numerous in males exposed to 35 °C. After exposure to 44 °C, vesicles contain only a few sperm or are completely empty. Since T. brassicae is an arrhenotokous parthenogenetic species (unfertilized eggs become males), these observations explain the reduced number of females in the second generation.[Journal translation]


2016 ◽  
Vol 107 (1) ◽  
pp. 93 ◽  
Author(s):  
Jaka RAZINGER ◽  
Špela MODIC ◽  
Annette HERZ ◽  
Gregor UREK

European corn borer (<em>Ostrinia nubilalis</em>)<em> </em>(ECB) is an important maize pest in central and northern Europe. Presently it is controlled by insecticides or biological agents such as <em>Trichogramma brassicae</em> in several European countries, excluding Slovenia, where the pest’s pressure is highly variable and no appropriate mechanization is available. Lessening the dependence on chemical pesticides is an integral part of the European Union’s agenda for agriculture. Mass release of <em>Trichogramma</em> spp. could be seen as a promising alternative for ECB control in countries with a highly fluctuating ECB pressure and no mechanization for insecticide applications. However, no records of naturally occurring hymenopteran parasitoids of ECB exist in Slovenia. To address this important under-researched topic and provide the expert basis for potential introduction of ECB egg parasitoids in Slovene maize production, a systematic inventarisation programme of ECB parasitoids was launched in 2010. Additionally, ECB flight was monitored in 2011 and 2012 at two locations in Slovenia: Jablje and Rakičan. In both locations two ECB generations  were observed. ECB was fist observed at the end of May in Rakičan. During the five years of the systematic survey we discovered two ECB parasitoid species. ECB egg masses were parasitized by <em>Trichogramma brassicae</em>, whereas ECB pupae were parasitized by <em>Tycherus nigridens</em>, with 6 or 7 % parasitation rate, respectively. <em>T. nigridens</em> represents a new taxon report for Slovenia. We conclude that there is a strong need for undertaking systematic surveys of natural enemies of agricultural pests.


BioControl ◽  
2006 ◽  
Vol 51 (5) ◽  
pp. 627-642 ◽  
Author(s):  
Leslie C. Lewis ◽  
Douglas V. Sumerford ◽  
Lori A. Bing ◽  
Robert D. Gunnarson

1992 ◽  
Vol 124 (1) ◽  
pp. 113-116 ◽  
Author(s):  
Lucie Royer ◽  
Jeremy N. McNeil

AbstractEuropean corn borer males have hair pencils located ventrally on the 8th sternite and these are extruded when a male approaches a calling female. The fact that (i) antennectomized females mated significantly less than both intact controls and individuals subjected to other forms of surgery, and (ii) males with hair pencils removed had a significantly lower mating success than control males, suggests that a male pheromone is involved in the mating system of the European corn borer.


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