LABORATORY ASSESSMENT OF PRESENCE AND LEVEL OF RESISTANCE TO THE PHOSPHINE IN POPULATIONS OF THE LESSER GRAIN BORER RHYZOPERTHA DOMINICA F. COLEOPTERA, BOSTRICHIDAE IN STORAGES AND SILOS IN BULGARIA | Лабораторна оценка за наличие и степен на резистентност към фосфин в популации на зърновия бръмар Rhyzopertha dominica F.(COLEOPTERA,BOSTRICHIDAE)от складово-силозното стопанство на България

Sixty-eight populations of the Lesser grain borer - Rhizopertha dominica F.were established in storages silos in Bulgaria from 2006 by 2009. In preliminary tests with populations by Phosphine Resistant Test Kit for DETIA-DEGESCH, resistance to phosphine was found in 8 populations: in wheat grain from Shumen, Varna, Isperih and Kardam; in barley from Vraca and Vidin ; in maize from Chirpan and Sofia Vrana. In the comparative assessment of resistance to phosphine in the trials three populations showed sensitivity in preliminary tests: in wheat grain from Brusarci and barley from Peturch, Nova Zagora and laboratory population breeded 6 years in the laboratory of IZR. It was found, that the highest resistance to phosphine showed the population from Kardam - LD50 and LD 99,9 0,0426 mg l and 0,956 mg l, respectively followed by population Isperih - 0,232 mg l and 0,843 mg l respectively. They showed 12 and 10 times higher resistant than sensitive populations from Vidin, Brusarci, Peturch and Nova Zagora. Considerable resistancе showed populations from Chirpan - 8 times, Vraca - 5 times, Sofia Vrana- 3 times. Laboratory population and that at Varna exhibit very weak signs of resistance. Individuals from the population from Vraca were heterogenous to phosphine, and those from Brusarci were most hоmogenous. Increased resistance to phosphine populations leads to longer the development of the individuals from 25.9daysin the susceptible to 49.3 days, increased weight of the pupae- respectively 0.997 and 1,643 mg,and a low reproductive rate number of eggs - 69.8 and 472.0 eggs respectively. The sex ratio in the resistant populations was in male favor. Keywords: lesser grain borer, Rhizopertha dominica F, population, resistance, phosphine.LABORATORY ASSESSMENT OF PRESENCE AND LEVEL OF RESISTANCE TO THE PHOSPHINE IN POPULATIONS OF THE LESSER GRAIN BORER RHIZOPERTHA DOMINICA F. (COLEOPTERA, BOSTRICHIDAE) IN STORAGES AND SILOS IN BULGARIA Firas Zidan, Doncho Obretenchev, Plant Protection Institute – Kostinbrod Abstract Sixty-eight populations of the Lesser grain borer - Rhizopertha dominica F.were established in storages silos in Bulgaria from 2006 by 2009. In preliminary tests with populations by Phosphine Resistant Test Kit for DETIA-DEGESCH, resistance to phosphine was found in 8 populations: in wheat grain from Shumen, Varna, Isperih and Kardam; in barley from Vraca and Vidin ; in maize from Chirpan and Sofia Vrana. In the comparative assessment of resistance to phosphine in the trials three populations showed sensitivity in preliminary tests: in wheat grain from Brusarci and barley from Peturch, Nova Zagora and laboratory population breeded 6 years in the laboratory of IZR. It was found, that the highest resistance to phosphine showed the population from Kardam - LD50 and LD 99,9 0,0426 mg / l and 0,956 mg / l, respectively followed by population Isperih - 0,232 mg / l and 0,843 mg / l respectively. They showed 12 and 10 times higher resistant than sensitive populations from Vidin, Brusarci, Peturch and Nova Zagora. Considerable resistancе showed populations from Chirpan - 8 times, Vraca - 5 times, Sofia Vrana- 3 times. Laboratory population and that at Varna exhibit very weak signs of resistance. Individuals from the population from Vraca were heterogenous to phosphine, and those from Brusarci were most hоmogenous. Increased resistance to phosphine populations leads to longer the development of the individuals from 25.9daysin the susceptible to 49.3 days, increased weight of the pupae- respectively 0.997 and 1,643 mg,and a low reproductive rate number of eggs - 69.8 and 472.0 eggs respectively. The sex ratio in the resistant populations was in male favor. : lesser grain borer, Rhizopertha dominica F, population, resistance, phosphine.