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J Insect Physiol

Title:		"Phorid fly, Pseudacteon tricuspis, response to alkylpyrazine analogs of a fire ant, Solenopsis invicta, alarm pheromone"
Author(s):		Sharma K; Vander Meer RK; Fadamiro HY;
Address:		"Department of Entomology & Plant Pathology, Auburn University, Auburn, AL 36849, USA"
Journal Title:		J Insect Physiol
Year:		2011
Volume:		20110414
Issue:		7
Page Number:		939 - 944
DOI:		10.1016/j.jinsphys.2011.04.007
ISSN/ISBN:		1879-1611 (Electronic) 0022-1910 (Linking)
Abstract:		"The phorid fly, Pseudacteon tricuspis Borgmeier, is a parasitoid of the red imported fire ant, Solenopsis invicta Buren. This fly has been reported to use fire ant chemicals, specifically venom alkaloids and possibly alarm pheromone to locate its host. A recent study identified 2-ethyl-3,6-dimethyl pyrazine as a component of the alarm pheromone of S. invicta. To determine the possible involvement of this fire ant alarm pheromone component in mediating fire ant-phorid fly interactions, we tested electroantennogram (EAG) and behavioral responses of P. tricuspis females to the commercially available mixture of 2-ethyl-3,6-dimethyl pyrazine and its 3,5-dimethyl isomer, as well as six structurally related alkylpyrazine analogs at varying doses. Pseudacteon tricuspis females showed significant EAG response to 2-ethyl-3,6(or 5)-dimethyl pyrazine (herein referred to as pheromone-isomer) at all doses, 0.001-10 mug. Among the tested alkylpyrazine analogs, 2,3-diethyl-5-methyl pyrazine showed significant EAG activity at 0.1 and 1 mug. 2,3-dimethyl pyrazine also showed significant EAG activity at 0.1 mug. Results of four-choice olfactometer bioassays demonstrated significant attraction of P. tricuspis females to the pheromone-isomer (2-ethyl-3,6(or 5)-dimethyl pyrazine) at all tested doses (0.01, 0.1, 1 and 10 mug). The analogs, 2,3-diethyl-5-methyl pyrazine and 2,3-dimethyl pyrazine were significantly better than the control at the higher doses (0.1, 1 and 10 mug). The pheromone-isomer was significantly better than both analogs at two doses, 0.1 and 1 mug. These results confirm that the reported fire ant alarm pheromone component plays a role in mediating attraction of phorid flies to host workers. Venom alkaloids were previously shown to attract P. tricuspis; therefore, we propose that fire ant alarm pheromones may act in tandem or synergistically with venom alkaloids to attract phorid fly parasitoids to fire ant workers"
Keywords:		"Animals Ants/*metabolism Behavior, Animal Diptera/*metabolism Electrophysiology Female Host-Parasite Interactions Pheromones/chemistry/*metabolism Pyrazines/chemistry/metabolism;"
Notes:		"MedlineSharma, Kavita Vander Meer, Robert K Fadamiro, Henry Y eng England 2011/04/29 J Insect Physiol. 2011 Jul; 57(7):939-44. doi: 10.1016/j.jinsphys.2011.04.007. Epub 2011 Apr 14"