POPULATION FLUCTUATIONS OF THE LEAFMINER FLY Liriomyza huidobrensis Blanchard AND THEIR PARASITOIDS IN GROWING BEANS IN THE EXPERIMENTAL STATION OF THE UNIVERSIDAD NACIONAL DEL CENTRO DEL PERU-HUANCAYO

Abstract

The study of population fluctuation of the pea leaf miner Liriomyza huidobrensis Blanchard and their parasitoides in “red UNCP” bean fields in the Mantaro Valley, was carried out in the experimental fields of the Mantaro Experimental Station of the Universidad Nacional del Centro del Peru; located at 11º49’00 South latitude and 75º22’05 West longitude. For sampling, the field was divided in 5 areas excluding at the margins a fringe of 5 meters to avoid the border effects. In the field phase the number of adults posed on the plant at 20 cm. diameter, 5 leaves were collected at random by area, completing 25 leaves/evaluation, those were placed in a paper kraft 20 bag and were taken to the laboratory. In the laboratory phase, based on 100 leaves evaluated we registered the number of adult ectoparasitoids, total of leaflets, mined leaflets, recovered puparia, viable puparia, non viable puparia, adults of L. huidobrensis, emerged endoparasitoids and diapausing individuals. The data of mean temperature (X1), relative humidity (X2), hours of sun light (X3) and precipitation (X4) were obtained at the Observatorio Metereológico of Jauja, located at 11°47´01” South latitude, 75°28’28 ‘’ West longitude, 3322 msnm . The highest incidence of adults of Liriomyza huidobrensis Blanchard occurred in the months of october , November and december in the fruition phase and maturation. The highest density of adults 495 was recorded in the evaluation of october 22. The highest species richness recovers starting from october 24 until the end of the campaign with seven species, made up of 4 endoparasitoids (Halticoptera arduine, Chrysocharis sp. Chrysocharis phytomyzae and Phaedrotoma sp. ) and 3 ectoparasitoids (Diglyphus begini, D. websteri and Closterocerus cinctipennis). The highest endoparasitism percentage was reached on november 26, while the highest number of individual endoparasitoids was registered on november 5 with 358 individuals that represented 52,6%. The highest endoparasitism percentage was registered between october and november in the fruition phase and maturation of the crop. The most abundant parasitoid was Halticoptera arduine reaching its highest percentage at beginning the macoll registering 50% in september and the largest number of individuals (258) on november 5 which represented 37,9% of parasitism in the fruition phase. Halticoptera arduine presents a slight diapause stage, of the recoveries from december to may in the phase and maturation of the crop, registered one diapausal period between 4 and 4,5 months. The most abundant ectoparasitoid was Diglyphus begini, with a maximum population density of 56 recovered individuals on the evaluation of october 15 in the flower phase.