Gall phenology, population trend and damage caused by Ophelimus migdanorum and its parasitoid Closterocerus chamaeleon on Eucalyptus globulus at two sites with different rainfall parameters in Bogotá

Abstract

Abstract The gall wasp Ophelimus migdanorum represents a pest risk for several Eucalyptus species established in Colombia. Biological development and damage could be conditioned by the climate and, in the tropical Andes, by precipitation. We studied gall phenology, population fluctuation, and leaf damage caused by O. migdanorum and its parasitoid Closterocerus chamaeleon over five months at two sites with contrasting rainfall in peri-urban areas of Bogotá, Colombia. Gall phenology and foliar damage were evaluated on ten trees per site for six months. We evaluated gall phenology through characterization of the gall size and color and the wasps´ development stage. We also evaluated gall phenology based on the affected leaf area and the gall´s density on the leaf blade. Likewise, the individuals found in five attractive traps at each site were quantified biweekly to record the population fluctuation. The effect of precipitation on wasp frequency and gall density between sites and sampling dates was compared with the Chi2 test, while the relationship with precipitation was evaluated with the Kruskal-Wallis test. Only females of the gall wasp and its parasitoid were observed during the evaluation, which showed multivoltine behavior. Six developmental stages of the galls were differentiated, each having typical coloration. Drier microclimates favored the gall´s size, stages development frequency, population trend, and foliar damage. A general trend indicates a greater abundance of the parasitoid C. chamaeleon than O. migdanorum. Our study indicates that in places with rainy microclimates, there´s a less damaging effect of O. migdanorum on E. globulus.