Descripción de los estados adultos e inmaduros y aspectos bioecológicos de Heterothrips cacti (Thysanoptera: Heterothripidae)

The immature stages of Heterothrips cacti Hood are described and illustrated and the biological and ecological features of this species in semi arid and high elevation zones of Jujuy province, Argentina, are discussed. Samplings were carried out every fifteen days in San Pedrito during the Opuntia sulphurea var. hildmannii flowering season in 2006-2007. The sample consisted of five flowers of each condition of development collected randomly. In order to know the host plants and the distribution of H. cacti, periodic samplings of the wild vegetation were carried out in the Prepuna and Puna of Jujuy province. The biological studies were performed in laboratory placing flowers of O. sulphurea with eggs of H. cacti in rearing cages in order to control their life cycle evolution. Heterothrips cacti is an anthophilous, oligophagous species associated to cactaceae, widely distributed in the Prepuna and Puna of Jujuy province. The biology of H. cacti is correlated with the one of its host plant, O. sulphurea, presenting two generations per year. Likewise, its life cycle is associated with the evolution of the cactaceous flower. The time of development of the immature stages of the first and second generation was 45 ± 1.5 days and 287 ±3 days respectively. The stage of development through which the species undergoes the period between inflorescences is larva II quiescent wrapped in a silk thread cocoon on the floor. At 5 ºC and 0 hrs light the quiescent state of H. cacti is inhibited. The incidence of larvi-pupal parasitoid Ceranisus sp. during the second generation of H. cacti was recorded.