Dinámica de población e indicadores ecológicos del ácaro Steneotarsonemus spinki Smiley 1968 (Acari:Tarsonemidae) en arroz de riego en Cuba

Abstract

1. spinki is known as economic important pest in rice (Oryza sativa L.) from the decade of ¨70s in the countries of the tropical Asia. At the end of 1997 it was detected in plantations of rice of the western region of Cuba, linked to the mushroom Sarocladium oryzae and a sintomatology characterized by a strong empty and spotted of the panicle and the leaf flag. The objective of this work was to study its population’s behavior in connection with different factors biotic and a biotic under the conditions of Cuba. In general, the works were carried out on cultivating Perla from Cuba, in plantation with watering in areas of the IIA, Havana from 11/1997 up to 2/1999. The behavior of this mite was determined by the phase phenology and the planting dates. The maximum population coincided with the emersion phase or exit of the panicle and it was bigger in the plantations germinated in March and July; among the 105 to 110 days in that of November; 91 at 100 in that of March, at the 80 in that of June and the J-104, variety of longer cycle, 63.6 mite / it plants to the 135 days. Two moments of minimum expression of growth were presented, of December to March for inferior temperatures to 240 C, and of July to September for the direct mortality that they cause the rains above the 60 mm in the dozen. The population of mites predators was 0 to 3.3 for plants, maximum at the end of the cycle of the summer planting; the entomophatogens exercised little influence. The necrosis and wither in the rachis of the panicle, it evidences interruption in the mechanism of circulation of the nutrients, in the moment of the flowering. Direct lesions were observed on the floral organ, the grain in formation, atrophies and blockade of the growth that they can be associated to the injection of toxic saliva during the feeding. The mite has not been detected starting from the maturation of the grain. Population’s structure is similar for adults, juvenile and eggs; at the end of the cycle, they decrease the females, the males increase, related with the dissemination and survival of the species. They prevail in the sheath of the leaves 3 and 4 starting from the 90 days of having germinated the plants. They are vulnerable to the negative effects of the atmosphere from the germination until end of ahijamiento and during the embroiling of the spike”, in this last one it can express their maximum capacity of dissemination of the mushroom S. oryzae.