COMPARATIVE THERMAL-TIME REQUIREMENTS FOR DEVELOPMENT OF MELOIDOGYNE ARENARIA, M. INCOGNITA, AND M. JAVANICA, AT CONSTANT TEMPERATURES [COMPARACIÓN DE REQUISITOS TÉRMICOS PARA EL DESARROLLO DE MELOIDOGYNE ARENARIA, M. INCOGNITA, AND M. JAVANICA TEMPERATU

Abstract

Understanding thermal-time relationships of plant-parasitic nematodes is necessary to predict their geographicaldistributions, population dynamics and potential for decreasing crop yields. Our objective was to compare the thermaltimerequirements for development of three major species that affect Florida agriculture, namely Meloidogyne arenariarace 1, M. javanica, and M. incognita race 4. The base temperature (Tb) and heat units expressed as degree-days (DD)required for nematode development from second-stage juveniles (J2) to egg-laying females were determined at constanttemperatures ranging from 12 to 35°C. Freshly hatched J2 of the three species were inoculated on okra (Abelmoschusesculentus) and placed in growth chambers. Data were subjected to regression analysis to estimate the base temperaturefor each species. The shortest time and average DD above base temperatures 10.3, 9.8, and 10.6ºC for development were19 days and 316 DD, 15 days and 300 DD, and 17 days and 334 DD, for M. arenaria, M. incognita, and M. javanica,respectively.