Potentials for early detection of red palm weevil (Coleoptera: Curculionidae)-infested date palm (Arecaceae) using temperature differentials

This study investigated thermal aspect potentials of date palm (Phoenix dactylifera (Linnaeus) (Arecaceae)) infested by red palm weevil (Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae)) in early detection. Palms were forced infested, i.e., fertile females and males were introduced inside the palms to initiate infestation. Effects of three infestation intensities on date palm were examined throughout a 24-day period. Temperature gradients inside infested and healthy palms of the commercial cultivar (Khalas) were determined using data loggers. Adult weevils and loggers were introduced inside holes drilled in palm trunks for measuring temperatures at 15-minute intervals during 24 consecutive days. These 24 days after infestation is the larval stage where most of the damage occurs and the infested palms can still be rescued through remedial control measures. A repeated measures analysis showed that the temperature of infested palms during the two seasons of the study were 33.22 degrees C and 30.08 degrees C, while for the healthy palms were 31.83 degrees C and 27.56 degrees C. Differences were significant during the first (F = 6.14, df = 3, P = 0.009) and the second (F = 3.89, df = 3, P = 0.038) season. The corresponding ambient atmosphere temperatures were 31.83 degrees C and 28.03 degrees C, respectively. This study provides valuable baseline information for developing a real-time sensor fusion system for a nondestructive early detection of insect infestation.