Biology of the coconut spike moth Tirathaba fructivora Meyr. and the functional response of predatory earwig Euborellia annulata Fabricius to the moth
2005
Alouw, J.C. | Murallo-Rejesus, B. | Ocampo, V.R., University of the Indonesian Coconut and Palmae Research Inst. (Indonesia); Philippines Univ. Los Banos, College, Laguna (Philippines). Crop Protection Cluster
The biology of the coconut spike moth, Tirathaba fructivora Meyr., on male coconut flowers was studied under laboratory conditions. The total development period from egg deposition to adult emergence was 25.05 plus or minus 1.32 days. The mean incubation period was 4.12 plus or minus 0.78 days. Based on the head capsules collected, larvae underwent five instars with a larval period of 17.35 plus or minus 1.39 days and a pupal period of 8 plus or minus 2.13 days. The mean longevity of adult female was 8 plus or minus 3.46 days and 8.15 plus or minus 2.13 days for adult male. Mating occurred at 1-3 days after emergence and took place at night or early in the morning. Oviposition took place in the evening. The mean number of eggs laid per female was 174.32 plus or minus 1.40 with mean hatchability of 80.58 plus or minus 17.81 percent. Upon hatching, the larvae moved towards and hide among the male coconut flowers. They bored into and fed on unopened flowers. The observed functional response of E. annulata to T. fructivora was a Holting's Type 2 response. It showed that the density and predator stage influence the predation behavior of E. annulata. The highest mean number of first instar larvae consumed in three days by the adult, fourth and third instar nymphs were 12, 48, 114.50 and 113.64, respectively. The values for the handling time (time to catch and consume the prey) indicated that the maximum number of preys that could be consumed by the predatory earwig is a function of prey stage.
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