Cost-benefit of trapping and population fluctuation of Rhynchophorus palmarum L. in coconut (Cocos nucifera L.) genotypes

Abstract

Introduction: Rhynchophorus palmarum L. is the most destructive pest in Cocos nucifera plantations in Mexico. Objective: To estimate the cost-benefit of collecting R. palmarum by trapping in two coconut genotypes and to determine the correlation of trapping with environmental factors. Materials and methods: R. palmarum insects were captured on the genotypes ‘Alto Pacífico ecotipo 2’ (AP) and ‘Enano-Verde de Brasil’ (EVB) for one year. Five types of traps were used (BT = bucket type, TCT = trash can type, GT = gallon type, CSAT = Colegio Superior de Agricultura Tropical, BT = bottle type). Trapping was counted weekly, and the cost-benefit of trapping was determined. Trapping was analyzed with quasi-Poisson distribution, deviancy analysis and least significant difference. Trapping correlation with climate variables was determined with the Spearman’s coefficient. Results and discussion: A total of 3 414 insects were captured in AP. TCT and CSAT were the most effective (P < 0.014) with 40.3 % and 32.7 % of the total adults, respectively; they also had the best cost-benefit, 4.3 MXN and 5.5 MXN per insect, respectively. In EVB, 3.56 times more insects were captured (4 799) compared to AP with a 29.6:6.4 ratio, using GT. In both orchards, the correlations of climate variables with trapping were weak (less than 50 %); relative humidity was the most highly correlated, but negative. Conclusions: The efficiency of traps and their cost-benefit will allow growers to determine which trap to use for mechanical and ethological (aggregation pheromone) control of R. palmarum