Introduction

The red ring disease can be effectively reduced by combining several control strategies. All infected plants must be removed by poisoning or cutting them, in order to reduce sources of inoculum of the nematode. At the same time, the population of the vector has to be reduced by eliminating breeding sites, and by putting in effect an adequate mass trapping program in the whole plantation. Very commonly, the population of palm weevils is so high that even if infected palms are removed the disease continues increasing.

The use of the male aggregation pheromone of R. palmarum in traps with a food source (commonly sugar cane) is an important new tool that can be used commercially to reduce the population of this insect (Chinchilla et al. 1994; Oehlschlager et al. 1993). In Costa Rica, a mass trapping program for R. palmarum was initiated in 1992, which caused red ring incidence to decrease to less than 10% of the original incidence in about two years. Disease reduction was closely related to a significant drop in insect captures in the traps .

In some regions of Colombia where M. hemipterus could be contributing in the dissemination of B. cocophilus, it might be necessary to mass trap both R. palmarum and M. hemipterus. Pheromone trapping can be carried out for each insect separately or both can be trapped at the same time. In this paper information is presented on the use of Rhynchophorol (RHYNCHO-LURE®) and nonanol (META-LURE®) (aggregation pheromones of R. palmarum and M. hemipterus respectively) in a trapping program to reduce the populations of these insects.

Capture of R. palmarum and M. hemipterus in pheromone-baited traps
Adults of the palm weevil are attracted by volatiles from fresh cuts in many palms and other plants. This behavior has been used to attract and kill the insects in traps made out of palm stem pieces and other tissues, such as sugarcane and pineapple. Nevertheless, captures can be significantly increased when the male produced aggregation pheromone, RHYNCHO-LURE® (Fig. 3) is used in the traps.

A similar situations occurs with M. hemipterus, which is also attracted to traps with sugarcane as a food source and the male aggregation pheromone META-LURE® (Fig.4).

Traps baited with RHYNCHO-LURE® are visited by M. hemipterus, and META-LURE® also attracts some R. palmarum adults, but captures are the highest when the right pheromone is used for each insect. However, a trap can be set which carries both pheromones and sugarcane allowing optimum catches for both insects.

The commercial product COMBO-LURE has both pheromones, and significantly attracts more M. hemipterus than RHYCHO-LURE®, and more R. palmarum than META-LURE, when these pheromones are used separately (Figs. 5-6).

When capturing R. palmarum, RHYNCHO-LURE® can be a slightly more efficient than COMBO-LURE®. Also, COMBO-LURE® attracts less M. hemipterus than META-LURE®. However, the cost per insect captured (R. palmarum or M. hemipterus) in one trap with COMBO-LURE® is less than when META-LURE® and RHYNCHO-LURE® are used separately in the same trap (Fig. 7).

REFERENCES

CALVACHE, H. MEJIA, A. HERNANDEZ, M. MUÑOZ, J. 1995. Acción de Metamasius hemipterus en la transmisión del anillo rojo de la palma aceitera. Palmas 15(4): 17-22.

CHINCHILLA, C. OEHLSCHLAGER, A.C. GONZALEZ, L. 1993. Management of Red Ring Disease in Oil Palm through Pheromone-Based Trapping of Rhynchophorus palmarum. PORIM International Palm Oil Congress. Kuala Lumpur. 19 p.

GRIFFITH, R. 1987. Red Ring Disease of Coconut Palm. Plant Disease 71: 193-196.

OEHLSCHLAGER, A.C. CHINCHILLA, C. GONZALEZ, L. JIRON, L. MEXZON, R. MORGAN, B. 1994. Development of a pheromone-based trapping system for the American Palm Weevil, Rhynchophorus palmarum. Journal of Economical Entomology 86(5): 1381-1392.