Pheromones

Pheromones and attractants for Rhynchophorus palmarum and Metamasius hemipterus

enfermas RHYNKO

The American palm weevil, Rhynchophorus palmarum, is the main vector of red ring disease that occurs in several species of palm trees due to the nematode Bursaphelenchus cocophilus. This disease can cause significant losses in coconut and oil palm plantations in the American tropics. M. hemipterus has been associated with red ring disease in Colombia, but its real role is unclear. However, in regions where possible indirect damage is suspected, farmers prefer to reduce their populations. In plantations of pejibaye (peach palm, Bactris gassipaes), M. hemipterus is a pest of recognized importance.

Given the importance of Rhynchophorus palmarum and Metamasius hemipterus as direct pests of several species of palms (and as a vector of red ring disease in the case of R. palmarum), ASD in collaboration with Simon Fraser University in Canada, developed a trapping system for these pests that is based on the use of attractants (pheromones and kairomones), which has proven to be extremely effective in fighting these insects and the damage they cause.

In the case of pheromones, these are marketed under the names of RHYNKO-LURE® and META-LURE®. Kairomone (ethyl acetate) is marketed under the name RHYNKO MAGNET® and it is a natural (volatile) substance that is released from cuts in the tissue of palm trees and decomposing fruits, and when used in conjunction with the pheromone, capture of the species mentioned is significantly increased.

The price of these attractants varies according to their type, and also according to the region or country to where they are exported and the size of the order. Orders are dispatched five days after the opening of a confirmed and irrevocable letter of credit against a bank recognized in the United States of America. Transfers of money to our current account and bank drafts are also accepted forms of payment. Queries and orders can be directed to our representatives and distributors in different countries.

What is 'red ring'?

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One of the most important phytosanitary problems of the coconut palm and oil palm in tropical America is caused by the nematode Bursaphelenchus (Rhadinaphelenchus) cocophilus that causes the disease known as red ring. The symptoms of this disease are very variable, but three manifestations can be distinguished (although with multiple points of convergence).

The classic or acute symptoms are characterized by a 'yellowing' and drying that starts in the older leaves and then progresses to younger leaves. Affected plants can die in a few months. Internally the plants show discolored areas on the trunk, which in the case of the coconut tree form a reddish ring. In oil palm, these discolorations on the trunk may or may not form a ring and the color varies from pink to very dark brown.

In contrast with these symptoms, there is a manifestation of 'small leaf', in which little or no 'yellowing' occurs, but the younger leaves produced are small in size, such that over time the upper part of the palm takes on a flattened appearance. These types of symptoms correspond to a chronic manifestation of the disease and the plants may not die for years. The third manifestation is a complex combination of these extreme symptoms.

The vector: Rhynchophorus palmarum

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There is ample evidence that the nematode that causes red ring disease is transmitted by the American palm weevil (Rhynchophorus palmarum). It is not known to be transmitted by other means such as seed, soil, harvesting tools, or even other insects, including other weevils (Curculionidae).

The adult weevils are attracted to palms that have suffered some physical damage (wounds from tools, lightning strikes, attack by rats, etc.), or a condition that causes tissue fermentation (diseases such as wet basal rot and spear rots). The females deposit their eggs on these palms and the developing larvae can themselves cause plant death. In the case that the adult is infested with the nematode B. cocophillus, the result is the transmission of red ring disease.

Fighting red ring disease

The fight against this disease is based on the reduction of the population of R. palmarum adults within the plantation and in its surroundings, in the prevention or treatment of plants with physical damage or decay, and in the elimination of plants with red ring symptoms. The reduction of the adult population of R. palmarum is achieved by eliminating the places where the weevils reproduce and by trapping them.

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Chemical attractants: the best weapon for capturin weevils

There are several types of traps and food baits for attracting and capturing adult weevils. Initially, these traps were made with stem pieces from several palm trees, but the catches were small. After a period of joint work with scientists from Simon Fraser University (British Columbia, Canada), the ASD Oil Palm Research Program identified, synthesized and field evaluated "rhynchophorol", which is the aggregation pheromone of R. palmarum. This substance is produced by the male insect to attract other individuals of the species to food sources, where copulation also takes place. "Rhynchophorol", which has proved to be very useful in combating the weevil and red ring disease, is marketed by ASD under the name RHYNKO-LURE.

In experiments it was found that the use of traps with RHYNKO-LURE and a sugarcane food source impregnated with a (low odor) insecticide such as flowable carbofuran or 80% carbaryl, captures 6 to 30 times more weevils than when traps are used without the pheromone. In addition, the joint use of the aggregation pheromone with ethyl acetate (Weevil Magnet®), increases captures even more.

RHYNKO-LURE is presented in a small sealed envelope of clear plastic containing the pheromone "rhynchophorol", which allows a regulated release of the substance into the environment. This bait attracts adult weevils of both sexes, and once placed in the field its effect lasts for approximately three months. However, this period may vary with extreme high or low temperatures. Ten to twenty RHYNKO-LURE bait units are packaged in hermetically sealed polypropylene bags. These can be kept in a common refrigerator for up to a year, without losing their original attractant qualities. By holding the plastic envelope up to the light, it is possible to determine whether or not the product has been exhausted, since it is a liquid.

Use of Rhynko-Lure

Of the various types of traps used to capture weevils, perhaps the most versatile and economical is a 5-liter plastic container; however, captures can be increased a little with larger volume containers.

The traps are usually made using white plastic containers with a capacity of 5-19 liters and openings on the upper edge for ventilation and to allow the entry of weevils. Baits (pheromone and/or ethyl acetate) are hung from the center of the lid. Precaution must be taken that the bait does not touch the walls of the container because ants and other insects can damage it. The wire on which the baits hang can be covered with petroleum jelly so that ants cannot climb on it. The food bait is placed on the bottom of the container and it usually consists of pieces of sugarcane forming two layers and molasses to maintain moisture. The bait can be impregnated with an insecticide, such as carbaryl.

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The traps are hung from the petiolar bases of the leaves on the trunk of the palm at a height of approximately 1.2 meters, ensuring that they remain in the shade and eliminating any epiphytic plants surrounding the trap on the palm trunk. Precautions should be taken so that the insects, which first alight on the trunk of the palm, may eventually walk into the trap. It is important to take care that the sugarcane is always kept moist, changing it immediately if it dries out. To ensure this condition the most prudent action is to submerge the sugarcane pieces in an insecticide solution for some time. The duration of this substrate depends on weather conditions and can be 10 to 15 days.

Trapping intensity

In areas where captures of more than 5-8 weevils per trap per week are initially obtained, we suggest using a density of one trap per 1-2 hectares. The adult population of weevils is aggregated within the plantation, which may necessitate changing the placement of the traps to find sites with higher catches. For example, it is common for weevils to come from other poorly managed plantations that harbor high populations of the insect. However, initially the traps can be placed in a grid for every 16 palms and 18 rows. The first trap can be placed on the eighth palm of the ninth row from the edge of the plot. This arrangement of the traps is maintained until the sites with the highest captures are identified.

Once the population is reduced to 1-2 insects/trap/week, trapping intensity can be reduced to one trap per five hectares. Finally, when the population is considered to be under control, a trap can be maintained every 10 ha (every 35 palms and 41 rows). It is prudent to keep track of the initial trapping system for at least six weeks to gather the necessary information for deciding on the final density of traps to be used.

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Comercial Name

RHYNKO-LURE Pheromone

Common Name

Rhynchophorol

Chemical Name

2-methyl-4hydroxi-hep-5-eno or its alternative name 6-methyl-2-(E)-hepten-4-ol

Structural Formula

(CH 3 ) 2 CHCH 2 CH(OH)CHCHCH 3 P.M. 130.23

Empirical Formula

C 8 H 19 O

Other Properties

Liquid, transparent. Contains no solvents, it is used pure. Contains no metallic elements.

Product Stability

Does not decompose at ambient temperature. In approximately 12 week, it releases the entire quantity of pheromone. After this period it is no longer active.

Conditios for its storage

Can be refrigerated for up to 12 weeks in its original packaging. The product has no chemical action on the container in which it is a sold.

Warnings and Precautions

In human beings, as for any other chemical product, it may produce allergy or irritation of the eyes or skin. There is no evidence of toxicity.