Coffee borer monitoring and management

The attack of the coffee borer, hypothenemus hampei (Ferrari, 1867) (Coleoptera: Curculionidae, Scolytinae) causes fruit drop, reduction in grain weight (quantitative damage) and reduction in coffee quality through changes in the type and sometimes the drink (qualitative damage). The damage is caused by the insect larvae, which live inside the coffee fruit, generally attacking a single seed, and rarely both, for food, and therefore the destruction of the fruit can be partial or total (Figure 1). Initially, losses are caused by falling fruit. For Coffea arabica L., it has already been found that the borer increases the percentage of natural fruit drop of around 8% to 13% and for Coffea canephora Pierre & Froehner (Conillon) the borer may be responsible for a fruit drop of around 46%, as it is more susceptible to attack by the borer. The broached fruits that remain on the plants suffer weight reduction, and it has already been experimentally demonstrated, in Minas Gerais, that these losses can reach 21% or 12,6kg per 60kg bag of processed coffee (Figure 2). It was also found that the quality of the coffee is altered by the borer attack, going from type 2 to type 7 only with the increase in pest infestation, as two to five bored beans constitute a defect. Losses increase during the shelling operation due to the fragility that the attacked grain becomes, being broken and discarded with the ventilation of the shelling machine. The damage caused by the borer begins when the infestation reaches 7% to 10% in the fruits of the largest bloom (Figure 2). The quality of the coffee drink is not directly influenced by the borer attack, but rather indirectly due to the ease that the damage provides for the penetration of microorganisms, such as fungi of the genus Fusarium e Penicillium, which are related to changes in the quality of the coffee drink.

Drill monitoring

In order for control to begin at the correct time, periodic sampling of the fruits (borer monitoring) must be carried out in the different plots of the crop, starting with the lowest and most humid parts.

Monitoring of the borer must begin during the insect's "transit" period, from November to January, approximately three months after the major flowering (October), when the first borer fruits are observed in the rosettes, and carried out until April. adult females of the insect abandon the remaining fruits from the previous harvest (fruits found in the off-season) where they bred, fly and pierce developed green fruits (leads) from the following harvest (Figure 3), without even laying eggs immediately after piercing them, which they do approximately 50 days later. Between November and January the fruits are very watery, with more than 80% moisture, not yet an ideal food for the insect larvae.

How to avoid borer attack

The chemical control tactic is often the only one available to keep the pest below the control level, which is 3% to 5% of bored fruits, if possible in those where the borer has not yet reached the seed, where it will be killed. at the gallery entrance due to the action of contact with the applied insecticide, without having yet laid eggs. If the percentage of bored fruits reaches between 7% and 10%, there will already be losses (Figure 1).

As the attack is not distributed evenly across a crop, control is recommended only in plots where infestation has already reached between 3% and 5% of the fruits, with adult borer females alive inside the galleries, during the so-called “transit” period. of the insect, which corresponds to the movement of the adult female from one fruit to another. Therefore, in most cases, control is not carried out throughout the crop, but is limited to a few plots. Generally, a single spray has been sufficient to borer control Old and closed crops require greater care, as in such conditions they are more susceptible to borer attack, as they offer a favorable environment for the insect, such as shading, greater humidity, a greater number of fruits remaining from the previous year, etc.

Cultural control

It is perhaps the most efficient method of controlling the coffee borer. Coffee plantations must be planted at spacings that allow greater aeration and light penetration in order to provide low air humidity inside, conditions that are unfavorable to the pest, in addition to allowing the circulation of sprayers attached to tractors.

Even more important is that the coffee harvest must be very well done, and it must be avoided that fruits remain on the plants and on the ground, where the borer can survive in the off-season (remaining fruits), especially if it is rainy. After harvest, if there are many grains left on the plants and on the ground, it is recommended to transfer or collect the remaining fruits from the harvest. This method, already practiced in the early days of Brazilian coffee farming, needs to be considered again in the management of the coffee borer, due to the high costs and the lack of efficient products for its control.

Study carried out on a coffee tree of the species C. canephora CV. Conillon, in Espírito Santo, showed, five months after harvest, that around 71,7% of the remaining fruits were attacked by the borer, which highlights the importance of a good harvest and transfer (collection of fruits that were not harvested), especially in non-mechanized crops, where spraying is difficult to carry out. In Rondônia, also in Conillon, an average infestation of 76,3% has been found in fruits in the off-season and those that have fallen to the ground.

The harvest must always begin in the plots that have the most infested coffee trees, in order to avoid further damage, as the borer has a great capacity for reproduction and, in years of high infestation, the last plots to be harvested will, without a doubt, present , increase in borer populations and consequently greater losses.

Conventional chemical control

In Brazilian coffee farming, the greater spacing, which allows spraying with sprayers attached to tractors, means chemical control of the borer is considered efficient and fast, unlike some producing countries that practice dense and/or shaded coffee farming.

There are three active ingredients registered in Brazil for use on coffee plants to control the coffee borer: [chlorpyrifos-ethyl 480 EC (organophosphate), etofenproxi 100 SC (diphenyl ether) and azadirachtin 12 EC (tetranortriterpenoid)].

The chemical control tactic is often the only one available to keep the pest below the control level, which is 3% to 5% of bored fruits, if possible even in those where the borer has not reached the seed, where it will be killed. by the action of contact with the applied insecticide, without having yet laid eggs.

As the attack is not distributed evenly across a crop, control is recommended only in plots where infestation has already reached more than 3% to 5% of the fruits. Therefore, most of the time, control is not carried out across the entire crop, but is limited to a few plots. In irrigated crops, chemical control may be necessary in most fields.

Research in progress

Agricultural research in coffee growing in Brazil has always been attentive to seeking new methods of controlling the coffee borer, including chemical methods, as it is believed to be the most efficient in controlling the pest.

In a survey carried out over 30 years of research into chemical control of the borer in Brazil, between 1973 and 2003, of 269 treatments surveyed, around 21% were carried out with endosulfan, whose efficiency ranged from 70% to 100%, a product already banned from being used to control any pest in Brazil. The other products did not show an efficiency equivalent to endosulfan, although some were promising and were never registered for use in coffee farming due to environmental problems or high control costs.

Of the various molecules being tested to control the coffee borer, two have stood out in the different coffee growing regions of Brazil. One is cyantraniliprole 10% OD (Cyazypyr), in the registration phase in Brazil under the name Benevia, an insecticide from the anthranilic diamide group developed in several countries by DuPont and which presents a new mode of action. It is a second generation (single action through the activation of ryanodine receptors), with a mode of action similar to chlorantraniliprole (Altacor, Rynaxypyr), another insecticide already in use in Brazil and registered for the control of leaf miner, Leucoptera coffeella (Guérin-Mènev. & Perrotet, 1842) (Lepidoptera: Lyonetiidae) in coffee trees.

Rynaxypyr in a mixture with abamectin may be registered by Syngenta, also in Brazil, for use in controlling the borer, under the name Voliam Targo, in the concentrated suspension (SC) formulation.

Both Cyazypyr and Rynaxypyr activate ryanodine receptors by stimulating the release of calcium reserves from the sarcoplasmic reticulum of muscle cells (mainly for chewing insects), causing poor regulation, paralysis and death in sensitive species. It has deep action and acts through ingestion and contact, demonstrating good adulticidal, ovi-larvicidal and larvicidal activity.

For predatory mites and other beneficial arthropods, found naturally on coffee trees in Brazil, Cyazypyr and Rynaxypyr proved to be selective, demonstrating that their use in integrated pest management in coffee plantations can be beneficial.

PICTURE'S DESCRIPTION

Figure 1 – Cut of a coffee fruit showing the presence of borer larvae inside (right) and partial destruction (a completely damaged seed). Photo: Paulo Rebelles Reis

Figure 2 - Weight loss of processed coffee depending on the percentage of infestation by the coffee borer. Control level up to 5% of boring fruits and between 7% and 10% onset of damage. Source: Reis et al. (1984); Kings (2002)

Figure 3 – Female coffee borer and penetration hole (gallery) on the side of the crown in a coffee fruit in the green (lead) stage. Photo: Paulo Rebelles Reis

Click here to read the article in issue 178 of Cultivar Grandes Culturas.