Guide to the Coffee Borer Beetle

Seventy countries in the tropics rely on coffee as their most valuable export commodity. The Coffee Berry Borer beetle (Hypothenemus hampei) is the most serious coffee pest threatening the coffee plants of these countries.

The coffee borer beetle is unique in that it's the only known pest to live and nest in the coffee bean itself. The coffee bean produces caffeine as a defense mechanism, which is known to be toxic to almost all pests.

World's Worst Coffee Pest is the Coffee Berry Borer Beetle

In the last two decades world production of coffee has increased due to the improved use of fertilizers, the cultivation of high yielding coffee plant varietals, and increased planting density.

During this same period new coffee diseases and pests have created new challenges and the primary coffee pest affecting crops is the coffee berry borer.

The Coffee Berry Borer is a small beetle native to Africa and currently affecting coffee crops in more than seventy countries, mostly in Latin America. The Coffee Berry Borer also is known by its Spanish names of broca del cafe, gorgojo del cafe and barrenador del cafe.

When Unchecked, Severe Damage Is Caused to Coffee Harvest

In some areas the coffee berry borer infestations have caused extreme damage to coffee crops including as much as 60% damage in Mexico, 70% in Malaysia, 90% in Tanzania, 70% in Jamaica, 60% in Colombia and 80% in Uganda. This is impacting some of the best coffees in the world.

Coffee Berry Borer Beetle Biology

The female coffee berry borer is about 1.5 mm long and infests the coffee fruit (called the coffee berry or coffee cherry) beginning about eight weeks after the time of the coffee plant's flowering until the time the cherry are harvested. This time range is typically about 32 weeks.

Male adult Coffee Berry Borer beetles are about 1.4 mm long while females are 1.6 mm long. Females have wings and males do not. Females can only fly a short distance.

The Coffee Berry Borer beetle larval stage lasts about two and one-half weeks. The white larva of the Coffee Berry Borer has a brown head. The larva is about 1 mm long by .4 mm wide. The beetle's pupae are approximately 1.2 mm long and exhibit a yellowish color.

The male Coffee Berry Borer typically lives about six weeks while the female lives about 17 weeks. The mating of the beetles occurs within the coffee bean with a single  coffee tree potentially containing several generations of the beetle.

About five weeks elapses from the time of the egg until the Coffee Berry Borer reaches adulthood although this varies with climate.

Once the female Coffee Berry Borer beetle drills her way into the coffee cherry (fruit) about 42 eggs are laid within about two days time. The genders of the beetle are mostly female with 13 female with only one male being produced for every thirteen females.

Female Beetle Bores into Coffee Fruit

Only the female coffee berry borer attacks the coffee fruit. When a coffee berry borer attacks a coffee fruit she first bores into the fruit's endosperm.

Each berry is attacked by only one female who is known as the colonizing female, and over a period of about 20 days she lays two or three eggs within the berry.

Physical Damage to Crops

Damages to coffee berry borer coffee crops occurs in two ways. One is that the infestation causes the coffee cherry to fall off the coffee tree prematurely.

Not only does the borer beetle physically damage the coffee bean, it causes the bean to rot and become unsellable.

The second is that the quantity and quality of the resulting coffee crop is affected because the coffee berry has fed inside the berry.

Infesting Female Stays with the Brood

The female coffee berry borer remains with the brood and does not leave the fruit. Females born in the berry may mate with males within the berry and then these females may either stay and lay eggs or leave the fruit. The males stay in the fruit.

Climate Impact on Infestations

Coffee berry borer populations in an infested area are significantly affected by climate factors including humidity and precipitation.

Climactic conditions including a relatively high relative humidity and temperature will trigger a higher rate of emergence of females from the berries. The female-male ratio of the coffee berry borer species is 10:1.

Coffee Borer Eradication

Wasps Prey on Coffee Berry Borer

Biological controls have been attempted to combat coffee berry borer beetle infestations of coffee crops.

Two African wasps, Prorops nasuta and Cephalonomia stephanoderis were used in North America and South America in the 1980s and 1990s though with very limited success.

A wasp called Heterospilus coffeicola also shows potential as a natural predator of the coffee berry borer beetle. It's use as a biological control agent has not been thoroughly tested, but studies in Uganda coffee fields have given researchers an indication of the predator's potential.

In addition numerous ant species are known to attack the coffee berry borer providing further areas for investigation of ways to control the harmful coffee pest.

Fungus Preys on Coffee Borer

A certain fungus can be used to help control coffee borer beetles.

The downside to the fungus is that it can also be toxic to the berry if left in place, so farmers are forced to used a fungicide to kill the fungus. This cycle has to be repeated on a 2-4 week basis, as long as coffee borer beetles are present.

Like the insecticide, the fungicide is incinerated during the roasting process and no traces remain in either organic or non-organic coffee.

Insecticides Not Recommended To Battle Coffee Beetle

Control of the coffee pest is often attempted through the application of highly toxic synthetic insecticides including chlorpyrifos (a crystalline organophosphate insecticide) and endosulfan.

These insecticides - while highly toxic to pests - are incinerated during the coffee roasting process, where's the coffee is exposed to temperatures over 400 degrees fahrenheit.

Researchers continue to search for more environmentally friendly methods of controlling the coffee berry borer.

Parasite Preys on Coffee Borer

A parasitoid eulophid called Phymastichus coffea was tried in America and India including mass releases in Colombian coffee fields in 1996 and 1997.

Subsequent efforts have been made to time the releases based on climate and blossoming dates of the coffee trees to optimize the ability of the parasitoid to prey on the coffee berry borer beetle and prevent coffee crop damage.

Steps To Stop the Coffee Berry Borer Beetle

In Colombia growers in areas infested with the coffee berry borer beetle began using fiber bags with a mesh size of 1 mm rather than plastic containers as this served to contain all of the coffee beetles and prevent them from escaping from the bags.

In addition the bags reduce the relative humidity level which has been shown to trigger the emergence of the coffee berry borer from within the coffee fruits.

Additional precautions are taken at the coffee fruit washing stations to catch the bugs as they emerge. Oil-smeared plastic covers are placed on the freshly harvested coffee cherry to trap the coffee beetles.

Further steps include proper composting of any pulp and other products of the processing with the goal of preventing any coffee berry borer beetles from escaping. A muslin cover on the coffee dryers also helps reduce the chance of any coffee pests returning to the fields.

Stop the Pest Before the Coffee Fruit is Ruined

P. coffea continues to show hope for use as a biological control of the coffee berry borer beetle since it attacks mainly the adult female beetles outside of the coffee fruits and previous to the damaging of the crop.

Other methods of combatting the coffee berry borer including insecticides and wasps primarily attack the coffee beetles after penetration of the coffee cherry.

Reducing Coffee Beetle Infestation

Of primary importance in reducing the infestation level of the coffee berry borer in coffee fields is making sure that all coffee fruit has been removed from the tree at the end of the harvest period.

In addition the ground should be kept free of all fallen fruit and the tree should be kept well pruned. These steps have been shown to cause substantial reductions in the level of infestation of the coffee berry borer.

After Harvest Handling

Another important step to take in dealing with a coffee borer beetle infestation is to carefully control how the coffee berries are handled subsequent to harvest making sure that no females infesting the berries are allowed to return to the coffee fields.

Researchers estimate that about 70% of coffee berry borer beetles in on a particular coffee plantation will be transferred to the coffee processing area during the harvesting period.

Poor handling will result in the return of many of the coffee pests to the fields while proper handling will ensure no berry borers return to the fields.

Ongoing Research

Research continues on ways to control coffee berry borer beetle infestations of coffee crops worldwide. The current level of damage caused by the coffee berry borer is about $500 million in a coffee industry that generates about $90 billion annually.

For example, research in 2015 was done to isolate the digestive enzymes that allowed the coffee borer beetle to digest caffeine - a unique trait in the animal world. Typically, caffeine is a defense mechanism plants use to kill pests.

Coffee Borer in Hawaii

Here are some facts about the coffee pest that was discovered in Kona on the Big Island of Hawaii in September of 2010 resulting in a quarantine of green coffee beans (unroasted coffee) as well as coffee plant parts and coffee bags.

What sort of damage is caused by the Beetle?

After the beetle's initial invasion into the coffee fruit there may be other invaders including fungi, bacteria and insects. The combined effect of these pests and diseases is that a coffee crop may be significantly reduced and in some cases whole coffee harvests have been destroyed.

How bad is the infestation in Kona?

Since it was discovered in September of 2010 more than twenty Kona coffee farms have reported the Coffee Berry Borer to be present. It is highly likely that the beetle is in many more fields as well since the survey was incomplete and many samples had yet to be tested.

Kona has more than 600 independent coffee farms producing cultivating more than 2,000 acres of coffee including a significant amount of organic coffee.

Another 4,500 acres of coffee is grown in other areas of Hawaii with an overall production of about 6.5 million pounds of Hawaii coffee annually. This includes a 500 acre plantation on Molokai and a 3,000 acre plantation on Kauai. One of Hawaii's premium coffees is Kona Peaberry Coffee.

The Kona coffee industry on the Big Island of Hawaii is threatened by a small beetle known as the Coffee Berry Borer (Hypothenemus hampei) which is known to be the most harmful coffee pest in the world.

Worldwide damage by the Coffee Berry Borer is estimated at $500 million per year which is significant in an overall coffee industry that generates about $90 billion per year. The most recent infestation has been on the Big Island of Hawaii where the Hawaii Department of Agriculture has declared a quarantine to stop the spread of the beetle.

The Coffee Berry Borer is one of the world's most damaging coffee pests and getting rid of it is made more difficult to to the perennial nature of the coffee trees which have up to eight flowering periods. The beetle may be transferred to new areas on green coffee beans, which are unroasted coffee beans which have been processed.

The infestation of the Coffee Berry Borer has had major effects on some country's economies by causing a reduction in coffee prices and by reducing coffee yields sometimes destroying entire harvests.

Chemical treatments

Some chemicals may be used to combat the Coffee Berry Borer beetle but these are only effective if applied before the borer breaks through the skin of the coffee cherry (coffee fruit). The most effective chemicals are illegal in the United States due to their harmful effects on the environment and on human health.

Hawaiian Beetle Predators

The predators, parasites and funguses above could all be used to combat infestations, but care must be taken when introducing foreign species.

None of these remedies are being discussed at this time in regards to the Coffee Berry Borer infestation in Kona. Introduced species pose their own problems in Hawaii which has the highest rate of endemic species in the world and many extremely endangered species in a fragile environment, thus researchers and conservationists are very wary of introducing foreign species into Hawaii.

State officials are rapidly moving to protect the premium gourmet coffees of the Kona region.