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Coffee and Culture  02/16/2012

Warehouse pests

Get to know the main pests found in warehouses and how to fight them.

By Flávio Borém*

Coffee quality can be affected, at first, by inappropriate management of the crop; then, during harvest and drying; and, finally, during storage.

During storage, biotic and abiotic factors may cause negative effects in coffee quality. Among the biotic factors, pests have special importance. For the insects that attack the coffee grains during storage, weevils and moths can be highlighted.

The coffee bean weevil (Araecerus fasciculatus) is a powerful pest of stored coffee. At first, it only attacked dry cherries in farms’ storage containers, but it eventually adapted to processed coffee and became a serious pest in coffee warehouses. The attack starts in the field and goes on up to the warehouse.

Weevils damage dried coffee in all its forms: naturals, pulped naturals and even after dry milling . They usually destroy some of the seeds, but they don’t change coffee’s color, aroma, and taste, so the coffee can still be roasted. The attack causes stored coffee to lose up to 30% of its weight in six months, and the greatest damage is caused in warehouses located in hot and humid places, like Santos (SP) or other sea ports.

The coffee berry borer (Hypothenemus hampei) is a major field pest which might continue its attack in warehouses, causing beans to lose weight.

Two species of moths can often be found in stored coffee.

Coffee moths (Auximobasis coffeaella) are small moths whose caterpillars feed largely off fruits’ skin. They don’t attack beans or perfect seeds, but they completely destroy broken seeds. Fruits affected by borers or weevils might be completely destroyed. It is only in these cases that the moth gets to eat coffee seeds’ endosperm.

Cocoons and insects’ excrement can affect exportation as they damage both coffee and the burlap bags.The need to replace destroyed bags adds to the losses.

Rice moths (Corcyra cephalonica) can be found in Santos and São Paulo. The damage they cause is similar to coffee moths’. The weight loss caused by them is around 2%.

Cleaning the warehouse and removing residues of stored coffee before the new harvest are ways of controlling these pests. The other control procedures are protective and corrective.

The control of weevils is done through fumigation and misting. In order to prevent weevils from attacking, warehouses should be misted every month. Another preventive measure is phosphine fumigation of lots that appear to have been infected with weevils.

Pulverization with pesticides is an effective complement to good cleaning practices in order to get rid of insects that were already in the warehouse and to prevent other insects from getting into the place. So, after cleaning the warehouse, it should be pulverized with registered pesticides.

Other pests can be found in warehouses, like bats, rodents and birds. Although not feeding with coffee beans, they might cause some kind of contamination.

The market is getting more and more demanding in terms of quality and food safety. In addition to the careful production of quality coffees free of chemical and biological contaminants, the guarantee of quality and food safety also involves good storage practices and pest control.

* Flávio Borém is a professor at the Universidade Federal de Lavras. He has a degree in Agronomy from the Universidade Federal de Viçosa (1986), a Master's degree in Agricultural Engineering from the Universidade Federal de Viçosa (1992), a Doctorate in Vegetable Crops Production from the Universidade Estadual do Norte Fluminense Darcy Ribeiro (1998), Ph.D in Agricultural Products Processing Engineering from the Wageningen University, The Netherlands (2006). He is an expert in coffee post-harvesting, drying, storage, and quality, is the author of the book "Pós-Colheita do Café", and over 50 published scientific articles, a cupping judge since 2007 and a Q Grader since 2010.