One or more of the features that are needed to show you the maps functionality are not available in the web browser that you are using.
Please consider upgrading your browser to the latest version or installing a new browser.
More information about modern web browsers can be found at http://browsehappy.com/
Attack by H. hampei begins at the apex of the coffee berry from about eight weeks after flowering. A small perforation about 1 mm diameter is often clearly visible though this may become partly obscured by subsequent growth of the berry or by fungi that attack the borer. During active boring by the adult female, she pushes out the debris, which forms a deposit over the hole. This deposit may be brown, grey or green in colour.
Infestation is confirmed by cutting open the berry. If the endosperm is still watery, the female will be found in the mesoderm between the two seeds, waiting for the internal tissues to become more solid. If the endosperm is more developed, the borer will normally be found there amongst the excavations and irregular galleries that it has made. The borer sometimes causes the unripe endosperm to rot, most commonly by species Erwinia, causing it to turn black (Sponagel, 1994) and the borer to abandon the berry.
Transportation of seeds containing the H. hampei has been the main cause of its spread worldwide. A few coffee-producing countries or zones within countries are still free from this insect and in these cases stringent quarantine precautions are strongly recommended. Hollingsworth et al. (2013) found that treatment of infested coffee berries at a temperature of approximately -15°C for 48 h provided 100% control of all life stages.
Harvesting coffee berries is itself an important control measure. Rigorous collection of remnant berries after harvest, both from tree and ground, can substantially reduce infestations as it breaks the cycle and leaves little substrate for immigrating H. hampei. Collected berries should be boiled or buried if infestation levels are high. If processed, they should be placed in a drier, or if sun-dried, placed under netting smeared with grease or oil to capture escaping borers. These methods are most successful when done carefully by resource-poor farmers (Le Pelley, 1968). However, such manual collection methods are laborious, especially the collection of fallen berries or those on the lower branches. Studies in Colombia have shown that farmers tend to leave many berries after harvest, especially low down on the trees and that the older the tree, the harder the farmers find it to remove the berries (Baker, 1997). Many experiments have been carried out in Colombia to accelerate decomposition of the fallen berries and on the feasibility of collecting them by manual or machine methods. So far no practical progress has been achieved (Baker, 1999).
There are some suggestions that populations of H. hampei tend to be lower under shade trees rather than in full sun. Armbrecht and Gallego (2007) recorded significantly more predation under shade than full sun coffee. Others however (e.g. Bosselmann et al., 2009) have found the reverse. It is likely therefore that the effect of shade is highly dependent on a number of local factors, for example, Jonsson et al. (2015) found higher levels of H. hampei under unshaded than shaded coffee in Uganda, whereas the reverse was true for the white stem borer (Monochamus leuconotus).
The two bethylid parasitoids, Cephalonomia stephanoderis and Prorops nasuta have been introduced from Africa to India and many Latin-American countries in the 1980s and 1990s. The few studies undertaken on their effectiveness suggest that in general they have only a moderate controlling effect and that it is rare to find more than 5% of perforated berries parasitized one or more years after releases were made (Barrera, 1994). However a follow-up study seven years after a campaign to rear and release large numbers of C. stephanoderis in different coffee growing areas of Pulney Hills, Tamil Nadu, India, recorded 16-45% parasitism from five different areas (Roobakkumar et al., 2014). Generally low parasitism may be because the berries are harvested before the wasps have a chance to emerge, though more studies are needed to explain their scarcity in the field. Both species parasitize only one berry: the female enters and stays with her brood, rather similar to the borer's maternal behaviour. From the point of view of biocontrol this is unfortunate as a parasitoid that lays eggs in many berries might be more effective. Mass release studies of C. stephanoderis in Colombia and other countries have been carried out but the costs of mass production are uneconomical and likely to remain so because of the high cost of the diet (coffee beans) for the borer host.
Phymastichus coffea was seen as a promising biocontrol agent because it attacks adults and thus might help to prevent establishment of the borer in the endosperm, where economic damage is caused. It can also parasitise borers from more than one berry and the few studies on this in the field have suggested that it may be more effective control agent than the bethylids (Baker, 1999). However, to date there are no follow up field studies that suggest it is having any suppressive effect on the borer in the field.
The fungus Beauveria bassiana is found naturally wherever H. hampei is present. In humid climates infection may reach more than 50% and is probably the most significant natural control agent of H. hampei. Pascalet (1939) found it prevalent in the forest zone of Cameroon and concluded that conditions favourable to an outbreak were a dense borer population, 20-30°C temperature, sufficient rain to produce the humidity necessary for vigorous sporulation, followed by one or two sunny days to induce an even distribution of spores, followed by light rains to favour development of spores on the bodies of the borers. Intensive efforts in Colombia, Nicaragua, Mexico and Ecuador have been made to develop an effective mycopesticide based on B. bassiana. Results have been very variable with sprays (with varying concentrations of fungal spores/tree) causing anything from 10-86% mortality (Lacayo, 1993; Sponagel, 1994; Bravo, 1995; Bustillo and Posada, 1996; Baker, 1999). High field mortality of H. hampei in the entry canal of the berry (80%+) have been achieved but only at uneconomically high doses. At lower doses the mortality is usually between 20-50% of adult females entering the berry. Further problems relate to the viability and virulence of commercially prepared formulations of the fungus and the product requires careful quality control and monitoring to ensure acceptable standards. Currently in Colombia, despite a concerted research and extension effort over many years, few farmers still apply the fungus. Benavides et al. (2012) suggest that applying a mix of B. bassiana strains may improve virulence. Another approach has been to inject B. bassiana into coffee in the hope that it might establish inside the plant and act as an endophyte to attack the borer when it drills into the berry (Vega et al., 2005).
More recently efforts to increase the virulence of Metarhizium anisopliae (a fungus which occasionally attacks H. hampei), by inserting a scorpion toxin gene through genetic engineering (Pava-Ripoll et al., 2008).
Vega et al. (2002a) have also studied the presence of Wollbachia in H. hampei, a bacterial infection that may be the cause of its skewed sex ratio. However to date there seems to be no practical way to use this knowledge to devise a novel control method.
In general nematodes would be difficult to apply to coffee trees, but might be easier to apply to the ground under the trees where the microclimate might be very suitable for them. The fallen berries under the tree are known to be a very important reservoir of re-infestation and yet difficult to control either by chemicals, fungi or manual collection and experimental releases of parasitoids suggest that few of them attack fallen berries. Hence what is needed is something that could actively search for an infested berry and tunnel its way into the berry to attack the coffee berry borer inside. Lopez-Nuñez of Cenicafé, Colombia, working with Steinernema carpocapsae (All strain), S. glaseri and Heterorhabditis bacteriophora has achieved infection and mortality of H. hampei in laboratory and small-scale field trials (Baker, 1999). Efforts continue to evaluate its performance in larger field trials.
In recent years there have been a number of studies to evaluate the effect of bird predation (e.g. Johnson et al., 2010; Karp et al., 2013 ) which through exclusion cage experiments show significant control effects in heavily infested field conditions. The presence of H. hampei in the diet of some birds has been confirmed through DNA analysis of faecal samples (Karp et al., 2014), however less than 10% of birds tested positive for H. hampei. Exclusion studies have also been carried out with ants (e.g. Solenopsis geminata;Trible and Carroll, 2014) which show a significant predation effect. To date though, no long term field experiments have been performed which demonstrate reliable and significant predation from a range of naturally occurring predators. The main difficulty is that generalist predators tend to search for high density prey and may switch away from H. hampei at levels above an acceptable economic threshold.
Thus despite intensive efforts over the last 25 + years, the impact of biocontrol on H. hampei continues to be disappointingly low.
Due to the variable regulations around (de-)registration of pesticides, we are for the moment not including any specific chemical control recommendations. For further information, we recommend you visit the following resources: