Population Dynamics and Distribution of the Coffee Berry Borer, Hypothenemus Hampei (ferrari) (coleoptera: Scolytidae) on Coffea Arabica L. in Southwestern Ethiopia

Population dynamics and distribution of coffee berry borer, Hypothenemus hampei (Ferrari) (Coleoptera: Scolytidae) were studied on Coffea arabica L. in southwestern region of Ethiopia. Thirty coffee trees were sampled at weekly intervals from 2000 to 2001. Findings of this study showed that coffee berry borer population had a marked seasonal variation both on dry leftover and fallen coffee berries. Number of adult borers on dry leftover berries was significantly higher than on fallen berries (χ2= 3.89, P < 0.05). All the developmental stages of the borer were more abundant during January to August. There were seasonal differences in the relative abundance of pre-brood, brood and post-brood female borers. Weather factors showed a marked influence on the population dynamics of the borer. Distribution of the borer covered a wide range of altitudes ranging from 1200–1770 m.a.s.l. Key words/phrases: Coffee berry borer, Coffea arabica, Ethiopia, Hypothenemus hampei, population dynamics * Author to whom correspondence should be addressed. INTRODUCTION The coffee berry borer, Hypothenemus hampei is a major insect pest of coffee in many of the world's main coffee producing countries causing a considerable damage (Le Pelley, 1968; Reid, 1983; Mansingh, 1991; Baker, 1999; 2000). The borer has expanded its distribution along with the extension of coffee plantation (Baker, 1999). At present, it is found in almost all the major coffee producing countries of the world. It attacks all commercial species of coffee (Coffea), which are primary hosts of the berry borer (Mansingh, 1991; Baker, 1999). Among its natural hosts, preference of the borer varies according to species and variety of coffee (Mansingh, 1991). Crop losses caused by this pest can be severe, ranging from 50 100% if no control measures are applied (Le Pelley, 1968). Davidson (1968) reported the first incidence of coffee berry borer in Ethiopia. Later on, its occurrence was reported from various parts of the country (Crowe et al., 1977; Crowe and Tadesse Gebremedhin, 1984; Million Abebe, 1987). Survey conducted in some coffee growing areas showed mean percentage infestation of 13.3% to 61% on dry leftover coffee berries (EARO, 2000). This suggested that a comprehensive assessment of coffee berry borer and loss posed by this pest in Ethiopia should be further investigated. Information on the population dynamics enables: to anticipate the seasonal occurrence of the pest; the time when plant damage may take place; and design proper management of the pest. However in spite of its increasing importance in the country, there is no published information on the population dynamics of the pest. Therefore, this study was initiated to determine population dynamics and distribution of the coffee berry borer. MATERIALS AND METHODS The research was conducted in the field at Jimma Agricultural Research Centre (JARC), which is located at around 7° 46’ N latitude and 36° E longitude, and at an elevation of 1750 m.a.s.l. It receives an average of 1595 mm annual rainfall and Esayas Mendesil et al. 128 the mean minimum and maximum temperatures are 11.3°C and 25.9°C, respectively. To investigate population dynamics of the coffee berry borer, one hundred dry leftover berries were collected from 30 coffee trees at weekly intervals from September 2000 to August 2001 at Melko, Jimma following the method of Rémond and Cilas (1997) and Baker and Barrera (1993). Similarly, fallen berries were collected from around each sample tree and placed in a labeled paper bag separately. All the berries collected were examined for the presence of an entry hole (perforation) on the berry, which is a typical symptom of coffee berry borer attack (Le Pelley, 1968; Baker, 1999). Damaged berries were separately dissected with surgical blade and the number of each of the four developmental stages of the borer was recorded. Then mean number of each stage of borer was calculated for each sampling month. In addition, female borers in infested berries were classified into prebrood, brood and postbrood and number of female borer in each category was determined following the method of Baker and Barrera (1993). To assess the effect of weather on the population dynamics of the berry borer, rainfall (RF), relative humidity (RH), minimum (MIT) and maximum temperature (MAT) data of the experimental site were obtained from the meteorology section of JARC. Mean monthly count of the different stages of the borer was correlated with mean monthly weather data. To study the distribution of the borer at different localities and to determine degree of damage, survey of the borer was conducted at 14 localities in the major coffee growing areas of southwestern Ethiopia from February to May 2001 (Fig. 1). At each site, thirty coffee trees were sampled and berries were collected from the top, middle and bottom canopy of the trees. All the berries collected were examined for the presence of an entry hole (perforation) on the berry, which is a typical symptom of the coffee berry borer damage (Le Pelley, 1968; Baker, 1999). Degree of damage due to feeding and tunneling activities of the coffee berry borer was assessed based on visual score based on the method recommended by Reid and Mansingh (1985) so that: Slight = less than 25% bean damage Moderate = 25 – 50 % bean damage Heavy = more than 50% damage Fig.1. Sampled localities of coffee berry borer in southwestern Ethiopia [1= Melko (Seka), 2=Agaro (Goma), 3=Limu Suntu (Kosa), 4=Metu and Ihud Gebeya (Metu), 5=Yayo (Yayo), 6=Tepi, Baya and Shosha (Yeki), 7=Sheko, Selale and Gezmeret (Sheko), 8= Kabo and Meti (Godere)]. SINET: Ethiop. J. Sci., 27(2), 2004 3 129