Management of Termite (Microtermes adschaggae) on Hot Pepper Using Powdered Leaves and Seeds of Some Plant Species at Bako, Western Ethiopia

A study was conducted to evaluate the field efficacy of eleven pesticidal plants against termites on hot pepper at Bako, western Ethiopia during the 2001, 2003 and 2004 cropping seasons. The powdered leaves and seeds of the pesticidal plant species were applied at the rate of 50 g per 12.6 m2 plot size. In all years, plants with the least termite damage were recorded from plots treated with Maesa lanceolata, Azadirachta indica and the insecticide diazinon 60% EC (2.5 lit ha-1). The highest stand count and yield were also obtained from plots treated with the same plant species and diazinon. Treatment with Shinus molle and Ficus vasta appeared to have the lowest effect on termite damage protection. Consequently, there was low plant population at harvest. The use of M. lanceolata and A. indica should be promoted as part of an integrated management system of termites on hot pepper, particularly by poor farmers.


Introduction
Termites have been regarded as serious insect pests that attack a wide range of agricultural crops, forest trees and buildings in western Ethiopia. Most of the prevailing termite species are Macroterms subhyalinus (Rambur) and Microtermes adschaggae (Sjosted). They are subterranean in nature and only a few species are mound forming and are difficult to locate and destroy. Termite attacks caused up to 62% and 36% reduction in yields of hot pepper and maize respectively in the region (Abdurrahaman, 1983;Abraham, 1990;Devendra et al., 1998). This devastating insect pest also causes soil degradation by reducing vegetation and leaving the soil surface barren and exposed to erosion (Abraham, 1990;Devendra et al., 1998). As a result, farmers are forced to abandon their farmlands and migrate to other places (Abraham and Adane, 1995). In addition, the consequences of termite infestation reduced farm productivity, increased land degradation and vulnerability of resource poor farmers (Altieri, 1984;Devendra et al., 1998).
Use of cultural control methods such as mound destruction, removal of the queen, flooding, use of hot ash, are not effective against termites. As a result, termite control methods depend heavily on synthetic chemicals, especially organochlorines such as aldrin (Abdurahaman, 1990). Many plant species have been reported to posses insecticidal and repellent properties against termites; however, only Azadirachta indica and Ipomea fistulosa products have been field-tested. According to Listinger et al. (1978), incorporating such plants and their derivatives into the annual cropping system may provide an ecologically-sound method of termite control. Hence, the present study reports on the field efficacy of some plant products against subterranean termites.

Description of the Study Site
The experiment was conducted at the Bako Agricultural Research Center (BARC), western Ethiopia. The center lies between 9 o 6' N latitude and 37 o 09' E longitude, 1650 meters above sea level. The mean annual rainfall is 1217 mm and its pattern is unimodal. The rainy period is from April to October. It has a warm humid climate with mean minimum, mean maximum and annual mean temperatures of 13 o C, 28 o C and 18 o C respectively (Table  1). Sixty percent of the soil is reddish brown Nitosols with a pH range of 5.0 -5.31. 42 applied at the rates of 207 kg/ha and 137 kg/ha respectively. Hand weeding was done three times.

Treatment Application
The leaves of the selected plant species were collected, dried and ground into fine powders. The powders of the plant species were applied at the rate of 50 gm /plot as a basal or root application at the transplanting and pod setting growth stages. Likewise, the recommended rate of diazinon 60% EC (2.5 lit /ha) was applied at the transplanting and pod setting growth stages. Untreated check plots were neither treated with the insecticide nor with leaves and seed powders of plants species.

Data Collection and Analysis
Two weeks after the first treatment application and every two weeks thereafter until physiological maturity, ten plants were randomly sampled per plot to assess for termite-damage. The mean of termite-damaged plants was expressed as a percentage of the total samples. To avoid double counting, tags were placed on sampled plants.
Stand count was taken at harvest. The six middle rows were harvested at physiological maturity. Dry pod yield per plot was converted to kg ha -1 . The percentage of termite-damaged plants and stand counts at harvest were square-root transformed to stabilize the variances. Oneway analysis of variance was used. The data were analyzed using MSTAT and the Least Significant Difference (LSD) was used for mean separation at P< 0.05. Yield advantage in Table 5, was calculated by comparing the untreated check plots with the treated plots.

Results and Discussion
In all the years, lower termite-damaged plants were recorded from plots treated with M. lanceolata, A. indica and diazinon 60% EC than from the remaining treatments (Tables 3 and 4). The highest stand count and yield were also obtained from plots treated with the same plant species and diazinon 60% EC. This was further verified in the large area in 2004 (  (1991) and Epilla et al. (1988) reported that these plants possess insecticidal, repellent, or antifeedant properties. Several species of plants have been reported as being toxic or repellent to termites. However, only A. indica and I. fistulosa products have been field-tested. Fekede and Kedir (2004) reported that M. lanceolata also had fungicidal properties comparable to the fungicide, thiram, used against sorghum head smut. The fact that these botanicals reduced the damage level of termites might be attributed to their antifeedant, repellant, insecticidal effects or a combination of them.   (Table 5). Brown (1962) reported that incorporating such plants and /or their derivatives into the annual cropping system may provide ecologically-sound methods of termite control. Similar findings were reported by Gold et al. (1991), Logan et al. (1999), and Schroth et al. (1992), where A. indica and I. fistulosa mulches were found to reduce termite activity for seven weeks and this should be given due consideration in termite control strategies.
Several plant species have been reported as being toxic or repellent to termites. However, only A. indica and I. fistulosa products have been field-tested (Gold et al., 1971). On the other hand, Gold et al. (1991) reported that A. indica and I. fistulosa mulches reduced termite activity for seven weeks after treatment. In conclusion, the use of M. lanceolata and A. indica should be promoted as part of an integrated management system of termites on pepper, particularly by (resource) poor farmers.