BIOECOLOGY AND MANAGEMENT OF COFFEE BEAN WEEVIL, (Araecerus fasciculatus De Geer) ON SOME STORED FOOD CROPS IN SELECTED STATES IN NIGERIA

Abstract

Stored Food Crops (SFC) serve as host to Insect Pests (IP). Araecerus fasciculatus (Af) is a major IP causing severe economic losses in Nigeria. In a bid to prevent deterioration on Food Crops (FC), farmers process FC into Dried Chips (DC), nonetheless, the DC are susceptible to Af damage. Use of synthetic insecticides to reduce activity of Af is a common practice but with attendant environmental hazards. Knowledge of Af Life Stages (LS) and its relationship with other IP on SFC are required for safe and effective control, however, specific information on its biology and safe management are scanty. Thus, the bioecology and management of Af on DC of selected SFC were investigated. Dried Chips (5kg each) of cassava, potato, Water Yam (WaY), White Yam (WhY) and plantain were collected in different markets in Osun, Oyo, Ondo, Kwara and Ekiti states where SFC were predominant to assess occurrence and abundance of IP using standard procedures. The LS of Af on different DC was assessed using standard procedures. Developmental Period (DP, days), Number of Eggs Laid (NEL), Adult Longevity (AL, days), morphometrics of adults (mm) were recorded. Management of Af on DC by blanching with mixture of fermented maize water (mL), water (mL) and lime (mL) in varying concentrations to obtain, T1 (250.0+747.5+2.5), T2 (250.0+745.0+5.0), T3 (250.0+742.5+7.5), T4 (250.0+740.0+10.0); controls comprised T5 (250.0+750.0+0.0) and T6 (0.0+1000.0+0.0), respectively were laid out in complete randomised design (r=4). The AL, DP and WL (g) of DC were determined using standard methods. Diversity of emerged IP was assessed using Shannon-Wiener (H`, low=0- 0.9; high=1-4.6) and evenness indices (low=0; high=1). Data were analysed using descriptive statistics and ANOVA at α0.05. Araecerus fasciculatus (93.22±3.14), Dinoderus minutus (74.89±1.62) and Prostephanus truncatus, (71.33±1.42), occurred as most abundant IP on DC across states. Araecerus fasciculatus had seven life-stages: egg, four larva-instars, pupa and adult. The DP of Af on plantain, potato, cassava, WhY and WaY were 42.25±1.44, 45.50±2.06, 47.00±0.91, 49.75±0.91 and 52.75±2.87, respectively. The NEL by Af was in order 100.00±3.24 (WhY) > 94.00±4.42 (WaY) > 62.00±4.05 (cassava) > 58.00±4.05 (plantain) and > 53.00±7.46 (potato). The AL on DC were 105.0 (WaY), 99.5 (WhY), 91.5 (Potato), 88.5 (cassava) and 66.5 (plantain). Male length and width were 2.74-3.89 and 1.06-1.28, while female length and width were 3.82-3.88 and 1.76-1.86. The AL (105.00±3.87) of WaY treated with T5 was significantly longer (31.75±1.18) than cassava treated with T4. The DP was longest (78.25±0.85) on WhY treated with T4 and significantly higher (42.25±1.93) than cassava treated with T5. The plantain DC treated with T5 had highest WL (37.13±1.10) and was significantly higher (0.34±0.10) than potato DC treated with T4. The H` and evenness indices ranged from 0.00-2.01 and 0.63-1.00, respectively. Araecerus fasciculatus was the major insect pest of dried chips in Nigeria with developmental period spanning 42 to 52 days. Blanching with mixture of 740 mL water with 250 mL fermented maize water and 10 mL lime protected dried chips and can be utilized for an effective management of Araecerus fasciculatus.