Assessment of Damage and Evaluation of Botanicals for Control of Millipede, SpirostreptusassiniensisAttems (Diplopoda) on Yam Tuber (DioscorearotundataPoir)

Millipede is an important soil pest of yam tuber in Benue State, Southern Guinea savannah ecological zone, Nigeria. Damage by the millipede, S. assiniensis on yam tuber was assessed under ambient laboratory temperature of 25°C and 73 2% RH. Adult millipedes were introduced to their substrate in cages with moist soil and observed for exposed period of 24 hrs, 48 hrs, 72hrs, 7days, 14 days and 21 days. Parameters assessed were number, depth and size of feeding holes on yam tubers. Field experiments were also conducted in the 2007 and 2008 wet seasons to evaluate the efficacy of three botanical powders on the arthropod pest and to compare the powders with the synthetic insecticide check. The treatments were replicated four times in randomized complete block design. The botanicals were applied at the rate of 5g/mound at 14 WAP and 16 WAP at the period of new tuber formation. The parameters evaluated were number, depth and diameter of feeding holes. Data collected were subjected to Analysis of Variance using SAS Model 2000 version (8) and means were separated using the least significance difference (LSD) at p=0.05. The Laboratory result showed significant (p < 0.05) increase in the number and depth of feeding holes bored in the tubers by the millipede at 14 and 21 days of exposure. The result from the field experiment showed that Parkia biglobosa husk powder, Azadiracha indica (A) juss leaf and seed powder significantly (p < 0.05) reduced the number,depth and diameter of feeding holes created by millipede on tubers compared with untreated tubers. However, A. indica leaf powder was the best treatment.This is the first report on the use of botanicals for control of millipede (Diplopoda).