Evaluation of sampling techniques for millipedes

Abstract

Reports of Crop damage by millipedes are widespread and attacks by this pest are sporadic, unpredictable and arise from populations, which built up previously. A good sampling technique is a useful tool in monitoring pest populations for effective management. Four techniques were compared to determine the most effective in sampling the population of two polyphagous millipede species (a) Spirostreptus assiniensis (Diplopoda: Spirostreptidae) and (b) Tibiomus species (Diplopoda: Odontopygidae). The four techniques were (i) Soil excavation by spade (ii) search through plant litters (iii) use of cassava root baits (iv) use of plant litters over cassava roots. Sampling was done on monthly basis for 12 months. Results showed that all the four techniques were effective in sampling millipedes. However, technique (iv) sampled significantly (P < 0.05) higher (34.7% and 53.0%) numbers of millipedes (a) and (b) respectively. Techniques (i), (ii) and (iii) sampled 17.8% and 6.7%; 21.9% and 14.6%; 25.6% and 25.6% respectively of millipedes (a) and (b). Technique (i) appeared to be ideal for the dry season and during high temperatures when these diplopods move into the lower layers of the soil to avoid desiccation. Techniques (ii), (iii) and (iv) appeared appropriate for wet season sampling as the millipedes prefer the top soil during this period to avoid waterlogged condition or excessive moisture. The four techniques derived from the natural habitat, food needs, suitable conditions of temperature and moisture dictated by time of sampling.

Key words: Millipedes; Spirostreptus assiniensis; Tibiomus sp.; sampling techniques

Moor Journal of Agricultural Research Vol.4(2) 2003: 230-235