Influence of Vitellaria Paradoxa Gaertn Depletion on the Incidence, Abundance and Distribution of Cirina Forda Westwood (Lepidoptera: Saturniidae) in Niger State, Nigeria

Abstract

The pallid emperor moth, Cirina forda, is a prominent edible insect in Niger State but currently at great risk of extinction. The incidence, abundance and distribution of Cirina forda, was investigated for four consecutive seasons, i.e. May-June 2010, 2011, 2012 and 2013 to ascertain the effect of the depletion of its host plant, Shea butter trees, Vitellaria paradoxa. in Niger State, Nigeria. C. forda egg clusters located on the host plants were enumerated to ascertain the seasonal abundance by visual counting using hand lenses and binoculars (MARCO-model 750/8 m-988000 m). At each location, 100m2 land area in which three 10m2 portions were mapped as replicate sites, were investigated for host plant density, egg cluster abundance and distribution within three host plant canopy height ranges. The 41 locations in six Local Government Areas (LGAs) where C. forda occurred in Niger State in 2010 were investigated. The result indicated the GPS of each of the locations and showed that Niger state had a very rich but fast dwindling population of V. paradoxa. C. forda egg cluster abundance across the six LGAs showed Niger state as highly endowed but ephemeral and highly unpredictable, especially in terms of location where they occurred. The egg cluster abundance reduced drastically from 58.1± 12.1 and 56.1±24.1 egg cluster/host plant in 2010 and 2011, respectively to 41.3 ± 8.3 and 29.7 ±5.1 egg cluster/host plant in 2012 and 2013 cropping seasons, respectively. Locational similarities were observed in the trends of C. forda host plant density reduction and egg cluster abundance over the four cropping seasons and these were corroborated across the State. The decreasing densities of Shea butter trees was identified as posing serious threats to egg laying by C. forda. The possibility of the extinction of C. forda was identified as imminent and a conservation approach that stems the indiscriminate destruction of host tree, V. paradoxa (Shea butter trees) was proposed.