Abstract:
Rodents are the greatest vertebrate pest problem in developing countries causing substantial damage to structures, food, crops, industrial and domestic property. They also act as reservoirs and vectors of zoonotic diseases. The current method for controlling rodents is the use of rodenticides which are toxic to non-target organisms, pollutants to environment and trigger resistance. In an effort to find eco-friendly alternatives to synthetic rodenticides, reproductive inhibition of Ricinus communis and Azadirachta indica seed oils were evaluated in albino female mice. Seed oils of A. indica and R. communis were extracted from mature dried seeds by cold pressing and boiling respectively and chemical compositions were determined using Gas Chromatography (GC)-Mass Spectrometry (MS). The constituents of both seed oils were dominated by saturated and unsaturated fatty acids, cyclic esters and methyl esters. The predominant constituents of R. communis were (Z)-6-Octadecenoic acid (37.33%), Ricinoleic acid (30.22%) and 13-Hexyloxacyclotridec-10-en-2-one (26.67%) while those of A. indica were 2-hexyl-1-decanol (30.97%), Octadecanoic acid (29.69%) and Oxalic acid, 6-ethyloct-3-yl ethyl ester (15.55%). Mature fertile female mice received A. indica and R. communis seed oils at doses (0.0-0.8 ul/kg body weight) for 14 days. The experimental design was a randomized block design (RBD) with six replicates of mice per treatment. Data on mating success was analyzed using Chi-Square Test while oestrous cycle, fertility index, gestation period, litter size and weekly body weight were analyzed using one-way analysis of variance (ANOVA). Data on percentage fertility and anti-implantation were corrected for homogeneity of variances using arcsine-transformation before being subjected to one-way ANOVA. Azadirachta indica and R. communis seed oils caused disruption of the oestrous cycle by increasing the frequency of diestrus and metestrus phases. At higher doses A. indica and R. communis seed oils reduced mating success to 67% and 83% respectively with a similar significant reduction in fertility index at 17% compared to the negative control. At a dose of 0.4ul, A. indica and R. communis seed oils caused a significantly prolonged gestation period of 24.33±0.33 and 23.33±0.33 days with reduced litter size of 3.33±0.33 and 2.67±0.88 young ones respectively. Subsequently, at higher dose none of the mice littered compared to the negative control. At concentrations of 0.6ul and 0.8ul, A. indica and R.communis showed anti-implantation activity of 100% compared to the negative control. Therefore A. indica and R. communis seed oils reduce rodent population and can be used as potential rodenticides.
