Abstract:
Arthropod succession on decomposing pigs (Sus scrofa L.) at Federal University of Technology, Akure, Ondo State, Nigeria ,was investigated and in this study, the specific objectives were to identify the different insect species and other arthropods observed on carcasses using a pig model and their numbers, describe the different stages of decomposition of pig in wet and dry seasons and determine the influence of seasons on insect succession pattern at Federal University of Technology, Akure, Ondo State.
A total of six 3- month old pigs, weighing between 12.6kg and 13 kg were used . Three pigs were tagged A, B, C and used as replicates in each season. The pigs were killed by cervical dislocation to minimize bleeding and pain to the animal. At the study site, the pig carcasses were placed each in a prepared cage at the three prepared locations at 100 m apart. Each cage measured 80 x 60 x 75 cm with 4 cm2 mesh. Each carcass of the pigs were visited twice a day and sampling of adult insects and arthropod was done including fly eggs and maggots until the carcasses reached skeletonization stage. Internal temperature, soil temperature, pig/soil interface temperature, relative humidity were recorded during the whole experiment using a calibrated mercury thermometer while rainfall was measured with raingauge during the two seasons. Results showed that a total of 496 arthropods were collected during the dry season while a total of 313 arthropods were collected during the rainy season.In the succession pattern, dipterous insects of the families Calliphoridae, Sarcophagidae, Muscidae, Nabidae, Formicidae, Staphylinidae, Acrillidae, and Alydidae, oviposited and fed on the carcasses. Their breeding biology led to the breakdown and exposure of the carcasses’ soft tissue to other groups of arthropods. There was variation in the rate of decomposition during the two seasons, pig carcasses in the dry season attained skeletonization or dry stage of decay on the 16th day while pig carcasses during the rainy season attained skeletonization or dry stage of decay on the 24th day . Pigs could be used when investigating the rate of decomposition and arthropod succession on carcass because of their close physiology with human and they are reasonable alternative to human bodies. Further studies should however, be carried out in order to know some micro-organisms that are involved in decomposition of pigs in different seasons.
