RESUMEN
Experiments were conducted on 20 fourth instar Anopheles stephensi larvae to explore behavior organisation. Twenty fourth instar larvae were placed in a glass aquarium and filmed using a handy cam video recorder and the recordings analysed in a laptop computer. Data of transitions from one behavior to another for all observations were collated into a matrix of preceding and succeeding behaviors to study sequential organisation and relationship among behaviors. Significant testing for first-order transition was done using G test at P< 0.005 and a kinematic graph constructed from significant transitions. A time budget and transition frequency data constructed for each behavior were subjected to cluster analysis to explore relationship between the behaviors. Result of the analysis showed that fourth instar Anopheles stephensi larvae behaviors occur in clusters in specific locations in their aquatic environment. Furthermore, the sequential organisation of behaviors is influenced by behavior frequency and the amount time a larva spent doing that behavior. When food is kept constant, other factors such as gas exchange requirements, behavior variation due to day-night cycle, presence of a predator, interlarval competition for food and the size of the aquarium (depth and width) maybe determining behavior organization.
RESUMEN
Intertidal snail-trematode communities in southern Thailand were examined before and after the South Asia tsunami. Infection rates and species diversity of cercaria in the host snail Cerithidea in tidal zones did not change significantly from one year before to one month after the tsunami. However, the host snails C. quadrata, C. alata and C. obtusa disappeared from greatly damaged sites. It is important to follow up on the intertidal snail-trematode community recovery process after destruction of the intertidal ecosystem.