Post-larvae movement network of marine shrimp during the 2013 outbreak of acute hepatopancreatic necrosis disease in Thailand

Abstract

This study aimed to assess the movement patterns of post-larvae (PL) of whiteleg shrimp and black tiger shrimp, which were linked to the epidemic of acute hepatopancreatic necrosis disease (AHPND) in Thailand in 2013, using social network analysis. Hatcheries or nurseries were assigned as origin nodes, whereas cultivated ponds were designated as destination nodes. From 376 farms, data of 1300 ponds were collected from network data using a questionnaire. We found that 1477 nodes with 1315 ties appeared in this study. These were divided into a network of cases and controls that presented 538 nodes with 436 ties and 1013 nodes with 879 ties, respectively. The top four out-degree centrality values in the entire partial network, cases, and controls were used to analyze ego-alter similarity. The results showed that each PL provider played a different role in the association with the disease sender. A simulated network using exponential random graph models presented edges as a significant microstructure. In addition, our analysis indicated that the hatchery or nursery (PL provider) is an important node for AHPND occurrence. In conclusion, this study led us to understand the source of PL, which plays a key role in the surveillance, prevention, and control of AHPND.

Keywords: Acute hepatopancreatic necrosis disease; Movement; Post-larvae; Social network analysis; Thailand.