Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/2013
Publication Date: 10/15/2013
Citation: Vargas, R.I., Stark, J.D., Banks, J., Leblanc, L., Manoukis, N., Peck, S. 2013. Spatial dynamics of two oriental fruit fly (Diptera: Tephritidae) parasitoids, Fopius arisanus (Sonan) and Diachasmimorpha longicaudata (Ashmead)(Hymenoptera: Braconidae), in a guava orchard in Hawaii. Environmental Entomology. 42(5):888-901. DOI: 10.1603/EN.2013-12274. Interpretive Summary: This paper describes the results of a study on the two parasitoids of the tephritid fruit fly Bactrocera orientalis. The changes in the numbers of each of the sexes of these three species over two years is considered, and show that the fruit fly begins dispersed around the guava field but ultimately settles into a clumped distribution as the fruit ripens. The parasitoids rise in numbers successively. There was a two to four week lag between the highest numbers of the fruit fly host and F. arisanus (one of the parasitoids), but this was not seen for D. longicaudata (the other parasitoid). Spatially, there was evidence that F. arisanus is moves less- there was a statistically significant pattern of density over space for this species, but not for the other two.
Technical Abstract: We examined temporal and spatial patterns of both sexes of Bactrocera dorsalis (Hendel) and its two most abundant parasitoids, Fopius arisanus (Sonan) and Diachasmimorpha longicaudata (Ashmead) in a commercial guava orchard. Bactrocera dorsalis spatial patterns were initially random, but became highly aggregated with host fruit ripening and the subsequent colonization of first, F. arisanus (egg-pupal parasitoid) and secondly, D. longicaudata (larval-pupal parasitoid). Populations of all three insects were never significantly correlated together within a specific time interval. However, there was a significant positive relationship between populations of B. dorsalis and F. arisanus during each of the F. arisanus increases, a pattern not exhibited between B. dorsalis and D. longicaudata. Generally, highest total numbers of males and females (B. dorsalis, F. arisanus, and D. longicaudata) occurred on or about the same date. There was a significant positive correlation between male and female populations of all three species; we measured a lag of 2-4 wk between increases of female F. arisanus and conspecific males. There was a similar trend in one of the two years for the second most abundant species, D. longicaudata, but no sign of a time lag between the sexes for B. dorsalis. Spatially, we found a significant positive relationship between numbers of F. arisanus in blocks and the average number in adjoining blocks. We did not find the same effect for B. dorsalis and D. longicaudata, possibly a result of lower overall numbers of the latter two species or less movement of F. arisanus within the field.