Spatial heterogeneity of Anastrepha ludens populations over a large citrus region including a sterile insect release area in northeastern Mexico

Abstract

We analyzed Anastrepha ludens (Loew) (Diptera: Tephritidae) populations for 2 years (2008–2009) over the most important area of citrus-growing in Tamaulipas, Mexico. This study aimed to characterize the spatial heterogeneity of A. ludens populations between areas with and without the release of sterile flies. The analyses include high populations of the pest during two periods per year: Valencia orange and grapefruit production. Populations were spatially characterized by using the geostatistical method indicator kriging integrated to a geographic information system. Through indicators as the upper quartile, the spatial-variation of the populations was ranked into four categories of probability to exceed the settled threshold: 0–25, 25–50, 50–75, 75–100%. Models indicated that spatial heterogeneity of A. ludens between 2008 and 2009 showed changes according to the citrus production period. In 2008, spatial distribution was more homogeneous across the region, but in 2009 in spite of higher populations than in 2008, a spatial heterogeneity was observed for the two periods of citrus production. Probability tendencies of high densities (>50%) of the pest were observed towards the west, while eastwards, where the release area was located, lower probability (<50%) was indicated. A more homogeneous density level of the pest was plotted on the release area in 2009, in contrast with the area without sterile fly release. This contribution supports an impact of the sterile insect technique and promotes use of spatial analysis tools for analyzing pest populations at regional scale in northeastern Mexico.