Global assessment of seasonal potential distribution of Mediterranean fruit fly, Ceratitis capitata (Diptera: Tephritidae)

Abstract

The Mediterranean fruit fly (Medfly) is one of the world's most economically damaging pests. It displays highly seasonal population dynamics, and the environmental conditions suitable for its abundance are not constant throughout the year in most places. An extensive literature search was performed to obtain the most comprehensive data on the historical and contemporary spatio-temporal occurrence of the pest globally. The database constructed contained 2328 unique geo-located entries on Medfly detection sites from 43 countries and nearly 500 unique localities, as well as information on hosts, life stages and capture method. Of these, 125 localities had information on the month when Medfly was recorded and these data were complemented by additional material found in comprehensive databases available online. Records from 1980 until present were used for medfly environmental niche modeling. Maximum Entropy Algorithm (MaxEnt) and a set of seasonally varying environmental covariates were used to predict the fundamental niche of the Medfly on a global scale. Three seasonal maps were also produced: January-April, May-August and September-December. Models performed significantly better than random achieving high accuracy scores, indicating a good discrimination of suitable versus unsuitable areas for the presence of the species.

Figure 1. Occurrence data for Ceratitis capitata used in the study.

Data with information about the month of occurrence is marked with red triangles. Countries/regions where Medfly is present are coloured with yellow and where it is eradicated are marked with green , .

Figure 2. Global environmental suitability for C. capitata occurrence as predicted by MaxEnt model.

Black triangles represent presence points used in the modeling. Blue, purple and red colors show high confidence in predicted suitability, while yellow represents low confidence and predicted absence.

Figure 3. 3-panel seasonal maps showing the environmental suitability for C. capitata occurrence annually according to the MaxEnt model.

Dots represent the seasonal presence points used in the seasonal potential niche modelling. Blue, purple and red colors show high confidence in predicted suitability, while yellow represents low confidence and predicted absence.