Abstract
Despite of the economic importance of the olive fly (Bactrocera oleae) and the large amount of biological and ecological studies on the insect, the factors driving its population dynamics (i.e., population persistence and regulation) had not been analytically investigated until the present study. Specifically, our study investigated the autoregressive process of the olive fly populations, and the joint role of intrinsic and extrinsic factors molding the population dynamics of the insect. Accounting for endogenous dynamics and the influences of exogenous factors such as olive grove temperature, the North Atlantic Oscillation and the presence of potential host fruit, we modeled olive fly populations in five locations in the Eastern Mediterranean region. Our models indicate that the rate of population change is mainly shaped by first and higher order non-monotonic, endogenous dynamics (i.e., density-dependent population feedback). The olive grove temperature was the main exogenous driver, while the North Atlantic Oscillation and fruit availability acted as significant exogenous factors in one of the five populations. Seasonal influences were also relevant for three of the populations. In spite of exogenous effects, the rate of population change was fairly stable along time. We propose that a special reproductive mechanism, such as reproductive quiescence, allows populations of monophagous fruit flies such as the olive fly to remain stable. Further, we discuss how weather factors could impinge constraints on the population dynamics at the local level. Particularly, local temperature dynamics could provide forecasting cues for management guidelines. Jointly, our results advocate for establishing monitoring programs and for a major focus of research on the relationship between life history traits and populations dynamics.
Highlights
Despite of the economic importance of Tephritidae fruit flies (“true fruit flies”), the factors governing their population dynamics have seldom been subject to in-depth analytical investigation
Aluja et al.’s study [6] contributed to our understanding of fruit fly population dynamics, the diversity of natural histories and ecologies encountered among fruit fly species, their broad geographic distribution and their economic importance have led fruit-fly ecologists to continued efforts to expand upon the current understanding of the population dynamics of this family of insects
Together with local weather conditions, we focused our analysis on the potential effects of the North Atlantic Oscillation (NAO), a global climatic indicator that has been shown to affect the population dynamics of Anastrepha fruit fly species [6] and recognized as an important factor affecting plant and animal populations in the Mediterranean region [39,40,41]
Summary
Despite of the economic importance of Tephritidae fruit flies (“true fruit flies”), the factors governing their population dynamics (i.e., population persistence and regulation) have seldom been subject to in-depth analytical investigation. Most insect populations express what is classically termed direct density-dependence dynamics [7,8,9,10]. Few studies have attempted to shed light on the effects of these factors on the population dynamics of fruit flies through the use of modern analytical tools. Aluja et al [6] published a comprehensive report on the population dynamics of three Tephritidae species of Anastrepha in the area of Veracruz, Mexico and related fluctuations in those populations to direct density-dependence and seasonal feedback processes. Their study demonstrated the importance of the effects of exogenous factors on the population dynamics of the three oligophagous and polyphagous species, as well as the effect of global climatic processes on the uncertainty inherent in predictions of population trends at a local and regional level. Aluja et al.’s study [6] contributed to our understanding of fruit fly population dynamics, the diversity of natural histories and ecologies encountered among fruit fly species, their broad geographic distribution and their economic importance have led fruit-fly ecologists to continued efforts to expand upon the current understanding of the population dynamics of this family of insects
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