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Skip oviposition is considered as an example of spatial bet hedging and involves a tradeoff between the benefit of reducing the risk of complete reproductive failure due to stochastic loss of a bre...

In phlebotomine sand fly, the topic of the factors stimulating or inhibiting egg hatching has been largely ignored. In this study, we evaluated the hypothesis that pharate neonate sand flies are able to regulate their hatching time adaptively in response to cues indicative of the presence of food or potential competitors. In this study, we evaluated the independent and combined effects of organic matter (OM) extract and proximity to conspecific eggs on the hatching proportion of Phlebotomus papatasi eggs. In one set of larval rearing jars, we introduced 16 eggs into a small hole in the center of a plaster base of the jar. In another set, we introduced a single egg into each small hole of a 4-by-4 symmetrical array. To one set, we added an aqueous OM extract, and to the other, we added deionized water (DI). OM stimulated egg hatching while egg clustering slightly inhibited egg hatching. Results of this experiment are biologically important because they show, for the first time, that pharate sand fly neonates are able to adaptively regulate their hatching time in response to external cues.

Populations at the edge of their geographic distributions are referred to as peripheral populations. Very little attention has been given to this topic in the context of persistence of infectious disease in natural populations. In this study, we examined this question using zoonotic cutaneous leishmaniasis (ZCL) caused by Leishmania major in the Negev Desert of Israel as a model system. Here, we suggest that the regional persistence of Phlebotomus papatasi populations and L. major transmission in the Sede Boqer region could be explained through processes akin to sink-source and/or mainland-island metapopulation dynamics. Given its potentially enzootically superior ecological conditions, we hypothesize that the Zin Valley ecotope constitutes the “mainland” or the “source” patch for the Sede Boqer area where L. major transmission is persistent and resistant to local extinctions (die-outs) whereas the local sand fly populations on the Zin Plateau (“island patch” or “sink patch”) are more prone to local extinctions. Between 2007 and 2008, we trapped sand flies and sand rats in the two areas and compared sand fly abundance and L. major infection prevalence in both. In both 2007 and 2008, sand fly abundance was high and continuous in the Zin Wadi but low and discontinuous in the Zin Plateau. Infection prevalence of sand rats was significantly higher in the Wadi (13%) compared with the Zin Plateau (3%). Minimum infection rate in sand flies did not differ significantly between the two areas. Overall, our results are consistent with the premise that the Zin Valley population is relatively robust in terms of L. major transmission, whereas transmission is potentially more tenuous in the plateau. Understanding the biotic and abiotic processes enabling the persistence of L. major and other vector-borne diseases in peripheral disease foci is important for predicting the effect of anthropogenic land use and climate change.