Relationship of Schistonchus caprifici (Aphelenchoididae) with fig inflorescences, the fig pollinator Blastophaga psenes, and its cleptoparasite Philotrypesis caricae

Abstract

The association of the nematode Schistonchus caprifici, the pollinator wasp Blastophaga psenes, and its cleptoparasite Philotrypesis caricae was studied in winter, spring and summer inflorescences (syconia) of caprifig trees (Ficus carica var. sylvestris) in southern Italy. This is the first report of a Schistonchus sp. associated with a cleptoparasite wasp. All the life stages of S. caprifici were found in the hemocoel of the winged females of B. psenes and of P. caricae. No association was observed with the wingless males of both wasps. For both these two fig wasps, the number of winged females transporting the nematode was greater in June than in March. However, the percentage of P. caricae wasps carrying S. caprifici was 50% (March) and 20% (June) smaller than that of B. psenes. The range of nematode number carried by each winged female was 1-3 and 1-23 for P. caricae and 1-4 and 1-116 for B. psenes in March and June, respectively. Morphometrics of entomogenous (originating from both wasps) and phytophagous females of S. caprifici did not differ. Histological examination of staminate caprifig florets infected by phytophagous specimens of S. caprifici revealed nematodes colonies inside and outside the clusters of anthers and anther filaments. Nematode feeding caused necrosis of epidermis and cortical parenchyma of anther filaments and the formation in the anthers of hypertrophied epidermal cells with darkly stained cytoplasm.