Domatia reduce larval cannibalism in predatory mites

1. Acarodomatia are small structures on the underside of leaves of many plant species, which are mainly inhabited by carnivorous and fungivorous mites. 2. Domatia are thought to protect these mites against adverse environmental conditions and against predation. They are considered as an indirect plant defence; they provide shelter to predators and fungivores and these in turn protect the plants against herbivores and fungi. 3. We studied the possible role of domatia of coffee (Coffea arabica L.) (Rubiaceae) and sweet pepper (Capsicum annum L.) (Solanaceae) in reducing cannibalism in the mites inhabiting the domatia. We measured cannibalism of larvae by adults of the predatory mites Iphiseiodes zuluagai Denmark & Muma and Amblyseius herbicolus Chant on coffee leaf discs and of the predatory mite Iphiseius degenerans (Berl.) on sweet pepper leaf. Domatia were closed with glue or left open. 4. Cannibalism in all three species increased when domatia were closed. With I. degenerans, moreover, we found that the previous diet of the cannibal attenuated the effect of domatia on cannibalism. 5. We conclude that domatia can protect young predatory mites against cannibalism by adults and that the diet of cannibals affects the rate of cannibalism

A systematic survey of floral nectaries

The construction of classifications, as well as the understanding of biological diversity, depends upon a careful comparison of attributes of the organisms studied (Stuessy, 1990). It is widely known that data from diverse sources showing differences from taxon to taxon are of systematic significance. Dur-ing the 20th century, systematists have emphasized that their discipline involves a synthesis of all knowledge (Stevens, 1994) or, in other words, the variation of as many relevant characters as possible should be incorporated into the natural system to be constructed. The extent to which particular characters are constant or labile will determine their usefulness to syste-matics. In general, more conservative characters will be valuable in defining families and orders, whereas more labile characters may be useful at the ge-neric and specific levels (Webb, 1984). There is no doubt that floral characters are among the most used in the classification of flowering plants. At the same time, they constitute essential features in diagnostic keys to taxa in both taxonomic treatments and Floras (Cronquist, 1981, 1988).Fil: Bernardello, Gabriel Luis Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentin