Effect of Fusarium, Paecilomyces and Trichoderma formulations against aphid Schizaphis graminum.

Fungal strains belonging to the genera Fusarium, Paecilomyces and Trichoderma were tested in vitro in order to study their effects against Schizaphis graminum, one of the major pests of cereal crops around the world. Biological assays were performed using a solid formulation that was obtained from fungal cultures grown on rice and then finely ground (<0.2 mm). The occurrence of toxic secondary metabolites (fumonisin B1 and beauvericin) produced by these fungi was also investigated. In each experiment, three groups of aphids: 15-hour old larvae, 5-day old nymphs with wing buds and wingless morphs were treated with a suspension of a fungal formulation. Some strains belonging to the genera Fusarium and Trichoderma significantly controlled the specimens of the three groups of S. graminum. The F proliferatum strain ITEM 1407, producing a high level of fumonisin B1 in the culture (1250 microg/g), and F larvarum strain ITEM 2139 had high insecticidal activity (>60%) within 10 minutes after application. As F. larvarum ITEM 2139 did not produce metabolites toxic to mammals, it might be a good candidate as a biocontrol agent of S. graminum in the field.

Cell-specific effects of lead on cultured neurons of the freshwater snail Planorbarius corneus.

Cultures of isolated neuronal populations from the central ganglia of the gastropod mollusc Planorbarius corneus were used for testing the effects of inorganic lead. The examined parameters were cell survival, neurite outgrowth and cytoskeletal morphology. In large heterogeneous neuronal populations as obtained from a whole cerebral or pedal ganglion, the different sensitivity to lead is reflected mainly on the cell survival. The neurons belonging to the homogeneous E cluster population are more sensitive; in fact a higher percentage of them do not survive in the presence of lead. Moreover, in this neuronal cell type the neurite outgrowth is dramatically affected by lead only when the neurons are cultured on conditioned substrate. Possibly, membrane mechanisms activated for the neurite outgrowth represent a target for inorganic lead. The few neurites sprouted in presence of lead do not evidence changes in the cytoskeletal components.