African water storage pots for the delivery of the entomopathogenic fungus Metarhizium anisopliae to the malaria vectors Anopheles gambiae s.s. and Anopheles funestus.

We studied the use of African water storage pots for point source application of Metarhizium anisopliae against the malaria vectors Anopheles gambiae s.s. and An. funestus. Clay pots were shown to be attractive resting sites for male and female An. gambiae s.s. and were not repellent after impregnation with fungus. M. anisopliae was highly infective and virulent after spray application inside pots. At a dosage of 4 x 10(10) conidia/m(2), an average of 95 +/- 1.2% of An. gambiae s.s. obtained a fungal infection. A lower dosage of 1 x 10(10) conidia/m(2) infected an average of 91.5 +/- 0.6% of An. gambiae s.s. and 91.8 +/- 1.2% of An. funestus mosquitoes. Fungal infection significantly reduced mosquito longevity, as shown by differences between survival curves and LT(50) values. These pots are suitable for application of entomopathogenic fungi against malaria vectors and their potential for sustainable field implementation is discussed.

Large-amplitude oscillations and chaos in a Hamiltonian plasma system with many degrees of freedom.

Taking the beam-plasma system as a reference Hamiltonian system with many degrees of freedom, the connection between the development of large amplitude oscillations and stochasticity of the system (measured through the time-dependent maximum Lyapunov exponent) is investigated. It is found that the development of self-consistent large amplitude oscillations occurs in correspondence with the onset of chaos, and is related to a well defined change of topology of the phase space of the system. It is also shown that in a (Hamiltonian) linearly stable regime the development of large amplitude oscillations can occur when weakly dissipative processes are introduced.