The effect of parasitism on the population dynamics of the macadamia nutborer Gymnandrosoma aurantianum (Lepidoptera: Tortricidae).

Biological control on crop infesting insects represent an useful method in modem agriculture. A search for parasitoids of the macadamia nutborer was carried out during a three year study, and their effect on the population fluctuation of the borer was determined. An egg parasitoid belonging to the family Trichogrammatidae and four larval parasitoids, Microgastrine I, Microgastrine II, Ascogaster sp.

Within-tree distribution of Ecdytolopha torticornis (Lepidoptera: Tortricidae) oviposition on macadamia nuts.

Vertical distribution of eggs of the macadamia nutborer Ecdytolopha torticornis Meyrick (Lepidoptera: Tortricidae) and its preference of oviposition sites within and between macadamia cultivars were studied in Turrialba, Cartago, Costa Rica, in 1992 (N = 6,939). E. torticornis eggs were found throughout the foliar parts of the tree, but fewer eggs were laid in the crown top than in the mid or lower crown.

Blue adaptation: an experimental tool for the study of visual receptor mechanisms and behaviour of Drosophila.

Physiological and behavioural studies with Drosophila to elucidate visual mechanisms have exploited the bi-stability of the visual pigment in the peripheral retinula cells R1-6, and the 'off-on switch' action of blue and orange light. Measurements of flicker fusion and response waveform from both receptor and lamina regions prior and subsequent to blue adaptation, which induces a prolonged depolarising afterpotential and loss of visual function in R1-6, show these retinula cells to have a high fusion frequency and R7/8, the central retinula cells, a lower fusion frequency. Such measurements also allow analysis of the extracellular response in terms of contributing cells, and its potential for studying the fly's ability to respond to various potential visual cues such as a rotating plane of polarised light.