Moth sensitivity, effects

Copper is toxic to sensitive species of terrestrial vegetation at >40 pg/L nutrient solution (seedlings of pines, Pirns spp.), at >10 mg/kg DW leaves (cucumber, Cucumis sativus), and >60 mg extractable Cu/kg DW soil (sweet orange, Citrus sinensis Table 3.4). Among sensitive species of terrestrial invertebrates, adverse effects on survival, growth, or reproduction occur at 2 pg Cu/cm2 on paper discs (earthworms), >50 mg Cu/kg diet (larvae of gypsy moth, Lymantria dispar), and 53 to 70 mg Cu/kg DW soil (earthworms and soil nematodes Table 3.4). 

Pheromones are powerful modulators of insect behavior. Since the isolation and identification of the first pheromone, (10E, 12Z)-hexadec-10,12-dien-l-ol, the sex attractant of the silk moth Bombyx mori, thousands of other insect pheromones have been identified. Our understanding of the sensory apparatus required for pheromone detection has also increased significantly. Coincidentally, B. mori was instrumental in many of these advances (see below). Volatile pheromones are detected by a specialized olfactory system localized on the antennae. The precise recognition of species-specific nuances in the structure and composition of pheromone components is essential for effective pheromone-based communication. The pheromone olfactory system of species studied so far exhibits remarkable selectivity towards the species-specific pheromone blend. Pheromones are emitted in low (fg-pg) quantities and are dispersed and greatly diluted in air plumes. Thus, pheromone olfaction systems are among the most sensitive chemosensory systems known. (Schneider et al., 1968). This chapter summarizes efforts (particularly over the past 10 years) to understand the molecular basis for the remarkable selectivity and sensitivity of the pheromone olfactory system in insects. The chapter will also outline efforts to design compounds that interfere with one or more of the early events in olfaction. 

At least as important as the live enemies is another enemy - the weather. The young caterpillars - especially those of the first generation - are highly sensitive to climatic variations. Rain, a drop in temperature or a strong wind after the caterpillars hatch is almost always fatal for the caterpillars. Cool and wet springs or summers can drastically reduce the codling moth risk. The effect of climate is thus much greater than that of natural enemies. 

For a low olfactory threshold several sensory functions need to be optimized. Odour molecules have to be a) effectively caught by the antenna from the air space, and b) conducted with little loss to the olfactory receptor neurons, c) The odour stimulus has to be most sensitively transduced into nerve impulses, and d) the stimulus-induced impulse firing has to be distinguished from the background of spontaneous impulse discharge from the unstimulated receptor neurons. This paper reviews quantitative work on these items in the male moth of a species which is attracted (i.e. stimulated to walk upwind, Kaissling 1997) by a single chemical pheromone component, (E,Z)-10, 12-hexadecadienol (bombykol) released by the female moth (Butenandt et al. 1959). 

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