Pheromones Management for Gardeners
This article is about pheromones management for gardeners. In each species for which pheromone release and pheromone responsiveness have been examined separately, these two phenomena correspond closel...
This article is about pheromones management for gardeners. In each species for which pheromone release and pheromone responsiveness have been examined separately, these two phenomena correspond closely in timing. For species that use sex pheromones to communicate over long distances. it would seem reasonable to assume the exact time of mating would be determined by the releasing sex. The process of pheromone release presumably initiates the premating communication sequence. Thus, when female cabbage loopers maintained on one time-of-day schedule were paired with males entrained to a light dark periodicity four hour out of phase, the mating time approximated that expected by the female cycle (Shorey 1966).
The mechanism controlling the time of occurrence of sex pheromone communication has been examined in several species of Lepidoptera (Mediterranean flour moth, Anagasta kiihniella (Zeller) (Traynier 1970b), oriental fruit moth, Graphomha molesta (Busck) (George 1965), cabbage looper moth (Shorey and Gaston 1965 Sower et al. 1970, 1971)). A circadian rhythm of pheromone-behavior has been found in each of these species. The phase of the rhythm is reset each day, occurring at some specific time with relation to the light: dark periodicity in the absence of the normal entraining light : dark cues, the rhythm reoccurs at an approximately 24-hr periodicity. Furthermore, in studies of the time of pheromone release by females of the Mediterranean flour moth, or the time of pheromone responsiveness by males of the cabbage looper moth or the Mediterranean flour moth, when the timing of the light : dark cycle was abruptly shifted by 12 hr, the timing of the behavioral rhythm became re-entrained, to its ‘normal’ phase with relation to the new cycle within 48 hr. This is influenced by long-range pheromone mating.
A seasonal shift in the characteristic time of night at which males become responsive to pheromone has been observed in two lepidopteran species, the cabbage articificially extruded pheromone glands of female cabbage loopers held in an air stream moving 100 cm/sec than in one moving 10 cm/sec. Enhancement of evapora- tion rate with increasing air velocities may be one of the factors that has led to the behavior, seen in many lepidopterous species, of a female vibrating her wings while extruding the sex pheromone gland.
Virgin cabbage looper females spent more time per night releasing pheromone when exposed to air velocities in the range 0.3 to 1.0 m/sec than in higher or lower velocities (Kaae and Shorey 1972). Apparently, females have evolved a behavioral reaction causing them to minimize the release of pheromone when wind conditions for pheromone dispersal or for male response ights are not favorable.
The, immature forms of some insect species are restricted to feeding on only one or a few host plant species. For certain of these monophagous or oligophagous insect species, mechanisms have evolved which cause males and females to aggregate at the larval feeding sites prior to mating.
A number of investigators have found that traps baited with females of a given insect species attract and capture large numbers of males only when located on or near the larval host plants (Holbrook et al. 1960.)
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ABOUT THE AUTHOR
Alexander P is a blogger from Los Angeles that studies pheromones.