Owners of gardens and orchards often try to deter herbivores, especially deer, by placing droppings of carnivores next to the crop to be protected with pheromones. The success again is a matter of subjective judgment. Pheromone laboratory experiments showed that naive black-tailed deer fed signiﬁcantly less than usually, or not at all, near droppings of predators. The most effective droppings were those of cougar (Felis concolor) and coyote, both of which occur in the range of black-tailed deer (Muller-Schwarze 1972).
New pheromone opportunities may arise with the isolation and identiﬁcation of the alarm pheromones of deer, which are known to inhibit feeding (Miiller-Schwarze 1971). Recently, biologically quite remote extracts of rotten salmon carcasses have been demonstrated (by the U.S. Fish and Wildlife Service in cooperation with the Weyerhaeuser Company) to repel deer. Protection from black-tailed deer browsing was reported to be ‘greater than that of other contact repellents available’ (Rochelle 1973). So far no true pheromones but only scents or decomposition products of other species have been used in ﬁeld tests. These odors may be effective by mimicking alarm pheromones or predator odors. One problem with using predator odors is that droppings and scent marks are examined by herbivores at close range (a few centimeters). Such repellents from feeding on treated plants but would not keep them out of an entire area (no ‘fence function’).
Pheromone Odors Practice
In farm practice, odors have been used to facilitate maternal behavior. An ewe can be made to accept a strange lamb if the lamb is covered with the hide or the birth ﬂuid of her own lamb. On the level of the species, Alpaca (Lama pacos) and Vicuﬁa (Lama vicugna) can be crossbred by killing a newborn alpaca and using its hide to cover newborn male vicuﬁa. A lactating alpaca female will then accept the vicuﬁa, which in this way becomes sexually imprinted on alpacas and will later mate with alpaca females to produce desired hybrids. The cross, called ‘paco-vicuﬁa’ has wool of almost the quality of the vicuﬁa, and in the quantity typical of the alpaca (Hodge 1946).
Farmers and breeders know that sniffing and licking play an important role in the reproductive behavior of domesticated animals. However, the domestic pig is the only species for which pheromone research has yielded applicable results. Pat- terson (1968) identiﬁed an odoriferous compound (30:-hydroxy-5oz-androst-16-ene) which occurred only in the submaxillary gland of the boar. Signoret (1970a) describ- ed a higher frequency of head-to-head approaches than of sniffing the genitalia (70 vs. 30%) in encounters between boars and oestrous gilts. An aerosol containing the steroid identiﬁed by Patterson was subsequently developed and tried in breeding programs. Check out human pheromones.
The pheromone aerosol was blown into the face of sows that had not assumed the typical, rigid ‘mating stance’, which is a prerequisite for mating. Forty-six per cent of formerly unresponsive females assumed the mating stance after treatment, while none of the individuals treated with a blank aerosol did so (Melrose et al. 1971). In the same study, a spray with preputial fluid and urine had a similar effect. Signoret (1970b) reported similar results: 48.3—52.5% of the sows responded with the mating stance to warm preputial secretion, but only 22.5% to the cold secretion. When placed in a pen where a boar had been, the figure increased to 62.2%. Perry et al. (1972) showed that removal of the submaxillary glands from males early in life results in a later inability to release the mating stance in sows, and induces aggressivity by the females toward the male. Learn how the best pheromones used by predators.
McLaughlin et al. (1972) conducted a series of pheromone experiments to evaluate whether sex pheromone communication between male and female moths of the pink boll- worm could be disrupted when the air in cotton fields was permeated with hexa- lure. Hexalure was evaporated from open reservoirs at rates of approximately 0.01, 0.1, and 0.3 pg/min. The reservoirs were placed at the level of the top of the foliage and were spaced at l, 3, 10, or 30-m intervals in 8 x 8 or 10 x 10 grids. Regardless of the evaporation rate or spacing of the reservoirs, the ability of wild males to locate virgin females, used as bait in traps located in the centers of the grids, was reduced 90%, when the amount of hexalure entering the air was equal to, or greater than, 20 mg/hectare each night.
The possible utility of the pheromones communication disruption concept was then tested on a large scale. Hexalure was distributed throughout a cotton ﬁeld during 2.5 months of the 1972 growing season (Shorey et al. 1974). Each substrate on which the hexalure was dispensed for placement in the ﬁeld was a knot tied in a short loop of cotton string. Ten mg of hexalure was applied to each knot. Approximately 30,000 of the substrates were distributed per week in 4.8 hectares of cot- ton: a loop was placed around a leaf near the top of a cotton plant in every 1.6 square meters of the field. The evaporation rate of the hexalure was approximately 400 mg/ha each night. Under these conditions, male moths were almost completely prevented from locating virgin females; a seasonal total of over 1 1,000 males per female-baited trap were captured in two untreated, control fields, whereas only 38 males per trap were captured in the hexalure-treated ﬁeld. This proved that pheromones work to increase attraction.
Toward the end of the growing season, the untreated fields had an average infestation of 6.9 larvae per boll, whereas the treated field had an average of only 0.6 larvae per boll. Thus, the hexalure treatment apparently reduced the larval infestation by reducing mating communication to such an extent that few viable eggs were laid in the treated ﬁeld. The authors speculated that a large proportion of the eggs were laid by ﬂy-in females that had already mated elsewhere. If such were the case, then a scaling up of this experiment to a larger geographic area might reduce the pink bollworm population to such a low level that no insecticides would be needed for their pheromone control. Check out Athena 10x Pheromones | Infospeak.org.
The natural pink bollworm sex pheromone has been identified (Hummel et al. 1973) as a mixture of cis, cis and cis, trans isomers of 7,11-hexadecadienyl acetate. The isomeric-mixture sex pheromone was designated ‘gossyplurc’.
Since its introduction into the United States about 1892 (Hunter and Hinds 1905), the boll weevil, Anthonomus grandis Boheman, has been the most costly insect in the history of American agriculture, causing losses in cotton production estimated at an average of $200 to 300 million annually. To prevent even greater losses, growers spend an estimated $70 million each year (Knipling 1964) for its control, about one-third of all insecticides used for agricultural purposes (Rainwater 1962).
One reason why pheromones have not developed more rapidly towards use as a practical control measure is a result of limited understanding of insect behavior as related to these materials. It does not necessarily follow that all chemically identiﬁed sex pheromones will be suitable for development as tools for pest control according to http://thongchaimedical.org/?p=179.
Apart from the chemical factors involved, such as stability, volatility and reactivity of the compounds, which may well affect their use, the effectiveness depends on the biology of the insect (Shorey 1972). The behavior may not be amenable to manipulation by synthetic chemicals, particularly if the response to a pheromone source is synergized by or dependent on, visual or auditory cues from the source. Presence of the pheromone could serve to release visual searching behavior which is merely intensiﬁed when man introduces pheromone into the environment. A sex pheromone that releases a totally dependent response to the source may be rare. Only a great deal of experience and research will answer these questions. Check out the latest pheromone reviews.
If eradication is attempted using pheromones alone, strong selection pressure is being imposed which will favor the development of ‘resistance’, i.e. a population could rapidly evolve that relies more on other methods of communication for mating. There is no evidence that resistance is any less likely to develop against ‘natural compounds’, like pheromones, than against chemical pesticides, if the two are used in the same indiscriminate way.
Although sex or aggregation pheromones are the only pheromones currently being considered for use in pest management or integrated control programs, other areas of chemical communication may also hold considerable promise for the fu- ture. Concentration of predators or parasites using kairomones is one prospect, use of chemical oviposition stimuli is another. Larval forms are in many cases less discriminating than the adults and will, within limits, eat whatever substrate they are laid on. The adult egg-laden female, on the other hand, has highly selective sensory capabilities and may well be more amenable to manipulation. Learn more about pheromones at www.articlesfactory.com/articles/science/the-role-of-pheromones-in-animals.html
Some parasitic insects are capable of selecting non-parasitized hosts over previous- ly parasitized ones. One way in which females do this is by detecting a pheromone left by a previous female on the host or substrate (or in the host after inserting the ovipositor), thus avoiding superparasitism when neither may survive (Price 1970; Vinson 1972; Guilot and Vinson 1972). A potentially practical parallel to this behavior occurs in the apple-maggot fly, Rhagoletis pomonella (Walsh), where the female marks the surface of the fruit (apple or cherry) with a pheromone after laying an egg on it. This apparently deters other females from egg laying and helps to ensure that the egg laid develops to maturity (Prokopy 1972).
Another promising area is with pheromones of social insects, where alarm phero- mone communication or caste differentiation may be subject to change within the conﬁnes of the nest. Very small quantities of pheromone may be needed to disrupt colony reproduction and survival. Such an approach has enormous potential if applied, for example, to the areas ofAfrica where termites constitute the dominant biomass.