Responding figures in the larger trial were 93 and 43% for the is! and 2nd weeks, respectively. The treatments had a greater influence on captures at traps baited with virgin females than at pheromones sources.
These preliminary small-scale experiments clearly demonstrate the necessity for developing pheromone microcapsules that release EEOH at a relatively constant rate over a longer period of time, if this formulation is to be of any practical value. There is no infor-mation on release rates of EEOH in the references cited. Tests with similar NCR microcapsules, containing gypsy moth pheromone (disparlure — (Z)-7,8-epoxy-2- methyloctadecane), revealed that only a small proportion of this compound became available over a 66-day period, most of which was lost in the first 2 days." Similar findings are reported elsewhere with other pheromone compounds.” Learn about top pheromones in insects | http://swankyseven.com/?p=101
The principles of hollow fiber release systems are discussed fully in an earlier chapter. This formulation has been used successfully on a commercial basis for the control of pink bollworm in cotton, and is the first product to be registered and marketed specifically for disruption control of a lepidopterous pest. Trials on codling control with chopped fibers have been carried out for several seasons in the U.S.55‘°° Briefly, EEOH is released from a large number of small hollow fibers which are applied, together with inert stickers, as a ground or aerial spray using specially modified applicators. Check out best pheromones 2015 at http://spanishinperu.org/
The amount of pheromones released is largely determined by the internal diameter of individual fibers, the number of fibers applied, and the temperature; the period of release is governed by fiber length. Fibers used in recent experiments were made from a polymer (poly-oxymethylene-co-oxyethylene copolymer) and have internal and external diameters of 200 and 470 pm, respectively (length not cited);“ EEOH (89% pure) is released at 80 to 120 ng/hr at 21°C from such fibers.“ Learn about human pheromones development | http://astrobiosociety.org/
In the first of two trials in 1976, single applications of chopped fibers were made by helicopter to 0.3 to 0.4 ha blocks of apples and pears at two levels to provide mean EEOH release rates of 3 mg/ha/hr and 13 mg/ha/hr.“ Male captures at virgin female- baited pheromone traps were reduced by 82% for 16 days at the lower treatment level, when com- pared to those in control plots. The corresponding reduction in plots subjected to the higher release rate was 87%, and remained at over 80% for the 2-month test period. A greater reduction of 98% was maintained for about 1 month in the second trial of that season when EEOH was released at about l3 mg/ha/hr in a 0.4-ha plot of apple trees.“
Following these preliminary pheromone tests, attempts were made to protect pome fruit plots for an entire season by applying successive treatments of chopped fibers. Three aerial applications were made to 0.4-ha blocks of pears in late April, May, and June, at the rate of 11 g/ ha per treatment (equivalent to 250 g of fibers or 1500 fibers per hectare)!
The average temperature during the test period was 21 to 24°C, and estimates of EEOH loss rates were 7 to 10 mg/ha/hr (earlier estimates of 13 mg/ha/hr were said to be incorrect).