Organic electrospun nanofibers as novel pheromone dispensers for Integrated Pest Management
Abstract: Conventional insecticide for plant protection require uniform distribution of toxicants in space. Traditionally, this requirement has been quite well fulfilled by liquid spray equipment available in a number of sophisticated varieties. Pheromones, on the other hand, represent the non-toxicological, “green” approach to integrated pest management (IPM) by influencing very specifically the behavioural reactions rather than the cellular physiology of their target. Unfortunately, there is today no generally agreed best way for applying insect pheromones. A large variety of pheromone traps are on the market, equipped with a multitude of different release substrates. The same applies to communication disruption schemes (without the use of traps but) with a number of high-tech pheromone release substrates. None completely satisfies all requirements. Responding to suggestions from practicing vineyard managers, organic electrospun nanofibers have recently been invented and added to the dispenser options suitable for IPM. The communication disruption effect achieved so far with organic polymer nanofibers made from Ecoflex® lasted for 7 weeks (equal to about one flight period of Lobesia botrana. Under the influence of synthetic female sex pheromone (E,Z)-7,9-dodecadienyl acetate released from nanofibers, male L. botrana were unable to locate virgin females. The effect was proven and quantified by the Doye field enclosure technique. In areas of the vineyard disrupted by artificial pheromone, both commercially available Isonet LE (positive control) and novel nanofiber dispensers (treatment) reduced pheromone communication to a level of 3-7% compared to untreated control sections, in which an observed recapture rate was arbitrarily set at a standardized 100% level. The resulting calculated disruption effect is highly significant and is quite acceptable to vineyard managers. As a distinctive feature, electrospun nanofiber dispensers, unlike commercially available ISONET LE (“spaghetti”) and chamber dispensers, are fully biodegradable within half a year. Recollecting of spent dispenser material at the end of the growing season is unnecessary, which saves expensive manual labour. In addition, the nanofiber-pheromone combination is environmentally unobjectionable as proven by independent eco-toxicological testing with standard terrestrial and aquatic organisms. The electrospinning of nanofibers and their distribution can be accomplished in a variety of ways. One successful procedure consisted in the electrospinning of fibers under controlled conditions in the lab onto a sturdy carrier like hail protection netting. This was then cut to size and hung into the vineyards at a certain density. The aim is to exceed the critical disruptive level per hectare. Alternatively, the electrospinning can also be accomplished directly in the vineyard from a prototype mobile spinning platform which still needs further mechanical development. Both application modes are protected by patents granted under European and US patent regulations.