‘Love potion’ kills bugs, protects Negev grapes

Love can make you happy, love can make you crazy, love can make you feel brand new, so they say — but in the case of vine mealybugs, love kills.

Scientists at Moshav Ein Yahav in Israel’s southern Negev desert have perfected a method to prevent a grapevine scourge from multiplying, deploying the bug’s own drive to reproduce as a weapon to destroy it. Moshav farmers release odors that indicate a female bug is in the area, and male mealybugs go into a frenzy, seeking out lovers that aren’t there – literally dying of exhaustion and preventing the next generation of bugs from being born.

Vine mealybugs live wherever grapes are grown. They can be found on roots, vines, and grapes themselves. The bugs secrete a white substance, called honeydew, which attracts ants, which protect themfrom predators. If ants are not present, the mealybugs keep producing honeydew, which can cause mold. In either case, the grapes are rendered unfit for human consumption.

Generally, pesticides are used to battle the bug, but Ein Yahav, one of Israel’s largest farming communities, is committed to reducing the use of pesticides, said Rami Sadeh, staff agronomist at Beauty of Vegetables. That’s a local organization that does research and development in a number of agricultural areas, including developing natural pesticides – bug killers based not on chemicals, but on biological processes and conditions, using nature against the pests that damage crops.

Among the innovations implemented at Ein Yahav, said Sadeh, is the deployment of an “army” of predatory – and very hungry – insects, consisting of bugs like Orius laevigatus (commonly called insidious flower bug), the “Svirski,” (Amblyseius Typhlodromips swirskii, a polyphagous predatory mite) the Presimillis (a mite eater), and parasitic wasps – all natural enemies of pests like thrips, whiteflies, and mites that can eat their way through the pumpkins, peppers, melons, tomatoes, and other crops grown in the moshav.

“We usually use natural enemies of insects that cause damage, and if we do spray it’s only on a small scale for the one or two plants with high infestation,” said Sadeh. “It costs us more money per dunam, but we can sleep well knowing we are not using chemicals.” By using bugs to control pests, he said, farmers have been able to cut pesticide use by about 80%.

The new system, which is being tested at the moshav, takes bug control a step further. Instead of deploying an enemy to battle vine mealybugs, Ein Yahav researchers figured out a way to get the pest to essentially commit suicide. Like many creatures, female mealybugs emit a signal, or pheromone, when they are ready to mate. Males pick up the scent and rush to the female’s side for mating – a priority for a creature whose life cycle lasts only for about 50 days under ideal circumstances, and is even shorter in hot climates like the Negev.

Scientists isolated this pheromone, and basically “bottled” it. When mealybugs show up in a vineyard, farmers release a compound that includes the pheromone in all corners of the field – and away from it.

The pheromone is released during a period when there is no “competition” from females, as they are not yet ready to mate – but the males don’t know that. Like males of most species, the male mealybugs are all instinct when it comes to sex – and when they detect the pheromone, they work themselves up into a sexual frenzy, looking for the “hot” females who they assume are ready to mate.

Except there are no females, and because bugs can’t “think” beyond the pheromone, they keep searching for those females – but to no avail. Eventually, the males give up – out of exhaustion. Having expended all their energy on a fruitless search for bug love, they simply lie down and die, said Sadeh. Without males, the females can’t reproduce, ending the scourge with the current bug generation.

Preliminary tests on the system, which was developed with a company called Makhteshim Adama, have been very successful, said Sadeh, with one caveat; all areas of the vineyards (Ein Yahav has 100 dunams, or 24.7 acres) must be treated at the same time, to ensure that all the males die. This is the first time a pheromone treatment will be used on such a large area to control pests, Ein Yahav said. According to Sadeh, Ein Yahav is the natural place to try out this technology – and his organization, he added, will continue to lead the way in developing natural pesticides.