Making Scents Of Insect Pheromones

In nature, insects use organic compounds called pheromones to communicate with each other by sending signals to attract a mate or find food. Females usually release sex pheromones to attract a male, who follow the scent and fly towards it. When it comes to controlling insect pests, this clever system can be mimicked with the help of synthetic pheromones. These are used to attract, trap and kill the males, thus preventing them from finding a female and disrupting the mating process.

Fruit flies are a home orchard pest

Fruit flies are an important pest in South Africa because of the wide range of host plants they feed on (including almost all crops grown in the country), the amount of damage they do and how hard they are to get rid of. In particular, the Natal fruit fly, Mediterranean fruit fly and Mango fruit fly are pests that no fruit grower wants to have hanging around.

Fruit flies are present all year round, but population sizes usually peak in late summer and early autumn. These small insects move from one host to the next as adult flies feed by sucking fruit juice and the honeydew left by Aphids, White fly, Leaf hopper and other scale insects on the surface of fruit. This makes them a pest on home fruit trees as well as larger orchards. Females search for the perfect place to puncture the surface of ripening fruit and deposit their eggs just under the skin. Each female may lay up to 10 eggs within one cavity, and many females can lay eggs in the same place.

Once hatched, the larvae cause significant damage as they feed on the fruit, while tunnelling towards the centre. Infestations cause fruit to decay and exposes it to secondary infestation by other pests and pathogens, and often leading to early fruit drop. In uncontrolled conditions, fruit flies can lead to up to 100% crop losses on a wide variety of fruit.

Unfortunately, the cycle doesn’t stop here. When the larvae emerge from the fruit, they drop to the ground and pupate in the top layer of the soil – emerging as adult flies and beginning the cycle all over again.

Follow the pheromones

Controlling fruit flies early on, before fruit starts to ripen and an infestation takes hold, is essential to prevent extensive losses from your home fruit trees.

If the fruit fly population becomes too large, there is little you can do that will be genuinely effective. Preventing fruit flies from starting a new generation is therefore crucial. This can be done by interrupting the mating and development cycle with the help of pheromones.

When looking for a mate, adult males are strongly attracted to female pheromones, which act as a scented sex attractant. The E.G.O. PheroLure® from Insect Science® mimics this process, luring males to a McPhail trap, where they are trapped and killed in order to prevent mating and the start of a new generation.

Combine the use of a pheromone trap with regular orchard sanitisation. This means removing and destroying the fallen fruits of host plants, in order to remove the larvae from the orchard and prevent them from pupating in the soil and emerging as adults. Waste removed from the orchard should either be burned or buried at least a foot deep.

The sooner you take action against fruit flies, the more successful your efforts will be!

Find out more and buy the Fruit Fly Toolkit at www.shop.insectscience.co.za

The Gardener