Farmers use insects to kill insects

A group of farmers assisted by scientists are now courting certain parasites and insects on their farms to act as natural enemies to other plant threatening parasites, in a model described as ‘sending a thief to catch a thief’.

Insects that include Ladybird beetles, spiders, bats and red fire ants, all long vilified as farmers’ greatest enemies, are now becoming farmers’ friends as multiple applications of synthetic pesticides by farmers fail to resolve the problems responsible for four fifths of the country’s harvests losses. Kenya currently spends close to Sh5bn a year on pesticides, much of it to battle insects.

However, the new farmers’ friend insects either secrete unique fluids that chase away pests, or feed directly and swiftly on the pests. According to many farmers, it takes just a week to rid a farm of pests with natural enemies, as against months when using synthetic pesticides.

Ladybird beetles have been in the frontline of the new techniques. The beetles, both in the adult and larvae stage of growth, prey on aphids, leafhoppers, mealybugs, mites, scales and whiteflies, which are known to devour cereals. A single ladybird consumes approximately 200 - 300 aphids over its lifetime of 1-3 months. Farmers have even begun growing wild sunflowers, with a higher pollen count than domesticated varieties, to attract the Ladybirds.

Rove beetles, another of the new friends, eat all stages of a wide range of insects in the soil or in the foliage, including bean flies, cutworms, scale insects and spider mites. Young larvae search the soil for cocoons of flies and after eating the pupa emerge sometime later as adults.

Last year, a unique parasitic wasp was even introduced into the country by the International Centre for Plant and Physiology and Ecology (ICIPE), Agricultural Ministry and Kenya Agricultural Research Institute (KARI) and has recorded impressive results in parts of Rift Valley where it was dispatched to tackle the notorious African fruit fly that feeds on mangoes and avocados.

Orchards that have introduced the wasp, such as Lakita Orchard in Naivasha, have delivered yields of around 10 tonnes a hectare compared with 4 tonnes a hectare when they were using synthetic pesticides.

Beating the fruit fly has been vital to export revenues. The proliferation of the fly on avocados led to an export ban to South Africa that was only recently lifted, and which cost Kenya Sh200m a year for 4 years, particularly hurting smallholders, which account for 85 per cent of Kenyan avocado exports.

Farmers in Busia county of Western Province have even moved from the bugs and parasites to courting bats as predators to fight moths and other insects. “Besides eating tons of insects they have also been feeding on cucumber beetles and even Stink bugs which damage our tomatoes,” said Wekesa, a large scale farmer in Busia who claims bats are the most effective natural enemy of all because they form large colonies and have a huge appetite. One bat can feed on 2kgs of insects nightly, and they forage over large distances.

Scientists have also developed other natural enemies in the laboratories like the Diamond Black moth, which is very swift in feeding on the large grain borer that is catastrophic to both maize and woods. Scientists have been releasing them onto farms when there is an acute invasion of parasites in farms.

The moth provides swift pest control but does not harm the crops and allows for naturally grown food. “I strongly feel when we afford to control all pests without touching any chemicals will be when we say we have passed on a healthy chemical free future to our generation, and one way is embracing an agricultural system that imitates a natural system,” said Dr Ladslas Ritwo, a scientist from the University of Nairobi College of Agriculture and a consistent crusader of organic pest control methods.

Written by Bob Koigi for African Laughter