Pests

: 17 October 2022; Hits: 442

Scientists make it cheaper to confuse & prevent crop pests

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By George Munene

According to research published in the Journal of Science, researchers have developed a cheaper and natural source of pheromones, i.e, behavior-influencing perfumed chemicals that confuse insects and prevent them from mating.

Currently, it costs Sh121,000 ($1000) to Sh423,640 ($3,500) to produce just one kilogram of artificial pheromones. By modifying plants to more effectively synthesize pheromones, researchers estimate they could slash the cost to just Sh8,477 ($70) and Sh15,137 ($125) per kilogram--similar to the current cost of pesticide application.

Speaking to the publication, entomologist Muni Muniappan at the Virginia Polytechnic Institute and State University noted that a lower price might make the pheromones accessible to farmers in the developing world.

But because these pheromones work best when applied to large areas and most farmers in developing regions work small fields, farmers would likely need to work together to see the benefits, he said. “You need to have farmer education and outreach in order to make that successful.”

Scientists at Lund University, Sweden, have been modifying plants to more effectively produce the chemical building blocks needed for synthesizing pheromones.

The Camelina, a relative of canola, was used as it has seeds rich in fatty acids--an important ingredient in getting plants to produce pheromones.

The team tested this pheromone blend in China to control the diamondback moth (Plutella xylostella), a problematic pest for Brassica group of plants (kale, cabbage). The findings showed the pheromone traps worked just as well as commercial synthetic pheromones.

Another test in Brazilian bean fields showed a single plant-made pheromone could disrupt the mating patterns of the destructive cotton bollworm (Helicoverpa armigera) just as well as synthetic pheromones.

Pheromones, unlike chemicals, are an environmentally friendly way of dealing with pests.

However, their high cost has seen them used by farmers growing high-value crops that require little land to turn a profit.

This has curtailed their widespread use by most of the farming population which grows crops such as maize and beans that do not sell for as much.

In 2020 global pesticide consumption stood at 2.7 million metric tons, a more than 57 per cent increase compared to 1990. According to FAO, Africa used an estimated 0.3 kilograms of active pesticides per hectare of cropland in 2018.

Incorporating pheromone use in controlling pests will reduce the application of conventional insecticides, providing sustainable and eco-friendly pest management in agriculture.

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: 14 October 2022; Hits: 997

Tharaka Nithi poultry farmer abandons antibiotics for papaya & moringa mix

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By George Munene

Mixing in dried papaya and moringa leaves into chicken feed has helped Daniel Muketha bolster the immune system of his poultry doing away with antibiotics.

The veteran poultry farmer who rears 700 Kenbro improved kienyeji and ornamental chicken, geese, turkey and pegions adviced: “I have been feeding crushed moringa and papaya leaves to my chicken since 2017. As long as they are vaccinated and they are introduced to the mixture while young, I have found that I do not have to worry about disease flare ups in my flock.”

He dries the leaves under shade to prevent the loss of their nutritive value before milling them into a fine powder in a feed mixer. For small-holder farmers who cannot afford this, he advices manually crushing the leaves.

He forms a meal with chicken feed and gives the ground leaves twice a week to his birds at a 1:2 ratio of papaya and moringa mix to chicken feed.

“Being naturally occuring, farmers do not have to worry much about under or overfeeding papaya or moringa to their birds,” he said.

According to scientific research moringa olifera extract is high in crude protein (25-30 per cent) making it a natural source of protein in poultry diets. It is a natural growth booster that mproves the growth rate of birds, their live weight, dressing percentage and health status.

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It is also prevents infection and boosts poultry immune systems making them resistant to diseases and is infused with a natural antimicrobial agent that helps chickens fight disease causing organisms.

It further improves their metabolism and enhances nutrient uptake.

Egg yolk, egg shell and bird feather quality is also enhanced.

Papaya for it's part has been shown to be effective against coccidiosis and Newcastle diseases as well as bacterium like Staphylococcus aureus, Bacillus cereus, Escherichhia coli, Salmonella aureus and Pseudomonas aeuroginosa.

Papaya extract can also reduce the prevelance of yeast infections.

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: 30 September 2022; Hits: 567

Sexual trapping to mitigate fall armyworm menace

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Integrated pest management practice is one of the most effective ways of controlling the invasion of the fall army worm (FAW), which is threatening food security in Kenya and Africa.

The pest, which attacks more than 80 plants (food and non food) including maize, cotton, pear sorghum, rice, tomatoes, cucumber, pastures, onions, kales, spinaches, among others, can cause up to 100 per cent loses if uncontrolled.

“Attack on maize at vegetative stage can result in 100 per cent loss if no control is taken. Attack on young maize can totally reduce plant density, warranting re-planting,” reads a joint warning statement from the agricultural government agencies.

Chemical control has not tamed the pest, as it also mutates to counter the effects of this knock-down method. But the use of sexual lures, known as pheromones to separate males from females could help arrest the pest by preventing reproduction.

The deadly worm was first reported in the country in mid March, 2017 in Trans Nzoia, but is has spread to Bungoma, Kakamega, Busia, Nakuru, Baringo, Kericho, Nandi and Uasin Gishu counties within a month.

It spread from Uganda, in about three months after being reported in the coast of Western Africa in September 2016.

The worm has caused damage in Zimbabwe, Zambia, Togo, among other Sub Saharan Africa.

FAW is indigenous to the North and South America.

Although deep ploughing exposes the pests to the sun and predators, mechanical killing also may control multiplication given that one female lays tens of eggs, which hatch within two to seven days.

Laying of many eggs, short hatching periods, mutations, among other characters, increase the chances of survival of the pest besides colonising new areas.

The worms are green, brown or black, depending on development stage.

Mature worms have distinct white lines between the eyes, forming an inverted ‘Y’ pattern in the face. There are also pronounced black spots aligned in a square near the back end of the caterpillar.

The larvae are the most destructive stages of the pest, drilling holes on leaves, ears of maize and whorls.

Given that the pest has moved from the western to the eastern world, the climatic conditions of the two extremes are diverse and therefore, chemicals may not effectively control it given that it is evolving fast to adopt to the new areas.

A UK firm, Russell IPM, recently reported remarkable success of its IPM products in trials against the pest in Zambia and South Africa, according to African Farming website.

It destroys the maize tassel and kernels.

The pest may soon colonise the Asian continent to become a global menace, and therefore, a threat to food security.

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