EXPLOITING CHEMICAL ECOLOGY FOR LIVELIHOOD IMPROVEMENT OF SMALL HOLDER FARMERS IN KENYA

Area of Science:

• Agricultural Entomology
• Chemical Ecology
• Sustainable Pest Management

Background:

• The "push-pull" strategy leverages chemical ecology principles for cost-effective pest management, particularly benefiting smallholder farmers in developing countries.
• Established in East Africa, primarily Kenya, over 15 years, this approach has seen substantial farmer adoption, increasing from dozens to over 80,000 by 2014.
• The classical push-pull method involves intercropping maize or sorghum with repellent (Desmodium spp.) and attractive (Melinis minutiflora) plants to deter stem borers like Chilo partellus.

Purpose of the Study:

• To investigate if the repellent volatile-producing legume Desmodium intortum induces defense responses in maize varieties (Zea mays).
• To monitor for the presence of the Western Corn Rootworm (Diabrotica virgifera virgifera), a cosmopolitan maize pest, in Kenya using pheromone-baited traps.
• To contribute to Kenyan economic development and livelihood improvement for smallholder farmers through sustainable agricultural practices.

Main Methods:

• Experiment 1: Assessed defense induction in two open-pollinated and two hybrid maize varieties when intercropped with Desmodium intortum.
• Experiment 2: Employed species-specific pheromone-baited traps (Metcalf sticky cup traps with 8-methyl-decane-2-ol propanoate) to monitor for male Diabrotica virgifera virgifera.
• Field studies were conducted in Kenya between September 2012 and February 2013.

Main Results:

• No significant defense induction was detected in maize varieties exposed to Desmodium intortum, possibly due to insufficient volatile production from leaves.
• Pheromone traps indicated the absence of a local Western Corn Rootworm population in the Mbita area, though presence in Nairobi or Mombasa cannot be ruled out.
• The classical push-pull strategy demonstrated a benefit-to-cost ratio of 2.5 and a significant reduction in stem borer infestation.

Conclusions:

• While the push-pull strategy is highly effective for stem borer control, further research is needed to understand the plant-defense induction mechanism, potentially involving flowers.
• Current evidence suggests the Western Corn Rootworm has not established a population in the studied region of Kenya, but continued monitoring is advised.
• Both investigated approaches offer complementary pathways to enhance agricultural sustainability and improve the livelihoods of smallholder farmers in Kenya.