Integrated pest management: the push-pull approach for controlling insect pests and weeds of cereals, and its potential for other agricultural systems including animal husbandry

Abstract

This paper describes the 'push-pull' or 'stimulo-deterrent diversionary' strategy in relation to current and potential examples from our own experiences. The push-pull effect is established by exploiting semiochemicals to repel insect pests from the crop ('push') and to attract them into trap crops ('pull'). The systems exemplified here have been developed for subsistence farming in Africa and delivery of the semiochemicals is entirely by companion cropping, i.e. intercropping for the push and trap cropping for the pull. The main target was a series of lepidopterous pests attacking maize and other cereals. Although the area given to the cereal crop itself is reduced under the push-pull system, higher yields are produced per unit area. An important spin-off from the project is that the companion crops are valuable forage for farm animals. Leguminous intercrops also provide advantages with regard to plant nutrition and some of the trap crops help with water retention and in reducing land erosion. A major benefit is that certain intercrop plants provide dramatic control of the African witchweed (striga). Animal husbandry forms an essential part of intensive subsistence agriculture in Africa and developments using analogous push-pull control strategies for insect pests of cattle are exemplified.

Figure 1

(a) Feeding marks of stem borer larvae on Napier leaves and (b) production of sticky exudate by Napier grass tissue in response to penetration by first- and second-instar stem borer larvae. Adapted from Khan & Pickett (2004).

Figure 2

Districts where push–pull is practised by the farmers and year they started. Adapted from Gatsby Occasional Paper (2005), courtesy Green Ink.

Figure 3

Maize : D. uncinatum at 1 : 1 in full push–pull in Suba district.

Figure 4

Women's group responsible for producing D. uncinatum seed.

Figure 5

Yield differences in push–pull and control plots in 14 districts in Kenya during the 2005 long rains. Within a district, bars marked by asterisk are significantly lower (p<0.05, t-test).