| Sumario: | Pests are major constraints to increased cowpea production in tropical subsistence agriculture where cash inputs are small. Breeding for pest resistance is therefore the major component of pest management strategies for crop improvement. Of paramount economic importance among these pests are flower thrips [Megalurothrips sjostedti (Tryb.)] which may cause abscission of flower buds, flowers and peduncles, leading to seed yield losses of up to 100% (refs 1, 2). It has been difficult to use available sources of moderate thrips resistance in a breeding programme because of thrips variation in time and space in field screening3. This paper reports that ethylene is produced when thrips infest cowpea peduncles. We have used this fact to develop a screening technique using the synthetic growth regulator ethephon (2-chloroethylphosphonic acid), which when sprayed on the plant is translocated to actively-growing tissue, where it breaks down to form ethylene4–6. Cultivars susceptible to abscission caused by thrips also show increased abscission with ethephon treatment. The technique may be useful in identifying sources of resistance to other abscission-causing agents.
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