Foraging behaviour of the egg parasitoid Uscana lariophaga : towards biological control of bruchid pests in stored cowpea in West Africa

F. van Alebeek

Research output: Thesisinternal PhD, WU


<br/>Seed beetles cause considerable losses in traditionally stored cowpea ( <em>Vigna unguiculata</em> Walp.) under subsistence farming conditions in West Africa. The indigenous egg parasitoid <em>Uscana lariophaga</em> Steffan (Hymenoptera; Trichogrammatidae) is evaluated as a candidate for a conservation strategy of biological control against the major pest <em>Callosobruchus maculatus</em> Fab. (Coleoptera; Bruchidae). Different aspects of <em>U. lariophaga</em> 's searching efficiency, such as host habitat location, host cluster location, the functional response, egg laying capacity and egg load, host handling time, arrestment response, photo- and geotaxis, dispersal and walking behaviour, have been investigated and results are reported in this thesis. <em>Uscana lariophaga</em> uses odour of uninfested cowpea seeds and of <em>C. maculatus</em> eggs to locate host habitats and host clusters therein. Host clusters with many eggs are more frequently located than clusters with few eggs, probably through olfaction. The parasitoid demonstrates a Holling Type II functional response, and the maximum number of hosts parasitized is determined by her ovarial egg load. Due to a strong arrestment response within host clusters, and area restricted searching behaviour after an oviposition, <em>U. lariophaga</em> parasitizes more eggs in host clusters with an even or clumped distribution than in clusters with a low density random distribution. <em>Uscana lariophaga</em> is positive phototactic and negative geotactic, and can move through cowpea stock over several meters a day. Under optimal conditions, <em>U. lariophaga</em> can significantly reduce losses in stored cowpea by <em>C. maculatus</em> . Further progress towards biological control of cowpea storage pests is discussed.
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • van Lenteren, Joop, Promotor
  • van Huis, Arnold, Promotor
Award date10 Dec 1996
Place of PublicationS.l.
Print ISBNs9789054856139
Publication statusPublished - 1996


  • Chalcididae
  • Eulophidae
  • Trichogrammatidae
  • animal behaviour
  • Vigna
  • cowpeas
  • insects
  • plant pests
  • Bruchidae
  • biological control
  • beneficial insects

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