Dr Peter Credland

Research interests

Overview of current research

My major interests lie in a field of stored products entomology and especially in the biology of seed beetles, Burchidae, infesting legume seeds such as peas and beans both in the topics and temperate regions of the world. Work has always been divided into two closely related areas:

One area is the study of aspects of beetle biology which impact directly on their status as pests. We have, for example, looked at parameters affecting population growth, sites of oviposition, and differences among beetle populations from diverse geographical locations. The objective of these studies is to identify targets for non-chemical control methods which might be applicable in developing countries. Such methods include the use of plant products, biological control and, most recently, the exploitation of polyphenism. We have participated in international projects with laboratories in France, The Netherlands, Burkina Faso, Togo, etc.) looking at biological control of cowpea seed beetles (Callosobruchus maculatus) in Africa using parasitoids, and also looked at the impact of "resistant" legume varieties on bruchid populations as potential means of limiting population growth of seed beetles in stores in both Africa and South America.

The second area of interest is the evolution of life histories. Seed beetles can be maintained in the laboratory with great ease in conditions extremely similar to those in which they occur in the store or field. They therefore provide a very simple model of natural insect populations and this has been used to explore aspects of the evolution of their life histories such as the relationships between egg distribution, development, and larval mortality, or the consequences of inbreeding on various characteristics of their life history.

Recent projects have included:

A study of Callosobruchus subinnotatus, the primary pest of bambara groundnuts in West Africa. We have been looking at the possibility of an entirely new potential control measure involving control of adult polymorphism. There are two distinct morphs of this insect: one produces many eggs in the presence of seeds and another which needs more complex external cues for reproduction to commence. If environmental conditions could be modified to ensure or even increase the production of the latter morph then pest populations would significantly decline.

Work in collaboration with the NRI (Natural Resources Institute) and institutions in Nigeria and Benin has been looking at the impact of resistant cowpeas on diverse populations of cowpea seed beetles bridging the gap from laboratory studies into the field situation. There are marked differences in the responses of populations, even those from geographically adjacent states in a single country. Therefore, the release and distribution of such seeds needs to take account of such differences and it cannot be assumed that a single resistant cultivar will be equally valuable throughout the range of the pest.

Other work

Recent projects have included:

A study of Callosobruchus subinnotatus, the primary pest of bambara groundnuts in West Africa. We have been looking at the possibility of an entirely new potential control measure involving control of adult polymorphism. There are two distinct morphs of this insect: one produces many eggs in the presence of seeds and another which needs more complex external cues for reproduction to commence. If environmental conditions could be modified to ensure or even increase the production of the latter morph then pest populations would significantly decline.

Work in collaboration with the NRI (Natural Resources Institute) and institutions in Nigeria and Benin has been looking at the impact of resistant cowpeas on diverse populations of cowpea seed beetles bridging the gap from laboratory studies into the field situation. There are marked differences in the responses of populations, even those from geographically adjacent states in a single country. Therefore, the release and distribution of such seeds needs to take account of such differences and it cannot be assumed that a single resistant cultivar will be equally valuable throughout the range of the pest.

Facilities

Populations of Callosobruchus maculatus, C. subinnotatus, C. analis and Zabrotes subfasciatus are maintained in the laboratory for comparative studies. The laboratory is fully equipped to undertake work with a range of stored product pest both from tropical and temperate climates.

Other Activities

I am the Editor-in-Chief of the Journal of Stored Products Researc, the premier international journal in its field (http://www.elsevier.nl/locate/jspr).

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