Taxonomy and biology of jumping plant-lice (Hemiptera: Psylloidea) of Cameroon, including pests of cultivated plants and forest timber and strategies for an integrated pest management.

Swiss Coordinator : Daniel Burkhardt, Naturhistorisches Museum, Basel
Main Foreign partner : Joseph Lebel Tamesse, Laboratory of Zoology, University of Yaounde
Cooperation with : Cameroon
Disciplines : Botany, Zoology

Abstract : Jumping plant-lice or psyllids (Hemiptera, Psylloidea) form a small group of plant-sap sucking insects. Currently there are some 3000 species described worldwide with an estimated further 5000 undescribed species. They are particularly species-rich in the tropics where the fauna is generally poorly known. Psyllids are characterised by their very narrow host ranges, i.e. many species develop on a single host plant species only. Often related psyllids occur on related host plants which makes them potentially interesting for coevolutionary studies in addition to the use as biological control agents of weeds. Only few publications are dedicated to the taxonomy of tropical African psyllids and even less is known of the psyllid fauna of Cameroon. So far 23 psyllid species have been recorded from Cameroon (see appendix 1). Recent field work yielded additional material containing several species not previously recorded from Cameroon and some 30 species which are new to science. Compared to temperate faunas, e.g. Central Europe with some 170 species (Burckhardt 2002) it can be expected that the psyllid fauna of Cameroon contains at least 200 species.
Local faunal and floral inventories are an important base for reaching the goals defined in the Convention on Biological Diversity (CBD 1992), i.e. the conservation and sustainable use of biodiversity. For large groups such as insects with over one million described species a major problem constitutes the large proportion of undescribed taxa. This situation has been termed the "taxonomic impediment". Psyllids are, in this respect, no exception as less than half of the existing species are described up to date.
Like other Hemiptera, psyllids may become serious pests on cultivated plants. A sound taxonomic base is also essential for the control of pests. This base, however, lacks almost completely in the tropics. In Cameroon several species of economically important agricultural crop plants and commercial timber species are attacked by psyllids that are responsible for big losses in orchards and plantations, e.g. Citrus (Citrus spp.), cocoa (Theobroma cocoa) and commercial timber species (Afzelia bipindensis, Antiaris africana, Detarium macrocarpum, Diospyros crassiflora, Irvingia gabonensis, Leucena glauca, Melicia excelsa, Triplochiton scleroxylon etc.). Psyllids damage their hosts in various ways: distortion of leaves, necrotic leaf damage by sucking, and induction of various types of galls on the leaves, stems or flowers. In some cases psyllid action can cause the death of the plants, more often the tree growths is slowed down causing economical loss. In nurseries psyllids can destroy young plants. Some psyllids act as vector of bacterial and viral diseases.
The present project proposes field surveys in Cameroon for collecting and observing psyllids in the their natural environment. Areas are chosen to represent a maximum diversity of habitats. Material is collected for subsequent identification and taxonomic analyses. Collections in the field are done with a sweep net and by use of yellow pan trays. Five selected sites will be surveyed monthly over two years for getting information on the phenology of the psyllids. Preliminary taxonomic work including conserving, mounting and labelling of specimens will be done in the laboratory in Yaoundé. The detailed taxonomic work including the confirmation of the identifications will be done at the Natural History Museum Basel which houses the second largest psyllid collection of the world. This collection is indispensable for any revisionary taxonomic work which necessitates the comparison of material. A collaboration between the Swiss and Cameroonian team is, therefore, vital. Biological data for a few selected pest species will be obtained from work in nurseries of forest crop plants in view of biological control of the psyllid pests.
The present project intends to constitute an inventory of the psyllid fauna of Cameroon, based on field surveys in different regions, and to produce a monographic treatment of the psyllid species from Cameroon containing descriptions, illustrations and keys for the identification of adults and larvae as well as information on host plants, distribution, phenology and biology. The results will consist of an electronic data base for the distributional data and a printed monograph/handbook for the identification of the Cameroonian species. If possible, the database and key will be also made accessible on the internet. Finally, a very important component of the project is to build a reference collection at Yaoundé which will serve for future research as well as training of students and young researchers.