Insects associated with fruit, seed and foliage of Uapaca kirkiana (Muell.arg.) (Euphorbiaceae) in Malawi

Meke, Gerald Simeon (1998-03)

Thesis (M. Sc.) -- University of Stellenbosch, 1998.

Thesis

ENGLISH ABSTRACT: Arthropods associated with Uapaca kirkiana in Dedza and Zomba, Malawi, were collected during October 1996, January 1997, June 1997 and August 1997 using various collection methods including beating, sweepnets, suction using an aspirator and collection of parts of plants with endogenous arthropods or on which external sessile arthropods were attached. A total of 12,849 arthropods were collected and sorted into 10 orders, 40 families and 51 morphospecies. Arthropod diversity was high in Dedza, but the few arthropods species that occurred in Zomba had more individuals per species. More arthropods were recorded on trees growing in woodlands dominated by either large or small Uapaca trees. Leafchewers and sapsuckers comprised the majority of the arthropods collected. Highest arthropod counts were registered in October 1996 and lowest in June1997. Six arthropod morphospecies namely Phycitidae (undetermined species), white scales (undetermined species), Gelechiidae (undetermined species), Lasiocampidae (undetermined), Bunaea alcinoe (Saturniidae) and Leptoglossus membraceus (Heteroptera) were observed causing significant damage. The other species were either natural enemies or did not significantly affect U. kirkiana trees. Most arthropod damage was observed on individual trees on the farm and in woodlands dominated by either large or small Uapaca trees. The low arthropod incidence and arthropod damage on U. kirkiana in mixed woodland and fire prone areas suggest that mixed woodland is the best option for managing U. kirkiana and that early controlled fire can also be used to minimize pests. The large number of arthropods without a direct effect on U. kirkianaunderlines the role of this tree as an alternative or alternate host to pests of associated crops.

AFRIKAANSE OPSOMMING: Geleedpotiges geassoseer met Uapaca kirkiana in Dedza en Zomba, Malawi, is versamel gedurende Oktober 1996, lanuarie 1997 en Augustus 1997. Verskillende versamelingsmetodes, insluitende afklop, die gebruik van sleepnette en suigwaaiers en die versameling van. plantdele met endogene insekte of waaraan sittende geleedpotiges vasgeheg is, is gebruik. 'n Totaal van 12,849 geleedpotiges is versamel en gesorteer in 10 ordes, 40 families en 51 morfo-spesies. Die diversiteit van geleedpotiges was hoog in Dedza, maar die paar geleedpotige spesies wat voorgekom het in Zomba het meer individue per spesie gehad. Meer geleedpotiges is versamel op borne wat in boslande, gedomineer deur groot of klein Uapaca borne, groei. Blaarkouers en sapsuiers verteenwoordig die meerderheid van die geleedpotiges wat versamel is. Die hoogste geleedpotige tellings is geregistreer in Oktober 1996 en die laagste in lunie 1997. Ses geeldpotige morfo-spesies, genaamd Phycitidae (onbepaalde spesie), wit skubbe . ( onbepaalde spesie), Gelechiidae ( onbepaalde spesie), Lasiocampidae ( onbepaalde spesie), Bunaea alcinoe (Saturniidae) en Leptoglossus membraceus (Heteroptera), wat beduidende skade aangerig het, is waargeneem. Die ander spesies was of natuurlike vyande, of het nie U. kirkiana borne beduidend geaffekteer nie. Die meeste geleedpotige skade is waargeneem op individuele borne op die plaas en in boslande wat deur groot of klein Uapaca borne gedomineer word. Die lae voorkoms van geleedpotiges en geleedpotige skade op U kirkiana in gemengde bosland en areas waar vure voorkom, suggereer dat gemengde bosland die beste opsie vir die bestuur van U. kirkiana is en dat vroee beheerde brande gebruik kan word om peste te verminder. Die groot aantal geleedpotiges wat nie 'n direkte effek op U. kirkiana het nie onderstreep die rol wat die borne as 'n altematief of altematiewe gasheer vir peste van geassosieerde gewasse speel.

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