Parasitism of Bemisia tabaci (Homoptera: Aleyrodidae) by Eretmocerus mundus (Hymenoptera: Aphelinidae) on cassava

Abstract

Parasitism rates of Bemisia tabaci (Gennadius) and searching and oviposition behaviours of its parasitoid Eretmocerus mundus Mercet were compared on two cassava varieties: a glabrous variety, Nase 4 and a hirsute variety, MM97/0245 with c. 88 leaf hairs/cm 2 . Parasitism was assessed after potted plants of both varieties were exposed in open fields to natural infestation by B. tabaci and its natural enemy. For the behavioural studies, naive, less than 24-h-old females were individually observed on infested cassava leaflets under a microscope for a maximum of 1 h each. The different foraging behaviours were recorded using the computer software 'The Observer 5.0' (Noldus Ltd, Wageningen, The Netherlands). Total per cent parasitism and parasitism by E. mundus did not differ significantly between varieties. Upon encounter with leaf hairs, the parasitoids stopped and groomed before resuming the host search. The frequency of repeat probing, host feeding and antennation after probing and host feeding were higher on the glabrous than on the hirsute variety, while the converse was observed when feeding on liquids on the leaf. The duration of host assessment, initial probing, grooming and resting on the leaf was higher on the glabrous than on the hirsute variety. Leaf hairiness at the density investigated caused some changes in the behaviour of the parasitoids, but did not have an overall effect on field parasitism. Since cassava is generally considered to have glabrous leaves and the variety MM97/0245 is one of the most hirsute varieties, we discount leaf hairiness as a factor in determining levels of parasitoid activity.

Bemisia: Bionomics and Management of a Global Pest

“…For B. tabaci, variants have been distinguished based on host range (Abdullah et al 2006;Attique et al 2003;Bird and Brown 1998;Butler and Brown 1985;Brown 1990, 1991;Costa et al 1991a, b;Costa and Russell 1975;Legg 1994Osmondi et al 2005;Sseruwagi et al 2006;Servin-Villegas et al 2006;Simon et al 2003;Thompson 2003) life history traits Costa et al 1991b;Demichelis et al 2005;Viscarret et al 2003), and other evidence for phenotypic variation, including differential virus transmission, which influences the epidemiology of viral outbreaks and their control (Brown et al , 2004aBrown and Bird 1996;Legg et al , 2008. For B. tabaci, variants have been distinguished based on host range (Abdullah et al 2006;Attique et al 2003;Bird and Brown 1998;Butler and Brown 1985;Brown 1990, 1991;Costa et al 1991a, b;Costa and Russell 1975;Legg 1994Osmondi et al 2005;Sseruwagi et al 2006;Servin-Villegas et al 2006;Simon et al 2003;Thompson 2003) life history traits Costa et al 1991b;Demichelis et al 2005;Viscarret et al 2003), and other evidence for phenotypic variation, including differential virus transmission, which influences the epidemiology of viral outbreaks and their control (Brown et al , 2004aBrown and Bird 1996;Legg et al , 2008.…”

“…The latter is thought to be a recent introduction that catalyzed the initiation of the severe cassava mosaic disease, which involves several virulent begomoviruses (Legg et al , 2008. The latter is thought to be a recent introduction that catalyzed the initiation of the severe cassava mosaic disease, which involves several virulent begomoviruses (Legg et al , 2008.…”

“…Even so it has proven useful for discerning certain geographical differences, namely in the demarcation of eastern and western haplotypes from cassava in Africa, which diverge by~7-8% (Brown et al 2004b;Legg et al 2008). It has also been used to a small degree for differentiation of haplotypes in Africa and India (Legg et al 2008). This marker also was used to discriminate the B biotype from the ISR-Q biotype in insecticide resistance studies among laboratory populations (Alon et al 2006).…”

Emerging threats of begomoviruses to the cultivation of medicinal and aromatic crops and their management strategies

“…However, neonicotinoids are applied to Bt cotton for controlling whiteflies, and this resulted in the selection of resistant Q-biotype of B. tabaci [54,63]. A balanced approach for vector management would be the natural enemies of B. tabaci [103]. Although effective sources of resistance have been identified for non-Bemisia whitefly species in Latin America [17] and have suggested that these are less effective against African B. tabaci, [84,85].…”

Approaches to disease management in organic crop production systems: a case of cassava mosaic disease and black pod disease of cocoa

“…Otim et al [48] suggested an urgent need to develop a balanced approach to CMD/CBSD/vector management, which can combine the deployment of CMD/CBSD/whitefly-resistant cultivars and alternative control methods, such as the use of B. tabaci natural enemies. Although effective sources of resistance have been identified for non-Bemisia whitefly species in Latin America [49], preliminary results suggest that these are less effective against African B. tabaci, and further research into alternative sources of resistance to B. tabaci is required [50][51].…”