Host plant resistance towards the cabbage whitefly in Brassica oleracea and its wild relatives
Pelgrom, K.T.B. ; Broekgaarden, C. ; Voorrips, R.E. ; Bas, N. ; Visser, R.G.F. ; Vosman, B.J. - \ 2015
Euphytica 202 (2015)2. - ISSN 0014-2336 - p. 297 - 306.
aleyrodes-proletella homoptera - glucosinolate polymorphism - insect-resistance - cultivars - populations - fruticulosa - tomato - tabaci
The cabbage whitefly (Aleyrodes proletella) is a phloem-feeding insect that is a serious problem in Brassica oleracea crops like Brussels sprouts, kale and savoy cabbage. In order to develop whitefly-resistant varieties it is essential to identify effective sources of resistance. In this study, we screened a large collection of 432 accessions, including wild material and landraces of Brassica oleracea as well as crop wild relatives, to determine whitefly performance in a no-choice field experiment. Putatively resistant accessions were further tested under greenhouse conditions. Resistant accessions were identified among B. oleracea var. capitata (cabbage) landraces and in the species B. villosa, B. incana and B. montana. Whereas resistance in cabbage is only expressed in plants of at least 12 weeks old, some wild relatives were already starting to express resistance at 6 weeks. This could open up possibilities for breeding cabbages that are resistant at a young(er) plant age. Our research also shows again the importance of crop wild relatives for finding pest resistances.
Differences in insect resistance between tomato species endemic to the Galapagos Islands
Lucatti, A.F. ; Heusden, A.W. van; Vos, R.C.H. de; Visser, R.G.F. ; Vosman, B. - \ 2013
BMC Evolutionary Biology 13 (2013). - ISSN 1471-2148 - 12 p.
whitefly bemisia-argentifolii - solanum section lycopersicon - natural enemies - wild tomatoes - glandular trichomes - demographic history - herbivores drive - spatial genetics - diversity - tabaci
Background The Galapagos Islands constitute a highly diverse ecosystem and a unique source of variation in the form of endemic species. There are two endemic tomato species, Solanum galapagense and S. cheesmaniae and two introduced tomato species, S. pimpinellifolium and S. lycopersicum. Morphologically the two endemic tomato species of the Galapagos Islands are clearly distinct, but molecular marker analysis shows no clear separation. Tomatoes on the Galapagos are affected by both native and exotic herbivores. Bemisia tabaci is one of the most important introduced insects species that feeds on a wide range of plants. In this article, we address the question whether the differentiation between S. galapagense and S. cheesmaniae may be related to differences in susceptibility towards phloem-feeders and used B. tabaci as a model to evaluate this. Results We have characterized 12 accessions of S. galapagense, 22 of S. cheesmaniae, and one of S. lycopersicum as reference for whitefly resistance using no-choice experiments. Whitefly resistance was found in S. galapagense only and was associated with the presence of relatively high levels of acyl sugars and the presence of glandular trichomes of type I and IV. Genetic fingerprinting using 3316 SNP markers did not show a clear differentiation between the two endemic species. Acyl sugar accumulation as well as the climatic and geographical conditions at the collection sites of the accessions did not follow the morphological species boundaries.
Symbiotic bacteria (Erwinia sp.) in the gut of Frankliniella occidentalis (Thysanoptera: Thripidae) do not affect its ability to transmit tospovirus
Vries, E.J. de; Wetering, F. van de; Hoek, M.M. van der; Jacobs, G. ; Breeuwer, J.A.J. - \ 2012
European Journal of Entomology 109 (2012)2. - ISSN 1210-5759 - p. 261 - 266.
western flower thrips - spotted wilt virus - insect vector - protein - tabaci
Tomato spotted wilt virus (TSWV) is one of the most harmful plant viruses and one of its most important vectors is the western flower thrips [Frankliniella occidentalis Pergande (Thysanoptera: Thripidae)]. Recently, we reported the close association of Erwinia sp. gut bacteria with this species of thrips. The first instar larvae acquire these bacteria from their food source. A high proportion of adult western flower thrips transmit TSWV after acquiring the virus during the first larval stage when there are no bacteria in their gut. A considerably lower proportion of adults that acquire the virus early in the second instar transmit virus and none of those exposed to virus late on in the second instar do so. The highest prevalence and total number of symbiotic bacteria are recorded in the guts of second instar thrips. This leads to the hypothesis that the build up of bacteria in the gut reduces the acquisition of TSWV, resulting in a lower capacity to transmit the virus. To test this hypothesis, the transmission of this virus by symbiotic and aposymbiotic adult thrips of the NL3 population was studied. Comparison of virus transmission by adult thrips, the larvae of which either had or lacked gut bacteria and were exposed to virus in either the first or second instar, revealed no difference in the ability of symbiotic and aposymbiotic adults to transmit this virus. We conclude that virus transmission is not affected by the number of the symbiotic bacteria Erwinia sp. present in the gut of thrips larvae
Identification of silverleaf whitefly resistance in pepper
Firdaus, S. ; Heusden, S. van; Harpenas, Asep ; Supena, E.D.J. ; Visser, R.G.F. ; Vosman, B. - \ 2011
Plant Breeding 130 (2011)6. - ISSN 0179-9541 - p. 708 - 714.
bemisia-argentifolii homoptera - hirsutum f-glabratum - trialeurodes-vaporariorum - sweet-pepper - wild tomato - aleyrodidae - tabaci - oviposition - cotton - insecticide
Whitefly is economically one of the most threatening pests of pepper worldwide, which is mainly caused by its ability to transmit many different viruses. In this research, we characterized pepper germplasm to identify whitefly-resistant accessions that will form the basis for future resistance breeding. Forty-four pepper accessions representing four species (Capsicum annuum, C. frutescens, C. chinense, C. baccatum) were screened for resistance to whiteflies. Screening parameters were adult survival (AS) and oviposition rate (OR) in a no-choice test and whitefly, egg and nymphal density in free-choice tests. To combine parameters in free-choice tests, a plant resistance value was calculated. The results show that AS and OR were significantly different among accessions and were positively correlated, which was also the case for the parameters in the free-choice tests. Accessions identified as highly resistant in no-choice and free-choice tests generally were C. annuum. Whitefly density and OR correlated positively with trichome density and negatively with cuticle thickness of leaves.
Selection of Bemisia nymphal stages for oviposition or feeding, and host-handling times of arrhenotokous and thelytokous Eretmocerus mundus and arrhenotokous E. eremicus
Ardeh, M.J. ; Jong, P.W. de; Lenteren, J.C. van - \ 2005
BioControl 50 (2005)3. - ISSN 1386-6141 - p. 449 - 463.
encarsia-formosa hymenoptera - trialeurodes-vaporariorum homoptera - biological-control agents - life-history parameters - amitus-fuscipennis - aphelinid parasitoids - foraging behavior - aleyrodidae - tabaci - strategies
Host-handling behavior is an important aspect of parasitoid foraging behavior. When a parasitoid encounters a potential host, the handling behavior starts with the evaluation of the host and continues if the host has been judged acceptable. Host handling is usually terminated after egg laying or host feeding and host marking. Host-handling behavior of an arrhenotokous population of two Eretmocerus species, E. mundus Mercet and E. eremicus Rose and Zolnerowich, along with a thelytokous population of E. mundus were compared under laboratory conditions. Several elements of host-handling behavior, including encountering, ascending, turning on host, descending, preening, egg laying, and host feeding were recorded. There were no correlations among the durations of these phases across parasitoid populations/species or host nymphal instars. Duration of different phases of host-handling behavior showed only slight and sometimes significant differences between different Eretmoceruspopulations/species. The actual laying of the egg had the longest duration of all host-handling behaviors, and was longer on third nymphal instars than on younger ones. Females of the three populations/species accepted the first three nymphal stages either for egg laying or for host feeding. Females spent a lot of time to make wounds in the host when preparing for host feeding, and eventually killed the host. The implications of these findings for the use of the different Eretmoceruspopulations/species in biological control are discussed
Pathogenicity of Aschersonia spp. against whiteflies Bemisia argentifolii and Trialeurodes vaporariorum
Meekes, E.T.M. ; Fransen, J.J. ; Lenteren, J.C. van - \ 2002
Journal of Invertebrate Pathology 81 (2002). - ISSN 0022-2011 - p. 1 - 11.
parasitoid encarsia-formosa - entomopathogenic fungi - biological-control - aleyrodis - survival - germination - greenhouses - tabaci
Entomopathogenic fungi of the genus Aschersonia are specific for whitefly and scale insects. They can be used as biological control agents against silverleaf whitefly, Bemisia argentifolii and greenhouse whitefly, Trialeurodes vaporariorum. Forty-four isolates of Aschersonia spp. were tested for their ability to sporulate and germinate on semi-artificial media and to infect insect hosts. Seven isolates sporulated poorly (less than 1 x 10(7) conidia/dry weight) and 10 were not able to infect either of the whitefly species. Several isolates were able to produce capilliconidia. Infection level was not correlated with germination on water agar. After a selection based on spore production and infection, virulence of 31 isolates was evaluated on third instar nymphs of both whitefly species on poinsettia (Euphorbia pulcherrima). Whitefly infection levels varied between 2 and 70%, and infection percentages of B. argentifolii correlated with that of T vaporariorum. However, mortality was higher for T vaporariorum than for B. argentifolii, as a result of a higher 'mortality due to unknown causes.' Several isolates, among which unidentified species of Aschersonia originating from Thailand and Malaysia, A. aleyrodis from Colombia, and A. placenta from India showed high spore production on semi-artificial medium and high infection levels of both whitefly species. (C) 2002 Elsevier Science (USA). All rights reserved.