Trap colour and aggregation pheromone dose affect the catch of western flower thrips in blackberry crops

Understanding the mechanisms involved in host plant resistance opens the way for improved resistance breeding programs by using the traits involved as markers. Pest management is a major problem in cultivation of ornamentals. Gladiolus (Gladiolus hybridus L.) is an economically important ornamental in the Netherlands. Gladiolus is especially sensitive to attack by western flower thrips (Frankliniella occidentalis (Pergande) (Thysanoptera:Thripidae)). The objective of this study was, therefore, to investigate morphological and chemical markers for resistance breeding to western flower thrips in Gladiolus varieties. We measured thrips damage of 14 Gladiolus varieties in a whole-plant thrips bioassay and related this to morphological traits with a focus on papillae density. Moreover, we studied chemical host plant resistance to using an eco-metabolomic approach comparing the 1H NMR profiles of thrips resistant and susceptible varieties representing a broad range of papillae densities. Thrips damage varied strongly among varieties: the most susceptible variety showed 130 times more damage than the most resistant one. Varieties with low thrips damage had shorter mesophylls and epidermal cells, as well as a higher density of epicuticular papillae. All three traits related to thrips damage were highly correlated with each other. We observed a number of metabolites related to resistance against thrips: two unidentified triterpenoid saponins and the amino acids alanine and threonine. All these compounds were highly correlated amongst each other as well as to the density of papillae. These correlations suggest that papillae are involved in resistance to thrips by producing and/or storing compounds causing thrips resistance. Although it is not possible to distinguish the individual effects of morphological and chemical traits statistically, our results show that papillae density is an easy marker in Gladiolus-breeding programs targeted at increased resistance to thrips.

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Temporal Analysis of Western Flower Thrips (Thysanoptera: Thripidae) Population Dynamics on Reunion Island

Environmental Entomology ◽

10.1093/ee/27.6.1437 ◽

1998 ◽

Vol 27 (6) ◽

pp. 1437-1443 ◽

Cited By ~ 9

Author(s):

Nathalie Boissot ◽

Bernard Reynaud ◽

Philippe Letourmy

Keyword(s):

Population Dynamics ◽

Western Flower Thrips ◽

Temporal Analysis ◽

Reunion Island ◽

Flower Thrips ◽

Réunion Island

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Stability of spinosad resistance inFrankliniella occidentalis(Pergande) under laboratory conditions

Bulletin of Entomological Research ◽

10.1017/s0007485308005658 ◽

2008 ◽

Vol 98 (4) ◽

pp. 355-359 ◽

Cited By ~ 12

Author(s):

P. Bielza ◽

V. Quinto ◽

C. Grávalos ◽

E. Fernández ◽

J. Abellán ◽

...

Keyword(s):

Resistant Strain ◽

Selection Pressure ◽

Frankliniella Occidentalis ◽

Western Flower Thrips ◽

Laboratory Conditions ◽

Flower Thrips ◽

Factors Influencing ◽

Stability Of Resistance ◽

The Stability ◽

Successive Generations

AbstractThe stability of spinosad resistance in western flower thrips (WFT),Frankliniella occidentalis(Pergande), populations with differing initial frequencies of resistance was studied in laboratory conditions. The stability of resistance was assessed in bimonthly residual bioassays in five populations with initial frequencies of 100, 75, 50, 25 and 0% of resistant individuals. There were no consistent changes in susceptibility of the susceptible strain after eight months without insecticide pressure. In the resistant strain, very highly resistant to spinosad (RF50>23,000-fold), resistance was maintained up to eight months without further exposure to spinosad. In the absence of any immigration of susceptible genes into the population, resistance was stable. In the case of the population with different initial frequency of resistant thrips, spinosad resistance declined significantly two months later in the absence of selection pressure. With successive generations, these strains did not change significantly in sensitivity. Spinosad resistance inF. occidentalisdeclined significantly in the absence of selection pressure and the presence of susceptible WFT. These results suggest that spinosad resistance probably is unstable under field conditions, primarily due to the immigration of susceptible WFT. Factors influencing stability or reversion of spinosad resistance are discussed.

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