Increased damage by western flower thrips Frankliniella occidentalis in chrysanthemum intercropped with subterranean clover

Abstract

Suppressive effects of intercropping on Frankliniella occidentalis (Pergande) infestations have been reported in several crops. However, this study demonstrates that in year-round chrysanthemum, Dendranthema grandiflora Tzvelev, undersowing with subterranean clover, Trifolium subterraneum L., results in an increased thrips feeding damage. In a pot experiment, performed with chrysanthemum plants (cultivars Reagan and Tiger) grown with or without subterranean clover, significantly more leaves with silver and growth damage were found in the chrysanthemum plants with subterranean clover in comparison with the monocropped chrysanthemum plants. Similarly, the degree of deformation of leaf perimeter and leaf surface was higher in the top leaves of the intercropped chrysanthemum plant. In the soil experiment (only performed with Tiger and plants were grown in the soil in the greenhouse) intercropped chrysanthemum plants suffered a higher feeding damage as well. Analysis of the relation between silver or growth damage and the thrips pressure demonstrates that at similar thrips pressure in the intercropped chrysanthemum plants suffered significantly more damage. The higher thrips pressure in the intercropped chrysanthemum only explains the differences in damage partly. Changes in the reaction of chrysanthemum plants to thrips feeding or in the behaviour of the thrips, mediated by the presence of the non-host crop, are discussed. Our explanation is that chrysanthemum plants grown with clover are more susceptible to thrips feeding than monocropped plants. We conclude that undersowing with clover does not contribute to reduce damage by F. occidentalis in year-round chrysanthemum. Also, the influence of crop diversification on a pest cannot be foreseen until the specific characteristics of each individual crop -pest system are studied.

Population densities of herbivorous lepidopterans in diverse cruciferous cropping habitats: Effects of mixed cropping and using a living mulch

“…Andow (1991) suggested that a single ecological theory could not account for the responses of all species to diversified plant systems. Further, Belder et al (1999) proposed that crop diversification influence on arthropods cannot be predicted without studying specific characteristics associated with each individual crop-pest community. Although, some of the key folivores of broccoli were reduced in vegetationally diverse habitats, endorsing its use is impractical at this time.…”

Effects of undersown clover on host‐plant selection by Thrips tabaci adults in leek

“…Den Belder et al (1999) showed that subterranean clover is a very poor host for the western flower thrips Frankliniella occidentalis and Toapanta et al (1996) had similar results with white clover. In our field experiment, only eight T. tabaci adults and no nymphs were found on the strawberry clover in the field throughout the observation period from June to October.…”

“…Evidently, clover affects resistance of the hostplant to thrips (den Belder et al, 1999). Damage caused by T. tabaci is lower in leek intercropped with subterranean clover than in leek monocropping at the same onion thrips density (Theunissen & Schelling, 1997).…”