Density, dispersal, and feeding impact of western flower thrips (Thysanoptera: Thripidae) on flowering chrysanthemum at different spatial scales

Abstract

Abstract. 1. This study evaluated the effect of dispersal on the density and feeding impact of a phytophagous insect in relation to the spatial distribution of its host plants.2. The interaction between density, dispersal, and feeding impact of western flower thrips on flowering chrysanthemum was quantified at three spatial scales, with infested and uninfested plants either isolated in 0.25 m2 individual cages, or enclosed together in 2.25 m2 communal cages or 75 m2 greenhouses.3. In individual cages, the rate of dispersal from chrysanthemum plants to blue sticky traps increased with the density of thrips for females but not males. Uninfested plants consistently had fewer thrips when they were individually caged rather than enclosed with plants infested with adults, indicating that dispersal mediates inter‐plant distribution of thrips.4. The feeding impact of thrips on inflorescences was evaluated using the absorbance of ethanol extracts at wavelengths characteristic of yellow carotenoid pigments associated with chrysanthemum inflorescences (415, 445, and 472 nm). Increasing absorbance of extracts with increasing density of thrips per inflorescence suggests that feeding by thrips results in ruptured cells leaching carotenoid pigments.5. In communal cages, the distribution of thrips was uniform for infested and uninfested plants, whereas the density and feeding impact of thrips in greenhouses were higher for infested than uninfested plants. These results suggest that short‐range dispersal by adults homogenises the density and feeding impact of thrips among host plants only on a small spatial scale.

Seasonal Dispersal Patterns of Frankliniella fusca (Thysanoptera: Thripidae) and Tomato Spotted Wilt Virus Occurrence in Central and Eastern North Carolina

“…Chu et al (2006) found that yellow stickycard traps caught more S. dorsalis adults than sticky traps of other colors, which suggested the thrips are probably diurnal. Local dispersal has been found to be important in the colonization success of thrips, and knowing how thrips disperse in plots is important in finding effective, long-term control strategies Nault et al 2003;Rhainds et al 2005). An improved understanding of the hierarchy of host plant preference, environmental conditions, and timing of S. dorsalis flight activity may help in predicting dispersal rates and in timing pesticide applications.…”

Population Dynamics ofScirtothrips dorsalis(Thysanoptera: Thripidae) and Other Thrips Species on Two Ornamental Host Plant Species in Southern Florida

“…Males may have been more active in local dispersal within a plot than in long-distance dispersal, and this would help account for these inconsistent results. Rhainds et al (2005) found that adult female ßower thrips F. occidentalis maintained uniform densities within 2.5-m 2 cages of chrysanthemums Dendranthema grandiflora (Tzelev). However, on a larger scale (75-m 2 greenhouse), the uniformity was reduced and density of thrips was greater near the source of infestations (Rhainds et al 2005).…”

“…Rhainds et al (2005) found that adult female ßower thrips F. occidentalis maintained uniform densities within 2.5-m 2 cages of chrysanthemums Dendranthema grandiflora (Tzelev). However, on a larger scale (75-m 2 greenhouse), the uniformity was reduced and density of thrips was greater near the source of infestations (Rhainds et al 2005). Short-range dispersal by adult F. occidentalis appears to have homogenized its density among host plants only on a small spatial scale (Rhainds et al 2005).…”

“…However, on a larger scale (75-m 2 greenhouse), the uniformity was reduced and density of thrips was greater near the source of infestations (Rhainds et al 2005). Short-range dispersal by adult F. occidentalis appears to have homogenized its density among host plants only on a small spatial scale (Rhainds et al 2005). For each host plant species in the current study, a 4 by 5 plant grid (3.4 m 2 ) was used and the resulting homogenous distributions were similar to the results of Rhainds et al (2005).…”

Thrips‐induced damage of chrysanthemum inflorescences: evidence for enhanced leakage of carotenoid pigments

“…Inflorescences of chrysanthemum represent a highquality food resource that allows for a rapid growth of thrips populations (de Jager et al, 1993;Rhainds & Shipp, 2003). The feeding activity of thrips causes a deterioration of inflorescences over time, eventually leading to an overexploitation of the food source and steep decline in abundance of thrips (van Dijken et al, 1995;Rhainds & Shipp, 2003;Rhainds et al, 2005). Symptoms of thrips-induced senescence of inflorescences include a drooping and discolouration of petals, as well as a reduction in fresh biomass (van Dijken et al, 1995;Rhainds & Shipp, 2003).…”