Effect of meadow spittlebug and Australian crop mirid on white clover seed production in small cages

Abstract

The effects of feeding by the Australian crop mirid (Sidnia kinbergi (StM» and the meadow spittlebug (Philaenus spumarius L.) on white clover (Trifolium repensL.) seedproduction weredetermined by comparing seedyieldcomponents fromuninfested plant clones with those from clones infested with varyingnumbersof the insects.Feedingby thelowest numberofAustralian cropmirid(oneperplant) caused a 50% reduction in the numbers of flower heads produced by the plants, an 18% reduction in the numberof buds producedon each flowerhead,and a 26%reduction inthenumbersof budswhichproduced florets. The number of seeds per head was also reduced. No effect on seed production was detected from meadowspittlebug feeding.

Effect of potato mirid(Calocoris norvegicus)on white clover seed production in small cages

“…Loss is based on $4 kg" 1 dressed seed. yields indicate that the bumble bees used for pollination in the cages were efficient, and support the observations made by Pearson (1991). Infestations of PM significantly reduced all components of white clover seed yield (Tables 1 and 2).…”

“…The intensities used were recalculated to densities in Table 2 to give an indication of seed yield losses incurred, which could then be used as the basis for developing economic thresholds for PM density in white clover crops. Pearson (1991) released different ACM numbers per white clover clonal plant, but concluded that the same experiment should be conducted within a crop to evaluate the influence of mirids feeding on other plant variables, as described in this experiment.…”

“…On 30 November, the plots were enclosed in 0.729 m 3 wooden-framed field cages covered in a fine mesh material, similar to those used by Pearson (1991). Five plots were left uncaged to determine any effects of the cages on plant growth and yield.…”

“…Artificial infestation techniques can thus make the study of loss assessment more direct and refined. Pearson (1991) studied the impact of different ACM densities on white clover seed yields in small field cages and found that with low densities of mixed instars (one per plant) white clover seed production was significantly reduced. Because ACM was uncommon (< 1 m~2) in field surveys carried out during the 1994-95 and 1995-96 seasons (Schroeder & Clifford 1995;N.…”

“…Pearson (1991) considered that ACM could have been a major cause of white clover inflorescence damage. However, Schroeder & Clifford ( 1996) found that ACM, brown shield bug, and wheat bug occurred too late in the season to have any major impact on white clover seed yields.…”