Population dynamics of Frankliniella species (Thysanoptera: Thripidae) thrips and progress of spotted wilt in tomato fields
1995
Puche, H. | Berger, R.D. | Funderburk, J.E.
The population of Frankliniella thrips, as monitored by captures on sticky traps, developed quite differently in 1990 compared to 1989. The first thrips in 1990 arrived 10 days earlier, increased at a 22% faster rate, and reached an asymptotic level that was nearly twice as high as the thrips in 1989. Despite the substantial differences in the thrips populations between the 2 years, the incidence of spotted wilt in tomatoes was low (<9%) both years. Although the thrips were present daily in the crop, the disease seemingly developed in only one-three separate monocycles. These monocycles were not correlated with apparent generations of thrips nor with specific weather events. The sigmoidal curves for the cumulative number of trapped thrips over time were fit well by the Weibull model with shape parameters of c = 2.16 and 2.55 for fields 1 and 2 in 1989 and c = 3.32 and 2.81 for the two fields in 1990. Three generations of migrating thrips apparently occurred in each season as detected by waves of increased numbers of thrips when the population curves were linearized. The diseased plants occurred mostly at random in the fields, which was evidence that the primary source of dispersal was by immigrating thrips. Polycyclic development undoubtedly was prevented in these commercial fields by weekly application of insecticides. Additional tactics are needed to prevent movement into tomato fields of viruliferous thrips that develop on hosts outside the fields.
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