Spatial Dependence, Dispersion, and Sequential Sampling ofAnaphothrips obscurus(Thysanoptera: Thripidae) in Timothy

Abstract

The spatial distribution and dispersion of Anaphothrips obscurus (Müller) (Thysanoptera: Thripidae) was examined with the goal of establishing a sequential sampling plan for this pest in timothy, Phleum pratense L. (Poaceae). Approximately 16 different California timothy fields were sampled twice yearly from 2006 to 2008 using direct observation and the beat cup method. For direct observation, the number of thrips on each leaf of the plant was counted. For the beat cup method, tillers were tapped into a cup and dislodged thrips were counted. Samples were separated by ≈3 m in 2006 and 2007 and exactly 3 m in 2008. Spatial autocorrelation of intrafield population distribution was tested for significance in 2008 using Moran's I, but autocorrelation was not detected. The population dispersion was assessed by Taylor's power law and was determined to be aggregated and density-dependent. Intraplant population dispersion and distribution for each year were also evaluated for adults, larvae, and total thrips. All lifestages were highly spatially dependent and more thrips were found near the top of the plant than the bottom. Direct observation proved to be a more accurate and precise method than the beat cup method, especially when thrips abundances were greater than one. However, the number of samples required to provide an accurate level of precision was unrealistic for both methods. A sequential sampling plan was evaluated, but was not practical for the beat cup method because few thrips were found using this method. Because there was no spatial autocorrelation at sampling distances of 3 m, samples can be taken at intervals at 3 m to obtain spatially independent population abundance estimates.

Spatiotemporal population dynamics of the banana rind thrips, Elixothrips brevisetis (Bagnall) (Thysanoptera: Thripidae)

“…We found that the abundance of thrips on suckers was first positively correlated with the height of the sucker, suggesting that the population dynamics of E. brevisetis may be resource dependent as has been shown for the thrips Anaphothrips obscurus (Reisig et al. ). An alternative hypothesis is that the number of thrips on the banana plant is dependent on the number of young leaves.…”

“…The thrips were enumerated by direct, visual observation because this method has been proven to be effective (Delattre and Torregrossa ; Reisig et al. ). At each observation time, we also collected information on the height of the sucker, the phenological status (pre‐flowering or flowering) of the mother plant and the presence of weeds in a 1‐m radius around each banana plant.…”

Comportamiento espacial y temporal de Thrips simplex Morison (Thysanoptera: Thripidae) en la región norte del Estado de México

“…en aguacate (Solares et al, 2011), Thrips spp. asociados al arándano (Rhodes et al, 2011), Thrips palmi Karny (Cho & Lee 2000) y Anaphothrips obscurus Müller (Reisig et al, 2011).…”

Within-Field Spatial Distribution of Stink Bug (Hemiptera: Pentatomidae)-Induced Boll Injury in Commercial Cotton Fields of the Southeastern United States

“…Variogram analysis, developed for geology and mining, has more recently been adapted for environmental and ecological studies. It has been used to describe spatial structure of western tarnished plant bugs, Lygus hesperus (Knight), in cotton (Carriere 2006); sunßower midge, Contarinia shulzi Gagne, in sunßower, Helianthus annuus L (Hodgson 2004); coffee berry borer, Hypothenemus hampei Ferrari, and leaf minor, Leucoptera coffeella, in coffee, Coffea arabica L. (Alves et al 2011); and grass thrips, Anaphothrips obscurus (Mü ller), in timothy, Phleum pratense L. (Reisig et al 2011). Results from MoranÕs I and variogram analysis can be used to further analysis, such as kriging interpolation (Alves et al 2011, Reisig et al 2011.…”