Horizontal and Vertical Distribution of Flower Thrips in Southern Highbush and Rabbiteye Blueberry Plantings, with Notes on a New Sampling Method for Thrips Inside Blueberry Flowers

Abstract

The dispersal behavior of flower thrips was studied during two field seasons within blueberry (Vaccinium spp.) plantings in Florida and southern Georgia. A "shake and rinse" technique used to extract thrips from inside the blueberry flowers was not significantly different from the conventional dissecting technique, but the time taken to complete the extraction of thrips was significantly shorter. Overall, the highest concentration of thrips was captured inside the canopy of blueberry bushes. Using a grid of traps to monitor the dispersal of thrips during the blueberry flowering season, we analyzed their dispersion with graphical and analytical methods to determine and describe their distribution within blueberry plantings. Thrips began to form "hot-spots" 5-7 d after bloom initiation. A hot-spot is defined as a large number of thrips concentrated in a small area of the field, whereas the rest of the field has a low population. The behavior of the population inside these hot-spots fit a Gaussian tendency and a regression was conducted to describe this tendency. Green's and Standardized Morisita's indices were used to determine thrips level of aggregation. Results showed significantly aggregated populations of thrips in both years. Formation of hot-spots in blueberry plantings seemed to be random. However, the formation of hot-spots was higher in places where more than seven thrips per day were captured on sticky traps, 5 to 7 d after the bloom begins. With these results, producers will be able to monitor thrips populations and locate and manage hot-spots before they become a more serious a problem on blueberry farms.

Assessing abundance and distribution of an invasive thrips Frankliniella schultzei (Thysanoptera: Thripidae) in south Florida

“…He suggested that males of F. schultzei aggregates on plant parts to attract conspecifics for mating, possibly by release of sex pheromones. In addition, there are several reports suggesting the clumped distribution of other thrips species of family Thripidae, including, T. flavus Schrank, T. major Uzel, T. atratus Haliday, F. occidentalis (Pergande) and a group of flower thrips (Morison, 1957;Kirk, 1985;Terry, 1995;Terry & Dyreson, 1996;Arevalo & Liburd, 2007) on various plant parts. Besides reproduction as a factor inducing clumping of F. schultzei population, there is not much information available on factors responsible for the aggregates forming behaviour of various thrips species.…”

Structure and Composition of a Thrips Community in the Chihuahua Desert, New Mexico, U.S.

“…For the purpose of this study, the sticky traps were the most indicated sampling method, because we do not detect differences in thrips captured among host plants in the preliminary sampling, and sticky traps have been widely used to sample thrips in many studies for different purposes (Diraviam & Uthamasamy1992;Higgins 1992;Cho et al1995;Shipp et al 2000;Finn 2003;Arévalo & Liburd 2007). However, some thrips specimens could of course be moved by winds and captured by traps set on plants that were not utilized by them, but those captures should be detected by the analysis and labeled as "random associations".…”

Effect of Humidity on Fecundity and Egg Incubation ofFrankliniella bispinosaandFrankliniella occidentalis(Thysanoptera: Thripidae)

“…The geographic distribution of thrips populations is influenced by a number of factors including temperature and humidity (Davidson & Andrewartha 1948a,b). Arévalo & Liburd (2007) recorded a clumped distribution of F. bispinosa in blueberry plantings in Florida, which they described as hot spots. The formation of these hot spots within fields was random, and the microclimate differences in temperature and humidity were believed to play a role in the development of these hot spots.…”