Population abundance and movement of Frankliniella species and Orius insidiosus in field pepper

Abstract

Summary1 A recent study revealed the capacity of the Orius insidiosus to suppress populations of Frankliniella spp. in field pepper during the spring when thrips are rapidly colonizing and reproducing. In this study, population abundance in pepper during spring, summer, and autumn was determined to understand better predator/prey dynamics under local conditions. Local movement between pepper flowers also was quantified to examine how population attributes of the predator allow suppression of rapidly moving populations of prey.2 Randomized complete block experiments established in the autumn of 1998 and the spring of 1999 included treatments of biological and synthetic insecticides, which altered the population densities of predator and prey. Numbers of O. insidiosus in relation to prey were sufficient in 1998 to prevent build‐up of thrips populations. In 1999, populations of thrips were unable to recover from near extinction owing to persistence of the predator. The predator rapidly recolonized plots treated with insecticide.3 Greenhouse plants of the same age as field plants were used to monitor movement by predators and prey. Movement by F. occidentalis was limited, whereas F. tritici and F. bispinosa moved rapidly to the greenhouse plants. The males of each thrips species moved more rapidly than the females. There was evidence that rapid movement assisted F. tritici and F. bispinosa in avoiding predation, but O. insidiosus also moved very rapidly to the greenhouse plants. This attribute explains the predator's ability to suppress thrips rapidly even when populations are rapidly colonizing and reproducing in the flowers.

Integrated Management Tactics for <I>Frankliniella</I> Thrips (Thysanoptera: Thripidae) in Field-Grown Pepper

“…Pepper is a suitable reproductive host for Frankliniella species, thus making primary and secondary disease cycles of thrips-vectored pathogens possible (see Puche et al 1995). Conversely, pepper also is a suitable host for many important natural enemies, such as Orius insidiosus (Say) (Heteroptera: Anthocoridae) and Geocoris punctipes (Say) (Heteroptera: Lygaeidae), that are capable of suppressing thrips populations (Schoenig and Wilson 1992, Funderburk et al 2000, Ramachandran et al 2001. However, if UV reßective mulch interferes with the ability of natural enemies to locate prey, its use could disrupt these valuable natural control mechanisms (see Parker 1969, Freund andOlmstead 2000, for role of vision in predatory Heteroptera).…”

“…Other Þeld studies have shown that O. insidiosus is capable of rapidly colonizing plants and suppressing Frankliniella spp. (Funderburk et al 2000, Ramachandran et al 2001). However, this valuable naturally occurring control may be disrupted if UV-reßective mulches retard colonization by natural enemies.…”

“…Ramachandran et al (2001) hypothesized that this anomaly is a function of the relative mobility of the different species. They found that F. tritici and F. bispinosa were able to colonize plants more rapidly than F. occidentalis.…”

Management Strategies for Western Flower Thrips and the Role of Insecticides

“…Ecologically, western flower thrips is highly polyphagous and capable of reproducing on numerous host plants (Northfield et al, 2008;Paini et al, 2007). As large populations can develop on non-crop hosts, mass dispersal into crops occurs, whether open field crops (Pearsall & Myers, 2001;Puche et al, 1995;Ramachandran et al, 2001) or crops in protected environments (Antignus et al, 1996). The potential for continual recolonization of crops limits the observed field efficacy of insecticides (Eger et al, 1998;Reitz et al, 2003).…”

“…Consequently, there is the potential for secondary virus spread from within the crop (Gitaitis et al, 1998). However, Funderburk et al (2000) demonstrated that the predator Orius insidiosus (Say) colonizes peppers and can effectively suppress thrips populations in the crop (Funderburk et al, 2000;Ramachandran et al, 2001). In particular, O. insidiosus preferentially preys on western flower thrips over the native species F. tritici and F. bispinosa (Baez et al, 2004;Reitz et al, 2006).…”