Study on the Optimum Pheromone Release Rate for Attraction of <I>Chilo suppressalis</I> (Lepidoptera: Pyralidae)

Abstract

Traditional chemical control against Chilo suppressalis Walker is currently being replaced in Spain by new methods based on pheromones. A key step to improve the efficacy of these methods is the determination of the optimum pheromone release rate, which is still uncertain for this pest. In this work, the pheromone release profile and the field performance of a new mesoporous dispenser was compared with a standard commercial dispenser. For this purpose, pheromone loads were extracted from field-aged dispensers and quantified by gas chromatography with flame ionization detector. In addition, a field trial was carried out with traps baited with one, two, or three mesoporous dispensers per trap, as well as with traps containing one standard dispenser. We found that the highest number of field catches did not correspond to the highest pheromone emission rate, which suggests a repellent effect of the insect if the emission is excessive. The results suggest that the attractant activity was maximized by emitting approximately 34 microg/d. The efficacy of the mesoporous dispenser and its possible improvements are discussed.

Uso de semioquímicos en el control de plagas. Estudios básicos y de aplicación

“…Similar behavior was observed for rice leaffolder moth, Cnaphalocrocis medicinalis (Guenée) (Kawazu et al, 2004). Vacas et al (2009b) found decreasing catches of Chilo suppressalis (Walker) below and above an optimal release rate of 34 µg per day. And Jactel and coworkers (2006) found an asymptotic increase response of catches of pine processionary moth (Thaumetopoea pytiocampa Denis & Schiffermüller) according to increasing doses of its pheromone from 0.5 to 20 mg, with 95% of maximum catch obtained with the 10-mg dosage.…”

“…However, only few studies determined the optimal release rate of attractants (de Groot & DeBarr, 1998;Cross et al, 2006;Vacas et al, 2009b). As mentioned above, catches do not always increase with increasing pheromone doses.…”

“…The √x-transformation of the numbers caught was used to normalize the data. Following the methodology applied in a previous study (Vacas et al, 2009b), multiple linear regression (MLR) was used to relate catch data to the emission rate, and to determine the relative maximum. The average number caught was highly variable from week to week.…”

“…However, actual release rates and the responses of flies in the field were not measured in this work. There are some studies showing a maximum attraction at a particular pheromone release rate, in Lepidoptera (Vacas et al, 2009b), Coleoptera (Obengofori, 1990;Franklin & Gregoire, 2001;Cross et al, 2006) or other Diptera (Michaelakis et al, 2007). The importance of the determination of optimum pheromone release rates has already been shown in research by Landolt & Heath (1988, testing behavioral responses of the tephritid female Papaya fruit fly, Toxotrypana curvicaudata Gerstaecker.…”

“…There are many experiences about the design and color of traps for tephritids (Epsky et al, 1995;Cornelius et al, 1999;Navarro-Llopis et al, 2008) but there are only a few studies comparing pheromone release rate and insect catches (Landolt & Heath, 1990;Domínguez-Ruiz et al, 2008;Suckling et al, 2008). Many studies have compared catches among several types or loads of dispensers for other insect families (Cork et al, 2000;Franklin & Gregoire, 2001;Kovanci et al, 2006) but only a few determined the optimal release rate of attractants in field trials (de Groot & DeBarr, 1998;Cross et al, 2006;Vacas et al, 2009b). …”