The Use of Semiochemicals by Tarnished Plant Bug Lygus lineolaris

Abstract

The overall goal of this research was to develop new approaches to monitoring and managing Tarnished Plant Bug (TPB), an important pest of strawberries and many other crops, through an improved understanding of its use of semiochemicals to find mates and host plants. We proposed to 1) Evaluate potential components of the TPB sex pheromone under realistic field conditions and 2) Initiate a study to identify attractive volatile compounds from a highly preferred weed host and test with virgin females and potential components of sex pheromone. We used funnel traps baited with either live, virgin females or different combinations of putative pheromone components and/or extracts of volatiles collected from Erigeron annuus or extracts from virgin females confined to traps in the field to test for attractiveness under field conditions. We also assessed antagonistic properties of putative pheromone components by placing single compounds beneath traps baited with virgin females. In addition, we attempted to test the relative role of visual and plant volatiles in host colonization. A total of 11 field experiments were conducted during the season using funnel traps, starting on 19 June and continuing until 3 September. Putative pheromone compounds in various combinations over this time period captured 5 male TPB while virgin females captured over 100 males. When placed beneath a trap baited with a live virgin female, 4-oxo-E-(2)-hexenal or its derivative appeared to enhance captures, while the other principal components (hexyl butyrate, and E-2-hexenyl butyrate) appeared to be antagonistic. An extract from the volatiles of flowering E. annuus alone or when added to the derivative of 4-oxo-E-(2)-hexenal did not result in any captures of TPB in live traps. When the plant extract was added with a virgin female we captured 4 males compared to 16 in traps baited with only the female. In late summer we used a battery, pump and filters to collect volatiles produced by virgin female TPB in the field. When placed in a live trap, the extracts from TPB captured 3 males while live virgin females captured 65 males. We conducted a choice test where we presented a group of TPB to chrysanthemum, a host plant of TPB, with or without its yellow flowers and with or without yellow cards or volatile extract from the flowers. Most TPB flew to top of the screen house and made no choice. Of the 9 TPB that moved to a plant, three colonized mums with flowers removed, but with yellow cards and flower extract added, three colonized chrysanthemums with flowers removed but yellow cards, one colonized flowering chrysanthemums (positive control) and two colonized chrysanthemums with flowers removed and nothing added (negative control). Although observation of colonization events were small, 7 out of 9 events were directed at plants with yellow color (cards or flowers) compared to 4 out of 9 events to flower odors.