The Search Behavior of Omnivorous Thrips Larvae is Influenced by Spider Mite Cues

Abstract

The western flower thrips is an omnivorous insect that consumes both leaf tissue and spider mite eggs. For this reason, these thrips are often described as 'opportunistic predators' of spider mites. Several studies have shown that western flower thrips are often found in association with spider mites, and the development time of thrips decreases and their survivorship increases when they consume spider mite eggs. We tested the hypothesis that thrips larvae may respond to chemical cues from spider mites, and that they may modify their prey-searching behavior when these spider mite-induced cues are present. We prepared hexane extracts from: 1) webbing of spider mites isolated from maize leaves, 2) webbing produced by spider mites inside an empty glass tube to exclude any plant-derived cues from the extract, and 3) spider mite cuticle extracts. These three extracts were subsequently applied in droplets to one-half of filter papers, and hexane alone was applied in droplets to the other half. We showed that residence time of thrips larvae was higher on filter paper with spider mite webbing extract, especially when the extract originated from spider mites isolated in glass tubes. In the presence of webbing extracts, we also observed: 1) a decrease in velocity, 2) an increase of angular velocity and 3) an increase in time immobile. Extracts from spider mite cuticle only increased velocity and proportion of time immobile of the thrips larvae. Our results suggest that chemical cues from spider mite webbing induce an arrestment response and play an important role in the non-random search behavior of thrips larvae searching for eggs on spider mite infested plant leaves.

A sticky situation: honeydew of the pear psylla disrupts feeding by its predator Orius sauteri

“…Our results suggest that psyllid honeydew could serve as a prey‐location and oviposition cue for O. sauteri , but may reduce foraging by these predators. Predators were attracted to honeydew compared to no‐honeydew controls as demonstrated by orthokinesis (stopping and/or slowing down) and klinokinesis (increase of turning rates) . Similarly, O. sauteri bugs spent more time foraging in zones when psylla honeydew was present compared to a blank control without honeydew (Fig.…”

“…Experimental arenas were divided into two equal‐sized zones to allow the simultaneous presentation of two stimuli (see Martini et al . 2015, for details). The four two‐choice comparisons that we included were (i) honeydew versus no stimulus (negative control), (ii) honeydew versus honey (positive control), (iii) honeydew versus pear psylla, and (iv) pear psylla + honeydew versus pear psylla alone.…”

“…The O. sauteri behaviors that were scored were: (i) proportion of time moving in each zone, (ii) proportion of time immobile in each zone, (iii) proportion of time spent in each zone, (iv) average velocity, (v) distance travelled, and (vi) turning frequency. Arenas were placed on a white platform 20 cm below a Panasonic® video camera (Panasonic Co., Beijing, China) and illuminated with four 45‐cm white cool light bulbs …”

“…For each observation, a single newly-emerged O. sauteri adult was placed at the center of the Petri dish and its behavior was tracked for 10 min using video tracking software (Observer version 5.0, Ethovision ® , Noldus, Wageningen, the Netherlands) as wileyonlinelibrary.com/journal/ps described in Martini et al 40 The O. sauteri behaviors that were scored were: (i) proportion of time moving in each zone, (ii) proportion of time immobile in each zone, (iii) proportion of time spent in each zone, (iv) average velocity, (v) distance travelled, and (vi) turning frequency. Arenas were placed on a white platform 20 cm below a Panasonic ® video camera (Panasonic Co., Beijing, China) and illuminated with four 45-cm white cool light bulbs.…”

Beyond Focal Pests: Impact of a Neonicotinoid Seed Treatment and Resistant Soybean Lines on a Non-Target Arthropod

“…In addition to consuming spider mite immatures [46,69], some research indicates that thrips are attracted to spider mite infested plants [70], engage in behavior associated with searching for prey when exposed to chemicals extracted from spider mite webbing [71], and play an important role in regulating spider mite populations [72]. However, the degree to which thrips consume spider mites appears to depend on the growth stage and condition of the host plant, with thrips less attracted to spider mites when plants are flowering [69,73], thrips eating more spider mite eggs as plant quality decreases [74], and thrips eating fewer eggs laid by mites feeding on plants where induced plant resistance was triggered [75].…”