Determining suitable observation times for testing odor preferences of a parasitoid wasp, Cotesia kariyai, using a four‐arm olfactometer

Abstract

Parasitoid wasps locate their hosts by tracking host‐related chemicals, such as herbivore‐induced plant volatiles (HIPVs). Attractiveness of HIPVs to parasitoid wasps has often been investigated using four‐arm olfactometers, but suitability of observation times for behavioral tests using olfactometers has received insufficient attention. In this study, we evaluated differences in results of two‐choice bioassays with multiple observation times in a four‐arm olfactometer. We found that odor preferences of the parasitoid Cotesia kariyai (Watanabe) (Hymenoptera: Braconidae) to host‐induced plant volatiles changed with time in a four‐arm olfactometer. These changes were detected only between 60–120 s from the start of experiments, and there were no changes in preference after 120 s. The gradual decrease in odor preference can be explained by habituation. It is necessary to consider habituation of parasitoid wasps to plant volatiles and to determine suitable observation times depending on the species, so that appropriate behavioral assays can be performed in a multi‐arm olfactometer or other equipment.

Identification and Characterization of Hibiscus mutabilis Varieties Resistant to Bemisia tabaci and Their Resistance Mechanisms

“…Solutions of these compounds were prepared in liquid paraffin at 10 −3 , 10 −2 , and 10 −1 mg/mL. A four-arm olfactometer, as described by Hou et al [ 26 ] and Mizuno et al [ 27 ], was used to assess the selection rate of B. tabaci for specific compounds at varying concentrations, with liquid paraffin serving as a control. The airflow of the olfactometer was set at 500 mL/min to channel odors towards the insects.…”

Scents and sensibility: Best practice in insect olfactometer bioassays

“…Four-arm olfactometer bioassay scoring typically involves recording the cumulative amount of time individuals spend in each arm as well as the number of times each arm is entered. Scoring can either be done manually with proprietary software such as OLFA (Nazzi, 1995) and Noldus Observer (Mizuno et al, 2022) or automatically with Noldus EthoVision (McCormick et al, 2016). There are many open-source alternatives, such as JWatcher (Bertoldi et al, 2019), to the proprietary software packages used in behavioural analysis.…”

Aversive effects of volatiles from intact plants help to fine tune host-searching behavior of the parasitoid wasp, Cotesia kariyai

“…source. Time that wasps spent in each olfactometer arena was monitored for 5 min (Mizuno et al, 2022) with a digital camera (Action Cam, AS100V, Sony, Japan) installed 37 cm above the arena, which was connected to an iPad (Apple Inc., Cupertino, CA) through Wi-Fi. The time that wasps spent actively moving (walking, antennating, hereafter referred to as "residence time") in each treated arm of the 4-arm olfactometer was recorded using The Observer XT ver.…”

“…We hypothesized that volatiles are the responsible agents. In order to test this hypothesis, in the absence of visual cues, we demonstrated effects of intact plant volatiles on host-searching C. kariyai in bioassays using a wind tunnel (Fukushima et al, 2001;Isono et al, 2019) and a 4-arm olfactometer (Thanikkul et al, 2017;Mizuno et al, 2022). In addition, we also compared volatile profiles of both intact and infested plants.…”