4.4. Insect Preference and Performance Experiments

The behavioral responses of ACP adults to sulfur volatile-exposed orange plants with olfactory and visual cues were examined in a wind tunnel, as described by [27] with some modifications. The wind tunnel was composed of a plastic glass box (150 × 40 × 60 cm) with two openable doors (40 × 60 cm) on opposite sides of the box. In the center of each door, there was a hole with a diameter of 5 cm. A treated orange plant was introduced into the box (20 cm from the openable door). Then, an electric fan was coupled on the hole and the wind speed in the box was set to 0.25 m s⁻¹. On the opposite side of the box, the hole was used to release insects into the device and covered with a piece of gauze. In this way, the airflow could pass through the internal part of the box carrying the plant volatiles in the direction of the insects. A total of 30 7- to 15-day-old ACP adults (~1:1 male: female ratio) were released, and 5 replications per treatment were performed (each box was considered a replication). The number of settled ACP on orange plants was assessed at 24 h after release. The experiments were performed under 26 ± 1 °C, 70–80% RH, and 16/8 h light/dark photoperiod conditions.

The oviposition of ACP females and the subsequent performance of the next generation on sulfur volatile-exposed orange plants were recorded [69]. Briefly, sulfur volatile–exposed plants and control plants (with three tender shoots, 2–3 cm) were separately introduced into the screen cages (60 × 60 × 80 cm) for oviposition. A total of 6 10- to 15-day-old ACP adults (sex ratio = 1:1) were introduced into each screen cage and allowed to oviposit for 48 h. Then, the adults were removed, and the number of eggs were carefully recorded under a microscope. The plants with ACP eggs were continuously cultivated, and the number of nymphs and their nymphal instars were recorded at 10 d. The cages were checked for adult emergence, and new adults were recorded daily and removed. The experiments were replicated five times (each plant was considered a replication). The experiments were conducted under the same room conditions as described for the wind tunnel tests.