Xiujun Wen

(Z,E)-9,12-Tetradecadien-1-Ol: A Major Sex Pheromone Component of Euzophera pyriella (Lepidoptera: Pyralididae) in Xinjiang, China

Abstract The moth Euzophera pyriella (Lepidoptera: Pyralididae) is one of the important fruit pests in the pear orchards of Xinjiang, China. Extracts from the sex pheromone gland of virgin female moths were analyzed with gas chromatography-mass spectrometry (GC-MS). Two components, (Z)-8-Dodecenyl acetate (Z8-12:Ac) and (Z,E)-9,12-Tetradecadien-1-ol (Z9E12-14:OH), were identified in extracts. Z9E12-14:OH was the most active in electroantennogram (EAG) and field attraction studies. Z8-12:Ac and other common components identified in Euzophera (including Z9-14:Ac, Z9-14:OH and Z9E12-14:Ac) neither elicited significant EAG responses nor attracted many males in field tests. Binary mixtures of Z9E12-14:OH and Z8-12:Ac in different ratios were active in field tests, but the number of male moths trapped did not differ between these binary mixtures and Z9E12-14:OH alone. We conclude that Z9E12-14:OH is a major component of the female sex pheromone of E. pyriella and could be used as an attractant for monitoring the populations of this moth species.

Aggregation and Feeding Preference of Gregarious Heortia vitessoides (Lepidoptera: Crambidae) Larvae to Aquilaria sinensis (Thymelaeaceae)

Abstract  Heortia vitessoides Moore (Lepidoptera: Crambidae) is a pest of the evergreen tree Aquilaria sinensis (Loureiro) Sprenger that is endemic to China and is the source of agarwood, a valuable fragrant wood used for traditional Chinese medicinal and incense industries. Aquilaria sinensis is endangered due to habitat loss and other factors. Twenty-one double-choice feeding bioassays were conducted to assess the response to and preference of H. vitessoides larvae to leaves collected from different A. sinensis plants showing varying degrees of larval feeding damage in the wild. Survivorship of larvae placed in the choice arenas exceeded 85% in all but two of the choice tests. Larvae also tended to aggregate and feed on one of the leaves in the choice test rather than being evenly disbursed on the two choices. Larval aggregation and feeding on leaves collected from a tree with <10% foliar damage while surrounding trees exhibited >90% damage were significantly lower in all double-choice tests conducted with that tree. Furthermore, aggregation and/or feeding on leaves removed from another tree with no damage due to the natural infestation of A. sinensis were significantly less in all but three double-choice assays. These results indicate that aggregation and feeding behavior of the gregarious H. vitessoides larvae may be influenced by the source of the leaves and that there may some levels of plant resistance among the various geographic sources of the tree.

A key compound: (Z)-9-tetradecen-1-ol as sex pheromone active component of Hypsipyla robusta (Lepidoptera: Pyralidae)

Previous research on Hypsipyla robusta revealed that females release and produce a three-component sex pheromone that consists of a 5:3:2 blend of (Z,E)-9,12-tetradecadienyl acetate (Z9E12-14:Ac), (Z)-9-tetradecenyl acetate (Z9-14:Ac) and (Z)-11-hexadecenyl acetate (Z11-16:Ac). However, the lure based on this formula was not effective or had no attraction to male H. robusta although used for monitoring H. robusta populations in the some field tests. We examined the sex pheromone active components of H. robusta in Guangdong, China. The pheromone gland extracts of female moths were analyzed by gas chromatography coupled with mass spectroscopy (GC–MS) and gas chromatography with electroantennographic detection (GC–EAD). GC–MS and GC–EAD analyses of courtship females (aerations) detected a new compound, (Z)-9-tetradecen-1-ol (Z9-14:OH). When Z9-14:OH was combined with Z9E12-14:Ac, Z9-14:Ac and Z11-16:Ac, the lures were attractive to male moths. The results suggested that Z9-14:OH was an important component in H. robusta female sex pheromone communication system. Adding Z9-14:OH to sex pheromone lure formulations would improve the efficacy of pheromone trap activity in China.

Does Soil Treated with Conidial Formulations of Trichoderma spp. Attract or Repel Subterranean Termites

Previous studies showed that many wood-rotting fungi were attractive to termites; however, little attention has been paid to the relationship between termites and soil fungus. In the present study, different designs of two-choice tests were conducted to investigate the behaviors of two subterranean termites, Coptotermes formosanus Shiraki (wood-feeding lower termites) and Odontotermes formosanus (Shiraki) (fungus-growing higher termites), in response to soil (or sand) treated with the commercial conidial formulations of Trichoderma harzianum Rifai (BioWorks) and Trichoderma viride Pers. ex Fries (Shuiguxin). The short-term (1 d) choice tests showed no significant difference in termite aggregation (C. formosanus and O. formosanus) between treated and untreated soil, regardless of Trichoderma species and concentrations. However, in the long-term choice tests, C. formosanus consumed significantly more wood in the chambers containing soil treated with the conidial formulation of T. viride (1 × 108 conidia/g) than that containing untreated soil. The tunneling choice tests showed that sand treated with T. viride (1 × 106 or 1 × 108 conidia/g) or T. harzianum (1 × 106 conidia/g) significantly increased the tunneling activities of C. formosanus. However, sand treated with T. viride (1 × 106 or 1 × 108 conidia/g) had a repellent effect on O. formosanus. Our study showed that the two subterranean termites behaved differently when responding to the conidial formulations of Trichoderma.

Essential Balm: A Strong Repellent Against Foraging and Defending Red Imported Fire Ants (Hymenoptera: Formicidae)

In the present study, the repellent effects of essential balm, a traditional medicine product in China, was tested against foraging and defending red imported fire ants, Solenopsis invicta Buren, under laboratory and field conditions. The laboratory study showed that both band- (width = 1 cm) and patch-smearing of essential balm at each concentration (0.5, 1, or 2 μl/cm(2)) significantly decreased the number of S. invicta foragers within the 6-h observation period. Moreover, band-smearing of 2 μl/cm(2) essential balm and patch-smearing of 0.5, 1, and 2 μl/cm(2) essential balm inhibited most S. invicta foraging activity at 3, 6, 6, and 24 h into the experiment, respectively. The field study showed that after a disturbance was created on the S. invicta mound, there were significantly less defending ants on the substance treated (patch-smeared) with 0.5, 1, and 2 μl/cm(2) essential balm than the controls, but the number of ants on the substance of these three concentrations was similar. Our study suggested that essential balm is a strong repellent against foraging and defending S. invicta and could be applied when temporary protection from S. invicta is needed.

Soil Moisture Effects on Pupation Behavior, Physiology, and Morphology of Heortia vitessoides (Lepidoptera: Crambidae)

Abstract  Previous studies show that pupating in soil is essential for Heortia vitessoides Moore (Lepidoptera: Crambidae) to complete its life cycle. However, little is known of the process. In the present study, we observed soil-burrowing and pupal-chamber construction by prepupae of H. vitessoides in 0.5-cm-wide acrylic plate interlayers. In bioassays, we also investigated pupation behaviors and pupal physiology and morphology in response to soil moistures of 5%, 25%, 45%, and 65% water saturation. Prepupae burrowed significantly deeper in soils with higher levels of soil moisture and constructed larger pupal chambers at 65% water saturation. H. vitessoides pupae also had significantly greater percentage biomass loss and lower body water content when the soil moistures were lower. Interestingly, pupae in 5% saturated soil were smaller and showed a significantly higher surface-to-volume ratio than at other soil moisture levels, which might pose challenges in water conservation.

Application technology of the sex pheromone of the tea geometrid Ectropis grisescens (Lepidoptera: Geometridae)

ABSTRACT The sex pheromone of Ectropis grisescens, one of the primary defoliator insects of tea plantations, has been identified, but its trapping parameters have not been optimized for field application. In this study, we investigated the effects of pheromone dose, trap height and trap type on the effectiveness of trapping E. grisescens in the field. Our results show that the optimal pheromone dose is 800 μg. The bucket-funnel trap hung 40 cm below the tea canopy had the highest trapping efficiency. This study establishes optimized parameters for the pheromone trapping of E. grisescens in tea plantations.

How do groups of red imported fire ants (Hymenoptera: Formicidae) feed on a droplet of sugar water?

Many previous studies have focused on the foraging behaviors and strategies of the red imported fire ants, Solenopsis invicta Buren on solid food or granular bait; little attention has been paid to how liquid sugar is fed upon. In the present study, behavioral responses of S. invicta to 25% sucrose water droplets were observed. Five foraging patterns were identified in S. invicta colonies under laboratory conditions: (i) no feeding, no sucrose water feeding was observed; (ii) surround feeding, ants surrounded and fed along the edge of the sucrose droplet; (iii) stacked feeding, ants stacked and fed along the edge of the sucrose droplet; (iv) droplet‐break feeding, ants broke the liquid droplet and sucked sucrose water that spread on surface of the substance or soil particles previously transported by ants; and (v) cover feeding, whole surface of the sucrose droplet was covered by layers of feeding ants. This is the first time cover feeding in S. invicta has been reported, which obviously requires more ants compared to the other patterns. In addition, individual ants were tracked in videos under laboratory conditions, and behavioral repertoires that led to stacking, covering and droplet‐breaking were identified and described. The field investigation showed that surround feeding was most frequently performed by S. invicta foragers; however, cover feeding was not observed under field conditions during this study. Both laboratory and field studies showed colony‐level variations in sugar‐water feeding.

Pupation Behaviors and Emergence Successes of Ectropis grisescens (Lepidoptera: Geometridae) in Response to Different Substrate Types and Moisture Contents

Abstract Ectropis grisescens Warren (Lepidoptera: Geometridae) is one of the most severe pests of tea plants in China. This species commonly pupates in soil; however, little is known about its pupation ecology. In the present study, choice and no-choice tests were conducted to investigate the pupation behaviors and emergence success of E. grisescens in response to different substrates (sand, sandy loam 1, sandy loam 2, and silt loam) and moisture contents (5, 20, 35, 50, 65, and 80%). Moisture-choice bioassays showed that significantly more E. grisescens individuals pupated in or on soil (sandy loam 1 and 2 and silt loam) that was at the intermediate moisture levels, whereas 5%- and 35%-moisture sand was significantly more preferred over 80%-moisture sand for pupating. Substrate-choice bioassays showed that sand was most preferred by E. grisescens individuals at 20%- and 80%-moisture levels, but no preference was detected among the four substrates at 50%-moisture content. No-choice tests showed that the percentage of burrowed E. grisescens individuals and pupation depth were significantly lower when soil was dry (20% moisture) or wet (80% moisture). In addition, 20%-moisture sandy loam 2 and silt loam significantly decreased the body water content of pupae and emergence success of adults compared to 50%-moisture content. However, each measurement (percentage of burrowed individuals, pupation depth, body water content, or emergence success) was similar when compared among different moisture levels of sand. Interestingly, pupae buried with 80%-moisture soil exhibited significantly lower emergence success than that were unburied.

Escaping and repairing behaviors of the termite Odontotermes formosanus (Blattodea: Termitidae) in response to disturbance

The escaping behavior of termites has been documented under laboratory conditions; however, no study has been conducted in a field setting due to the difficulty of observing natural behaviors inside wood or structures (e.g., nests, tunnels, etc.). The black-winged termite, Odontotermes formosanus (Shiraki), is a subterranean macrotermitine species which builds extensive mud tubes on tree trunks. In the present study, 41 videos (totaling ∼2,700 min) were taken on 22 colonies/subcolonies of O. formosanus after their mud tubes were partially damaged by hand. In general, termites consistently demonstrated three phases of escape, including initiation (wandering near the mud-tube breach), individual escaping (single termites moving downward), and massive, unidirectional escaping flows (groups of termites moving downward). Downward moving and repairing were the dominant behavioral activities of individuals and were significantly more frequent than upward moving, turning/backward moving, or wandering. Interestingly, termites in escaping flows moved significantly faster than escaping individuals. Repairing behavior was observed shortly after the disturbance, and new mud tubes were preferentially constructed from the bottom up. When predators (i.e., ants) were present, however, termites stopped moving and quickly sealed the mud-tube openings by capping the broken ends. Our study provides an interesting example that documents an animal (besides humans) simultaneously carrying out pathway repairs and emergency evacuation without congestion.