Female Sex Pheromone of Cystidia couaggaria couaggaria (Lepidoptera: Geometridae): Identification and Field Attraction

Identification of the Female Sex Pheromone of Grammodes Geometrica (Lepidoptera: Erebidae: Erebinae)

The female sex pheromone of Grammodes geometrica (Lepidoptera: Erebidae: Erebinae) was identified as a 2:100:4 mixture of (3Z,6Z,9Z)-3,6,9-icosatriene (T20), (3Z,6Z,9Z)-3,6,9-henicosatriene (T21), and (3Z,6Z,9Z)-3,6,9-tricosatriene (T23) through chemical and electrophysiological analyses of female gland extracts. T23 is a novel sex pheromone component in Erebinae species. Field trapping tests demonstrated optimal male captures in attractant-baited traps when using a 2:100:4 blend of T20, T21 and T23, with a significant decrease in captures observed when T20 or T23 were removed from the full blend. Traps were set in early August, but males began to be captured in early September. The seasonal prevalence showed a bimodal peak, occurring on September 11 and October 9. These findings provide valuable insights into the chemical communication and ecological dynamics of this species within the subfamily Erebinae.

Pupal Warning Coloration of Three Species of Cystidia (Lepidoptera: Geometridae: Ennominae) in Relation to Their Pupation Sites

Many insects display a cryptic color to avoid detection by predators that search for prey by sight. However, some species with chemicals that predators dislike may display a warning color (aposematism) to predators. The predators can learn easier that the species is unsuitable as prey if the color is more conspicuous. Therefore, it is assumed that the acquisition of the warning color requires not only unpalatability, but also exposure of the color to predators and the ability of predators to recognize and learn it unpalatable. In the moths of the subfamily Ennominae, almost all of genera produce uniformly brown or green pupae, but the pupae of the genus Cystidia have conspicuous coloration of yellow background and black spots. In this study, to clarify whether the color of these pupae is the warning color or not, we compared the coloration, pupation site, and palatability among the three species of this genus: C. couaggaria, C. truncangulata, and C. stratonice. Learning by the predators was also examined using lizards as a potential predator of the moths. The results showed that all three species were repelled (unpalatable) by the lizards, and that repeated providing of the pupae to the lizards decreased their willingness to prey on them (probably due to learning). Pupation sites of C. couaggaria and C. truncangulata were located on the surface of branches and leaves high above the ground, whereas C. stratonice pupated in the space of leaves spun with course silk at lower site above the ground. Thus, the conspicuous coloration of pupal Cystidia is considered to be a warning color, but the pupae of C. stratonice are more blackish than those of the most closely related C. truncangulata. The pupal color of C. stratonice is likely to have a dual meaning as cryptic and warning colors. The dark colored pupa may be inconspicuous when hidden within the leaf space, but once detected by the predators, the yellow color of the pupa may function as a warning color.

Analysis of Tea Geometrid (Ectropis grisescens) Pheromone Gland Extracts Using GC-EAD and GC×GC/TOFMS

The tea geometrid, Ectropis grisescens Warren, is one of the most severe defoliator insect pests in tea plantations, China. The use of insecticides, etc., is forbidden on organic tea plantations. No female-produced sex pheromones of E. grisescens had been previously identified. In the present study, female gland extracts were analyzed by gas chromatography coupled with electroantennographic detection (GC-EAD) and two-dimensional gas chromatography (GC×GC) using a time-of-flight mass spectrometric detector (TOFMS). Two components, (Z,Z,Z)-3,6,9-octadecatriene (Z3Z6Z9-18:Hy) and (Z,Z)-3,9-6,7-epoxyoctadecadiene (Z3Z9-6,7-epo-18:Hy), were identified from pheromone gland extracts, and their electrophysiological and behavioral activity evaluated. Under laboratory conditions, Z3Z9-6,7-epo-18:Hy elicited a stronger electrophysiological response than Z3Z6Z9-18:Hy. In the field, traps baited with Z3Z9-6,7-epo-18:Hy alone showed better results than traps baited with Z3Z6Z9-18:Hy, and the binary mixture of Z3Z9-6,7-epo-18:Hy and Z3Z6Z9-18:Hy in a ratio of 4:1 (approximate ratio of females emitting pheromone) caught more males than the single components or any other blends. This study showed that Z3Z6Z9-18:Hy and Z3Z9-6,7-epo-18:Hy are the sex pheromone components of E. grisescens and that they prove useful in developing alternative management tools for the pest.

Promotion of plant growth by Pseudomonas fluorescens strain SS101 via novel volatile organic compounds

Volatile organic compounds (VOCs) from plant growth-promoting rhizobacteria (PGPR) play key roles in modulating plant growth and induced systemic resistance (ISR) to pathogens. Despite their significance, the physiological functions of the specific VOCs produced by Pseudomonas fluorescens SS101 (Pf.SS101) have not been precisely elucidated. The effects of Pf.SS101 and its VOCs on augmentation of plant growth promotion were investigated in vitro and in planta. A significant growth promotion was observed in plants exposed Pf.SS101 under both conditions, suggesting that its VOCs play a key role in promoting plant growth. Solid-phase micro-extraction (SPME) and a gas chromatography-mass spectrophotometer (GC-MS) system were used to characterize the VOCs emitted by Pf.SS101 and 11 different compounds were detected in samples inoculated this bacterium, including 13-Tetradecadien-1-ol, 2-butanone and 2-Methyl-n-1-tridecene. Application of these compounds resulted in enhanced plant growth. This study suggests that Pf.SS101 promotes the growth of plants via the release of VOCs including 13-Tetradecadien-1-ol, 2-butanone and 2-Methyl-n-1-tridecene, thus increasing understanding of the role of VOCs in plant-bacterial inter-communication.