Altering the Sex Pheromone Cyclo(l-Pro-l-Pro) of the Diatom Seminavis robusta towards a Chemical Probe

As a major group of algae, diatoms are responsible for a substantial part of the primary production on the planet. Pennate diatoms have a predominantly benthic lifestyle and are the most species-rich diatom group, with members of the raphid clades being motile and generally having heterothallic sexual reproduction. It was recently shown that the model species Seminavis robusta uses multiple sexual cues during mating, including cyclo(l-Pro-l-Pro) as an attraction pheromone. Elaboration of the pheromone-detection system is a key aspect in elucidating pennate diatom life-cycle regulation that could yield novel fundamental insights into diatom speciation. This study reports the synthesis and bio-evaluation of seven novel pheromone analogs containing small structural alterations to the cyclo(l-Pro-l-Pro) pheromone. Toxicity, attraction, and interference assays were applied to assess their potential activity as a pheromone. Most of our analogs show a moderate-to-good bioactivity and low-to-no phytotoxicity. The pheromone activity of azide- and diazirine-containing analogs was unaffected and induced a similar mating behavior as the natural pheromone. These results demonstrate that the introduction of confined structural modifications can be used to develop a chemical probe based on the diazirine- and/or azide-containing analogs to study the pheromone-detection system of S. robusta.

Development of polygynous colonies of Messor muticus ants in laboratory conditions

The process of growing a family of reaper ants Messor muticus (Nylander, 1849) in a test tube incubator according to the method proposed by G.M. Dlussky and M.P. Bukin (1986) considers its structure and principle of operation. The queens were captured during the flight and identified in accordance with the phylogenetic analysis of F. Steiner. The test ant colonies were divided into 3 experimental and one control groups. The main factors influencing the polygyny development of ant colonies, such as nest size and temperature are considered. The features of the destructive behavior of worker ants and their participation in the regulation of oviparous queens number in the family, as well as the influence of pheromone activity on the relationship between workers and reproductive individuals are described. The main goal of the experiment was to confirm the theory of the effect of nest size and temperature on the development of dimatological colonies of a species with a monogyny family structure. The experiment was carried out for 71 days, observations were recorded every week, the results were summed up on the 8th and 10th weeks of the experiment. The conclusion confirms the theoretical assumptions about the influence of temperature and the size of the primary nest on the development of polygynous colonies of reaper ants Messor muticus. The data obtained can serve as a basis for further study of polygyny in ant colonies, ants behavior in an unnatural habitat and the existence of ants under controlled conditions.

Effect of size, color and height of pheromone baited sticky traps on captures of Dacus oleae flies

The size of sticky pheromone traps has no effect on Dacus οleae catches when insect population densities are low. At high population densities trap catches increase with surface area. There were no differences in the numbers of D. οleae caught on yellow and white pheromone traps in periods of high pheromone effectiveness, which coincide with periods of high insect reproductive activity. During periods of reduced pheromone effectiveness, due either to low temperatures at the time of pheromone activity (dusk) or reduced insect reproductive activity, traps of yellow hues tend to capture more insects than traps of white color. The height at which pheromone traps are located inside the tree canopy has no effect on catches of D. οleae.

Alarm Pheromone Activity of Nymph-specific Geraniol in Chrysanthemum Lace Bug Corythucha marmorata against Adults and Nymphs

The exotic insect pest Corythucha marmorata (Uhler) is increasingly spreading in Japan using the weed Solidago canadensis L. as a major host plant. The nymphs form colonies on the backs of leaves where they crowd together; however, aggregation does not occur in the adults. When an individual nymph is crushed using a needle tip and further the needle tip covered with the nymph's bodily fluids is moved slowly toward the center of the crowd, the surrounding nymphs display an escape behavior and their aggregation is disrupted. We detected geraniol as a nymph-specific volatile component. Bioassay results indicated that geraniol was effective as an alarm pheromone on second to fifth instar nymphs. Furthermore, we found that male and female adults responded sensitively to the alarm pheromone produced by nymphs. These results suggest that although the adult insects do not secrete geraniol, they can detect it produced by nymphs, thereby retaining the ability to escape from danger while suppressing the cost of geraniol production. The present study is the first to demonstrate that an alarm pheromone secreted by nymphs is also effective in adults among Tingidae.