Jan Bergmann

Identification of a Sex Pheromone Produced by Sternal Glands in Females of the Caddisfly Molanna angustata Curtis

In the caddisfly Molanna angustata, females produce a sex pheromone in glands with openings on the fifth sternite. Gas chromatographic analyses of pheromone gland extracts with electroantennographic detection revealed four major compounds that stimulated male antennae. These compounds were identified by means of gas chromatography–mass spectrometry and enantioselective gas chromatography as heptan-2-one, (S)-heptan-2-ol, nonan-2-one, and (S)-nonan-2-ol in the approximate ratio of 1:1:4:10, respectively. Field tests showed that the mixture of the two alcohols was attractive to males whereas addition of the corresponding ketones reduced trap catches. The sex pheromone of M. angustata, a species in the family Molannidae within the suborder Integripalpia, is similar to the pheromones or pheromone-like compounds previously reported from six other trichopteran families, including members of the basal suborder Annulipalpia. This suggests that minimal evolutionary change of the pheromone chemistry has taken place within the leptoceroid branch of integripalpian Trichoptera compared to the ancestral character state.

Female Sex Pheromone of Cameraria ohridella Desch. and Dim. (Lepidoptera: Gracillariidae): Structure Confirmation, Synthesis and Biological Activity of (8E,10Z)-8,10-tetradecadienal and Some Analogues

Mass spectrometric investigations confirmed the structure of the female produced sex pheromone of the horse-chestnut leafminer Cameraria ohridella Desch. and Dim. to be (8E,10Z)-8,10-tetradecadienal. Pure samples, prepared in a straightforward synthesis, were highly attractive in field tests and proved to be suitable for monitoring of flight activities and population dynamics. In mixtures with the synthetic pheromone, analogues like 9-tridecynal and 7-dodecynyl formate were shown to reduce trap catches. In electroantennographic experiments, pheromone analogues were less active than the pheromone. 9-Tridecynal was the most EAG active analogue tested, followed by 7-dodecyn-1-yl formate and 7-undecyn-1- yl formate.

Influence of different plants substrates on development and reproduction for laboratory rearing of Pseudococcus calceolariae (Maskell) (Hemiptera: Pseudococcidae)

El chanchito blanco citrofilo, Pseudococcus calceolariae, es una plaga polifaga de gran impacto en frutales en Chile, y ademas tienen importancia cuarentenaria en mercados de destino. Para estudiar alternativas de control es importante contar con metodos de crianza eficientes. El objetivo de este trabajo fue determinar el desarrollo de Pseudococcus calceolariae en tres sustratos: papas etioladas, frutos de limon y zapallo Butternut. Los insectos fueron inoculados en los sustratos y mantenidos a 25°C en oscuridad hasta completar su desarrollo. El avance en el desarrollo poblacional fue medido contando los exuvios cada uno a cuatro dias. Se determino el tiempo de desarrollo promedio para cada estado, longevidad de adultos, fertilidad y fecundidad de hembras. El tiempo de desarrollo preimaginal fue similar para hembras y machos, pero difirio entre sustratos. En hembras el desarrollo preimaginal fue nueve dias menos en papas en comparacion con zapallos y limones. En machos fue 12 dias mas en zapallos que en los otros sustratos. El periodo de preoviposicion y tiempo generacional fue mas largo en zapallos. La longevidad de hembras adultas fue similar en los sustratos, cerca de 31 dias, pero para machos fue de seis dias en papas y limones y cuatro en zapallo. La fecundidad de las hembras fue mayor en papas y zapallos que en limones. No se observo reproduccion por partenogenesis. Por lo tanto, los tres sustratos probados son adecuados para criar P. calceolariae, pero en papas etioladas se obtienen los tiempos generacionales mas cortos y la mayor fecundidad y fertilidad de hembras.

Insect pheromone research in South America

Insect pheromone research has a long and rich history built up primarily by studies conducted in the Northern hemisphere. Not surprisingly, these studies have largely targeted species relevant to these regions of the world, for the most part agricultural and forest pests. Pheromone research in South American countries came a few decades behind, albeit their strong dependence in agriculture and therefore in pest management. In the last 20 years, a combination of economic, environmental and technical factors have come together to generate a small but rising number of chemical ecologists working in pheromone chemistry and biology in South America. In this article we summarize the results of this trend. We review pheromone studies in which South American scientists have participated in collaboration with foreign scientists, mostly chemistry groups, as well as the ever-growing number of studies carried out completely within the region. We have focused mainly in research involving the characterization of pheromones from native species, which involve the most important insect orders, namely Lepidoptera, Coleoptera, Heteroptera and Hymenoptera. We also present a simple meta-analysis including geographical distribution, trends in collaborative or independent work, and a 20-year evolution of published articles in the field. Finally, we emphasize the importance of a coordinated effort to further promote the growth of this field in Latin America, through the endorsement of international collaborations within the region. Such goal would be facilitated by a regional academic organization, which would in turn initiate the occurrence of regular scientific meetings.

Response of workers of Atta sexdens rubropilosa (Hymenoptera: Formicidae) to mandibular gland compounds of virgin males and females

Abstract The secretion from the mandibular glands of males of the leaf‐cutting ant Atta sexdens rubropilosa is responsible for the reaction of workers outside the nest at the time of sexual swarming. Workers respond with excitability and aggression when presented with the natural mixture of 4‐methyl‐3‐heptanol and 4‐methyl‐3‐heptanone, which is contained in the secretion of the male mandibular glands. Workers respond quickly to fractional amounts of one male equivalent. 4‐Methyl‐3‐heptanone, from the virgin female mandibular glands causes much less response in workers, whereas an equimolar mixture of male and female pheromones gives a still less clear response. The male pheromone plays the most important part in the communication of workers outside the nest at this time.

Identification of a Novel Moth Sex Pheromone Component from Chilecomadia valdiviana

Chilecomadia valdiviana (Philippi) (Lepidoptera: Cossidae) is an insect native to Chile. The larval stages feed on the wood of economically important fruit tree species such as apple, pear, olive, cherry, and avocado, and also on eucalyptus. This causes weakening and, in case of severe infestation, death of the tree. We report identification of the sex pheromone produced by females of this species. Hexane extracts of the abdominal glands of virgin females were analyzed by gas chromatography (GC) with electroantennographic detection, GC coupled with mass spectrometry, and GC coupled to infrared spectroscopy. The major pheromone component was identified as (7Z,10Z)-7,10-hexadecadienal (Z7,Z10–16:Ald), and minor components present in the extracts were (Z)-7-hexadecenal and (Z)-9-hexadecenal, hexadecanal, and (9Z,12Z)-9,12-octadecadienal. Structural assignments were carried out by comparison of analytical data of the natural products and their dimethyl disulfide adducts with those of authentic reference samples. In field tests, traps baited with Z7,Z10–16:Ald captured significantly more males than control traps.

Evidence that Cerambycid Beetles Mimic Vespid Wasps in Odor as well as Appearance

We present evidence that cerambycid species that are supposed mimics of vespid wasps also mimic their model’s odor by producing spiroacetals, common constituents of vespid alarm pheromones. Adults of the North American cerambycids Megacyllene caryae (Gahan) and Megacyllene robiniae (Forster) are conspicuously patterned yellow and black, and are believed to be mimics of aculeate Hymenoptera, such as species of Vespula and Polistes. Adult males of M. caryae produce an aggregation-sex pheromone, but both sexes produce a pungent odor when handled, which has been assumed to be a defensive response. Headspace aerations of agitated females of M. caryae contained 16 compounds with mass spectra characteristic of spiroacetals of eight distinct chemical structures, with the dominant compound being (7E,2E)-7-ethyl-2-methyl-1,6-dioxaspiro[4.5]decane. Headspace samples of agitated males of M. caryae contained five of the same components, with the same dominant compound. Females of M. robiniae produced six different spiroacetals, one of which was not produced by M. caryae, (2E,7E)-2-ethyl-7-methyl-1,6-dioxaspiro[4.5]decane, and five that were shared with M. caryae, including the dominant (2E,8E)-2,8-dimethyl-1,7-dioxaspiro[5.5]undecane. The latter compound is the sole spiroacetal produced by both males and females of a South American cerambycid species, Callisphyris apicicornis (Fairmaire & Germain), which is also thought to be a wasp mimic. Preliminary work also identified spiroacetals of similar or identical structure released by vespid wasps that co-occur with the Megacyllene species.

Monitoring Pseudococcus calceolariae (Hemiptera: Pseudococcidae) in Fruit Crops Using Pheromone-Baited Traps

ABSTRACT The citrophilus mealybug, Pseudococcus calceolariae (Maskell), is an important pest of fruit crops in many regions of the world. Recently, its sex pheromone has been identified and synthesized. We carried out field experiments with the goal of developing monitoring protocols for P. calceolariae using pheromone-baited traps. Traps checked hourly for 24 hours showed a distinct diel pattern of male flight, between 18:00 and 21:00 h. The presence of unnatural stereoisomers did not affect trap captures, with isomeric mixtures capturing similar amounts of males as the biological active isomer. Dose of isomeric mixture pheromone (0–100 µg) had a nonlinear effect on male captures, with 10, 30, and 50 pg capturing similar amounts. The effective range of pheromone traps was determined by placing traps at different distances (15, 40, and 80 m) from an infested blueberry field, loaded with 0, 1 and 25 pg of the pheromone. For all distances, 25 µg dose captured more males, and was highly attractive up to 40 m. There was a significant effect of lure age on male captures (0–150 d), with similar amount of males captured up to 90-day-old lure, and lower captures in the 150-day-old lure compared with fresh ones. We found significant positive correlations between P. calceolariae males caught in pheromone traps with female abundance and fruit infestation at harvest. Our results show the usefulness of P. calceolariae pheromones for monitoring at field level and provide information for the design of monitoring protocols.

Biological Activity of the Larval Secretion of Chilecomadia valdiviana

The carpenter worm, Chilecomadia valdiviana (Lepidoptera: Cossidae), is a polyphagous insect native to Chile that is associated with trees and bushes, including economically important species such as eucalyptus, avocado, and apples. We used a Y-olfactometer to analyze the olfactory responses of larvae to conspecific larvae, hexane extracts of larvae, and synthetic samples of the major components present in the extract (i.e., (Z)-5,13-tetradecadienyl acetate, (Z)-5-tetradecenyl acetate, and dodecyl acetate). The results obtained provide empirical evidence that (Z)-5,13-tetradecadienyl acetate is used as an aggregation pheromone by the larvae. The results are discussed in view of the existing information.

Identification and synthesis of some fatty acid derivatives from larvae of Chilecomadia valdiviana (Lepidoptera: Cossidae)

Larvae of Chilecomadia valdiviana (Lepidoptera: Cossidae) were extracted and the extract was fractionated by chromatography on silica. As shown by gas chromatography–mass spectrometry, the major fraction contained saturated and unsaturated straight-chain acetates, with (Z )-5,13-tetradecadienyl acetate and dodecyl acetate as the main components, while in a minor fraction the corresponding alcohols were detected. The identification of the compounds and the synthesis of some reference material are presented.