Behaviorally Active Green Leaf Volatiles for Monitoring the Leaf Beetle, Diorhabda elongata, a Biocontrol Agent of Saltcedar, Tamarix spp.

Biological activity and chemistry of host plant volatiles were investigated for Diorhabda elongata, Brullé (Coleoptera: Chrysomelidae), a biological control agent for the invasive tree, saltcedar (Tamarix spp., Tamaricaceae). Gas chromatographic–electroantennographic detection (GC-EAD) analysis of volatiles collected from adult D. elongata feeding on saltcedar foliage or from saltcedar foliage alone showed 15 antennally active compounds. These compounds were more abundant in collections from beetle-infested foliage. Antennally active compounds were identified by GC–mass spectrometry (MS) and confirmed with authentic standards. The emissions of the most abundant GC-EAD-active compounds, green leaf volatiles (GLV), were quantitated by GC-MS. A blend of four GLV compounds, mimicking the natural blend ratio, was highly attractive to male and female D. elongata in the field, and a combination of GLV and male-produced aggregation pheromone attracted significantly greater numbers of D. elongata than did either bait alone. A preliminary experiment with a blend of seven additional GC-EAD-active saltcedar volatiles did not show any behavioral activity. The combination of the pheromone and the green leaf odor blend could be a useful attractant in detecting the presence of the biocontrol agent, D. elongata, in stands of saltcedar newly colonized by the beetle.Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.     

Aggregation Pheromone of the Cereal Leaf Beetle: Field Evaluation and Emission from Males in the Laboratory

The previously identified, male-specific compound of the cereal leaf beetle (CLB, Chrysomelidae; Oulema melanopus), (E)-8-hydroxy-6-methyl-6-octen-3-one, was studied further with respect to field activity and emission rate from male beetles. In a 5-week field experiment in Oregon, the compound was shown to function as an aggregation pheromone in attracting male and female CLBs migrating from overwintering sites in spring. Traps baited with the synthetic compound (500 g per rubber septum) caught 3.3 times more CLBs than control traps. Lower doses of the pheromone (50 and 150 g) were less attractive than the 500 g dose. One relatively abundant, volatile compound from the host plant (oats), (Z)-3-hexenyl acetate, that elicited responses from beetle antennae was not attractive, either by itself or as a synergist of the pheromone. Both sexes were captured about equally for all treatments. We also measured daily pheromone emission by male beetles in the laboratory. Individual males feeding on oat seedlings under greenhouse conditions emitted as much as 6 g per day, which is about 500 times higher than had been previously observed under incubator conditions. The pheromone emission rate was at least five times higher during the day than at night, and in one male, emission spanned a period of 28 d. The release rate of synthetic pheromone from the 500 g septa was very similar to the maximum from single males; thus, future experiments should evaluate even higher doses. The field results indicate that the pheromone has potential as a monitoring tool for early detection of CLBs as they move from their overwintering sites into newly planted cereal crops in spring.     

DIMBOA Glucoside, a Wheat Chemical Defense, Affects Host Acceptance and Suitability of Sitobion avenae to the Cereal Aphid Parasitoid Aphidius rhopalosiphi

The influence of hydroxamic acids (Hx), plant secondary metabolites associated with aphid resistance in wheat, on the host acceptance and suitability of the aphid Sitobion avenae to the cereal aphid parasitoid Aphidius rhopalosiphi was evaluated. Aphids showed a reduction in mean relative growth rate and in body size in the wheat cultivar with higher Hx level. Reduction in aphid size was related to a decreased success in avoiding parasitoid oviposition. A minor increase in A. rhopalosiphi developmental time was observed in aphids feeding on the higher Hx cultivar. Experiments with different concentrations of DIMBOA glucoside, the main Hx in wheat, in artificial diets showed an increase in parasitoid developmental time at the highest concentration, with no change in other performance variables. The evidence is discussed in relation to the compatible utilization of host-plant resistance and biological control in integrated pest management.     

Chemical Communication in Chagas Disease Vectors. Source, Identity, and Potential Function of Volatiles Released by the Metasternal and Brindley's Glands of Triatoma infestans Adults

Compounds from the metasternal and Brindley's glands of the blood-sucking bug, Triatoma infestans, were identified by solid phase microextraction (SPME) and gas chromatography-mass spectrometry. Volatile compounds released by adult bugs during copulation or after mechanical disturbance were also characterized. Six compounds were identified and found consistently in all samples from metasternal glands. The most abundant were 3-pentanone, 2-methylbutanol, 3-pentanol, and an unidentified compound. The metasternal gland blends did not differ qualitatively between sexes. Compounds found in Brindley's glands were short chain acids, alcohols, esters, and a ketone with no qualitative differences between sexes. Isobutyric acid was the main component of this blend, and two new confirmed compounds were described as products of these glands: 2-butanone and 2-methylbutyric acid. 3-Pentanone was collected from the headspace over 33% of the copulating pairs of T. infestans. Volatiles found in the headspace of disturbed T. infestans adults included short-chain fatty acids, alcohols, esters, and ketones, with no qualitative differences between sexes. Both types of glands apparently discharge their contents after disturbance. However, most of the volatiles released by bugs after disturbance came from Brindley's glands. The locomotor activity of fourth instars increased significantly after stimulation with the odors emitted by disturbed adults, as compared with larvae stimulated by the odor of undisturbed adults or by clean air. We also studied the directional behavioral response of fifth instars to the disturbance scent in a locomotion compensator. Larvae exposed to volatiles released by disturbed adults walked away from the direction of the odor. The results suggest that this blend or part of it functions as an alarm pheromone for T. infestans. We suggest that the metasternal glands of this species are involved both in the sexual and the alarm contexts, and that the Brindley's glands probably have both alarm and defensive roles.     

Roots of the Invasive Species Carduus nutans L. and C. acanthoides L. Produce Large Amounts of Aplotaxene,a Possible Allelochemical

The invasive thistle Carduus nutans has been reported to be allelopathic, yet no allelochemicals have been identified from the species. In a search for allelochemicals from C. nutans and the closely related invasive species C. acanthoides, bioassay-guided fractionation of roots and leaves of each species were conducted. Only dichloromethane extracts of the roots of both species contained a phytotoxin (aplotaxene, (Z,Z,Z)-heptadeca-1,8,11,14-tetraene) with sufficient total activity to potentially act as an allelochemical. Aplotaxene made up 0.44 % of the weight of greenhouse-grown C. acanthoides roots (ca. 20 mM in the plant) and was not found in leaves of either species. It inhibited growth of lettuce 50 % (I ₅₀) in soil at a concentration of ca. 0.5 mg g^?1 of dry soil (ca. 6.5 mM in soil moisture). These values gave a total activity in soil value (molar concentration in the plant divided by the molarity required for 50 % growth inhibition in soil?=?3.08) similar to those of some established allelochemicals. The aplotaxene I ₅₀ for duckweed (Lemna paucicostata) in nutrient solution was less than 0.333 mM, and the compound caused cellular leakage of cucumber cotyledon discs in darkness and light at similar concentrations. Soil in which C. acanthoides had grown contained aplotaxene at a lower concentration than necessary for biological activity in our short-term soil bioassays, but these levels might have activity over longer periods of time and might be an underestimate of concentrations in undisturbed and/or rhizosphere soil.     

Sterols of the adult and juvenile forms of ivy,Hedera helix L.

Sterols have been isolated from both adult and juvenile ivy in free and esterified form. Stigmasterol or its C-24 isomer, poriferasterol, is the main component, and lesser amounts of sitosterol, α-spinasterol, 5α-stigmast-7-en-3β-ol, cholesterol, and campesterol also were detected. Flowers and fruits were found to contain a glycoside fraction in which stigmasterol, together with some sitosterol, could be detected.     

How Cold Shock Affects Ploidy Level and Early Ontogenetic Development of the Sterlet,A. ruthenus L.

The objective of the present research was to study the effect of cold shock (3 °C and 6 °C) on fertilized eggs of the sterlet, Acipenser ruthenus L. Cold shock was applied for various durations (30, 60 and 90 min) and the ploidy levels, survival, and genotypes of the treated embryos/larvae were recorded. Analysis of ploidy levels confirmed the presence of diploid, triploid, and mosaic (1n/2n, 2n/3n, and 1n/2n/3n) genotypes in experimental groups, while it was strictly diploid in control groups. Microsatellite genotyping confirmed both the incidence of polyspermy and retention of the 2nd polar body in experimental groups. However, patterns of inheritance in all diploid offspring in experimental and control groups revealed classical Mendelian disomic inheritance. Interestingly, the observed mosaic sterlets had normal morphology and were alive. However, some larvae had abnormal morphology which may be due to haploid syndrome. In all treatment groups (treatments: 3 °C–30 min; 3 °C–60 min; 3 °C–90 min; 6 °C–60 min), where the percentage of polyploid/mosaic larvae were high, the mortality was also high. Whereas, in the control groups (where there were only diploid (2n) larvae), the mortality was relatively low.     

The lipids of the common house cricket,Acheta domesticus L. I. Lipid classes and fatty acid distribution

The lipids of the common house cricket,Acheta domesticus L., have been examined with the following results. The fatty acids associated with the lipid extracts do not change significantly from the third through the eleventh week of the crickets' postembryonic life. The major fatty acids are linoleic (30–40%), oleic (23–27%), palmitic (24–30%), and stearic acids (7–11%). There are smaller amounts of palmitoleic (3–4%), myristic (∼1%), and linolenic acids (<1%). The fatty acid composition of the cricket lipids reflects but is not identical to the fatty acids of the dietary lipids: linoleic (53%), oleic (24%), palmitic (15%), stearic (3%), myristic (2%), and linolenic acid (2%). The amount of triglycerides present in the crickets increases steadily from the second through the seventh or eighth week of postembryonic life, then drops sharply. Other lipid classes, such as hydrocarbons, simple esters, diglycerides, monoglycerides, sterols, and free fatty acids remain about constant. The composition of the fatty acids associated with the tri-, di-, and monoglycerides and the free fatty acid fraction are all about the same. The fatty acids associated with the simple esters are high in stearic acid. Postdoctoral Research Associate, Department of Chemistry, University of Michigan, 1965–1967.     

Identification and Molecular Cloning of Putative Odorant-Binding Proteins from the American Palm Weevil, Rhynchophorus palmarum L.

We have identified and cloned the cDNAs encoding two odorant-binding proteins (OBPs) from the American palm weevil (APW) Rhynchophorus palmarum (Coleoptera, Curculionidae). Degenerate primers were designed from the N-terminal sequences and were used in polymerase chain reaction (PCR) in order to obtain full-length sequences in both males and females. In both sexes, two different cDNAs were obtained, encoding 123 and 115 amino acid-deduced sequences. Each sequence showed few amino acid differences between the sexes. The proteins were named RpalOBP2 and RpalOBP4 for male, RpalOBP2' and RpalOBP4' for female, with the types 2 and 4 presenting only 34% identities. These proteins shared high identity with previously described coleopteran OBPs. In native gels, RpalOBP2 clearly separated into two bands and RpalOBP4 into three bands, suggesting the presence of several conformational isomers. Thus, OBP diversity in this species may rely on both the presence of OBPs from different classes and the occurrence of isoforms for each OBP.     

End product specificity of triacylglycerol lipases from intestine,fat body,muscle and haemolymph of the American cockroach,Periplaneta americana L.

The triacylglycerol-hydrolyzing capacity of tissue homogenates has been investigated for midgut, fat body, thoracic musculature and haemolymph of the American cockroach,Periplaneta americana. The greatest lipolytic activity was demonstrated in midgut homogenates with decreasing levels of activity present in fat body, muscle and haemolymph. Comparison of the lipolytic products resulting from triacylglycerol hydrolysis indicates that midgut homogenates effect the production ofsn-2-monoacylglycerols and free fatty acids, whereas the other tissues that were examined favor the accumulation of diacylglycerols. Stereospecific analysis of the diacylglycerol products of triacylglycerol hydrolysis demonstrated that the lipolytic activities of midgut and muscle homogenates result in the production of a racemic mixture of thesn-1,2-andsn-2,3-enantiomers, but the fat body and haemolymph show a preference for the accumulation of thesn-1,2-isomer.     

A discussion of the paper “Influence of pre-rusting on steel corrosion in concrete” by P. Novak, R. Mala, and L. Joska

The authors of this paper deserve to be congratulated for their study on the influence of pre-rusting on steel corrosion in concrete. The report of this kind of study is very scarce in the technical literatures. The topic of the study is very interesting as in the actual construction practice generally pre-rusted steel bars are used. We also are planning to do some study on this matter in the near future. After reading this article, we found that the authors did not provide/explain enough information/discussion related to the experimental setup and the experimental results. Further explanation on these matters will be very useful to us and also to other interested readers of the cement and concrete research journal.