Journal of Chemical Ecology

Dahbi, Abdallah; Cerdá, Xim; Hefetz, Abraham; Lenoir, Alain

doi: 10.1007/BF02029538pmid: 24227295

Nestmate recognition was studied in the polydomous antCataglyphis iberica (Formicinae) in the laboratory. The study examined six colonies collected from two different populations 600 km apart in the Iberian peninsula (Barcelona and Murcia). Introduction of an alien worker into an allocolonial arena always ended in death to the intruder, demonstrating that in this species societies are extremely closed. Dyadic encounters composed of individuals from different colonies in a neutral arena confirmed the existence of high aggression between allocolonial individuals. We also investigated variability in the composition of the major cuticular hydrocarbons between the colonies used in the behaviorial tests. There were marked quantitative differences between the profiles of ants from the two populations, suggesting that the populations are completely segregated. Cuticular profiles within a population tended to be more similar, but were nevertheless colony specific. The degree of colony closure inC. iberica seemed to be independent of geographic distance since aggression between the colonies was always at its maximum, irrespective of their population origin.

Shore, T.; Lindgren, B.

doi: 10.1007/BF02029539pmid: 24227296

The response ofT. lineatum to ethanol and α-pinene, when used with the pheromone lineatin, was tested for two trap types. Funnel traps, which are passive barrier traps, caught significantly more beetles than drainpipe traps, which require an active response by the beetle to enter the trap. However, the response ofT. lineatum to the semiochemical treatments did not significantly differ for the two trap types. Treatments that included α-pinene with the pheromone, either with or without ethanol, caught significantly moreT. lineatin than those with the pheromone alone. When ethanol and or α-pinene were added to the pheromone significantly more female beetles were trapped than with pheromone alone. Male-female ratios were significantly lower for both types of traps when ethanol was included in the bait than for lineatin alone or with α-pinene. A higher percentage of male beetles entered the drainpipe traps than was captured with funnel traps.

Rebach, Steve

doi: 10.1007/BF02029540pmid: 24227297

Rock crabs,Cancer irroratus, respond to food odors in low concentration as measured by changes in antennular flicking rate. The responses of rock crabs to prey odor were tested in the presence and absence of visual cues to determine the role of chemical cues in prey recognition. Crabs were attracted to the source of mussel odor introduced into one arm of a Y maze. Natural and artificial prey shells and resin boxes were presented to crabs with and without the presence of mussel extract. The crabs were able to see, handle, and manipulate these objects. Crabs opened and consumed contents that emitted chemosensory cues and ignored identical objects that did not. Rock crabs were attracted to food odors and are capable of utilizing chemical cues to detect, locate, and identify food items.

Elakovich, Stella; Yang, Jie

doi: 10.1007/BF02029541pmid: 24227298

Two of the majorNuphar alkaloids, nupharolutine and 6,6′-dihydroxythiobinupharidine, were isolated from the aquatic perennial herbNuphar lutea (L.) Sibth. & Sm., yellow water lily. In a lettuce seedling bioassay of the two pure compounds, the former was inactive and the latter was highly inhibitory of radicle elongation at concentrations greater than 2 ppm. Structures and stereochemistry of the two compounds were confirmed by DEPT,1H-1H COSY,1H-13C COSY, and1H-1H NOESY experiments.

Sütfeld, Rainer; Petereit, Frank; Nahrstedt, Adolf

doi: 10.1007/BF02029542pmid: 24227299

Resorcinol (1,3-dihydroxybenzene) was identified as one of the major constituents of the exudate ofNuphar lutea seedlings, which were raised from seeds and cultivated under axenic conditions. The compound is released from the plants in considerable amounts (up to 15 nmol/seedling/day). Highest rates of resorcinol exudation were measured when the seedlings were incubated under physiological conditions (macronutrient and light supply) that resembled those of natural stands of the plant. An inverse correlation exists between nitrate and/or light supply and resorcinol production. Because of its generally toxic properties, resorcinol is suggested to play a role as an allelochemical in interactions between macrophytes and other organisms of the aquatic ecosystem. A first approach of resorcinol application to zooplankton and phytoplankton organisms resulted in deleterious effects against aDaphnia species. Two Cryptophyceae species reduced resorcinol concentration to zero, showing a concomitant increase of the size of starch granule enclosures. Cyanophyceae and Chlorophyceae seemed not to be affected.

Phillips, Thomas; Phillips, Joel; Webster, Francis; Tang, Rong; Burkholder, Wendell

doi: 10.1007/BF02029543pmid: 24227300

Female cowpea weevils,Callosobruchus maculatus, produce a sex pheromone that elicits orientation and sexual behavior in males. Bioassay-directed isolation of the sex pheromone was conducted and compounds in the active fraction were identified and synthesized. Volatiles were collected from individual virgin females by adsorption on filter paper dises and hexane extraction. A bioassay was used in which the locomotory response of single males in glass vials was recorded upon exposure to treatments or controls. Crude extracts were subjected to silica gel column chromatography with solvents of increasing polarity; all activity eluted with methanol. Activity in the highly polar methanol fraction suggested a carboxylic acid or a compound with multiple polar functionality. Acid-base partitioning of the crude extract isolated all activity in the acid fraction, confirming that the pheromone was a carboxylic acid. The acid fraction was further fractionated by preparative GC with a Carbowax column. The most active GC fraction contained the following five 8-carbon acids identified by GC-MS and comparison with synthetic candidates: 3-methyleneheptanoic acid, (Z)-3-methyl-3-heptenoic acid, (E)-3-methyl-3-heptenoic acid, (Z)-3-methyl-2-heptenoic acid, and (E)-3-methyl-2-heptenoic acid. Each of the synthetic acids was active individually for males, and combinations of two or more of the acid pheromones had an additive effect. Upwind flight responses to natural and synthetic pheromones were observed in a flight tunnel. (Z)-3-Methyl-2-heptenoic acid was previously identified as the sex pheromone for the relatedC. analis, but this and the other four acid pheromones fromC. maculatus were inactive for maleC. analis. There was no cross-attraction betweenC. maculatus andC. analis in reciprocal studies using extracted volatiles from females of both species, GC-MS analysis ofC. analis female volatiles failed to detect any of theC. maculatus compounds but did find an unidentified C-8 acid with a GC retention time different from any of theC. maculatus pheromones.

Kochansky, Jan; Hill, Ada; Neal, John; Bentz, Jo-Ann; Roelofs, Wendell

doi: 10.1007/BF02029544pmid: 24227301

The pheromone system of the eastern tent caterpillar,M. americanum, has been identified as a mixture of (E,Z)-5,7-dodecadienal and the corresponding alcohol. Field data on the attractiveness of the aldehyde alone were not consistent, but mixtures of aldehyde and alcohol in varying proportions were attractive to males. Addition of small amounts ofE,Z acetate toE,Z aldehyde had no effect on male response, but larger amounts reduced trap catch. Traps baited withZ,E, E,E, orZ,Z aldehydes were not more attractive than blank traps. Pherocon IC traps fortified with extra adhesive and baited with lures consisting of 500 µg (E,Z)-5,7-dodecadienal with either 250 or 100 µg of the corresponding alcohol trapped as many as 100 males/trap/night with means of 15–20. Lures prepared from purified (94%E,Z) aldehyde and alcohol were more attractive than those prepared from unpurified (58%E,Z) materials.

Tan, Zhong-Xing; Gries, Regine; Gries, Gerhard; Lin, Guo-Qiang; Pu, Guan-Qin; Slessor, Keith; Li, Jianxiong

doi: 10.1007/BF02029545pmid: 24227302

(6Z-9S, 10R)-Epoxy-octadecene (SR-1) and (3Z, 6Z-9S, 10R)-epoxy-octadecadiene (SR-2) are sex pheromone components of the mulberry looper (MBL),Hemerophila atrilineata Butler. Compounds extracted from female MBL pheromone glands were identified by coupled gas chromatographic-electroantennographic detection (GC-EAD) and GC-mass spectrometry. In field experiments in China,SR-2,RS-2, or both combined were hardly attractive, butSR-2 in combination withSR-1 attracted significant numbers of MBL males. Synergistic behavioral activity ofSR-1 plusSR-2, but not of corresponding antipode mixtures, indicates enantiospecificity of MBL pheromone communication. Because blends of racemic and enantiospecific (SR)1 plus2 were similarly attractive, racemic1 plus2 may have potential for mass trapping or confusion of MBL males in commercial mulberry plantations.

Torto, Baldwyn; Njagi, Peter; Hassanali, Ahmed; Amiani, Habert

doi: 10.1007/BF02029546pmid: 24227303

Hexanal, octanal, nonanal, decanal, hexanoic acid, octanoic acid, nonanoic acid, and decanoic acid were identified in the volatile emissions from fifth instars ofSchistocerca gregaria by coupled gas chromatography-electroantennography (GC-EAD) detection and coupled GC-mass spectrometry (MS). In laboratory assays, synthetic blends of the eight compounds, with acids and aldehydes tested separately, evoked strong aggregation responses from fifth instars, similar to responses evoked by a crude volatile extract of the nymphs. A nymphal fecal volatile phenolic blend of guaiacol and phenol, which we have previously shown to evoke an aggregative response from different stages of the insect, significantly synergized the activity of the blend of eight compounds, suggesting mutually augmentative roles for nymphal and fecal volatiles in evoking aggregation. These results indicate that the aggregation behavior of gregarious second to fifth instars is modulated by three sets of pheromonal compounds: aldehydes and acids emitted by the nymphs themselves and phenols associated with their feces.

Markovic, Ingrid; Norris, Dale; Cekic, Miodrag

doi: 10.1007/BF02029547pmid: 24227304

Green ash is one of the few tree species rejected as food by larvae of the generalist gypsy moth,Lymantria dispar L. (Lepidoptera: Lymantriidae). Such rejection is based especially on chemicals present in green ash foliage. The gypsy moth larval feeding-inhibitory activity is contained in the ethyl acetate extractables of green ash foliage. Three representative columnchromatographed fractions of the extractables contained antifeedant activity. Individual fractions showed weaker antifeedant activity compared to the total ethyl acetate extractables. Acid hydrolysis of the extractables destroyed antifeedant activity and yielded feeding stimulant activity at higher concentrations. The aqueous extractables were not feeding-inhibitory. Compounds in the green ash extractables were separated by TLC, HPLC, CC, and GC.