Journal of Chemical Ecology

Luijendijk, Teus; Meijden, Ed; Verpoorte, Rob

doi: 10.1007/BF02027718pmid: 24226242

The involvement of the glucoalkaloid strictosidine in antimicrobial and antifeedant activity inCatharanthus roseus leaves was investigated. Strictosidine and its deglucosylation product, specifically formed by the enzyme strictosidine glucosidase, were shown to be active against several microorganisms. In contrast, neither the intact glucoside, nor the aglycone product(s) was found to exhibit antifeedant activity againstSpodoptera exigua larvae, as was found for intactC. roseus leaves and leaf extracts. Besides alkaloids further downstream in the biosynthesis pathway, a more apolar, yet unidentified compound may be involved in this activity.

Klepzig, Kier; Smalley, Eugene; Raffa, Kenneth

doi: 10.1007/BF02027719pmid: 24226243

This study considered how host plant allelochemicals may contribute to defense against insects and fungi that jointly colonize the subcortical tissues of trees, the relative roles of constitutive and inducible chemistry in these defenses, and how the actions of two different feeding guilds might be interrelated. Our model consisted of the coniferous treePinus resinosa, the root- and lower stem-colonizing beetlesHylastes porculus andDendroctonus valens, and their associated fungiLeptographium procerum andL. terebrantis, and the stem-colonizing bark beetleIps pini and its associated fungusOphiostoma ips. In a novel bioassay, extracts from reaction tissue elicted by wound inoculation withL. terebrantis were more repellent to beetles than were similar extracts from constitutive or mechanically wounded tissue. The effect on beetle behavior was more pronounced in nonpolar extracts, which contain mostly monoterpenes, than in polar extracts, which contain mostly phenolics. Synthetic monoterpenes at concentrations present in the various tissues exerted similar effects and were likewise repellent in dose-response experiments. Growth ofL. procerum andL. terebrantis was inhibited by polar extracts from constitutive and reaction tissue. Inhibition was higher in wounded than control tissue, but the inhibition response did not vary with the type of wounding. Synthetic monoterpenes strongly inhibited spore germination and mycelial growth of both fungi. Colonization of red pine roots byLeptographium spp. altered the subsequent effects of extracts of stem phloem tissue onI. pini. These effects varied with host condition. Beetles preferred extracts from constitutive stem phloem tissue of healthy trees to that of root-diseased trees. However, extracts from reaction tissues of healthy trees were more repellent toI. pini than were the reaction tissues of root-diseased trees. The implications of these results to plant defense against insect-fungal complexes and interactions among different feeding guilds are discussed.

Giblin-Davis, Robin; Peña, Jorge; Oehlschlager, A.; Perez, Alice

doi: 10.1007/BF02027720pmid: 24226244

Response of adults of the West Indian sugarcane weevil,Metamasius hemipterus sericeus, to various semiochemical treatments and physical trap designs was studied in southern Florida in field-grown banana and Canary Island date palms. Ethyl acetate released alone at 860–1007 mg/day was as effective for the capture ofM. h. sericeus as a combination of ethyl acetate (844–919 mg/day), ethyl propionate (348–362 mg/day), and ethyl butyrate (117–137 mg/day) and in one trial was more effective than fermenting sugarcane (250 g), ethyl propionate alone (353–384 mg/day), ethyl butyrate alone (123–174 mg/day), or no treatment. Ethyl acetate released alone at 675–683 mg/day was as attractive as 250 g of fermenting sugarcane or the racemic blend of the male-produced aggregation pheromones [(±)-5-methyl-nonan-4-ol and (±)-2-methyl-heptan-4-ol (8:1 ratio) “metalure”] at 3 mg/day. Weevil counts increased with binary combinations of ethyl acetate, sugarcane, and/or metalure over these treatments alone and the ternary combination was two to three times more effective than any of the binary treatments. Attraction to ethyl acetate released alone at 777 mg/day with metalure was greater than to the hydrolysis products of ethyl acetate (ethanol and/or acetic acid each released at about 6–8 mg/day) with metalure. Weevil counts from traps baited with 250 g of sugarcane and metalure increased with increasing dose of ethyl acetate to about 400 mg/day and then appeared to plateau. Ethyl acetate (about 700 mg/day) and metalure increased weevil counts in traps with increasing amounts of sugarcane (0–2 kg). Molasses (45 g) + water (158 ml) substitutes for sugarcane were about as effective for capturingM. h. sericeus as 250 g of fermenting sugarcane [all treatments with ethyl acetate (847 mg/day) and metalure]. Early experiments used a lethal pitfall trap. We demonstrated that several alternative trap designs were more effective than the lethal pitfall trap for capturing weevils. Color and height (on ground vs. 1 m on pole) did not affect trap efficacy when baited with the ternary combination of ethyl acetate (672–825 mg/day), sugarcane (250 g), and metalure.

Brooke, Anne; Decker, Denice

doi: 10.1007/BF02027721pmid: 24226245

The distinctive odor ofNoctilio leporinus arises from oily secretions found beneath the wings in the subaxillary region. Analysis of secretions by gas chromatography-mass spectrometry identified 372 lipid compounds. Differences in number and chemical composition of glycolipids suggest that secretions of males from the same roost are more similar to each other than to other males or females. Differences in number and chemical composition of nonpolar lipids indicate that secretions of males are more similar to each other than to females. Since secretions differ between sexes, information on sexual identity and reproductive condition may be communicated. Individually unique lipid compositions further suggest that bats may be recognizable by their odor within the roost and while flying.

Leal, Walter; Ueda, Yasuo; Ono, Mikio

doi: 10.1007/BF02027722pmid: 24226246

GC profiles of the airborne volatiles produced by adult males and females of the rice bug,L. chinensis showed no qualitative chemical dimorphism. However, GC-EAD experiments showed that eight of the compounds elicited strong responses in male and female antennae. Ruling out alarm pheromone and compounds that were not found in the whole-body extracts of the bugs, four compounds remained to be tested as possible attractants. In field experiments, the whole mixture or tertiary blends were not attractive: however, males were strongly attracted to a 5 : 1 mixture of 2-(E)-octenyl acetate and octanol. The attractancy of the binary mixture was decreased by the addition of 3-(Z)-octenyl actetate. Although the binary lure specifically attracted males, there was no evidence that it triggered any response of sexual behavior in males.

Bogner, Franz

doi: 10.1007/BF02027723pmid: 24226247

This study suggests that alkaloid deficiency inUtetheisa (Lepidoptera: Arctiidae) is a main cause of cannibalism; moreover, cannibalism can be predicted on the basis of alkaloid deficiency and of systemic alkaloid accumulation. This chemical plays a central role in the life of this species, because, first, it provides acquired chemical protection from potential predators, and, second, it determines mating success (as the alkaloid is an essential precursor of the male pheromone). Consequently, losers in the larval sequestering of alkaloids, which would result in a lack of chemical protection and in decreased mating success, tend to target conspecific winners, which are normally substantially protected against a variety of predators; by cannibalizing those accumulated alkaloid sources the losers tend to become the winners of cannibalistic encounters while making up their shortfall of these chemicals. What is a presumptive advantage in selection under high predation pressures and/or high alkaloid availabilities could become a disadvantage under high conspecific population densities and shortages of alkaloid supplies for larval uptake. Cannibalism may be expected to have general ecological importance in the evolutionary play ofUtetheisa and may contribute to a balanced regulation of the acquired alkaloid contents in these arctiid populations.

Govindachari, T.; Narasimhan, N.; Suresh, G.; Partho, P.; Gopalakrishnan, Geetha

doi: 10.1007/BF02027724pmid: 24226248

The antifeedant and insect growth-regulating activities of salannin, nimbin, and 6-deacetylnimbin, in comparison with azadirachtin-A, have been studied againstSpodoptera litura, Pericallia ricini, andOxya fuscovittata. Salannin deterred feeding, delayed molt by increasing larval duration, caused larval and pupal mortalities, and decreased pupal weights in the two lepidopterans. Salannin also caused molt delays and nymphal mortalities inOxya fuscovittata. The role of salannin and other compounds in conferring bioactivity, along with azadirachtin-A, to neem oil/neem seed extracts is emphasized.

Terrill, William; Dusenbery, David

doi: 10.1007/BF02027725pmid: 24226249

The behavioral responses by the nematodeCaenorhabditis elegans to 12 organic compounds was explored using tethered nematode and computer tracking methods. Results indicate that the nematode is attracted to acetone, diethyl ether, isoamyl acetate, isoamyl alcohol, 2,4-pentanedione, andn-propanol. No responses were detected to acetaldehyde, acetylcholine, ethanol, formaldehyde, i-propanol, and valerate. Isoamyl acetate and acetone were found to be the most potent attractants eliciting minimal responses at concentrations near 10−10 M. The geometry and charge distribution of a single hypothetical receptor that would interact with all the compounds that elicited a response and none of the compounds that failed to elicit a response is explored.

Hamilton, J.; Dawson, G.; Pickett, J.

doi: 10.1007/BF02027726pmid: 24226250

The principal volatile component (99 + %) of the sex pheromone glands ofLutzomyia longipalpis from Lapinha, Brazil, has been isolated and characterized as a novel homosesquiterpene with the specific structure proposed as 9-methylgermacrene-B, (E,E)-8-(1-methylethylidenyl)-1,5,10-trimethyl-1,5-cyclodecadiene.

Murray, Anna; Iason, Glenn; Stewart, Colin

doi: 10.1007/BF02027727pmid: 24226251

Heather (Calluna vulgaris), a common dietary component of many mammalian herbivores, contains a broad range of tannin phenolics, flavonoids, and simple phenolic compounds. These may lead to a number of negative effects on herbivores as a result of toxicity or digestive inhibition. We assessed the effect of some simple phenolic compounds from heather on rumen microbial activity using thein vitro consecutive batch culture technique. The compounds tested were orcinol, quinol, and arbutin, a glucoside of quinol. At a concentration of 10 mM, both orcinol and quinol depressed production of gas and volatile fatty acids (VFAs). Orcinol and, to a lesser extent, quinol also reduced digestion of the substrate. In contrast to these negative effects on rumen microbial fermentation, arbutin stimulated both gas and VFA production, probably due to the presence of the fermentable sugar moiety. The presence of arbutin also resulted in different concentrations and proportions of VFAs compared to the presence of orcinol and quinol. Since many simple phenolic compounds are found in plants in the form of glycosides, the negative digestive effects of the phenolic moieties may be accompanied by the positive effect of the sugar moiety, which is liberated in the gastrointestinal tract on hydrolysis by glycosidase enzymes. This study suggests that when phenolics are present as glycosides, they do not necessarily adversely affect digestion by herbivores.