Correlations between traits may constrain ecological and evolutionary responses to multispecies interactions. Many plants produce defensive compounds in nectar and leaves that could influence interactions with pollinators and herbivores, but the relationship between nectar and leaf defences is entirely unexplored. Correlations between leaf and nectar traits may be mediated by resources and prior damage. We determined the effect of nutrients and leaf herbivory by Manduca sexta on Nicotiana tabacum nectar and leaf alkaloids, floral traits and moth oviposition. We found a positive phenotypic correlation between nectar and leaf alkaloids. Herbivory induced alkaloids in nectar but not in leaves, while nutrients increased alkaloids in both tissues. Moths laid the most eggs on damaged, fertilized plants, suggesting a preference for high alkaloids. Induced nectar alkaloids via leaf herbivory indicate that species interactions involving leaf and floral tissues are linked and should not be treated as independent phenomena in plant ecology or evolution.

Summary1. Secondary compounds are common in floral nectar but their relative effects on nectar consumption and utilization in nectarivorous birds are unclear. 2. We studied the effect of two pyridine alkaloids, nicotine and anabasine, present in Tree Tobacco ( Nicotiana glauca ) nectar, on food consumption, gut transit time and sugar assimilation efficiency of the Palestine Sunbird ( Nectarinia osea ), a pollinator of N. glauca in east Mediterranean ecosystems. 3. Sunbirds demonstrated dose-dependent deterrence; they were not deterred by the lowest natural concentrations of these alkaloids in nectar (0·1 ppm nicotine and 0·6 ppm anabasine) but they were significantly deterred by the average concentrations detected in nectar (0·5 ppm nicotine and 5 ppm anabasine). 4. The two pyridine alkaloids reduced gut transit time (by 30 -42%) and sugar assimilation efficiency (by 9-17%) compared with the control alkaloid-free diet. 5. Sunbirds are able to cope with low, but not average, concentrations of nicotine and anabasine in N. glauca nectar. If sunbirds are efficient pollinators of N. glauca they may induce selection on it to reduce pyridine alkaloid production in the nectar. Alternatively, high concentrations in some N. glauca plants may lead the birds to visit more plants with lower alkaloid concentrations. Hence, they will be more efficient pollinators, especially if other nectar-producing plants are scarce.

Due to their complex structure with several chiral centres important anticancer agents are still extracted from plants and not synthesized chemically on a commercial scale. Sustainable bioproduction of the compounds of interest may be achieved by plant in vitro cultures. Undifferentiated callus and suspension cultures, which can be cultivated in large bioreactors easily, very often fail to accumulate the compounds of interest, whereas shoot and root cultures as well hairy roots normally produce the same compounds as in the appropriate organs. The production of anticancer compounds, such as the alkaloids vinblastine, vincristine, paclitaxel (Taxol®), camptothecin, or the lignan podophyllotoxin, by plant in vitro cultures is reviewed. Taxanes can be produced in bioreactors using cell suspensions of various Taxus species with good yields; presently paclitaxel is produced on a commercial scale by Phyton Biotech (Germany). Camptothecin has low yields in suspension cultures of Camptotheca acuminata or Nothapodytes foetida (0.0003–0.01%), but a good production (0.1–0.3% dry wt) in root and hairy root cultures of Ophiorrhiza pumila, O. mungos and C. acuminata. Podophyllotoxin can be produced in cell suspension and root as well as hairy root cultures of Podophyllum and various Linum species up to 130 mg/l (Linum album cell suspensions); its derivative 6-methoxypodophyllotoxin is accumulated in hairy roots of L. persicum up to about 500 mg/l. The in vitro production of dimeric indole alkaloids in Catharanthus roseus has failed so far both in undifferentiated and differentiated in vitro cultures. In cases where in vitro cultures show good yields, they can be employed in biotechnology for the sustainable production of valuable products.

Wild Solanum species are characterized by several types of glycoalkaloids (GAs), which are usually not found in commercial potato cultivars. These alkaloids serve as defence compounds against herbivores and microorganisms, especially fungi. In this study, the GA composition of tuber and leaf material of 17 wild Solanum species was analysed qualitatively by liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) and quantitatively by high-performance liquid chromatography. The GAs identified were α-solanine, α-chaconine, β-chaconine, solasonine, solamargine, demissine, dehydrodemissine, α-tomatine, dehydrotomatine, commersonine, dehydrocommersonine, leptine I and leptine II. Most species accumulated the common potato GAs α-solanine and α-chaconine in tubers and solasonine and solamargine additionally in leaves. In some species, such as S. acaule ssp. acaule, S. demissum and S. polyadenium, substantial amounts of unusual alkaloids were detected. By using LC-ESI-MS, we detected several minor alkaloids such as dehydrogenated forms of α-tomatine, demissine and commersonine for the first time. Total GA content, expressed as the sum of the four main alkaloids α-solanine, α-chaconine, solamargine and solasonine differed from species to species. In general, GA contents in leaf tissue were higher and GA patterns were more complex than those of tubers.

Abstract-Nectar of many bee flowers contains secondary compounds, which are considered toxic for honeybees on repeated exposure. Although many anecdotal reports indicate the toxicity of secondary compounds to bees, only a few studies have tested the extent of toxicity at different honeybee ages, especially at the larval stages. Honeybees encounter nicotine at trace concentrations (between 0.1 and 5 ppm) in floral nectar of a few Nicotiana spp. and in Tilia cordata. Adult honeybee workers tolerate these nicotine concentrations. In controlled nonchoice feeding experiments with caged bees, we investigated the effect of nicotine on hatching success and larval and forager survival. Naturally occurring concentrations of nectar-nicotine did not affect hatching success of larvae or their survival, but the latter was negatively affected by higher concentrations of nicotine (50 ppm). Concentrations of nicotine in fresh honey samples from the hives were 90% lower than the concentrations in the offered experimental sucrose solutions. Our results indicate that honeybees can cope with naturally occurring concentrations of nicotine, without notable mortality, even when consumed in large quantities for more than 3 weeks.