Variations in direct and indirect defenses against herbivores on young plants of <Emphasis Type="Italic">Mallotus japonicus</Emphasis> in relation to soil moisture conditions

Some plant species develop multiple defense traits. To test the hypothesis that plants with both direct and indirect defense traits mainly develop the direct and indirect defense traits under the low and high soil moisture conditions, respectively, the development of multiple defense traits on the young plants of Mallotus japonicus (Thunb.) Muell. Arg., and the number of ants on the plants were experimentally examined under different soil moisture conditions. Under the low soil moisture condition, the plant growth declined, and the trichomes and pellucid dots developed well. The pearl bodies developed on the plants under the high soil moisture condition. The volume of extrafloral nectar secreted and the number of ants on the plants significantly increased under the high soil moisture condition. These results clearly show that the young plants of M. japonicus firmly develop sound direct defense traits under the low soil moisture condition, and they develop indirect defense traits that are less reliable but have relatively low costs under the high soil moisture condition.     

Plasticity in the expression of direct and indirect defence traits of young plants of <Emphasis Type="Italic">Mallotus japonicus</Emphasis> in relation to soil nutritional conditions

Although soil nutrients can influence the defence strategy of plants that have multiple defence traits, to date, there have been few studies to examine this. To evaluate the effect of soil nutrients on multiple plant defences, we cultivated Mallotus japonicus under three soil nutritional conditions in the field, and experimentally examined the expression of a physical defence trait (trichomes), chemical traits (pellucid dots), and biotic traits (extrafloral nectaries (EFNs) and pearl bodies) of the plants, and the number of ants visiting them. Under the low soil nutritional condition, plants strongly expressed the physical defence by trichomes and chemical defence by pellucid dots, meaning that the young plants adopted direct defences under the poor soil nutritional condition. Under the high soil nutritional condition, in contrast, the plants strongly expressed the indirect defence traits. They produced abundant EFNs and pearl bodies, and attracted many ants. These results suggest that young plants of M. japonicus use different defence modes in response to different soil nutritional conditions.     

Effects of light on direct and indirect defences against herbivores of young plants of Mallotus japonicus demonstrate a trade-off between two indirect defence traits

Background and Aims

Although most studies on plant defence strategies have focused on a particular defence trait, some plant species develop multiple defence traits. To clarify the effects of light on the development of multiple defence traits, the production of direct and indirect defence traits of young plants of Mallotus japonicus were examined experimentally under different light conditions.

Methods

The young plants were cultivated under three light conditions in the experimental field for 3 months from May to July. Numbers of ants and pearl bodies on leaves in July were examined. After cultivation, the plants were collected and the developments of trichomes and pellucid dots, and extrafloral nectaries (EFNs) on the leaves were examined. On plants without nectar-collecting insects, the size of EFNs and the volume of extrafloral nectar secreted from the EFNs were examined.

Key results

Densities of trichomes and pellucid dots did not differ significantly among the plants under the different light conditions, suggesting that the chemical and physical defences function under both high and low light availability. The number of EFNs on the leaves did not differ significantly among the plants under the different light conditions, but there appeared to be a trade-off between the size of EFNs and the number of pearl bodies; the largest EFNs and the smallest number of pearl bodies were found under high light availability. EFN size was significantly correlated with the volume of extrafloral nectar secreted for 24 h. The number of ants on the plants was smaller under low light availability than under high and moderate light availability.

Conclusions

These results suggest that direct defence traits function regardless of light conditions, but light conditions affected the development of indirect defence traits.     

Concentration and retention of chlorophyll around the extrafloral nectary of Mallotus japonicus

Plants need to allocate some of their limited resources for defense against herbivores as well as for growth and reproduction. However, the priority of resource allocation within plants has not been investigated. We hypothesized that plants with extrafloral nectaries (EFNs) invest more chlorophyll around their EFNs—to support a high rate of carbon fixation there—than in other leaf parts of young leaves. Additionally, this chlorophyll may remain around EFNs rather than in the other leaf parts. We used Mallotus japonicus plants to investigate the chlorophyll content at leaf centers and edges and around EFNs at four stages of leaf development: middle‐expanded young leaves, fully expanded mature leaves, senior leaves, and leaves prior to abscission. These four stages of development were located at the third, fifth, eighth, and eleventh leaf positions from the apex, respectively. The results revealed that the chlorophyll content around the EFN side of the third‐position leaves was higher than that at the leaf center or edge. Although the chlorophyll content in the fifth‐position leaves did not differ between those at the leaf edge and around EFNs, the chlorophyll content around EFNs in the eighth‐position leaves was higher than that at the leaf centre and edge. The volume of EF nectar was positively correlated with the chlorophyll content around EFN during the leaf stage, but it was not correlated with the chlorophyll content in the leaf center and edge, except in fifth‐position leaves. These findings suggest that M. japonicus plants facilitate and maintain secretion of EF nectar in their young and old leaves, respectively, through the concentration and retention of chlorophyll around EFNs.     

Extrafloral nectary-bearing plant Mallotus japonicus uses different types of extrafloral nectaries to establish effective defense by ants

Extrafloral nectary (EFN)-bearing plants attract ants to gain protection against herbivores. Some EFN-bearing plants possess different types of EFNs, which might have different effects on ants on the plants. Mallotus japonicus (Thunb.) Muell. Arg. (Euphorbiaceae) bears two types of EFNs, including a pair of large EFNs at the leaf base and many small EFNs along the leaf edge. This study aimed to determine the different roles of the two types of EFNs in biotic defense by ants. A field experiment was conducted to investigate the effect of leaf damage on EFN production and on the distribution pattern of ants. After leaf damage, the number of leaf edge EFNs increased in the leaves first-produced. The number of ants on the leaves also increased, and the foraging area of ants extended from the leaf base to the leaf tip. An EFN-covering field experiment revealed that leaf edge EFNs had a greater effect than leaf base EFNs on ant dispersal on leaves. The extended foraging area of ants resulted in an increase of encounter or attack rate against an experimentally placed herbivore, Spodoptera litura. These results suggest that M. japonicus plants control the foraging area of ants on their leaves using different types of EFNs in response to leaf damage, thus achieving a very effective biotic defense against herbivores by ants.

     

Developmental Changes in Direct and Indirect Defenses in the Young Leaves of the Neotropical Tree Genus Inga (Fabaceae)

Plant fitness is affected by herbivory, and in moist tropical forests, 70 percent of herbivore damage occurs on young leaves. Thus, to understand the effects of herbivory on tropical plant fitness, it is necessary to understand how tropical young leaves survive the brief, but critical, period of susceptibility. In this study, we surveyed three species of Inga during young leaf expansion. Three classes of toxic secondary metabolites (phenolics, saponins, and tyrosine), extrafloral nectar production, leaf area, and extrafloral nectary area were measured at randomly assigned young leaf sizes. In addition, all defenses were compared for potential trade‐offs during leaf expansion. No trade‐offs among defenses were found, and the concentration of all defenses, except tyrosine, decreased during leaf expansion. We suggest that plants continued to increase phenolic and saponin content, but at a rate that resulted in decreasing concentrations. In contrast, tyrosine content per leaf steadily increased such that a constant concentration was maintained regardless of young leaf size. Nectar production remained constant during leaf expansion, but, because young leaf area increased by tenfold, the investment in extrafloral nectar per leaf area significantly decreased. In addition, nectary area did not change during leaf expansion and therefore the relative size of the nectary significantly decreased during young leaf expansion. These results support the predictions of the optimal defense hypothesis and demonstrate that the youngest leaves have the highest investment in multiple defenses, most likely because they have the highest nitrogen content and are most susceptible to a diversity of herbivores.     

伤害和挥发物对棉花花外蜜的诱导效应

植物花外蜜的分泌是一种植物间接防御反应。为了明确植食性昆虫、机械伤和机械伤诱导的挥发性气体在植物花外蜜诱导分泌中的作用,分析了咀嚼式口器昆虫棉铃虫Helicoverpa armigera(Hübner)、刺吸式口器昆虫棉蚜Aphis gossypii Glover取食、剪刀机械伤、剪刀机械伤+棉铃虫反吐物、针刺机械伤以及机械伤诱导挥发物、顺式-茉莉酮对棉花Gossypium hirsutum L.叶片花外蜜分泌量的影响。结果表明,棉铃虫取食、剪刀机械伤、剪刀机械伤+棉铃虫反吐物处理均显著增加了被处理叶片花外蜜的分泌量。棉花花外蜜的诱导效应在处理叶片上表现明显,并且在较幼嫩的第3片真叶上也有系统性增长。顺式-茉莉酮和机械伤挥发物处理1 d对棉花较幼嫩的第4、5片真叶花外蜜有诱导效应。棉花叶片花外蜜的诱导主要与植物组织损伤有关;不同口器类型的昆虫对棉花叶片花外蜜的诱导量不同,咀嚼式口器的棉铃虫对棉花花外蜜的诱导强度显著高于刺吸式口器的棉蚜;顺式-茉莉酮和机械伤诱导的挥发物能作为棉花植株间交流的信息物质诱导棉花幼嫩叶片花外蜜的分泌。     

Temporal variation in extrafloral nectar secretion in different ontogenic stages of the fruits of Alibertia verrucosa S. Moore (Rubiaceae) in a Neotropical savanna

In this study, we evaluate the temporal variation in extrafloral nectaries (EFNs) secretion in different ontogenic stages of Alibertia verrucosa (Rubiaceae) fruits in a Neotropical savanna. We observe greater nectar secretion rate in fruits of intermediate size compared with young or ripe fruit, indicating that they are possibly more protected by ants. In addition, the nectar secretion was higher at night, a pattern that could be associated with an increase of herbivore pressure and water stress during the daylight hours. In fact, due to the high temperature and low humidity during the day in savannas, most herbivores display strong nocturnal activity, and plants can avoid nectar secretion in this period. Our results indicate that A. verrucosa can change the ants' attraction according to EFN secretion during the ontogenic stages of the fruits, probably secreting more nectar when the biotic defense are more necessary for the protection of the fruits and the plant as a whole.     

Aggressiveness of ants attracted to the extrafloral nectary‐bearing plant,Mallotus japonicus,and temporal fluctuations in their abundance

Many plants that bear extrafloral nectaries (EFNs) attract various ant species that can exclude herbivores. The aggressiveness of the attracted ants and their temporal activity patterns are important factors that can affect the efficiency of herbivore exclusion from the plant. However, the characteristics of this mutualistic relationship between EFN‐bearing plants and ants have not been sufficiently elucidated. We investigated the aggressiveness of six ant species against the common armyworm, Spodoptera litura Fabr., and temporal fluctuations in the abundance of four aggressive ant species on an EFN‐bearing plant, Mallotus japonicus (L.f.) Müll. Arg. Workers of Crematogaster teranishii Santschi, Pheidole noda Smith, Pristomyrmex punctatus Smith and Formica japonica Motschoulsky were observed to be highly aggressive. In contrast, workers of Camponotus vitiosus Smith showed low aggressiveness. Paratrechina flavipes Smith workers did not attack the herbivore. The activity patterns of the four aggressive ant species greatly differed. Crematogaster teranishii and Ph. noda workers were constantly active throughout the day and night. In contrast, F. japonica was diurnal. Pristomyrmex punctatus was principally nocturnal. Formica japonica workers foraged solitarily, whereas workers of the other three species foraged in a group or recruited nestmates. Our results suggest that the efficacy of the indirect defense in M. japonicus depends principally on the attracted ant species.     

Testing the optimal defense hypothesis in Stryphnodendron adstringens (Fabaceae,Mimosoideae) leaves: the role of structure,number, position and nectar composition of extrafloral nectaries

Stryphnodendron adstringens is a common Cerrado tree that possesses extrafloral nectaries (EFNs) on its leaves, which are located at the base and apex of the rachis and along the secondary veins. The position of EFNs and their nectar production can be affected by defense strategies because plant organs possess different values and herbivory vulnerability. Here we aimed to elucidate anatomy, histochemistry, nectar composition and EFN number on leaves of S. adstringens in the light of the optimal defense hypothesis. We found a convergence on anatomy and histochemical characterization because the three studied types of EFNs have epidermis, secretory parenchyma and vascular tissue, showing phenolic compounds and polysaccharides in the secretory parenchyma cells. The nectar contained glucose, fructose and sucrose, which attract ants of the Camponotus and Cephalotes genus. We found differences in the number of EFNs along the secondary veins and in the nectar composition between EFNs located at the base and apex of the rachis of the leaf. The number of EFNs on the secondary veins increases from the base to the apex, suggesting a strategy to induce ant patrolling over the entire leaf region. EFNs at the base secreted more nectar, which should be related to the protection of the leaf base, which is the part most vulnerable to herbivore attack and the most valued organ. We concluded that EFNs of S. adstringens are anti‐herbivore defenses whose pattern matches the predictions of the optimal defense hypothesis.     

Detection of anti-tuberculosis activity in some folklore plants by radiometric BACTEC assay

Aims: The anti‐tubercular drugs are less effective because of the emergence of multi‐drug resistant (MDR) and extensively drug resistant (XDR) strains of M. tuberculosis, so plants being an alternative source of anti‐microbial compounds. The aim of this study was to investigate anti‐tuberculosis potential of the plants using Mycobacterium smegmatis as a rapid screening model for detection of anti‐mycobacterial activity and further to evaluate the active plants for anti‐tuberculosis activity against M. tuberculosis using radiometric BACTEC assay. Methods and Results: The 15 plants were screened for anti‐mycobacterial activity against M. smegmatis by the disk diffusion assay. The ethanolic extracts of Mallotus philippensis, Vitex negundo, Colebrookea oppositifolia, Rumex hastatus, Mimosa pudica, Kalanchoe integra and Flacourtia ramontchii were active against M. smegmatis in primary screening. The anti‐tuberculosis potential was identified in the leaves extracts of Mallotus philippensis by radiometric BACTEC assay. The ethanolic extract of M. philippensis showed anti‐tuberculosis activity against virulent and avirulent strains of M. tuberculosis H₃₇Rv and M. tuberculosis H₃₇Ra with minimum inhibitory concentration 0·25 and 0·125 mg ml^?1, respectively. The inhibition in growth index values of M. tuberculosis was observed in the presence of ethyl acetate fraction at a minimum concentration of 0·05 mg ml^?1. Conclusion: We found that BACTEC radiometric assay is a valuable method for detection of anti‐tuberculosis activity of the plant extracts. The results indicate that ethanolic extract and ethyl acetate fraction of M. philippensis exhibited significant anti‐mycobacterial activity against M. tuberculosis. Significance and Impact of the Study: These findings provide scientific evidence to support the traditional medicinal uses of M. philippensis and indicate a promising potential of this plant for the development of anti‐tuberculosis agent.     

Relationship between physical leaf characteristics and growth and survival of polyphagous grasshopper nymphs, <Emphasis Type="Italic">Parapodisma subastris</Emphasis> (Orthoptera: Catantopidae)

Common types of plant defense mechanisms are thought to affect the host ranges of polyphagous herbivorous insects, yet few studies have examined the relationship between host plant suitability for polyphagous insects and defense against them. We investigated the suitability of the 19 plant species growing in the habitat of the polyphagous grasshopper, Parapodisma subastris, to determine the relationship between the physical characteristics of leaves and the growth and survival of grasshopper nymphs. We examined leaf toughness, trichome density, and length. Nymph survival was greater on plants with characteristics ranging from soft leaves and dense trichomes to tough leaves and few trichomes than on plants with soft leaves and few trichomes. The exception was Rorippa indica, a plant with soft leaves and few trichomes that uses biotic defense, on which nymph survival was maximal. Higher-quality plants that share common physical characteristics over families may favor polyphagy by grasshoppers that possess ability to overcome the physical defense easily with their robust mandibles.An erratum to this article can be found at     

Trade-offs among anti-herbivore resistance traits: insights from Gossypieae (Malvaceae)

Plant defense theories commonly predict negative correlations among anti-herbivore resistance traits. Although this prediction has been widely accepted, the majority of empirical studies have failed to account for similarities among species due to common ancestry, thus risking pseudoreplication. Wild cotton plants possess traits conferring both direct resistance (toxic leaf glands and trichomes) and indirect resistance (extrafloral nectaries that reward enemies of herbivores). The evidence for negative phenotypic correlations among these resistance traits was examined at two levels: within Gossypium thurberi (wild cotton) and across species in the cotton clade (Gossypieae). A phylogenetic analysis controlled for shared ancestry among species. Across the Gossypieae, a strong negative correlation emerged between the direct resistance traits, leaf gland and trichomes. This correlation may reflect costs of these traits, a negative genetic correlation, or redundancy in their actions against herbivores. In contrast, the direct resistance traits (glands and trichomes) were not correlated with the indirect resistance trait of extrafloral nectar, either within or across species. The robust lack of correlation suggests that these direct and indirect resistance mechanisms evolve independently over evolutionary time scales. This conclusion conflicts with both predictions of plant defense theory and the majority of prior comparisons of direct and indirect resistance traits and may reflect the facultative nature of indirect resistance in Gossypieae.     

The role of leaf cutting and fire on extrafloral nectaries and nectar production in Stryphnodendron adstringens (Fabaceae,Mimosoideae) plants

Herbivory pressure is an important ecological aspect to determine quantitative variation in plant defenses, such as the number of extrafloral nectaries (EFNs) and their nectar amount and quality. Extrafloral nectaries can attract ants, which can be considered a type of induced plant defense. Besides, plants tend to invest more in defense when they are more vulnerable to herbivores. Therefore, we aimed to elucidate if Stryphnodendron adstringens (Fabaceae), a common Cerrado tree species, when subjected to damage (by manual leaf cutting and experimental fire) would produce a greater number of EFNs and changes its nectar quality on newly produced leaves in comparison with plants not subjected to these treatments. Leaf damage was performed artificially directly on the plant branches and at the entire plant canopy (by means of scissors or fire events). Extrafloral nectary density was higher in new leaves produced after the treatment application (artificial herbivory and fire) in comparison with plants under control treatment. The amount of nectar was also higher under treatments in comparison with control, with a significant change on nectar quality in plants subjected to the treatments of artificial herbivory. The results provided support for the hypothesis that EFNs are an inducible defensive strategy in S. adstringens, confirming the existence of phenotypic plasticity given environmental pressures.     

PEARL BODIES OF A NEOTROPICAL TREE,OCHROMA PYRAMIDALE: ECOLOGICAL IMPLICATIONS

Multicellular, spherical or club-shaped pearl bodies characterized by large intracellular lipid vesicles are produced on leaves and stems of juvenile Ochroma pyramidale, a tree of second growth vegetation in lowland wet forest of the neotropics. Several lines of evidence suggest that pearl bodies are linked to maintenance of foraging ants on the plant: (1) their production is closely associated with foliar nectar secretion; (2) they are abundant on saplings grown in the glasshouse (averaging 402 bodies leaf^–1) but were not observed in the field where ants are predictably associated with Ochroma samplings; (3) pearl bodies are energy- and lipid-rich averaging 27.80 kJ/g dry wt^–1 and 74.4% lipid; (4) they are constricted at the base and easily detach from the leaf; (5) four ant species collect pearl bodies from artificial depots and return them to their nests. Chelaner sp. detaches pearl bodies from the leaf and returns them to the nest. Production of pearl bodies represents about 25% of the energy allocated to foliar nectar by saplings. Characteristics of the pearl bodies of Ochroma are consistent with those of a widespread group of trichomes and leaf emergences suggesting a common ecological role as ant food for these structures.     

<Emphasis Type="Italic">Catalpa bignonioides</Emphasis> alters extrafloral nectar production after herbivory and attracts ant bodyguards

Inducible anti-herbivore defenses are found within many plant taxa, but there are fewer examples of inducible indirect defenses that incorporate the third trophic level. This study links caterpillar foraging, herbivore-induced changes in extrafloral nectar production, and the attraction of ants to vulnerable leaves and plants. Catalpa bignonioides Walter (Bignoniaceae) uses extrafloral nectar to attract ant (Forelius pruinosus(Roger)) bodyguards in response to Ceratomia catalpae (Boisduval)(Lepidoptera: Sphingidae) herbivory. Ant density per leaf increased with the sugar content of extrafloral nectar excreted by sampled leaves, suggesting that increased nectar production could attract or retain beneficial arthropods. The masses of sucrose, fructose, glucose and all three sugars combined in the extrafloral nectar increased two- to three-fold on attacked leaves within 36 h of the experimental addition of caterpillars. Production rates for neighboring non-attacked leaves and non-attacked leaves on adjacent plants did not differ over the same time period. Ant attendance at caterpillar-attacked leaves increased two- to three-fold within 24 h of herbivory, relative to attendance at neighboring, undamaged leaves. These attacked leaves attracted the fewest ants prior to the onset of herbivory, suggesting the specialist caterpillar may avoid or be excluded from leaves with more bodyguards. The removal of leaf tissue with scissors did not alter ant attendance at damaged leaves. Mean ant attendance per leaf on attacked plants increased 6- to 10-fold after caterpillar introduction, relative to adjacent unattacked plants. The plant's biotic defense thus operates at two scales; the number of bodyguards (ant workers) on the plant increases after attack, and this increased workforce is biased towards attacked leaves within plants. Fewer caterpillars remained on plants that attracted greater numbers of ants, suggesting these bodyguards benefit the plant.     

Is nectar reabsorption restricted by the stalk cells of floral and extrafloral nectary trichomes?

Reabsorption is a phase of nectar dynamics that occurs concurrently with secretion; it has been described in floral nectaries that exude nectar through stomata or unicellular trichomes, but has not yet been recorded in extrafloral glands. Apparently, nectar reabsorption does not occur in multicellular secretory trichomes (MST) due to the presence of lipophilic impregnations – which resemble Casparian strips – in the anticlinal walls of the stalk cells. It has been assumed that these impregnations restrict solute movement within MST to occur unidirectionally and exclusively by the symplast, thereby preventing nectar reflux toward the underlying nectary tissues. We hypothesised that reabsorption is absent in nectaries possessing MST. The fluorochrome lucifer yellow (LYCH) was applied to standing nectar of two floral and extrafloral glands of distantly related species, and then emission spectra from nectary sections were systematically analysed using confocal microscopy. Passive uptake of LYCH via the stalk cells to the nectary tissues occurred in all MST examined. Moreover, we present evidence of nectar reabsorption in extrafloral nectaries, demonstrating that LYCH passed the stalk cells of MST, although it did not reach the deepest nectary tissues. Identical (control) experiments performed with neutral red (NR) demonstrated no uptake of this stain by actively secreting MST, whereas diffusion of NR did occur in plasmolysed MST of floral nectaries at the post‐secretory phase, indicating that nectar reabsorption by MST is governed by stalk cell physiology. Interestingly, non‐secretory trichomes failed to reabsorb nectar. The role of various nectary components is discussed in relation to the control of nectar reabsorption by secretory trichomes.     

Nonglandular leaf trichomes as short-term inducible defense of the grey alder,Alnus incana (L.), against the chrysomelid beetle,Agelastica alni L.

Summary The grey alder compensates leaf area losses due to insect grazing by continuously producing new leaves throughout the vegetative period. Different degrees of defoliation were attained experimentally by a controlled release of the oligophagous beetle Agelastica alni on arbitrarily selected trees from a homogenous population of young alders. The reduction in leaf area per tree significantly influenced the density of leaf trichomes, assessed 10–30 days later, on newly sprouting leaves only. Cross-correlations between leaf area reduction and trichome density were strongest for leaves which completed unfolding 14–21 days after damage. Dualchoice assays suggested a negative influence of trichomes on oviposition rate of A. alni. Removal of trichomes by shaving demonstrated the highly significant effect of trichomes on feeding behavior of adults and larvae in dual-choice assays. The role of the induced increase in trichome density as a possible short-term defense reaction against herbivorous insects is discussed.     

Variations in abiotic defense within myrmecophytic and non-myrmecophytic species of Macaranga in a Bornean dipterocarp forest

We examined the interspecific variations in intensity of total abiotic (chemical and physical) defenses in five sympatric Macaranga (Euphorbiaceae) species, including three myrmecophytic species. The intensity of the total abiotic defense for each Macaranga species was estimated by measuring inhibiting effects on the growth performance of the common cutworm, Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae) when the cutworm larvae were fed fresh leaves of each Macaranga species. Indices of the growth performance, number of dead larvae, pupal weight and length of larval period were obtained. We found that the intensities of total abiotic defense of the two non-myrmecophytic species were significantly stronger than those of the three myrmecophytic species, and that there was a significant difference in intensity even within the three myrmecophytic species. The former result supports the hypothesis that, unlike non-myrmecophytic species, myrmecophytic species cannot invest so many metabolic resources in abiotic defense, because they have to allocate nutrients to biotic defense (toward biotic defense agents). Moreover, the latter result suggests the possibility that the three sympatric myrmecophytes have different defense strategies, with a trade-off between abiotic and biotic defense, and/or with a trade-off between defense and other life-history traits such as growth and reproduction. Abiotic defense can be roughly separated into physical and chemical mechanisms. To assess the intensity of the physical defense of Macaranga leaves, we measured the leaf toughness of each species. In addition, to assess the intensity of the plants general chemical defense, cutworm larvae were reared on an artificial diet containing dry leaf powder of each Macaranga species, and their growth performances were compared. The estimated orders of intensity of both leaf toughness and general chemical defense coincided with that of the total abiotic factors measured by the growth performance of cutworm on fresh leaves. This suggests the presence of both physical defenses, represented by leaf toughness, and a general chemical defense affecting the intensity of the total abiotic defense in similar ways.     

Conservation of an Ant–plant Mutualism in Native Forests and Ecologically‐managed Tree Monocultures

The Brazilian Atlantic Forest has been replaced by homogeneous tree monocultures with potentially drastic effect on ecological interactions. We expect that ecologically‐managed tree monocultures, however, can help to mitigate this impact. Here, we carried out an experiment with Inga vera (Fabaceae), an extrafloral nectary bearing plant, to test if the efficiency of ants as anti‐herbivory defense is affected by the replacement of its natural habitat (Araucaria Forest) by ecologically‐managed tree monocultures (plantations of Araucaria, Pinus, and Eucalyptus). Seedlings of Inga vera were transplanted to three patches of each habitat and ants were excluded from half of the plants. The abundance of ants and herbivores was low, similar among habitats, and exhibited temporal asynchrony. Number of herbivores and accumulated herbivory levels were lower in plant with ants. Rates of herbivory were extremely low and lower for young leaves than for mature leaves. The presence of ants did not affect plant performance traits measured by their growth in height, and their final numbers of leaves and leaflets. Contrary to what might be expected, ant‐protected plants produced fewer leaves and leaflets than unprotected ones. In conclusion, Inga vera‐ant interaction was similar between its natural habitat and the tree monocultures, indicating that potentially both species diversity and ecological processes can be conserved in ecologically‐managed tree monocultures.