Bionomics of <Emphasis Type="Italic">Momordica cochinchinensis</Emphasis> Fed <Emphasis Type="Italic">Aulacophora foveicollis</Emphasis> (Coleoptera: Chrysomelidae)

The effects of feeding on root by the larvae and three types of Momordica cochinchinensis Spreng (Cucubitaceae) leaves (young, mature and senescent) by the adults of Aulacophora foveicollis Lucas (Coleoptera: Chrysomelidae) were studied under laboratory conditions. Total larval developmental time was 19.7 ± 0.2 days by feeding on young roots. Adult males lived for 28.4 ± 1, 65.7 ± 1.1 and 22.8 ± 1.3 days on young, mature and senescent leaves, respectively; whilst adult females lived for 34.3 ± 1.2, 68.5 ± 0.9 and 26.4 ± 1.4 days on young, mature and senescent leaves, respectively. Fecundity was highest in mature leaves fed insects (202.2 ± 10.6). Total carbohydrate, protein, lipid, nitrogen and amino acid were much higher in root followed by mature leaves than young and senescent leaves. Moisture content was highest in mature leaves than the roots, young and senescent leaves. Phenols were greatest in young leaves followed by mature leaves and least in senescent leaves and roots of the said plant. Flavonols were higher in young leaves and least in root. These results suggest that A. foveicollis adults perform better on mature leaves than young and senescent leaves for their nutrition.     

Influence of host plant on growth and reproduction of Aphis nerii and feeding and prey utilization of its predator Menochilus sexmaculatus

Influence of different physiological stages (young, mature and senescent) of Calotropis gigantea leaves on growth and reproductive ability of A. nerii and feeding, prey utilization, fecundity and lipid content of its predator M. sexmaculatus were investigated. Increased reproductive period, total life span and reproduction of nymphs per female of A. nerii were observed when reared on mature leaves. This relative preference of A. nerii and maximum utilization of mature leaves as compared to other physiological aged leaves are mainly due to changes in the chemical composition such as protein, carbohydrate, lipid, amino acid, nitrogen and phenolic of C. gigantea. Further, aphids reared on mature leaves influenced its predator's (M. sexmaculatus) growth, prey utilization and reproductive performances. Fecundity and longevity were high, while developmental time of predator was shorter on mature leaves fed aphid. Maximum prey utilization and increased efficiency of ingested and digested food of predator was observed on mature leaves reared aphid. The results are interpreted and discussed in relation to plant aphid and predator interaction (tritrophic).     

Complementary Behaviors of Maternal and Offspring <Emphasis Type="Italic">Spodoptera littoralis</Emphasis>: Oviposition Site Selection and Larval Movement Together Maximize Performance

The selection of oviposition and feeding sites within cotton plants by Spodoptera littoralis was investigated in the field in 2 years, 2007 and 2008. The female moths exhibited significant oviposition preference for young leaves (YL), particularly the 3rd and 4th leaves from top. The larvae originating from egg batches deposited on YL fed mostly in situ for about 5 days, after which they gradually moved their feeding site toward fully expanded or mature leaves on the same individual plant or on neighboring plants. Larvae hatching from batches deposited on fully expanded leaves (FE) fed in situ only for about 2 days, after which they moved toward younger leaves, where they fed for about 3 more days. After the fifth day, however, larvae of the two groups dispersed mainly downward and outward from their hatching site until the end of a 12-day observation. Larvae hatching from eggs deposited on mature or pre-senescent leaves (MP) moved mainly horizontally to other plants after a slight upward shift. The YL and FE larvae grew significantly faster than MP larvae, both in the field and in a laboratory experiment. In the laboratory experiment, the larval period was shorter and the pupal weight was higher when the animals were offered young leaves or young and fully expanded leaves, than when the animals were offered mature and pre-senescent leaves during the first 5 days after hatching. Possible causes and advantages of the exhibited oviposition preference, as well as the apparent ability of larvae to correct for small egg misplacements made by the females, are discussed.     

Fallback Foods of Red Leaf Monkeys (Presbytis rubicunda) in Danum Valley, Borneo

Animals in Southeast Asia must cope with long periods of fruit scarcity of unpredictable duration between irregular mast fruiting events. Long-term data are necessary to examine the effect of mast fruiting on diet, and particularly on the selection of fallback foods during periods of fruit scarcity. No such data is available for colobine monkeys, which may consume substantial amounts of fruits and seeds when available. We studied the diet of red leaf monkeys (Presbytis rubicunda, Colobinae) in Danum Valley, Sabah, northern Borneo, using 25 mo of behavioral observation, phenology and vegetation surveys, and chemical analysis to compare leaves eaten with nonfood leaves. The monkeys spent 46% of their feeding time on young leaves, 38% on seeds, 12% on whole fruits, 2.0% on flowers, 1.0% on bark, and 1.2% on pith. They spent more time feeding on seeds and whole fruit when fruit availability was high and fed on young leaves of Spatholobus macropterus (liana, Leguminosae) as fallback foods. This species was by far the most important food, constituting 27.9% of the total feeding time, and the feeding time on this species negatively correlated with fruit availability. Consumed leaves contained more protein than nonconsumed leaves, and variation in time spent feeding on different leaves was explained by their abundance. These results suggest that red leaf monkeys show essentially the same response to the supra-annual increase in fruit availability as sympatric monogastric primates, increasing their seed and whole-fruit consumption. However, they depended more on young leaves, in particular Spatholobus macropterus, as fallback foods during fruit-scarce periods than did gibbons or orangutans. Their selection of fallback food appeared to be due to both nutrition and abundance.     

Effects of Leaf Age on Oviposition and on Offspring Fitness in the Imported Willow Leaf Beetle Plagiodera versicolora (Coleoptera: Chrysomelidae)

Imported willow leaf beetles Plagiodera versicolora oviposit on willow leaves, and both larvae and adults feed on the leaves. In the field, eggs were found on leaves near the center of branchlets, and the number of eggs per cluster was independent of the leaf area and position. However, in the laboratory, females chose young leaves over old leaves, for both oviposition and feeding and choice did not rely on information on relative position or size of leaves. Developing on young versus old leaves may provide both advantages and disadvantages. In the laboratory, larvae developed more quickly and attained a greater adult weight when fed young versus old leaves, perhaps because of increased mandibular wear of larvae fed old leaves. However, in the field, survival of eggs was lower on young versus old leaves. In the laboratory, rates of cannibalism and survivorship to adulthood did not differ on young versus old leaves.     

<Emphasis Type="Italic">Virola sebifera</Emphasis> Aubl. (Myristicaceae) leaf chemical composition and implications on leaf-cutter ant foraging choice

Leaf-cutter ant plant material choice is essential for colony maintenance and growth. Plant material is used as a substrate for cultivating symbiotic fungus, and the ants’ preference for particular leaves, tends to be determined by vegetal age-related physicochemical factors. The plant species Virola sebifera Aubl. (Myristicaceae), for example, shows a large number of leaf surface trichomes. Although non-glandular, V. sebifera trichomes may gradually retain an increasing amount of chemical compounds over the lifetime of the leaf. Thus, the present study aims to investigate the role of plant chemical compounds on Atta sexdens rubropilosa preference for V. sebifera leaves of different ages. For this purpose, the chemical composition of trichomes on young and senescent leaves was analyzed, and ants’ preference tested. The chemical compositions differ between V. sebifera young and senescent leaves, with triacontane (C30) predominance in young leaves and tetratriacontane (C34) predominance in senescent leaves. Ants’ preference choice was tested by randomly offering leaves of different ages to A. sexdens rubropilosa workers, following six different treatments: (1) young leaf fragments; (2) young leaf fragments with few trichomes removed; (3) loose trichomes from young leaves; (4) senescent leaf fragments; (5) senescent leaf fragments with few trichomes removed, and (6) loose trichomes from senescent leaves. Ants’ preference was observed for young leaves fragments with a few trichomes removed and also for young leaves loose trichomes. Ants’ preference might be due to specific volatile compounds (GLV) preset in V. sebifera young leaves. Results suggest occurrence of ants’ selectivity resulting from changes on trichomes chemical composition between V. sebifera leaves different age stages.     

Diamondback moth performance and preference for leaves of Brassica oleracea of different ages and strata

The preference–performance hypothesis predicts that moth behaviour links plant variations with caterpillar attack and distribution, and the plant‐age hypothesis states that specialist herbivores are more successful in exploring younger plant tissue. We integrated these predictions to investigate underlying mechanisms by which moths and caterpillars of Plutella xylostella L. (Lepidoptera: Plutellidae) track and exploit within‐plant variability of leaf age and stratification. We measured leaf proteins, glucosinolates and fibre, as well as larval choice, developmental performance, and moth oviposition preference with regard to leaf age classes (young, mature and senescent) of three varieties (collard, cauliflower and cabbage) of the main host plant Brassica oleracea L. Larvae consistently fit the prediction that specialist herbivores prefer and perform better on young, upper leaves that have the highest protein level, despite the highest content of defence compounds. Conversely, moths laid more eggs on fibrous and less nutritious leaves from the lower and senescent stratum. We argue that the leaf stratification of host plants imposes conflicting selective pressures concerning offspring feeding and protection on adult females. If egg mortality is catastrophic on the upper nutritious leaves in a particular microclimatic context (e.g. sun, heat, winds, drought or rain‐washing), then oviposition preference will remain for the suboptimal lower and senescent leaves. The ability of larvae to spread upwards over the plant to access the more nutritious leaf stratum is critical when eggs are preferentially laid on the protective low‐quality leaves.     

Feeding by flea beetles (Coleoptera: Chrysomelidae; Phyllotreta spp.) is decreased on canola (Brassica napus) seedlings with increased trichome density

Laboratory and field studies were undertaken to determine the effects of increased numbers of trichomes on seedling stems, petioles, and first true leaves of Brassica napus L., canola, on the feeding and behavior of the crucifer flea beetle Phyllotreta cruciferae (Goeze) (Coleoptera: Chrysomelidae). Seedlings of 'Westar' canola with genes inserted from Arabidopsis thaliana L. for increased trichome production, called Hairyl, were tested against Westar seedlings in no-choice and choice laboratory tests, and against parental plants and other cultivars grown from seed with and without insecticide in field trials at Saskatoon and Lethbridge, Canada. Analyses ofprefeeding and feeding behavior in no-choice tests of first true leaves found that flea beetles interacted with their host while off Hairyl leaves more so than beetles presented with leaves of Westar. Beetles required twice as much time to reach satiation when feeding on leaves with increased pubescence than on Westar leaves. In laboratory choice tests, flea beetles fed more on cotyledons and second true leaves of Westar than on comparable tissues of the transgenic line. In field trials, variations in feeding patterns were seen over time on cotyledons of the line with elevated trichomes. However, all four young true leaves of Hairyl seedlings were fed upon less than were the parental lines. Feeding on Hairyl plants frequently occurred at levels equal to or less than on cultivars grown from insecticide-treated seed. This study highlights the first host plant resistance trait developed in canola, dense pubescence, with a strong potential to deter feeding by crucifer flea beetles.     

The Occurence of delta-Tocopherylquinone in Higher Plants and Its Relation to Senescence

delta-Tocopherylquinone (deltaTQ) content was determined in tobacco and yellow maple leaves, green ivy leaves and cactus tissues. It was found that the concentration of delta-TQ was highest in mature or senescent tissues, such as white tobacco leaves (0.02 mumole/g dry wt) while its detection was uncertain in young, green leaves from the apex of tobacco plants. Fractionation by centrifugation of senescent tobacco leaves showed that the osmiophilic globule fraction was enriched in delta-TQ. Electron microscope studies of young, mature and senescent tobacco tissues showed progressive changes in the size and number of osmiophilic globules. After chloroplast breakdown in senescent tobacco leaves, these globules became the predominant constituents of the organelle. delta-TQ which is associated with osmiophilic globules may play a role in the development of plants, particularly during senescence.     

Prey-induced changes in the accumulation of amino acids and phenolic metabolites in the leaves of <Emphasis Type="Italic">Drosera capensis</Emphasis> L

Effect of prey feeding (ants Formica fusca) on the quantitative changes in the accumulation of free amino acids, soluble proteins, phenolic metabolites and mineral nutrients in the leaves of carnivorous plant Drosera capensis was studied. Arginine was the most abundant compound in Drosera leaves, while proline was abundant in ants. The amount of the majority of amino acids and their sum were elevated in the fed leaves after 3 and 21 days, and the same, but with further enhancement after 21 days, was observed in ants. Accumulation of amino acids also increased in young non-fed leaves of fed plants. Soluble proteins decreased in ants, but were not enhanced in fed leaves. This confirms the effectiveness of sundew’s enzymatic machinery in digestion of prey and suggests that amino acids are not in situ deposited, but rather are allocated within the plant. The content of total soluble phenols, flavonoids and two selected flavonols (quercetin and kaempferol) was not affected by feeding in Drosera leaves, indicating that their high basal level was sufficient for the plant’s metabolism and prey-induced changes were mainly N based. The prey also showed to be an important source of other nutrients besides N, and a stimulation of root uptake of some mineral nutrients is assumed (Mg, Cu, Zn). Accumulation of Ca and Na was not affected by feeding.     

小猿叶甲对寄主植物衰老和缺乏的适应

小猿叶甲Phaedon brassicae Baly是十字花科蔬菜上的一种重要害虫,具有复杂的生活史。测定小猿叶甲取食幼嫩和衰老小白菜叶片后的滞育比率和食料缺乏条件下小猿叶甲成虫的存活时间。研究结果表明,在25℃配合光周期12L∶12D条件下,小猿叶甲取食衰老期小白菜叶片后的滞育比率显著高于取食幼期小白菜叶片后的滞育比率。在25℃、12L∶12D条件下以幼期小白菜叶片饲养小猿叶甲,其成虫羽化后取食0～7d,再分别转入30℃、14L∶10D,不供食的条件下,其结果表明,雌雄成虫存活时间随取食时间延长而延长;羽化成虫取食5d以上,成虫存活时间显著延长,雌雄成虫平均存活时间均在75d以上。最后,讨论小猿叶甲对寄主植物衰老和缺乏的可能适应机制。     

Diet and Food Choice of Trachypithecus francoisi in the Nonggang Nature Reserve, China

We studied the diet and food choice of 1 group of Fran?ois’ langurs (Trachypithecus francoisi) from August 2003 to July 2004 in the Nonggang Nature Reserve, Guangxi province, China. The langurs consumed 90 plant species, including 14 unidentified species. Leaves constituted 52.8% of the diet (38.9% young leaves and 13.9% mature leaves). Fruits and seeds accounted for 17.2% and 14.2%, respectively. Flowers and other items—including petioles, stems, roots, and bark—contributed to 7.5% and 7.4% of the diet, respectively. The langur diet varied according to season. They fed on more young leaves from April to September. Consumption of seeds, petioles, and stems increased between October and March, when young leaves were scarce. The diet shift corresponded to higher dietary diversity during the young leaf-lean period. Though the langurs fed on many plant species, 10 species accounted for 62.2% of the diet, only 2 of which were among the 10 most common tree species in vegetation quadrants, and the percentage of feeding records on a plant species and the percentage of individuals of the species in vegetation quadrants does not correlate significantly. Fran?ois’ langurs fed selectively, and they did not base their diet simply on the abundance of plant species in the habitat.     

Free fatty acids from the weed,Polygonum orientale leaves for attraction of the potential biocontrol agent,Galerucella placida (Coleoptera: Chrysomelidae)

Extraction, thin layer chromatography and gas chromatography-mass spectrometry of leaf surface waxes of Polygonum orientale L. (Polygonaceae) weed revealed 11, 15 and 11 free fatty acids in young, mature and senescent stages. Oleic acid was the predominant in young leaves (5950 ± 111 µg); whereas palmitic acid was the predominant fatty acids, representing 4247.5 ± 23 and 6644 ± 110 µg in mature and senescent leaves, respectively. Both tridecanoic and heneicosanoic acids were not detected in young and senescent leaves, and myristic and heptadecanoic acids were not identified in young leaves; whereas lauric and nonadecanoic acids were not detected in senescent leaves. The free fatty acids from young, mature and senescent weed leaves, and the mixtures of synthetic fatty acids mimicking free fatty acids of three types of weed leaves attracted female Galerucella placida (Coleoptera: Chrysomelidae) at the minimal amounts of 2, 1 and 2 leaf equivalent free fatty acids, respectively, in Y-shaped glass tube olfactometer bioassays under laboratory conditions. Individual synthetic pentadecanoic, palmitoleic, stearic, nonadecanoic and docosanoic acids at 44.82, 9.91, 92.22, 18.33 and 15.88 µg, respectively, elicited attraction of the insect. A synthetic blend of 3.59, 7.89, 44.82, 9.91, 32.31, 18.33 and 15.88 µg of lauric, myristic, pentadecanoic, palmitoleic, heptadecanoic, nonadecanoic and docosanoic acids, respectively, indicated highest attraction of the insect.     

转双价基因(Bt+CpTI)棉对棉铃虫中肠羧酸酯酶活性的诱导作用

为了明确棉铃虫Helicoverpa armigera(Hübner)取食转双价基因(Bt+CpTI)棉叶以及取食一段时间转基因棉叶后,再取食常规棉叶,对棉铃虫取食量、体重增长量及中肠羧酸酯酶活性的影响,本研究分别用转双价基因棉叶和常规棉叶饲喂4龄棉铃虫幼虫5 d,比较考察了棉铃虫的取食量、体重增长量及中肠羧酸酯酶的活性;另外分别考察了棉铃虫取食转基因棉叶1 d及3 d后再取食常规棉叶,其中肠羧酸酯酶的变化。结果表明,持续取食常规棉花叶片5 d的棉铃虫,其中肠羧酸酯酶的活性持续升高;而持续取食转基因棉叶5 d的棉铃虫,其中肠羧酸酯酶的活性先升高后降低。取食转基因棉花叶片1 d后,取食常规棉叶的棉铃虫,其中肠羧酸酯酶的活性,随着换取常规棉叶时间的延长,活性逐渐降低;而棉铃虫在取食3 d转基因棉叶后再取食常规棉叶,其中肠羧酸酯酶活性却一直保持较高。可见,棉铃虫在取食转基因棉花后,其羧酸酯酶活性可以被诱导,这应与棉铃虫对转基因棉的抗性及防御性有一定关系。     

The Occurence of δ-Tocopherylquinone in Higher Plants and Its Relation to Senescence

δ-Tocopherylquinone (δTQ) content was determined in tobacco and yellow maple leaves, green ivy leaves and cactus tissues. It was found that the concentration of δ-TQ was highest in mature or senescent tissues, such as white tobacco leaves (0.02 μmole/g dry wt) while its detection was uncertain in young, green leaves from the apex of tobacco plants. Fractionation by centrifugation of senescent tobacco leaves showed that the osmiophilic globule fraction was enriched in δ-TQ. Electron microscope studies of young, mature and senescent tobacco tissues showed progressive changes in the size and number of osmiophilic globules. After chloroplast breakdown in senescent tobacco leaves, these globules became the predominant constituents of the organelle. δ-TQ which is associated with osmiophilic globules may play a role in the development of plants, particularly during senescence.     

Examination of the pronounced increase in auxin content of senescent leaves

When a conventional IAA extraction procedure was used, the levelof auxin in senescent leaves was ten times that in young leaves.The level estimated by an improved procedure, in which IPyrAwas excluded at a high rate from the extract, was only onefourthto one-fifth and less than one-tenth that obtained by the conventionalprocedure in senescent leaves of bean and pea plants, respectively.The Trp content of detached leaves increased with the progressof leaf senescence, though TTA activity decreased. The highlevel of auxin in senescent leaves might be largely due to contaminationwith IPyrA. (Received October 30, 1978; )     

Red young leaves have less mechanical defence than green young leaves

In many plants, leaves that are young and/or old (senescent) are not green. One adaptive hypothesis proposed that leaf color change could be a warning signal reducing insect attack. If leaf coloration involves less herbivory, it remains unclear why leaves in many species are constantly green. To examine whether green leaves reduce herbivory by physical defense as an alternative to the supposed warning signal of red leaves, we conducted comparative analyses of leaf color and protective tissues of 76 woody species in spring. The protective features (trichomes, enhanced cuticle and multiple epidermis) and the distribution of red pigments within leaves were examined in both young and mature leaves. We observed that redness was more frequent in young leaves than in senescent leaves. Compared to 36 species with red young leaves, 40 species with green young leaves showed a significantly higher incidence of enhanced cuticle and trichomes in both phylogenetic and non‐phylogenetic analyses. The phylogenetic analysis indicated that the multiple origins of mechanical protection were generally associated with loss of red coloration. Our finding of relatively poor mechanical protection in red young leaves provides additional evidence for the adaptive explanation of leaf color change.     

粘虫高龄幼虫对转Bt基因玉米的消化和利用

在室内用重量法研究了粘虫Mythimna separata (Walker)高龄幼虫对转Bt基因玉米MON810和Bt11叶片的消化和利用,以明确Bt玉米对暴食期幼虫取食的影响。结果表明,在连续测定的5天中,取食MON810和Bt11两种Bt玉米叶片时,幼虫存活率和取食量均显著低于各自的对照组幼虫,取食Bt玉米叶片的幼虫体重呈下降趋势,第3 天时分别比第2 天减少12.2 mg 和7.4 mg,而取食对照玉米叶片时的幼虫日增重显著的高于处理组的幼虫,第3 天的日增重分别为100.4 mg 和119.9 mg。取食Bt玉米叶片的幼虫对食物的转化率(ECI和ECD)均为负值,在最初4 天的ECI和ECD都显著低于对照组幼虫,但取食两种非Bt玉米叶片的幼虫的近似消化率(AD) 随取食时间的延长而逐渐下降,取食第5 天分别为20.6 %和15.1 %;而取食MON810和Bt11叶片时幼虫的AD均显著地高于对照组幼虫。     

Do birch-feeding caterpillars make the right feeding choices?

Summary The effects of leaf quality on caterpillar performance are frequently investigated, as are the feeding preferences of caterpillars, but rarely are the two considered together to see how preferences match performance. I looked at the preferences and performance of the specialist feeder Achlya flavicornis and the generalist Spilosoma luteum on Betula pendula leaves which were artificially damaged, mined or left undamaged, and on leaves of different ages. Often feeding preferences were not for the leaf types that gave faster development, larger pupae or greater survival. A. flavicornis preferred medium aged to older leaves though medium aged leaves produced smaller pupae. They did not discriminate between young and medium aged leaves, though larvae fed young leaves developed more slowly, and had lower survival and lower adult emergence. S. luteum larvae did not discriminate between damaged and undamaged leaves, though feeding on damaged leaves gave smaller pupae and lower adult emergence. I suggest that generalists like S. luteum might be unable to make feeding choices between leaves that are on the same tree and vary only slightly because populations are exposed to much greater variation across the wide range of potential food plants individuals may encounter. Possible differences in within-plant feeding selectivity between generalists and specialists should be investigated. A. flavicornis is a leaftier for which selection of a suitable leaf for tying could be more important in the first instance than feeding considerations. Larvae preferred younger to older leaves for tying, and larvae tended to feed on the tied leaves, so tying preferences explain the initial feeding preferences.     

Peroxisomal NADP-Dependent Isocitrate Dehydrogenase. Characterization and Activity Regulation during Natural Senescence

The peroxisomal localization and characterization of NADP-dependent isocitrate dehydrogenase (perICDH) in young and senescent pea (Pisum sativum) leaves was studied by subcellular fractionation, kinetic analysis, immunoblotting, and immunoelectron microscopy. The subunit molecular mass for perICDH determined by immunoblotting was 46 kD. By isoelectric focusing (IEF) of the peroxisomal matrix fraction, the NADP-ICDH activity was resolved into four isoforms, perICDH-1 to perICDH-4, with isoelectric points (pIs) of 6.0, 5.6, 5.4, and 5.2, respectively. The kinetic properties of the NADP-ICDH in peroxisomes from young and senescent pea leaves were analyzed. The maximum initial velocity was the same in peroxisomes from young and senescent leaves, while the Michaelis constant value in senescent leaf peroxisomes was 11-fold lower than in young leaf peroxisomes. The protein levels of NADP-ICDH in peroxisomes were not altered during senescence. The kinetic behavior of this enzyme suggests a possible fine control of enzymatic activity by modulation of its Michaelis constant during the natural senescence of pea leaves. After embedding, electron microscopy immunogold labeling of NADP-ICDH confirmed that this enzyme was localized in the peroxisomal matrix. Peroxisomal NADP-ICDH represents an alternative dehydrogenase in these cell organelles and may be the main system for the reduction of NADP to NADPH for its re-utilization in the peroxisomal metabolism.