Deterrent chemicals as a basis of oligophagy in Locusta migratoria (L.)

Abstract. (1) One hundred and two plants were offered to locust nymphs after a 5 h period without food. Large meals were only taken on grasses and on Juncus. Most dicotyledons were totally rejected.
(2) All the plants which were relatively unpalatable yielded an extract which reduced the amount eaten, but no inhibition of feeding was induced by extracts of plants which were freely eaten. Very few of the extracts increased the amount eaten.
(3) Over 100 chemicals, mostly non-nutritional, known to occur in leaves, were tested for their inhibitory effect on feeding. Some had no effect, but most progressively inhibited feeding as their concentration was increased until no feeding at all occurred. Chemicals of many classes had this effect, but alkaloids and monoterpenoids were the most consistently deterrent at the lowest concentrations.
(4) It is concluded that the failure to eat most plants results from the presence in the leaves of one or more chemicals in amounts which inhibit feeding. Grasses and a few other plants are readily acceptable because they do not contain deterrent chemicals in sufficient quantity to limit feeding.     

甘肃鼠兔贮草越冬及其生物学意义

对采自草甸、灌丛和弃耕地3 种类型栖息地共27 个甘肃鼠兔草堆的研究结果表明, 每个草堆干重在23.8～984.2 g 之间, 平均184.2 g , 总计含有26 种双子叶植物和一些禾本科单子叶植物。分析显示, 草堆大小(食物重量) 与栖息地植被类型无关。在贮存干草堆时, 甘肃鼠兔对不同植物成分具有强烈的选择性, 其中, 单子叶植物和双子叶植物分别占总重量的8.06 %和84.61 % , 与它们各自在栖息地中的生物量百分比51.76 %和39.57 %形成鲜明对照。甘肃鼠兔对植物种类的选择性在一定程度上受栖息地植被类型的影响, 但最喜食的几种植物却基本不变, 它们是美丽风毛菊、棘豆、麻花艽、禾草、线叶龙胆。人工去除栖息地中的干草堆后, 甘肃鼠兔种群越冬存活率从对照样地的51.84 %下降到21.33 % , 表明草堆食物对其成功越冬有一定正效应。野外观察证实, 甘肃鼠兔的鸣声不及同域分布的高原鼠兔发达, 但前者具有贮存食物越冬的习性, 而后者却不贮存越冬食物, 此结果不支持“鼠兔类动物建立草堆的行为与鸣声行为平行发育”的观点。     

The relationship between plant acceptability and suitability for survival and development of the polyphagous grasshopper,Schistocerca americana (Orthoptera: Acrididae)

The feeding behavior of final-instar nymphs ofSchistocerca americana was observed when they first encountered plants that ranged in acceptability from being eaten in large amounts to not being eaten at all. Growth and survival on the same plants through the last stadium were also studied and the results combined as a suitability index to facilitate comparison with the behavior. Although the plants that were eaten most gave the highest suitability index and those that were not eaten permitted no survival, there was no simple relationship between the amounts eaten and the suitability for growth and survival. The possibility that the insects might become habituated to plants that were initially unacceptable was investigated, but no habituation was found over a 3-day period. It is suggested that food intake is largely determined by the presence of deterrent compounds in the less acceptable foods and that nutritional differences between the plants are likely to have been of minor importance. The behavior on some foods suggests that food aversion learning may be involved. It is concluded that the variability of the insects' behavior makes it impossible to predict the suitability of a plant from their immediate behavioral responses. In the field, insects may sometimes reject foods that would be suitable for survival and development, and feed on plants that are nutritionally deficient or even toxic.     

The Susceptibility of Monocotyledons to Agrobacterium tumefaciens

The susceptibility of 257 monocotyledon species belonging to 139 genera and 27 families, has been tested and the literature on this subject reviewed. In contrast with dicotyledons and gymnosperms, monocotyledons are much less susceptible to Agrobacterium tumefaciens: only 3 % of the species of monocotyledons tested were host plants, whereas 60 % of the dicotyledons and gymnosperms were susceptible. Only the closely related monocotyledon orders Liliales (6 families) and Arales (1 family) contained species that were susceptible. These results are consistent with a proposed taxonomic relationship between the Liliales and the dicotyledons. A correlation between host biochemical capabilities and susceptibility to crown gall is suggested.     

Response of plants to calcium concentration in flowing solution culture with chloride or sulphate as the counter-ion

Summary Solution calcium concentrations required for the growth of a range of plant species, including both monocotyledons and dicotyledons, were determined in two experiments in which plants were grown in flowing solution culture at constantly maintained calcium concentrations ranging from 0.5 to 3000 μM. Calcium chloride was used as the calcium source in the first experiment, calcium sulphate was used in the second. At calcium concentrations of 10 μM and below, all species developed calcium deficiency symptoms. The severity of the deficiency was more pronounced in the dicotyledons than in the monocotyledons. However, cassava was much more tolerant than all other dicotyledons and equally as tolerant as rice, the most tolerant monocotyledon. Solution calcium concentrations required for 90% of maximum yield were generally lower for monocotyledons (3 to 20 μM) than for dicotyledons (7 to 720μM) when calcium chloride was used as the calcium source. When calcium sulphate was used, 7 out of 11 species, including 3 monocotyledons, required external calcium concentrations of 1200 μM and above. The results are discussed in relation to effects of solution composition and the choice of counter-ions on plant response to calcium and other macronutrient cations. It is concluded that yield depressions due to toxicity of excesses of chloride, and possibly other counter-ions, can lead to serious underestimation of limiting external cation concentrations for plant growth.     

Feeding ecology of mandrills (Mandrillus sphinx) in campo animal reserve,Cameroon

A field study on the ecology of mandrills (Mandrillus sphinx) was carried out for 28 months in Cameroon. Fresh food remnants and large quantities of fresh feces were collected by following the groups. Analyses of these products indicated that fruit (including seeds), monocotyledonous plant leaves and insects (especially ants and termites), were frequently eaten. Mandrills mostly ate the plant and animal foods in the lower forest stratum and on the ground. Fallen seeds and monocotyledonous plant leaves were eaten more frequently in the minor fruiting season than in the major fruiting season presumably to compensate for the shortage of fresh fruit during the former. Daily travel distances were shorter during the minor fruiting season than during the major fruiting season, because in the minor fruiting season mandrills forage for small food items, such as the new leaves and piths of monocotyledons and fallen seeds which are sparsely distributed on the ground, while in the major fruiting season they search for widely distributed food such as fruit. The daily pattern of group movement and a food intake experiment suggest that mandrills move and feed continuously throughout the day. Use of fallen seeds and monocotyledonous plant leaves appears to enable mandrills to maintain a terrestrial life in the tropical rain forest. The feeding and ranging characteristics of mandrills are basically similar to those of other baboon species in open land, though their environments differ extremely.     

Factors restricting the feeding of the cabbage stem flea beetle (Psylliodes chrysocephala)

The feeding acceptability of 40 different plants to Psylliodes chrysocephala L. (Coleoptera: Chrysomelidae) was determined using leaf disc consumption tests for the adult, and stem or petiole penetration tests for the larvae. Only plants that contained glucosinolates were accepted as food, but addition of the glucosinolate sinigrin to rejected food plants did not make them acceptable to adults. Of the 34 plants that contained glucosinolates, nine were either totally or mostly rejected. Solvent extracts of the rejected plants applied to oilseed rape inhibited feeding by adults. The feeding of P. chrysocephala within the group of plants tested is influenced by the presence or absence of glucosinolates, which may act as feeding stimulants, and other, unidentified chemicals which act as feeding inhibitors.     

Factors' governing ingestion by the earthworm Lumbricus terrestris (L.), with special reference to apple leaves

Captive worms fed little on fresh apple leaves, but did so readily after the leaves had been leached in water. This was due to their being soft and easy to fragment and not to loss of unpalatable substances during the leaching process. A simple apparatus to measure leaf texture is described. Worm feeding rates were similar for leaves of similar texture but of different phenolic content. Filter paper was accepted as food. The addition of leaf leachates to filter paper disks increased feeding rates, so did added bacterial cells. The part played by leaf micro-organisms in the nutrition of worms and their effect on leaf texture is discussed. Unsoftened leaf material was readily eaten provided it was small enough to be swallowed whole. Leaves from various aromatic plants were eaten by starved worms, but rejected by well-fed ones. Starved worms given aromatic leaf material together with apple leaf preferred the latter. Various unusual materials were eaten, but polyester foam was accepted only when coated with bacterial cells. Responses to chemical as well as to tactile stimuli seem to be involved.     

THE VASCULAR SYSTEM OF THE INFLORESCENCE AXIS OF ANDROPOGON GERARDII (GRAMINEAE) AND ITS BEARING ON CONCEPTS OF MONOCOTYLEDON VASCULAR TISSUE

The vascular bundles in the inflorescence axis of Andropogon gerardii occur in inner and outer systems. The inner system is made up of large, early developing strands that, at earliest stages of development, are precocious (= the appendage they are to serve has not yet been initiated). The outer system consists of later developing smaller strands that are open ended in a proximal direction (= strands differentiate basipetally in the cortex below the appendage they serve). Bundles of both the inner and outer systems are not connected to other procambium early in their development but exist as isolated strands. The veins of the inner system of the inflorescence axis occur as sympodia. The presence of inner and outer systems in the vascular tissue is common to most monocotyledons. However, amongst monocotyledons, only certain grasses have been shown to have strands of the inner system that are isolated early in development. Many dicotyledons have large strands which are precocious and some have smaller, later developing strands which are open ended in a proximal direction, hence they occur as isolated strands. These smaller strands in dicotyledons occur between large strands. Certain dicotyledons have an inner and an outer system of veins. Of these, some have veins of the inner system that differ from the inner system bundles of monocotyledons in that they also form part of the outer system of veins, or develop at a different time. One other dicotyledon with an inner and outer system, Bougainvillea, differs from monocotyledons only in that the bundles of the outer system do not seem to be isolated early in their development and anastomoses are seen between the inner and outer systems. Thus, it appears that monocotyledons differ from dicotyledons only in the presence of independent inner and outer systems of vascular bundles in the former. Thus, the hypothesis of Zimmermann and Tomlinson that there are basic differences between monocotyledon and dicotyledon vascular systems is not substantiated. It is even suspected that monocotyledon and dicotyledon vascular systems will be demonstrated to be modifications of a basic plan consisting of large, acropetally differentiating and smaller, basipetally differentiating strands.     

FOOD PREFERENCES OF BLACK RHINOCEROS IN THE TSAVO NATIONAL PARK

Food preferences of the black rhinoceros population in Tsavo National Park, Kenya were studied from 1967 to 1969. Feeding rhinoceros were watched for a period of 1 h, and the plants which they selected and rejected were identified, either as they were feeding or when they had moved on. A technique was used which provided an indication of the relative importance of certain plants in the diet during the wet and dry seasons. A total of 70 h was spent actually watching feeding rhinoceros in six habitat types representative of the changing ecosystem; 3,600 feeding stations were examined. Black rhinoceros were observed eating 102 species from 32 botanical families. In all habitat types the rhinoceros is very selective for herbs and shrubs, and shows a marked preference for legumes. Available grasses are very rarely eaten. Results of food preference studies in other areas of East Africa are compared with the present study. It is suggested that the abundance and distribution of certain kinds of leguminose flora may be the key to an optimum black rhinoceros habitat.     

Diet of wild chimpanzees (Pan troglodytes verus) at Mt. Assirik,Senegal: I. Composition

The composition of the diet of a savanna-living population of wild chimpanzees (Pan troglodytes verus) at Mt. Assirik in Senegal is presented. The study site had a prolonged dry season, high temperatures, and vegetation dominated by grasses. Data came from direct observation, fecal specimens, and feeding traces; thus, strict criteria for acceptance of the indirect data were specified. Composition of diet was given in terms of species and family of prey, parts eaten, life-form, type of habitat, and criteria for inclusion. Forty-three species of plants with 60 parts were eaten; mostly fruits, from trees, in woodland. Nine species of animal prey were eaten, mostly social insects. An additional 41 species of plants with 53 parts were classed as likely to be eaten by chimpanzees, mostly on the grounds of their being eaten by sympatric anthropoids. Overall, the diet of the apes at Mt. Assirik resembles that of this species elsewhere in Africa, but the size of the dietary repertoire seems small and the proportion of low-quality foodstuffs high. The latter are mostly time-consuming to collect or tedious to obtain or process, and include underground storage organs.     

Food preferences of an insular population of Rattus rattus

The food preferences of an insular population of Rattus rattus inhabiting colonies of the Short-tailed shearwater Puffinus tenuirostris are described from results obtained during analyses of stomach contents and droppings collected from Big Green Island, Furneaux Group, Tasmania. It was found that rats on the island maintained themselves by eating a predominantly vegetarian diet and results suggest that there was some selective feeding on monocotyledons rather than the dicotyledons present in the area. Green parts of plants were taken throughout the year and rats may select these as a water source during the summer months. Plants made up 77.2% of the 254 stomach contents analysed and of this 57.7% was green material. Insect remains were found in 24.8% of the 1400 droppings examined and made up 14.3% of the stomach contents. Few feathers of the shearwater Puffinus tenuirostris were found in the stomachs or droppings and preliminary behavioural experiments suggested that the rat does not actively predate the bird though it may remove unattended eggs and eat dead chicks.     

Divergence in larval responses to food plants between temperate and tropical populations of the black swallowtail butterfly

ABSTRACT.

• 1 Larvae of the black swallowtail butterfly, Papilio polyxenes Fabr., from New York and Costa Rica were reared under the same environmental conditions on Daucus carota L. and Spananthe paniculata Jacq. (Umbelliferae), which are the host plants most commonly used by the two populations, respectively. Feeding rates, growth rates and feeding efficiencies of the fifth instar larvae were measured by standard techniques.
• 2 Larvae from each population grew faster on the host-plant species from their region of origin than did larvae from the other population, though differences on S.paniculata were not significant. On D.carota the faster growth by New York larvae was attributable to greater efficiency. On S.paniculata, by contrast, the somewhat faster growth by Costa Rican larvae seemed to have resulted chiefly from faster feeding. The two populations have thus come to differ in metabolic and, probably, behavioural responses to host plants.
• 3 S.paniculata was a superior host plant for larvae of both populations, even though the total energy, nitrogen and water content of its foliage was similar to that of D.carota.
• 4 These results are consistent with the hypothesis that insects in the two populations have diverged in adaptation to their host plants following curtailment of gene flow between them as the species colonized Central America from the north.

     

How oilseed rape (Brassica napus) genotype influences pollen beetle (Meligethes aeneus) oviposition

Oviposition of phytophagous insects is determined either by adaptive behaviours allowing evaluation and response to host plant quality and/or by nutritional constraints occurring during oogenesis. Besides differences found among host plant species, plant intraspecific diversity can also affect insect oviposition. However, to date few studies have extensively investigated the factors accounting for the effect of this intraspecific variation. We addressed this question using oilseed rape (Brassica napus) and the pollen beetle (Meligethes aeneus), a phytophagous insect that uses the same plants and plant organs both for feeding and laying eggs. Our objectives were to test for a genotypic effect of oilseed rape on pollen beetle oviposition and identify the origin of the possible intergenotypic differences. We tested three hypotheses: oviposition is directly linked to (1) the amount of food eaten; (2) the nutritional quality of the food eaten; (3) a preference of females for certain plant genotypes. Results showed intergenotypic differences in both the number and the size of eggs laid. The factor that best accounted for most of these differences was the amount of food eaten. Nutritional quality of the pollen was of minor importance and females exhibited no preference among genotypes. These results reveal the importance of adult feeding on subsequent oviposition in phytophagous insects, an often neglected factor which partly determines the amount of energy available for oogenesis. Taking into account this factor may be of crucial importance in studies conducted on synovogenic insect species feeding on the same plant on which they lay eggs.     

Food preferences of Shorelarks Eremophila alpestris,Snow Buntings Plectrophenax nivalis and Twites Carduelis flavirostris wintering in the Wadden Sea

Capsule Seeds of plants from lower salt marsh communities are preferred, with insects less important.

Methods Droppings of Shorelarks Eremophila alpestris, Snow Buntings Plectrophenax nivalis and Twites Carduelis flavirostris sampled in the German Wadden Sea were analysed and compared with food abundance to assess preferences.

Results Shorelarks prefer seeds of Salicornia sp., Suaeda maritima, Atriplex sp., Halimione portulacoides and unidentified small grass seeds. Insects are eaten mainly in periods of seed shortage, but are consumed in smaller amounts during the winter. The food composition of Snow Buntings is very similar, but additionally Triglochin maritimum is commonly eaten. Twites are specialized on seeds of Salicornia sp. and Suaeda maritima and rarely ingest other seeds and insects. All seeds consumed were of plants from lower salt marsh communities. Many halophyte seeds, and especially those that birds feed on, are rich in energy. Large seeds and those which need a long handling time are avoided.

Conclusion Changes in the lower salt marshes of the Wadden Sea by embankments and intensified grazing might have been responsible for the rapid population decline from the 1960s to 1980s.     

Spittlebug indicators of nitrogen-fixing plants

Abstract.

• 1 Spittlebugs (Homoptera: Cercopoidea) are preferentially associated with nitrogen-fixing angiosperms. Generally, the Aphrophoridae associate with legumes, the Clastopteridae with actinorhizal plants, and the Cercopidae with associative nitrogen-fixing grasses. This is the first reported insect—host association specific to nitrogen-fixing plants.
• 2 It is probable that spittlebugs are attracted to nitrogen-fixing plants because these hosts provide a relatively rich, reliable source of organic nitrogen compounds for xylem-sucking insects.
• 3 Many spittlebugs live on plants that do not fix nitrogen, and ecological, mechanical or chemical factors may bar some spittlebugs from otherwise suitable nitrogen-fixing plants.
• 4 Among nitrogen-fixing hosts, spittlebugs appear to prefer plants that transport fixed nitrogen as amino acids and amides to plants that transport fixed nitrogen as ureides.

     

Plant feeding site selection on soybean by the facultatively phytophagous predator Orius insidiosus

Experiments were conducted to test whether the facultatively phytophagous predator Orius insidiosus (Say) (Heteroptera: Anthocoridae) ingested phloem, xylem or mesophyll contents from soybean plants (Glycine max L.). Potential uptake of phloem sap was examined by radiolabeling photosynthate with ¹⁴CO₂ and then measuring the accumulation of radiolabeled metabolites in feeding animals. Most O. insidiosus feeding on radiolabeled plants ingested no or very low levels of label; only 3% ingested small amounts of label, indicating the experimental insects fed very little, if at all, on the phloem. In contrast, well known phloem feeding insects used as positive controls accumulated substantial levels of labeled metabolites after feeding on known host plants. O. insidiosus did feed on xylem contents, as shown by ingestion of safranin-labeled xylem fluid. A few of the insects showed signs of feeding on the mesophyll, as indicated by the presence of chloroplasts in the gut. However, the small diameter of the food canal may cause limited passage of chloroplasts, which would contribute to an underestimation of the frequency of mesophyll feeding. Some radiolabeled metabolites remain in the mesophyll so those insects that ingested low levels of radiolabel probably ingested label from the mesophyll, which supports the notion that some level of mesophyll feeding occurred. Feeding site determines the nutrients ingested during phytophagy. These insects obtain water from the xylem, and may ingest small amounts of starches, sugars, and amino acids from the mesophyll. The results suggest that facultative phytophagy by this heteropteran predator primarily provides the insect with water, but also may provide some nutrients that supplement a prey diet and help the predator survive periods when prey are scarce.     

THE FEEDING HABITS OF THE WHITEWINGED BLACK TERN ON LAKE KARIBA

Bego, G. W. 1973. The feeding habits of the Whitewinged Black Tern on Lake Kariba. Ostrich 44: 149–153.

The stomach contents of 33 Whitewinged Black Terns were examined over the period 26 August 1971 to 6 January 1972. The most important single food item was the sardine, Limnothrissa miodon. This sheds new light on the habits of this fish. The terns fed primarily during calm weather. Sardines are caught by hovering and diving. Fishes of the genera Haplochromis and Synodonlis, also appeared in the stomach contents. Terns taken from marginal localities appear not to feed on fish. Of the insects eaten Odonata are the most important aquatic source of food, while many terrestrial insects are eaten (Orthoptera, Hemiptera, Coleoptera, Isoptera). Such insects could have been found drifting on mats of Salvinia on which the terns rest, otherwise insects are either hawked or skimmed from the surface of the water.     

Plant feeding of yellow baboons (Papio cynocephalus) in Mikumi national park,Tanzania, and the relationship between seasonal feeding and immature survival

Focal-animal feeding data obtained from 64 adult baboons during a 3-year period were used together with equivalent data from 46 infants to evaluate hypotheses predicting selection for a birth peak and to study the baboon’s eclectic/selective feeding adaptation, with emphasis on differential feeding by sex, developmental trends, and seasonal use of food classes (fruit, leaf, flower, grass, etc.). The findings suggest that feeding conditions are better in the wet season than in the dry season. Despite large sexual dimorphism, estimates of total amounts eaten were virtually identical for males and females. Infants used all of the same plant-food classes as adults, but proportional differences occurred for some food classes in amounts eaten. Foods eaten proportionately less by infants were probably harder for them to obtain and process or were chosen through inexperience or for exploration. There was considerable between-year variation in amounts of food classes eaten, but the within-year standard deviations were similar, as were also the mean amounts eaten per year. An eclectic/selective feeding adaptation has the advantage of permitting long-run acquisition of adequate nutrition within a context of high feeding variation from season to season and year to year. Mixed results were obtained from hypotheses about selection for a birth peak. Although a peak occurred in the early dry season, this was not the optimal time of birth for survival. Survival was highest for individuals born in the late wet season, when the availability and probably the quality of food for lactating mothers were greatest.     

Feeding preferences of Melanoplus femurrubrum grasshoppers on native and exotic grasses: behavioral and molecular approaches

Generalist insect herbivores, such as grasshoppers, may either avoid feeding on exotic plants, potentially enabling these plants to become invasive in the introduced range, or insects may incorporate exotic plants into their diet, contributing to the biotic resistance of native communities and potentially preventing plant invasions. Accurate determination of insect diet preferences with regard to native and exotic plants can be challenging, but this information is critical for understanding the interaction between native herbivores and exotic plants, and ultimately the mechanisms underlying plant invasions. To address this, we combined behavioral and molecular approaches to accurately compare food consumption of the polyphagous red‐legged grasshopper, Melanoplus femurrubrum (De Geer) (Orthoptera: Acrididae), on native [Andropogon gerardii Vitman and Bouteloua curtipendula (Michx.) Torr.] and exotic, potentially invasive grasses [Miscanthus sinensis Andersson and Bothriochloa ischaemum (L.) Keng] (all Poaceae). We found that M. femurrubrum grasshoppers demonstrated strong feeding preferences toward exotic grasses in experiments with intact plants under both field and greenhouse conditions, but they showed no preference in experiments with clipped leaves. Additionally, we sampled the gut contents of M. femurrubrum collected in the field and identified the ingested plant species based on DNA sequences for the non‐coding region of the chloroplast trnL (UAA) gene. We found that exotic plants were prevalent in the gut contents of grasshoppers collected at study sites in Ohio and Maryland, USA. These results suggest that the generalist herbivore M. femurrubrum does not avoid feeding on exotic grasses with which they do not share coevolutionary history. In addition, by demonstrating greater food consumption of exotic plants, these grasshoppers potentially provide biotic resistance should these grasses escape cultivation and become invasive in the introduced range.