Competition and coexistence in a small carnivore guild

The potential for strong competition among small sympatric carnivores results in a need for coexistence strategies whereby competitors partition along spatial, temporal and dietary axes as a means to reduce ecological overlaps. We determined spatial and temporal partitioning patterns of a guild of small African carnivores: the African wildcat Felis silvestris lybica, grey mongoose Galerella pulverulenta, small-spotted genet Genetta genetta, striped polecat Ictonyx striatus, and the yellow mongoose Cynictis penicillata. We quantified the degree of spatial and temporal co-occurrence of the small carnivores using camera trap data over a year-long period. Carnivores separated into two temporal groups: nocturnal species (wildcat, polecat and genet) and diurnal species (mongooses). In addition, carnivores within the same temporal group had strong patterns of reduced spatial co-occurrence. The smaller bodied carnivores showed lower co-occurrence with the larger bodied African wildcat than expected by chance, supporting the idea of dominant competitor avoidance. Thus, small carnivores likely minimise competitive interactions through spatio-temporal habitat partitioning.     

Assessing resource and predator effects on habitat use of tropical small carnivores

Habitat use of animals is influenced by a combination of factors including food abundance and interactions with other species. Animals typically must forage while simultaneously avoiding predation from multiple potential predators, but habitat use in tropical forest ecosystems that assesses effects of both predation risk and resources has rarely been conducted. We used camera traps and occupancy analyses to document small mammalian carnivore occurrence in relation to food abundance and interactions with large predators. We hypothesized that habitat use of six small mammalian carnivores (≤15 kg) would be influenced by (1) abundance of resources (fruit, rodents, and streams) and/or (2) large predators. Predictions regarding food and habitat resources were only supported for one species (crab-eating mongoose, Urva urva), which was positively associated with rodents and streams. Three small carnivores (masked palm civet Paguma larvata, common palm civet Paradoxurus hermaphroditus, yellow-throated marten Martes flavigula) were affected negatively by leopard and mesopredators as predicted. Counter to our predictions, two species (masked palm civet and yellow-throated marten) showed spatial avoidance of tiger suggesting that an apex predator might also pose predation risk to small carnivores. The focal small carnivores and large predators of this study appeared to have moderately to highly overlapping temporal activity indicating no temporal avoidance. In conclusion, food resources appeared to have minimal effects for six small carnivores in this ecosystem probably due to continuous resource availability. Predation risk appeared to affect some species in terms of spatial occupancy but not in temporal activity, indicating perhaps complex, but not entirely negative interactions between larger carnivores and this guild of small carnivores. The mechanisms which facilitate co-occurrence between small carnivores and large predators may, however, operate at finer spatiotemporal scales than we investigated here.     

Influence of Fruit Availability on Fruit Consumption in a Generalist Primate,the Rhesus Macaque <Emphasis Type="Italic">Macaca mulatta</Emphasis>

Fluctuations in resource availability occur in all ecosystems. To survive, species must alter their foraging strategies according to the quantity, quality, and distribution of available food. The rhesus macaque (Macaca mulatta), a commensal primate, is considered a generalist omnivore and very few studies have addressed how its feeding strategies change with respect to resource availability. We examined dietary diversity and frugivory levels in a group of rhesus macaques at the Buxa Tiger Reserve in northern India across one year. Using behavioural observations of diet and phenological monitoring, we found that although rhesus macaques fed on 107 food items including leaves, flowers, fruits, seeds, and insects, fruits made up ca. 74% of their diet. Fruit consumption correlated positively with fruit availability, but fruit preference appeared to play an important role; 16% of all the fruit species they fed on accounted for >50% of all fruit feeding observations. We suggest that afforestation programs involving preferred fruit species at the agricultural land–forest interface would prevent forest groups of rhesus macaques from gravitating toward human habitations and reduce conflict over anthropogenic resources. We further propose that the movement of certain primates in the direction of human habitations may be contingent on resource availability and food preference rather than an inherent propensity to gravitate to anthropogenic areas.     

Attractiveness of Different Food Resources to Dung Beetles (Coleoptera: Scarabaeidae) of a Dry Tropical Area

Excrement scarcity is one of the main historical factors leading dung beetles to adapt to other food resources. In the Caatinga, a seasonally tropical dry forest, harsh environmental conditions seem to restrict the availability of food resources. In this scenario, the aim of our study was to experimentally investigate the attractiveness of different potential food resources to these insects in the Caatinga. Field samplings were performed, and we tested five resources in pitfall baited traps: excrement, carrion, fruits of two species of columnar cacti, and seeds of one species of Euphorbiaceae (Jatropha mollissima (Pohl)). In a controlled setting, we tested dietary preferences of Deltochilum verruciferum Felsche by offering one or two resources simultaneously. In the field experiments, 297 dung beetles (9 species) were recovered from the traps, and D. verruciferum was the most abundant species. Carrion and excrement were the most attractive resources. Controlled dietary preference tests with D. verruciferum evidenced that these beetles used all tested food resources, excrement and carrion most pronouncedly. Our findings support copro-necrophagy as the main feeding habit of D. verruciferum, but also suggest that alternative resources might be utilized if preferred resources are scarce.     

Food habits of three carnivore species (Viverricula indica, Herpestes urva, and Melogale moschata) in Fushan Forest, northern Taiwan

The food habits and degrees of dietary overlap of lesser oriental civet ( Viverricula indica ), crab-eating mongoose ( Herpestes urva ), and ferret badger ( Melogale moschata ) inhabiting the Fushan Forest, northern Taiwan, were studied using faecal analysis between February 1993 and June 1994. Laboratory analysis of 154 civet faeces, and 174 mongoose faeces showed that both species fed on a wide variety of food items, including mammals, birds, reptiles, amphibians, fish, crustaceans, insects, oligochaetes, gastropods, chilopods, arachnids, and plants. Insects, oligochaetes, plants, and mammals were the four most important food items in the civets' diet, whereas crustaceans, insects, amphibians, and reptiles were the four most important food items consumed by mongooses. Amphibians were the only vertebrates, together with invertebrates and plants, found in the 64 ferret badger faeces we analysed, and oligochaetes, insects, and amphibians were the most important food items consumed by ferret badgers. The diversity of diet was highest in the mongoose, followed by the civet, and was lowest in the ferret badger.
The degree of dietary overlap was greatest between the civet and the ferret badger, followed by that of the civet and mongoose. The mongoose and ferret badger had the lowest degree of dietary overlap. However, the degree of dietary overlap varied in different seasons. Invertebrates were the most important food source for the carnivores in Fushan Forest.     

Modelling large spotted genet (Genetta tigrina) and slender mongoose (Galerella sanguinea) occupancy in a heterogeneous landscape of South Africa

Drivers of distribution patterns of poorly known species are among the most important aspects in conservation biology. We studied the proportion of area occupied by the large spotted genet (Genetta tigrina) and the slender mongoose (Galerella sanguine) in response to land use variables using camera-trapping data in Drakensberg Midlands, South Africa. Average estimated occupancy of large spotted genet and slender mongoose were 0.42 ± 0.10 and 0.41 ± 0.04 respectively using single season occupancy models. Altitudinal variation was found to be significant in the distribution of both species, along with human abundance for genet and availability of bushland for mongoose. Autumn influenced detection probability of both species negatively, while summer influenced slender mongoose positively. Relative human abundance was positively associated with detection probability of slender mongoose, and for large spotted genet, availability of bushland influenced positively while relative abundance of jackal (Canis mesomelas) influenced negatively. Occurrence of both species suggests that high elevations may not provide favourable ecological conditions, and bush cover appeared to be favourable habitats for both species. Either positive occurrence or detection of small carnivores to human abundance indicated their tendency to subsist in low-lying human populated areas. The present study shows the influence of a range of factors on the distribution of lesser known carnivores.     

Interspecific killing between wolves and golden jackals in Iran

Interspecific killing is a widespread phenomenon among mammalian carnivores; being common, for instance, within the canid guild. The canid guild in Hamadan province, west of Iran, comprises three species: the gray wolf Canis lupus pallipes, the golden jackal Canis aureus, and the red fox Vulpes vulpes. In this area, habitat transformation and agricultural land uses have significantly reduced wild prey populations. In search of food, members of the canid guild are often driven to human settlements. Due to inefficient waste management, the major source of food for canids here is anthropogenic food resources, such as livestock and pet carcasses, and domestic waste illegally dumped near poultry farms and rural areas. Here, we described one of the first reports in the literature of a case of interspecific killing between a wolf and a golden jackal. On June 13, 2016, a collared wolf (adult male) killed an adult jackal (adult male). Further studies are required to understand intraguild competition among red fox, golden jackals, and wolves in this area.     

First results of a study of the feeding habits of <Emphasis Type="Italic">Synodontis</Emphasis><Emphasis Type="Italic">comoensis</Emphasis> (Siluriformes: Mochokidae) in a West African river (Comoé River,Comoé National Park,Côte d’Ivoire)

The feeding habits of Synodontis comoensis (Siluriformes, Mochokidae) have been studied for the first time. Specimens caught in the Comoé River (Comoé National Park, Côte d’Ivoire) had fed on different types of food including insects (Diptera, Ephemeroptera, Hymenoptera, and Isoptera), molluscs (gastropods and bivalves), oligochaetes, and macrophytes. The food items most frequently found in the stomach contents were chironomid larvae, oligochaetes, vegetable detritus, fruit, and gastropods. Correlation studies based on the index of preponderance of food items revealed noticeable variation in S. comoensis diet composition with fish size and season. Preferred food items of young fish were oligochaetes in the rainy season and vegetable detritus in the dry season. Food items preferred by larger fish were fruit and gastropods in the rainy season and chironomid larvae in the dry season.     

Asymmetric competition for nectar between a large nectar thief and a small pollinator: an energetic point of view

There are two alternative hypotheses related to body size and competition for restricted food sources. The first one supposes that larger animals are superior competitors because of their increased feeding abilities, whereas the second one assumes superiority of smaller animals because of their lower food requirements. We examined the relationship between two unrelated species of different size, drinking technique, energy requirements and roles in plant pollination system, to reveal the features of their competitive interaction and mechanisms enabling their co-existence while utilising the same nectar source. We observed diurnal feeding behaviour of the main pollinator, the carpenter bee Xylocopa caffra and a nectar thief, the northern double-collared sunbird Cinnyris reichenowi on 19 clumps of Hypoestes aristata (Acanthaceae) in Bamenda Highlands, Cameroon. For comparative purpose, we established a simplistic model of daily energy expenditure and daily energy intake by both visitor species assuming that they spend all available daytime feeding on H. aristata. We revealed the energetic gain–expenditure balance of the studied visitor species in relation to diurnal changes in nectar quality and quantity. In general, smaller energy requirements and related ability to utilise smaller resources made the main pollinator X. caffra competitively superior to the larger nectar thief C. reichenowi. Nevertheless, sunbirds are endowed with several mechanisms to reduce asymmetry in exploitative competition, such as the use of nectar resources in times of the day when rivals are inactive, aggressive attacks on carpenter bees while defending the nectar plants, and higher speed of nectar consumption.     

Similar dietary but different numerical responses to nonnative tamarisk (<Emphasis Type="Italic">Tamarix</Emphasis> spp.) by two native warblers

Native species can have a range of responses to nonnative introductions, from negative to positive, and understanding how and why native species respond differently to nonnatives remains an important management challenge. Based on differences and similarities in ecology and behavior, we predicted how abundance and diet of two native warblers, Lucy’s warbler (Oreothlypis luciae) and yellow warbler (Setophaga petechia), would differ in habitats with different amounts of nonnative tamarisk trees and the three nonnative insects obligately dependent on tamarisk (Tamarix spp.). Specifically, we predicted that Lucy’s warblers would have similar densities across sites, yellow warbler densities would be inversely related to tamarisk cover, and both warblers, being generalist insectivores, would incorporate tamarisk biocontrol insects in their diet. Based on point counts and fecal samples at six sites along the Virgin River in the southwestern United States, we found that yellow warblers decreased in abundance with increasing tamarisk cover, while Lucy’s warbler abundance did not and that diet of the two warblers did not differ, with both species exhibiting strong selection for the nonnative tamarisk weevil (Coniatus splendidulus) and weak to no selection for the nonnative tamarisk leafhopper (Opsius stactogalus). Both warblers showed negative selection for the tamarisk beetle (Diorhabda carinulata) and its larvae, even when those insects were 10–100 times more abundant during outbreaks. Although both warblers exploited the novel food resources offered by tamarisk, with those insects contributing half or more of total prey biomass, Lucy’s warblers were better able to maintain densities in tamarisk habitats. We hypothesize this was due to the Lucy’s warbler’s ability to exploit a broader array of habitats surrounding tamarisk sites and its cavity nesting habit that buffers its nests from the higher temperatures and lower humidity of tamarisk-dominated habitat. Our results suggest that predictions based on detailed knowledge of the form and function of native and nonnative species can be used to predict native bird response to nonnatives.     

Anthropogenic influences on spotted hyaena diet in the Kruger National Park,South Africa

Rapid urban expansion has led to an increase in carnivores that live close to human dominated environments. Some carnivore species have successfully adapted to these novel conditions and taken advantage of opportunities associated with human habitation. Whilst many studies have compared carnivores living in protected areas to those in an urban setting, few have looked at the relationships between carnivores and human habitation within protected areas. In this study, we examined the effects of human habitation on the diet of spotted hyaenas (Crocuta crocuta) in the Kruger National Park (KNP), South Africa. Our results suggested a limited effect of anthropogenic resources on spotted hyaena diet in the KNP. We found neither temporal nor spatial variation in the amount of, nor types of, anthropogenic material in spotted hyaena scats, despite observations of more road side litter close to large anthropogenic sites. We therefore suggest that anthropogenic resources may not have been utilised completely according to abundance. We encourage further research evaluating potential secondary effects of human activity and infrastructure on spotted hyaena diet and also stable isotope approaches that may provide further insights into the importance of anthropogenic food for spotted hyaenas inside the KNP.     

Diversity,Daily Flight Activity and Temporal Occurrence of Necrophagous Diptera Associated with Decomposing Carcasses in a Semi-Arid Environment

The harsh conditions of the Brazilian seasonally dry tropical forest known as Caatinga pose challenges to the insects specialized in the exploitation of ephemeral resources. We investigated the diversity and daily flight activity of dipterans associated with decomposing rat carcasses in a field experiment performed in the semi-arid region of Pernambuco State, Brazil. We also analyzed the temporal arrival of adult insects on the carcasses at three stages of decomposition: early, intermediate, and advanced. We collected 1173 individuals, of which Muscidae had the highest abundance (36.5%), followed by Sarcophagidae (28.1%), Calliphoridae (25.2%), and Fanniidae (10.2%). Chrysomya albiceps (Wiedemann, 1819) (Calliphoridae), Fannia pusio (Wiedemann, 1830) (Fanniidae), Atherigona orientalis (Schiner, 1868), and Musca domestica (Linnaeus, 1758) (Muscidae) were the most abundant species. The richness reached its maximum value on the second day of decomposition, with 18 species, decreasing to 8 species on the last day of decomposition (7 days). The ecological indices of diversity, dominance, and evenness varied little among the stages. There was an overlap of most species throughout the decomposition, although the overall abundance was higher at the intermediate stage for Calliphoridae, Muscidae, and Sarcophagidae. In accordance to previous studies, nocturnal flight was rare, as approximately 8% of insects were captured at night. Our results expand the knowledge on ecological and behavioral aspects of necrophagous flies under inhospitable environments, such as the dry season in the Caatinga. The dominance of the invasive species C. albiceps reinforced here illustrates its geographical expansion towards the countryside of Northeastern Brazil.     

Slow Lorises (<Emphasis Type="Italic">Nycticebus</Emphasis> spp.) Really Are Slow: a Study of Food Passage Rates

The characteristics of food ingested by a primate affect its assimilation of energy by modulating food passage rate. In general, digestive time increases in folivorous primates and decreases in frugivorous primates when they are fed higher fiber diets but this relationship is understudied in exudativorous primates. We compared the food passage rate of five slow loris species. We studied 34 wild-caught slow lorises (15 Nycticebus coucang, 15 N. javanicus, and 4 N. menegensis) in an Indonesian rescue center and four captive-born slow lorises (2 N. bengalensis and 2 N. pygmaeus) in a UK institution. We fed the Indonesian subjects two different diets: a captive-type diet comprising fruits, vegetables, and insects and a wild-type diet formulated to be similar in nutrients to that consumed by slow lorises in the wild, consisting of gum, insects, vegetables, and nectar. We fed the UK subjects a diet of gum, vegetables, insects, and hard-boiled eggs. We formulated this diet to mimic the wild diet, with notably higher fiber fractions and lower soluble sugars than the previous diet. We measured two variables: the transit time (TT) and the mean retention time (MRT). We mixed 1 tsp. of glitter in bananas or gum as our markers and fed them to the slow lorises immediately before their main diet. We noted the date and time of feeding and of appearances of the marker in feces. We weighed food given and left over for each individual to calculate ingested foods and nutrients. We found that TTs were not affected by diet treatment but MRTs were significantly longer for all species fed the wild-type diet. Our results show that Nycticebus spp. have long MRTs for their body weight, and N. pygmdaeus may have the slowest MRT of all primates in relation to body mass. The digestive flexibility of exudativorous primates should allow them to maximize fermentation opportunities when they ingest more (appropriate) fiber by increasing the amount of time the fiber substrate stays in the large intestine. Exudativorous primates appear to have plastic digestive strategies that may be an adaptation to cope with relatively nutrient-poor staple food sources such as gum. The provision of gum in a captive setting may therefore provide benefits for gut health in slow lorises.     

Could the ‘vulture restaurants’ be a lifeboat for the recently rediscovered bone-skippers (Diptera: Piophilidae)?

The European bone-skippers Thyreophora cynophila and Centrophlebomyia furcata (Diptera: Piophilidae) had been considered as globally extinct or extinct in Europe, respectively, until their recent rediscovery in Spain. Improved hygienic conditions in livestock management and disposal of large carcasses (the preferred breeding sites for the bone-skippers) have been implicated as the main cause for their disappearance. The decline of many European avian scavenger populations in the last centuries has also been attributed to the same cause, which has promoted the creation of the commonly named ‘vulture restaurants’. Although these supplementary feeding stations are important to support scavenging bird populations, the present work demonstrates that they provide a guaranteed supply of food for rare necrophagous species like the European bone-skippers which have recently been rediscovered.     

Is the maximum reproductive rate of <Emphasis Type="Italic">Centris analis</Emphasis> (Hymenoptera,Apidae, Centridini) associated with floral resource availability?

Spatiotemporal variation in the availability of food resources may be a determining factor for reproductive success and maintenance of bees, but the extent of these variations is poorly understood. For management and conservation of bees, the first step is to know the behavior and the food resources used. Currently, urban areas are considered refuge zones for bees, and understanding the availability of floral resources and the influence on reproductive processes is very important for management of bees. We used the protocols applied in phenological studies with bees and plant species to evaluate both throughout the year in an urbanized area. At the same time, we used palynology protocols to analyze the pollen material collected from brood cells (food and feces) of immature Centris analis. These protocols allowed to evaluate the availability of floral resources in the studied area and the plant species effectively used by C. analis females to feed immature larvae during the reproductive period. The maximum reproductive period of C. analis was not associated with the highest floral resources availability. However, there was a strong selectivity of pollen in flowers of Malpighia emarginata (Malpighiaceae), which represented more than 59% of all the pollen grains provisioned throughout the year. This means that in the case of more specialized bees like C. analis, the availability of the preferred plants is more important than the overall floral resource availability in the area. Thus, to keep C. analis in the city, it is necessary to maintain or introduce Malpighiaceae species in the urban planning. On the other hand, at least 27% of the plant species found in the study area are pollinated by C. analis, emphasizing the importance of preserving this bee.     

Trophic niches and feeding relationships of shorebirds in southern Brazil

Niche theory predicts that sympatric species should differ in some ecological characteristic, to allow co-existence and reduce competition for key resources. Food is critical on wintering grounds and stopover areas for migratory species that need to accumulate reserves in order to complete their migration. Wetlands of the Rio Grande do Sul coastal plain, in southern Brazil, host several species of shorebirds with similar morphology, foraging methods and diet. When these species are in sympatry, some trophic niche overlap is expected. Diets and trophic niches of migratory and resident shorebirds were investigated during the austral summer on Torotama Island, Lagoa dos Patos Estuary, Brazil. Complementary methods were used to determine the trophic ecology of three shorebird species; diet was determined through analysis of feces and food samples, using stable isotopes of carbon and nitrogen. The local invertebrate community was sampled to determine potential prey and ascertain feeding preferences of birds. Coleoptera was the most abundant taxon in the feces of all shorebirds. Trophic niche overlap in the diets was high, with the widest trophic niche found for the buff-breasted sandpiper Calidris subruficollis. Isotopic mixing models indicated differences in the main food sources of shorebirds. The isotopic niche breadth was widest for the American golden-plover Pluvialis dominica. These species, as well as the resident southern lapwing Vanellus chilensis, consumed some prey in higher proportions over others, although they had generalist diets. Migratory species with generalist habits benefit from heterogeneous environments such as floodplains during the non-breeding season.     

Trophic Facilitation or Limitation? Comparative Effects of Pumas and Black Bears on the Scavenger Community

Scavenging is a widespread behaviour and an important process influencing food webs and ecological communities. Large carnivores facilitate the movement of energy across trophic levels through the scavenging and decomposition of their killed prey, but competition with large carnivores is also likely to constrain acquisition of carrion by scavengers. We used an experimental approach based on motion-triggered video cameras at black-tailed deer (Odocoileus hemionus columbianus) carcasses to measure the comparative influences of two large carnivores in the facilitation and limitation of carrion acquisition by scavengers. We found that pumas (Puma concolor) and black bears (Ursus americanus) had different effects on their ecological communities. Pumas, as a top-level predator, facilitated the consumption of carrion by scavengers, despite significantly reducing their observed sum feeding times (165.7 min±21.2 SE at puma kills 264.3 min±30.1 SE at control carcasses). In contrast, black bears, as the dominant scavenger in the system, limited consumption of carrion by scavengers as evidenced by the observed reduction of scavenger species richness recorded at carcasses where they were present (mean = 2.33±0.28 SE), compared to where they were absent (mean = 3.28±0.23 SE). Black bears also had large negative effects on scavenger sum feeding times (88.5 min±19.8 SE at carcasses where bears were present, 372.3 min±50.0 SE at carcasses where bears were absent). In addition, we found that pumas and black bears both increased the nestedness (a higher level of order among species present) of the scavenger community. Our results suggest that scavengers have species-specific adaptions to exploit carrion despite large carnivores, and that large carnivores influence the structure and composition of scavenger communities. The interactions between large carnivores and scavengers should be considered in future studies of food webs and ecological communities.     

Capture of large prey and feeding priority in the cooperative pseudoscorpion <Emphasis Type="Italic">Paratemnoides nidificator</Emphasis>

The social pseudoscorpion Paratemnoides nidificator is a common species in the Brazilian tropical savannah (Cerrado), where colonies are found under the bark of trees. In this environment, colonies hunt for large insects, subduing them by cooperative effort. Small insects are offered as food to nymphs, but large prey tends to be shared by colony members. We investigated the cooperative capture of large prey (Scarabaeidae beetles) by colonies of P. nidificator. During this process, some adults are involved in the immobilization and killing of prey. However, other adults stay as profiteers and do not offer help to subdue the prey. After prey immobilization, pseudoscorpions perform a hierarchical food share in which the attackers begin sucking the prey. These individuals favor the nymphs, offering them the prey and protection during feeding. Profiteer individuals are the last to feed on the carcass. In P. nidificator, obligatory parental care probably favors the evolution of behavioral strategies that prioritize the feeding of juveniles. This mechanism can provide better-quality food for the attackers but offers food to all colony members.     

Difference in parenting in two species of burying beetle, <Emphasis Type="Italic">Nicrophorus orbicollis</Emphasis> and <Emphasis Type="Italic">Nicrophorus vespilloides</Emphasis>

Burying beetles (Nicrophorus) are model parents among insects, with all studied species known to regurgitate flesh from vertebrate carcasses to their offspring. However, most studies focus on a very few species, yet the interpretation of the function and importance of care is typically generalized to all burying beetles. Here we characterize subtle variation within and between individuals and sexes, and how this variation differs between two species of burying beetle. We find that Nicrophorus orbicollis exhibits low variance, with a normal distribution of parental care provided during peak care periods. In N. vespilloides, however, the distribution is more uniform as values of care are spread across the possible phenotypic spectrum. This suggests that there is stabilizing selection on care in N. orbicollis, but relaxed or disruptive selection in N. vespilloides. Although repeatability was similar between both species, transitions from other care behaviors into feeding were more common in N. orbicollis than N. vespilloides. Thus, while parenting is coarsely similar across the genus, variation in its expression should not be extrapolated to all Nicrophorus. We suggest that subtle variation both within and among species merits greater attention, and could inform us about the factors that lead to different distributions of care.     

Feeding preferences and performance of an aquatic lepidopteran on macrophytes: plant hosts as food and habitat

Although host preferences in phytophagous insects may be generated by several factors, few studies have simultaneously examined several potential host choice determinants. In this study we tested the impact of the following potential host choice determinants on host preference of the semi-aquatic lepidopteran Munroessa gyralis (Pyralidae): growth on different host plants; protein content, polyphenolic content, toughness, and chemical extracts of different host plants; prior feeding experience; and predation pressure on the caterpillar by fishes. Two water lilies, Brasenia schreberi and Nymphaea odorata, were preferred in cafeteria-style feeding experiments over 14 other species of vascular plants. The most preferred water lily (Brasenia) also afforded the fastest growth relative to three other species on which growth was measured. Feeding preferences across species were unrelated to protein content, polyphenolic content, or toughness. Domiciles constructed by caterpillars from leaf fragments were protective from field assemblages of fishes, but domiciles made from preferred or unpreferred host species conferred no significant protection from fish in the laboratory. Caterpillars responded positively to chemical cues of water lilies, and prior feeding experience increased preference for an otherwise unpreferred water lily (Nuphar advena) within the life-span of individual caterpillars. M. gyralis is a generalist herbivore exhibiting modest preference induction and preferences for and among members of the family Nymphaeaceae. Our results suggest that relative growth rates, chemical cues, and previous feeding experience are important factors determining feeding preference. Protein content, polyphenolic content, and toughness appear less important, and the importance of fish predators remains in question. As pupation seems to occur exclusively on Nymphaea, we suggest that host use may be restricted due to life-stage-specific developmental constraints that are not apparent from the results of growth or preference assays. It is currently unknown how often specific life-stages may restrict host use, but our work suggests this as a potentially important area of inquiry.