Does diet breadth control herbivorous insect distribution size? Life history and resource outlets for specialist butterflies

Although butterfly distributions are known to be positively correlated with the number of larval hostplants used it is not known to what extent larval hostplant number uniquely influences butterfly distributions and to what extent effects are indirect through other variables. This issue is central to understanding the part generalism and specialism in host use play in organism persistence and conservation. Here, we have modelled the links between larval hostplant number and butterfly distributions using data from the UK. The model identifies the key variables that connect number of hostplants used by butterflies and the size of butterfly distributions. Significant correlations between variables give support to the model. Access to more hostplants is shown to affect a number of resource and life history variables impinging on butterfly population abundances and butterfly distributions. Butterfly distributions are largely accounted for (R²>81%) by a set of resource and life history variables linked to numbers of hostplants: biotope occupancy, nectar sources used, utilities (the number of structures used by each life-cycle stage) and hostplant abundance. Application of partial regression demonstrates that the unique contribution of hostplant number to butterfly distributions is relatively small (R² = 14% to 33%), indicating that host use generalism has a limited direct impact on distributions. The modest correlations linking variables within the model illustrates that specialist phytophage feeders have a number of potential, distinct outlets, via resource and life history variables, to compensate for lack of supplementary larval hosts within their geographical ranges and enabling them to persist. Variables in the model each have considerable independence of action; without this, specialist feeders would have difficulty in expanding their distributions and acquiring new hosts, functionally-linked processes affecting evolutionary dynamics and persistence. We also question the nature of a direct functional link between local population abundance and distributions. Our model suggests a more complex functional relationship with implications for conserving insect herbivores.     

Nectar and hostplant scarcity limit populations of an endangered Oregon butterfly

As grassland habitats become degraded, declines in juvenile and adult food resources may limit populations of rare insects. Fender's blue butterfly (Icaricia icarioides fenderi), a species proposed for listing as endangered under the US Endangered Species Act, survives in remnants of upland prairie in western Oregon. We investigated the effects of limited larval hostplants and adult nectar sources on butterfly population size at four sites that encompass a range of resource densities. We used coarse and detailed estimates of resource abundance to test hypotheses relating resource quantity to population size. Coarse estimates of resources (percent cover of hostplant and density of nectar flowers) suggest that butterfly population size is not associated with resource availability. However, more detailed estimates of resources (density of hostplant leaves and quantity of nectar from native nectar sources) suggest that butterfly population size is strongly associated with resource availability. The results of this study suggest that restoring degraded habitat by augmenting adult and larval resources will play an important role in managing populations of this rare butterfly. Received: 20 June 1998 / Accepted: 25 November 1998     

The scale of resource specialization and the distribution and abundance of lycaenid butterflies

Numerous hypotheses have been proposed for the commonly observed, positive relationship between local abundance and geographic distribution in groups of closely related species. Here I consider how hostplant specialization and abundance affect the relative abundance and distribution of lycaenid butterflies (Lepidoptera: Lycaenidae). I first discuss three components of specialization: local specialization, turnover of specialization across a species’ range, and the minimum number of resources (or habitats) required by a species. Within this framework, I then consider one dimension of a lycaenid species’ niche, larval hostplant specialization. In a subalpine region of Colorado, I surveyed 11 lycaenid species and their hostplants at 17 sites. I compare this local information to continental hostplant use and large-scale distributions of the lycaenids and their hostplants. Local abundance of a lycaenid species is positively correlated with its local distribution (the number of sites occupied), but not with its regional or continental distribution. Neither local specialization (the number of hostplants used within one habitat) nor continental specialization (the number of hostplants used across many habitats) is correlated with local lycaenid abundance. Continental specialization is positively correlated with a species’ continental distribution, however. Finally, while generalist butterflies tend to have more hostplant available to them, differences in resource availability do not explain the differences in butterfly abundance. Although local abundance is correlated only with local distribution, I suggest that abundance-distribution relationships might emerge at regional and continental scales if local abundance were averaged across many habitat types. Consideration of the scale of a species’ resource specialization (within or among habitats) appears to be key to understanding the relationships between resource specialization, resource availability, and a species’ abundance and distribution. Received: 1 September 1999 / Accepted: 12 December 1999     

Impact of reassociation with a coevolved herbivore on oviposition deterrence in a hostplant

Although selection by herbivores for increased feeding deterrence in hostplants is well documented, selection for increased oviposition deterrence is rarely examined. We investigated chemical mediation of oviposition by the parsnip webworm (Depressaria pastinacella) on its principal hostplant Pastinaca sativa to determine whether ovipositing adults choose hostplants based on larval suitability and whether hostplants experience selection for increased oviposition deterrence. Webworms consume floral tissues and florivory selects for increased feeding deterrents; moths, however, oviposit on leaves of pre-bolting plants. Exclusive use of different plant parts for oviposition and larval feeding suggests oviposition should select for increased foliar deterrents. Recent webworm colonization of New Zealand (NZ) allowed us to assess phenotypic changes in foliar chemicals in response to webworm oviposition. In a common garden experiment, we compared NZ populations with and without a history of infestation from 2004 to 2006 for changes in leaf chemistry in response to oviposition. Three leaf volatiles, cis- and trans-ocimene, and β-farnesene, elicit strong responses in female moth antennae; these compounds were negatively associated with oviposition and are likely oviposition deterrents. Leaf β-farnesene was positively correlated with floral furanocoumarins that deter florivory; greater oviposition on plants with low floral furanocoumarins indicates that moths preferentially oviposit on parsnips most suitable for larval growth. Unlike florivory, high oviposition on leaves did not lower plant fitness, consistent with the fact that NZ parsnip foliar chemistry was unaffected by 3–6 years of webworm infestation. Thus, in this system, selection by ovipositing moths on foliar chemistry is weaker than selection by larvae on floral chemistry.     

The influence of ants on patterns of colonization and establishment within a set of coexisting lycaenid butterflies in a south-east Asian tropical rain forest

In Peninsular Malaysia ten species of lycaenid butterflies use leaf flushes or inflorescences of the legume tree Saraca thaipingensis as larval hostplant. Resource partitioning among these species is regulated by a complex mixture of patterns of interaction with ants. Females of obligately myrmecophilous species lay their eggs exclusively on trees colonized by their specific host ants. On trees colonized by weaver ants, only specialist mutualists adapted to these territorial ants are able to survive, while larvae of other species are killed. The formicine ant Cladomyrma petalae, which inhabits hollow twigs of the myrmecophytic hostplant, likewise precludes oviposition by female butterflies. Lycaenid larvae confronted with this ant species never survive, but one concealed feeding species (Jamides caeruleus) escapes removal due to the cryptic life-habits of the larvae. Two facultative myrmecophiles associate in a mutualistic way with a wide and largely overlapping range of ant genera which forage at the extrafloral nectaries of leaf flushes. One species (Cheritra freja) is not myrmecophilous, but is tolerated by all but the most territorial ants. Ant-dependent hostplant selection and egg-clustering characterize the obligate mutualists, whereas facultative myrmecophiles and the non-myrmecophile distribute their eggs singly over appropriate hostplants. Signals mediating caterpillar-ant communication are highly specialized in one obligate myrmecophile (Drupadia theda), but rather unspecific in four other species tested. Altogether our observations indicate that colonization and establishment of lycaenid butterflies on S. thaipingensis trees are governed by specializations as well as opportunistic use of resources (ants and hostplant parts). Therefore, the diversity of this species assemblage is maintained by deterministic as well as stochastic factors.     

Variable chemical defence in the checkerspot butterfly Euphydryas gillettii (Lepidoptera: NymphaIidae)

Abstract.

• 1 Like other checkerspots, Euphydryas gillettii butterflies may contain the defensive chemicals, iridoid glycosides, which are sequestered from their hostplants during larval feeding.
• 2 We analysed the iridoid glycoside content of E.gillettii adults from two different populations, Warm Lake, Idaho, and Granite Creek, Wyoming, that have different patterns of hostplant use.
• 3 Gas chromatographic analysis of thirty butterflies from the Wyoming population showed that they contained a mean of 1.27 (±0.19 SE) % dry weight iridoid glycosides. Notably, 20% of these butterflies contained no detectable iridoid glycosides.
• 4 In contrast, nineteen butterflies from the Idaho population contained a mean of 3.89 (±0.38 SE) % dry weight iridoid glycosides, and all butterflies contained iridoid glycosides.
• 5 These results illustrate how the chemical defence of herbivorous insects varies according to differential use of potential hostplants.

     

Coevolution of pierid butterflies and their cruciferous foodplants

Summary The suitability of several Cruciferae species for the survival and development of the larvae of Anthocharis cardamines, which are seed and flower predators, was investigated. Large differences, consistent in time and space, were observed between the survival of sub-populations on different hostplants. Foodplants influenced A. cardamines survival and development by allelochemical and mechanical defences, which may also weaken a larva against pathogen attack. Oviposition by females appeared surprisingly maladaptive however with proportionately most eggs being laid on the hostplants yielding poorest larval survival, in opposition to previous expectations of coevolutionary theory. The evolutionary consequences of butterfly predation for Cruciferae are discussed, and juxtaposed to the needs of pollination.     

El Niño and dry season rainfall influence hostplant phenology and an annual butterfly migration from Neotropical wet to dry forests

We censused butterflies flying across the Panama Canal at Barro Colorado Island (BCI) for 16 years and butterfly hostplants for 8 years to address the question: What environmental factors influence the timing and magnitude of migrating Aphrissa statira butterflies? The peak migration date was earlier when the wet season began earlier and when soil moisture content in the dry season preceding the migration was higher. The peak migration date was also positively associated with peak leaf flushing of one hostplant (Callichlamys latifolia) but not another (Xylophragma seemannianum). The quantity of migrants was correlated with the El Niño Southern Oscillation, which influenced April soil moisture on BCI and total rainfall in the dry season. Both hostplant species responded to El Niño with greater leaf flushing, and the number of adults deriving from or laying eggs on those new leaves was greatest during El Niño years. The year 1993 was exceptional in that the number of butterflies migrating was lower than predicted by the El Niño event, yet the dry season was unusually wet for an El Niño year as well. Thus, dry season rainfall appears to be a primary driver of larval food production and population outbreaks for A. statira. Understanding how global climate cycles and local weather influence tropical insect migrations improves the predictability of ecological effects of climate change.     

Indirect effect on survivorship of caterpillars due to presence of invertebrate predators

Summary An indirect effects is defined here as a reduction in prey survivorship as a consequence of a reduction in growth rate of prey due to the presence of a predator that alters prey behavior. A method for partitioning the direct and indirect effects of predators on prey survivorship indicated that predatory wasps (Polistes sp.:. Vespidae) had both direct and indirect negative effects on survivorship of buckmoth caterpillars (Hemileuca lucina: Saturniidae). In a field experiment, the direct and indirect effects together accounted for 61% of the mortality of the caterpillars. A third of this reduction in survivorship due to the wasps was attributed to an indirect effect, due to the decreased growth rate of the caterpillars that moved into the interior of the hostplant to escape from the wasps. In contrast, in another field experiment, although predatory stinkbugs (Podisus maculiventris: Hemiptera) contributed to 56% of the mortality of buckeye caterpillars (Junonia coenia: Nymphalidae), the indirect effect of stinkbugs on buckeye caterpillars only accounted for 2% of the reduction in survivorship of these caterpillars. These differences in the indirect effect are discussed in particular relative to the behavior of predators and prey, ratio of predator to prey sizes, and morphology of the hostplants.     

Just how important are structural elements as habitat components? Indications from a declining lycaenid butterfly with priority conservation status

Recently, it has been suggested that habitats for insect herbivores have been too narrowly defined, often on the basis of larval hostplants; in particular, non-consumable resources (called utilities; structural elements) have been ignored. Here, the importance of utility resources for roosting and mate location has been examined in the silver-studded blue butterfly Plebejus argus (L.) (Lycaenidae) on the Great Ormes Head, North Wales, UK. The methods included using dedicated surveys and correspondence analysis applied to behavioural observations in relation to vegetation structure on a transect through a key patch for this metapopulation model species. A substantial and significant bias in roosting (97%) and mating (75%) is found to occur outside hostplant areas on shrubs and rank bunched grasses and forbs. Population density is higher in shrubby areas and shrubs are increasingly occupied during the afternoons and night, during the late flight season and in cloudy, cool and windy weather. These findings suggest that shrubs are a valuable habitat component for this butterfly, at least at this coastal location, and important for their conservation. As scrub growth is inimical to calcicolous grassland, population status will depend on a fine balance between shrub and hostplant cover dependent on grazing and browsing by the indigenous goat, sheep and rabbit populations as well as on controlled cutting and burning. Opportunities exist for increasing population size and distribution on the headland but this will need to be managed carefully. There are also implications for metapopulation dynamics studies; the status of shrubs neighbouring host plant areas switches from that of barriers to resources and refuges.     

Complete elimination of hostplant quinolizidine alkaloids by larvae of a polyphagous lycaenid butterfly,Callophrys rubi

Caterpillars of the lycaenid butterfly Callophrys rubi accept a variety of hostplants. When fed inflorescences or leaves of Genista tinctoria (a natural hostplant) or Lupinus polyphyllus (a non-host), the larvae completely eliminate quinolizidine alkaloids ingested from their food in their frass. No alkaloids are stored. Infestation by the parasitoid wasp Distatrix sancus (Braconidae) did not affect alkaloid elimination. The presence of an effective anti-toxin system is discussed with reference to the evolution of hostplant relationships in the genus Callophrys. There is no evidence that in the secondarily myrmecoxenous larvae of C. rubi hostplantderived chemical defense takes the place of former myrmecophily.     

Sources of intraspecific variation in the hostplant seeking behavior of Colias butterflies

Summary Egg-laying females of the legume-feeding butterfly Colias philodice eriphyle were observed within a high-altitude study site during 1977 and 1978. Average oviposition selectivity showed two patterns of seasonal variation. First, second-brood females laid eggs more frequently after alighting upon hostplants than did first-brood females in both years. Second, a consistent decline in post-alighting oviposition probability near the end of the second brood corresponded with a dramatic decrease in the water content of hostplant foliage near the end of the dry summer season. In addition to seasonal variation in oviposition behavior, individual females landed and oviposited upon widely varying sets of legume hostplant species. By sampling hostplant abundances along the flightpaths of observed females, we show that individuals varied in their tendency to land upon different hostplants. Females tended to specialize upon one or two species, at least in the short term, and the pattern of oligophagy for the population as a whole is partly generated by variation in the host-seeking behavior of individual females.     

Growth and survival of larvae of Thaumetopoea pinivora inside and outside a local outbreak area

1 Outbreaks of herbivorous insects tend to be spatially restricted, possibly because of demographic differences between inside and outside the outbreak area. In some cases, the margin of the outbreak area is distinct, allowing comparisons of adjacent areas that may identify factors leading to such differences in abundance. The northern pine processionary moth Thaumetopoea pinivora presently occurs at outbreak densities within a well‐defined area of approximately 3000 ha on the island of Gotland, south Sweden. We investigated whether cohorts of young larvae (first and second instar) had higher growth rate and survival inside or outside the outbreak area. 2 Group‐feeding appears to promote outbreaks in certain insect groups. Because T. pinivora larvae are highly social, we also compared larval performance between groups of different sizes inside and outside of the outbreak area: ‘small’ (33 eggs/group) and ‘normal’ (100 eggs/group). 3 Averaged over group size, whole colony mortality through the first two instars was two‐fold higher in the non‐outbreak area compared with the outbreak area. Mortality of individual larvae in the surviving colonies, however, did not differ between the two areas. There were only small differences in food quality (toughness, nitrogen content) between the areas, with no detectable effects on larval performance. 4 Larval relative growth rate did not differ between reduced and normal‐sized groups, which is surprising given that growth rate is known to increase with group size in other group‐feeding lepidopterans. 5 Reduced group size negatively affected larval survival, particularly in the outbreak area; by contrast, normal‐sized groups survived equally well in the two areas. Wood ants (Formica spp.) were more common outside the outbreak area, and appeared to be the main cause of colony mortality at low larval density. A different result was observed with regard to per‐capita mortality, which was higher in the outbreak area. We speculate that this could have been due to solitary predators being locally specialized on T. pinivora in the high‐density area.     

Salinity Adaptations of the Gastropods Littorina mandshuricaand L. squalidafrom a Marine Bay and an Estuary

The authors examine the effect of decreased salinity on adult and larval periwinkles Littorina mandshuricaand L. squalidafrom two different habitats, a marine bay and an estuary in Vostok Bay, Sea of Japan. Considerable differences were found in salinity tolerance of adult periwinkles, larval growth and survival, and morphology of the egg capsules. Using the stepwise acclimation method, no genotypic differences were found in salinity tolerance limits of gastropod mollusks from different populations. It is assumed that despite marked physiological differences these populations appear not to be different physiological races.     

I. Abhängigkeit der Zellkerngrösse von verschiedenen Wirtspflanzen

Zusammenfassung Die Volumina der Zellkerne in den Speicheldrüsen von M. persicae sind nicht konstant, sondern variieren je nach Wirtspflanze der Blattlaus. Dabei kann es bei einzelnen Zelltypen zu starken Kernschwellungen kommen. Das Ausmaß der Kernschwellungen und die davon betroffenen Zelltypen können von Wirtspflanze zu Wirtspflanze wechseln. In der Diskussion wird auf die Beziehung zwischen Zellstoffwechsel und Kerngröße hingewiesen und vermutet, daß die Anteile der einzelnen Komponenten in der Speichelflüssigkeit wirtspflanzenabhängig sind. Im Hinblick auf wirtspflanzenabhängige Vektorleistungen der Blattläuse wird die Rolle des Speichels bei der Übertragung phytopathogener Viren diskutiert.

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Summary The nuclei of the different cell types in the salivary gland of Myzus persicae may show considerable variation in their sizes depending on the hostplants on which the aphids have been reared. This influence of the hostplants has been studied in efforts to elucidate the role of the salivary gland in plant virus transmission. The results are summarized in Fig. 1. The designation of the different cell types is the same as in earlier publications (Weidemann 1968, 1970). It is seen that the extent of nuclear swelling and the type of cells affected by this phenomenon vary depending on the hostplants. The swelling is accompanied by structural changes in the nuclei (Figs 4–6). In view of known relationships between the cell function and nuclear size it is suggested that the hostplant may have an influence on the composition of the saliva of the aphids. This influence could also be responsible for differences in the ability to transmit virus of aphids reared on different hostplants. The kind of structural changes of the nuclei suggests that different mechanisms may be responsible for the nuclear swelling in different cell types.

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Herrn Prof. Dr. G. Birukow, Göttingen, zum 60. Geburtstag.     

Host-plant effects on larval survival of a salicin-using leaf beetle Chrysomela aeneicollis Schaeffer (Coleoptera: Chrysomelidae)

Several species of willow leaf beetles use hostplant salicin to produce a defensive secretion that consists of salicylaldehyde. Generalist arthropod predators such as ants, ladybird beetles, and spiders are repelled by this secretion. The beetle larvae produce very little secretion when they feed on willows that lack salicylates, and salicin-using beetles prefer salicylate-rich willows over salicylate-poor ones. This preference may exist because the larvae are better defended against natural enemies on salicylate-rich willows. If this is true, the larvae should survive longer on those willows in nature. However, this prediction has not been tested. I determined the larval growth and survival of Chrysomela aeneicollis (Coleoptera: Chrysomelidae) on five willow species (Salix boothi, S. drummondiana, S. geyeriana, S. lutea, and S. orestera). These species differed in their salicylate chemistries and in leaf toughness but not in water content. The water content varied among the individual plants. Larval growth of C. aeneicollis did not differ among the five species in the laboratory, but it varied among the individual plants and it was related to the water content. In the field, C. aeneicollis larvae developed equally rapidly on the salicylate-poor S. lutea and on the salicylate-rich S. orestera. Larval survival was greater on S. orestera than on S. lutea in one year (1986), but there was no difference between them during three succeeding years. In another survivorship experiment, larval survival was low on the medium-salicylate S. geyeriana, but high on the salicylate-poor S. boothi and on S. orestera. Larval survival in the field was related to the larval growth and water content that had been previously measured in the laboratory. These results showed that the predicted relationship between the host plant chemistry and larval survival did not usually exist for C. aeneicollis. One possible reason for this was that the most important natural enemies were specialist predators that were unaffected by the host-derived defensive secretion. One specialist predator, Symmorphus cristatus (Hymenoptera: Eumenidae), probably caused much of the mortality observed in this study. I discuss the importance of other specialist predators to salicin-using leaf beetles.     

Carry-over effects of the larval environment on post-metamorphic performance in two hylid frogs

Life history theory and empirical studies suggest that large size or earlier metamorphosis are suitable proxies for increased lifetime fitness. Thus, across a gradient of larval habitat quality, individuals with similar phenotypes for these traits should exhibit similar post-metamorphic performance. Here we examine this paradigm by testing for differences in post-metamorphic growth and survival independent of metamorphic size in a temperate (spring peeper, Pseudacris crucifer) and tropical (red-eyed treefrog, Agalychnis callidryas) anuran reared under differing larval conditions. For spring peepers, increased food in the larval environment increased post-metamorphic growth efficiency more than predicted by metamorphic phenotype and led to increased mass. Similarly, red-eyed treefrogs reared at low larval density ended the experiment at a higher mass than predicted by metamorphic phenotype. These results show that larval environments can have delayed effects not captured by examining only metamorphic phenotype. These delayed effects for the larval environment link larval and juvenile life history stages and could be important in the population dynamics of organisms with complex life cycles.     

Lekking in Neotropical Owl Butterflies, Caligo illioneus and C. oileus (Lepidoptera: Brassolinae)

We demonstrate that the mating patterns of owl butterflies Caligo illioneus (Cramer)and C. oileus (Felder) are leks. During 1993–1994, we recorded distributions of male and female butterflies and larval hostplants in a lowland Neotropical rain forest in Panama. Caligo illioneus males aggregated along forest edges and defended territories against both conspecifics and males of the related species C. oileus, which exhibited similar behaviors. Male perch sites were not associated with hostplant dispersion or the local abundance of females. However, unmated female C. illioneus were observed to arrive and copulate with males on territories that were located near where streams intersected the roadway. We found some evidence that these leks overlap to form multiple-species aggregations. Caligo illioneus and C. oileus used the same sites at similar frequencies during 1993, a pattern that was repeated during 1994. We could not detect if members of different species were being attracted by similar environmental features or if they were effectively attracting one another to the display sites. Independent of population growth, the abundance of males at a particular site was correlated with the abundance of heterospecific males during 1993, but this pattern was not confirmed in 1994. Overlap in the leks serves as evidence against a resource-based hot-spot hypothesis of lek formation.     

Two ecologically distinct subspecies ofHypochaeris radicatal L.

Summary The present paper is part of a series of papers comparing two ecologically distinct subspecies ofHypochaeris radicata L.Hypochaeris radicata ssp.radicata grows in more fertile soils thanH. radicata ssp.ericetorum.The dry-weight yield of plants grown from seeds was measured after a 25 days culture period on varying levels of nitrate. Roots and shoots were analyzed for total organic nitrogen and free nitrate. Dry-weight yield showed an almost identical response over the whole range of nitrate concentrations used. The chemical analysis did not reveal differences between the subspecies that could explain the distribution in the field. In a second experiment the growth rate of the two subspecies was measured under optimal nitrate supply during a two month period. Both subspecies exhibited initially the same relative growth rate but one month after sowing the growth rate of both subspecies declined, with a sharper decline in ssp.ericetorum resulting in an 82 per cent difference in dry-weight between both subspecies two months after sowing. Some pronounced formative differences became evident. Shoot to root ratio of ssp.ericetorum showed little response to increasing nitrate concentrations whereas ssp.radicata was clearly responsive in this respect.The contribution of the tap root in total plant dry-weight was relatively higher in ssp.Ericetorum. The decline in growth rate and the formative differences can explain the absence of ssp.ericetorum from nutrient rich soils. when grown on ammonium ssp.radicata had a slightly but not significantly higher yield than ssp.ericetorum. The difference was even greater at low pH. It is concluded that both subspecies are adapted to ammonium nutrition at pH 4.5 as well as at pH 6 and that the absence of ssp.radicata from acidic soils cannot be explained by the low pH. The possibility that both subspecies have different abilities to reduce their growth when nitrate resources become limiting, and yet remain capable for further growth and reproduction is discussed.Grassland species research group, publ. no.16.     

Hostplants and classification: a review of nymphalid butterflies

In reviewing the hostplant associations of nymphalid butterflies, particular emphasis is placed on the intractable problem of nymphalid classification. Although offering few certain conclusions, if used in conjunction with more formal morphological characters, the data presented should contribute toward a resolution of the inter-relationships of the many widely recognized groupings within the Nymphalidae, several of which seem to be broadly characterized by typical host families. As a direct result of this analysis, the presumed association between larval hostplants and unpalatability is re-appraised.