Arctia Caja Research Articles

Possible Batesian mimicry to sexually different models in the tussock moth Numenes albofascia with a great sexual color dimorphism

AbstractMimicry with warning colors includes Batesian and Müllerian mimicries. If we divide mimicry by sex, there are theoretically four types of mimicry: unimodal, female‐limited, male‐limited and dual mimicry. The latter three cases cause sexual dimorphism in body color and marking pattern but are rarely reported. In this study, we show that the tussock moth Numenes albofascia is possibly a dual mimic. The wing color and marking pattern of male and female N. albofascia are completely different, with the male's pattern resembling that of the smoky moth Pidorus atratus, while the female pattern resembles that of the tiger moth Arctia caja. Body size also differs greatly between the sexes of N. albofascia, matching the mimicry model species of each sex. These moths are distributed sympatrically in Japan, and their adult seasons overlap with each other. According to lizard feeding experiments, N. albofascia is palatable, while both male and female model species are unpalatable. Actograms in the laboratory and the light trapping in the field suggest that females of N. albofascia fly actively from sunset to midnight, while males fly during the twilight period around dawn. Therefore, male and female N. albofascia might be Batesian mimics of diurnally active P. atratus and nocturnally active A. caja, respectively, and the great sexual dimorphism of this moth could be caused by dual mimicry.

Missed chances? Sequestration and non-sequestration of alkaloids by moths (Lepidoptera)

Some butterflies and moths sequester and retain noxious phytochemicals for defence against predators. In the present study, three moth species, the garden tiger moth, Arctia caja, the death hawk moth, Acherontia atropos, and the oleander hawk moth, Daphnis nerii, were tested whether they sequester alkaloids from their host plants. Whereas A. caja consistently sequestered atropine from Atropa belladonna, also when atropine sulfate was added to the alkaloid-free diet of the larvae, A. atropos and D. nerii were found to be unable to sequester alkaloids, neither atropine nor eburnamenine from Vinca major, respectively. Instead of acquiring toxicity as chemical defence, nocturnal lifestyle and cryptic attitudes may improve their chances of survival.

Review of the northern Holarctic Arctia caja complex (Lepidoptera: Noctuidae: Arctiinae)

AbstractArctia olschwangi Dubatolov, formerly known only from Arctic Siberia, Russia, is recorded from northern Alaska, United States of America. Distinguishing characters between northern populations of Arctia brachyptera Troubridge and Lafontaine, Arctia caja (Linnaeus), A. olschwangi Dubatolov, and Arctia opulenta (Edwards) are discussed. Arctia brachyptera Troubridge and Lafontaine is hypothesised to be a subspecies of A. olschwangi Dubatolov but more specimens need to be examined before this taxonomic change is made.

Phenotypic changes and reduced genetic diversity have accompanied the rapid decline of the garden tiger moth (Arctia caja) in the U.K.

Abstract 1. Previous studies have quantified the recent decline of numerous Lepidopteran species in the U.K., including the garden tiger moth (Arctia caja), in which abundance has decreased by 85% over the past 30 years. At the same time that overall numbers have been falling, the distribution of abundance of this species has been moving northwards. In this study, morphological and genetic data were used to investigate the possibility that these changes in abundance and distribution have been accompanied by microevolutionary changes.2. A comparison of wing size and shape in current and historical moth samples revealed that wing shape has altered significantly over the past century, resulting in longer, narrower hindwings and narrower forewings for a given forewing length. Habitat fragmentation and increased suitability of northerly sites provide a plausible explanation for the selection of increasingly dispersive individuals.3. Mitochondrial DNA revealed no phylogeographic structuring either before or after the population decline. However, a comparison of mtDNA haplotypes from current and museum specimens indicated that the recent population decline across the U.K. has been accompanied by a significant loss of genetic diversity.4. The changes in wing shape suggest recent adaptation to environmental change, whereas a loss of genetic diversity may limit the ability of garden tiger moths to adapt to future environmental change.

Large-Scale Temporal Changes in Spatial Pattern During Declines of Abundance and Occupancy in a Common Moth

We examined the changes in spatial pattern that accompanied the population decline of the garden tiger moth, Arctia caja (L.) in Britain between 1968 and 1999 using Spatial Analysis by Distance Indices (SADIE) techniques. A principal co-ordinate analysis of all pair-wise spatial associations between years indicated three groupings of years: 1969–1978,1979–1990,1991–1999, which revealed three phases during the population decline: an early period with highly structured spatial pattern; a middle period with nearly random distribution overall; and a recent period with highly structured spatial pattern but small abundance overall. The change in spatial structure in the early 1980’s accompanied rapid changes in abundance but preceded a sharp decline in occupancy and confirms that the sharp decline in abundance included decreases from widespread high-density sites. Perhaps unusually, A. caja varied from spatially aggregated to randomly distributed and back to spatially aggregated, all while its abundance declined sharply. Present distribution pattern may reflect past abundance changes poorly in this species. Areas showing the greatest variation in abundance displayed the greatest range in spatial structure, but also the greatest stability of spatial pattern, indicating changes between extremes of spatial pattern occurred slowly. SADIE techniques are a powerful method to quantify temporal changes in spatial pattern and relate them to temporal changes in abundance.

Isolation and characterization of highly polymorphic microsatellite loci for the garden tiger moth Arctia caja (Lepidoptera: Arctiidae)

AbstractA set of microsatellite markers was isolated from Arctia caja, a species that has been declining in UK for several decades. As has been found with other Lepidoptera species, this proved to be a difficult task. Eight enriched libraries identified 103 positive clones, and these yielded only seven polymorphic microsatellites. Allelic diversity ranged from 10 to 23 alleles per locus in a population of 30 individuals. Significant heterozygosity deficits were shown by three of these loci, presumably due to null alleles. The remaining four loci were in Hardy–Weinberg equilibrium and will be used to investigate the population genetic structure of A. caja.

Fearful symmetry? Intra-individual comparisons of asymmetry in cryptic vs. signalling colour patterns in butterflies

The signalling role of asymmetry has attracted considerable recent interest among evolutionary biologists. Although it has been studied primarily within the context of sexual selection, symmetry of signals may play a role also in inter-specific communication, such as predator–prey interactions. Both theory and experimental evidence suggest that asymmetry may impair the efficacy of visual warning signals used to deter potential predators, but increase the protective value of non-signalling, cryptic colour patterns used to decrease the risk of detection. Here we tested the prediction from this hypothesis by means of intra-individual comparisons of asymmetry in colour pattern elements in three species of moths (Arctia caja (L.), Noctua orbona (L.), Smerinthus ocellata (L.)) that possess cryptic fore wing patterns and signalling hind wing patterns. Mean asymmetries constituted 4.3% (range 2.1–7.0%) of trait size for colour pattern elements, whereas individual asymmetry levels reached as high as 26%. Asymmetry tended to be somewhat larger in cryptic patterns on fore wings than in signalling patterns on hind wings in five of six comparisons, but in only one case was the difference statistically significant. In addition, pattern elements were somewhat more asymmetric on fore wings also in Saturnia pavonia (L.), which possesses identical signalling eyespots on both fore and hind wings. The relatively low levels of asymmetry also in cryptic patterns imply either that selection does not favour increased asymmetry in cryptic patterns, or that the evolution of pronounced asymmetry is developmentally or genetically constrained.

East Atlantic teleconnection pattern and the decline of a common arctiid moth

AbstractTeleconnection patterns are large‐scale atmospheric circulation systems and variation in them is often associated with impacts on climate and weather over broad areas. Arctia caja L. is a well‐known, widespread and charismatic tiger moth. In recent decades, the abundance of A. caja in UK has fallen abruptly. The annual abundance of A. caja in UK is known to be affected adversely by wet winter weather and warm spring temperatures. We examined A. caja population dynamics from 1968 to 1999 for weather and climatological effects. Population growth rate displayed endogenous effects of abundance in the previous two seasons. Accounting for this, growth rate in the present season was still affected significantly by winter precipitation and spring temperature. Annual abundance of A. caja was inversely related to winter East Atlantic teleconnection pattern (winter EA index) and annual population growth rate was inversely related to winter EA in the present and previous two seasons. An index of the North Atlantic Oscillation (NAO), commonly used as an indicator of winter climate in northern Europe, did not show a significant relationship with growth rate. We noted, for the first time, that the winter EA index has increased steadily over the past five decades. The model presented here therefore implies a further decline of A. caja population growth rates and abundance in the future. This is the first demonstration of a relationship between EA and population dynamics and indicates the EA and other lesser‐known teleconnection patterns may prove useful in modeling the ecological effects of climate change.

Long-term decline in abundance and distribution of the garden tiger moth (Arctia caja) in Great Britain

The garden tiger moth (Arctia caja) was once widespread and common in the UK. Data collected using the standard light-traps of the Rothamsted Insect Survey over Great Britain from 1968 to 1998 showed that A. caja abundance fluctuated near 4.2 captures per site until 1983, and then fell 28% to an average of 3.0 captures per site after 1984. The collated index, frequently used to monitor UK butterfly abundance, was not suitable to detect this large, 1-year population change. Four years after the sudden decrease in abundance, the proportion of sites occupied also fell rapidly from an average of 0.60 to an average of 0.42 (30%). Contrary to most UK butterflies, which are expected to increase under the UK climate change scenarios of global warming, linear regression modelling showed that warm, wet winters and springs may be detrimental to A. caja and it is therefore predicted to decrease further.

An abundance–occupancy time‐lag during the decline of an arctiid tiger moth

The positive interspecific abundance–occupancy relationship is one of the most general patterns in ecology. Positive intraspecific relationships should also exist within species over time, and so a species should occupy more sites in years when it is more abundant. However, positive intraspecific relationships are not as ubiquitous as their interspecific counterparts. It has been hypothesized that low levels of temporal variation and time‐lags between changes of abundance and occupancy within species make positive intraspecific relationships difficult to detect. We analyse 31 years of U.K.‐wide data on the decline of an arctiid moth, Arctia caja, which provides the first empirical demonstration of an abundance–occupancy time‐lag for any species. Such time‐lags are probably common and we discuss their impact on the intraspecific abundance–occupancy relationship and their implications for conservation management. In A. caja, the time‐lag indicates that the decline of the species is probably not driven by habitat loss.

The two Faces of Pyrrolizidine Alkaloids: the Role of the Tertiary Amine and its N‐Oxide in Chemical Defense of Insects with Acquired Plant Alkaloids

Larvae of Creatonotos transiens (Lepidoptera, Arctiidae) and Zonocerus variegatus (Orthoptera, Pyrgomorphidae) ingest 14C-labeled senecionine and its N-oxide with the same efficiency but sequester the two tracers exclusively as N-oxide. Larvae of the non-sequestering Spodoptera littoralis eliminate efficiently the ingested alkaloids. During feeding on the two alkaloidal forms transient levels of senecionine (but not of the N-oxide) are built up in the haemolymph of S. littoralis larvae. Based on these results, senecionine [18O]N-oxide was fed to C. transiens larvae and Z. variegatus adults. The senecionine N-oxide recovered from the haemolymph of the two insects shows an almost complete loss of 18O label, indicating reduction of the orally fed N-oxide in the guts, uptake of the tertiary alkaloid and its re-N-oxidation in the haemolymph. The enzyme responsible for N-oxidation is a soluble mixed function monooxygenase. It was isolated from the haemolymph of the sequestering arctiid Tyria jacobaeae and purified to electrophoretic homogeneity. The enzyme is a flavoprotein with a native Mr of 200000 and a subunit Mr of 51000. It shows a pH optimum at 7.0, has its maximal activity at a temperature of 40-45 degrees C and an isoelectric point at pH 4.9. The reaction is strictly NADPH-dependent (Km 1.3 microM). From 20 pyrrolizidine alkaloids so far tested as substrates, the enyzme N-oxidizes only alkaloids with structural elements which are essential for hepatotoxic and genotoxic pyrrolizidine alkaloids (i.e. 1,2-double bond, esterification of the allylic hydroxyl group, presence of a second free or esterified hydroxyl group at carbon 7). A great variety of related alkaloids and xenobiotics were tested as substrate, none was accepted. The Km values of senecionine, monocrotaline and heliotrine, representing the three main types of pyrrolizidine alkaloids, are 1.3 microM, 12.5 microM and 290 microM, respectively. The novel enzyme was named senecionine N-oxygenase (SNO). The enzyme was partially purified from two other arctiids. The three SNOs show the same general substrate specificity but differ in their affinities towards the main structural types of pyrrolizidine alkaloids. The enzymes from the two generalists (Creatonotos transiens and Arctia caja) display a broader substrate affinity than the enzyme from the specialist (Tyria jacobaeae). The two molecular forms of pyrrolizidine alkaloids, the lipophilic protoxic tertiary amine and its hydrophilic nontoxic N-oxide are discussed in respect to their bioactivation and detoxification in mammals and their role as defensive chemicals in specialized insects. Pyrrolizidine-alkaloid-sequestering insects store the alkaloids as nontoxic N-oxides which are reduced in the guts of any potential insectivore. The lipophilic tertiary alkaloid is absorbed passively and then bioactivated by cytochrome P-450 oxidase.

The ocelli of arctiid moths: ultrastructure of the retina during light and dark adaptation

The ultrastructure of the dorsal ocelli of two arctiid moths ( Arctia caja ( A. caja) and Creatonotos transiens ( C. transiens) was investigated. The two ocelli are positioned laterally on the vertex of the head posterior to the antennae, close to the dorsal margin of the compound eyes. The biconvex corneal lens is located at the apex of a cone-shaped cuticular elevation, which encapsulates the retina. The corneagenous cell layer and the cup-like retina with about 100–130 receptor cells in A. caja (70–90 receptor cells in C. transiens) are adjoined proximally. The retina is completely enclosed by the perineurium and thus separated from the corneagenous cells and the surrounding hemolymph. Irregularly shaped rhabdomeres, consisting of densely packed microvilli, are present in the distal region of the receptor cells. Up to three cells may form a rhabdom. Thus a loose network of photoreceptive structures over the whole retina results. A unique feature of these arctiid ocelli are photoreceptor vacuoles containing microvilli. The function of these organelles is unknown. The rhabdomeric arrangement within the light and dark adapted retina differs considerably. The ultrastructure of the rhabdomeres indicates an intense membrane turnover. However, changes in adaptation state are not accompanied by dramatic changes in the photoreceptive area of an ocellus.

Sequestration of pyrrolizidine alkaloids in several arctiid moths (Lepidoptera: Arctiidae)

Sequestration of dietary pyrrolizidine alkaloids (PA) by larvae and adults of six European arctiid moth species (Spilosoma lubricipeda, Arctia caja, Phragmatobia fuliginosa, Callimorpha dominula, Diacrisia sannio, andTyria jacobaeae) was investigated for comparison with the well-studied Asian arctiidCreatonotos transiens. Larvae of all species metabolized free PA bases into the respectiveN-oxides. Only adults ofA. caja, P. fuliginosa, andS. lubricipeda, but not their larvae, converted dietary 7(S)-heliotrine to 7(R)-heliotrine, a direct precursor of a male pheromone in some arctiids, 7(R)-hydroxydanaidal. The larval integument figures as the main storage site for resorbed alkaloids; only minor amounts were found in other tissues. In addition, a significant amount of alkaloid is deposited in the cocoon ofArctia caja; only traces of alkaloids could be found in the meconium and the exuviae of this species. A substantial part of the alkaloids fed was degraded to unknown, nonalkaloidal products.

Parental Correlates of the Variability in Body Mass at Hatching in Arctia caja Larvae (Lepidoptera: Arctiidae)

Parental Correlates of the Variability in Body Mass at Hatching in Arctia caja Larvae (Lepidoptera: Arctiidae)

The influence of arctiid moth clicks on bat echolocation; jamming or warning?

1. Many arctiid and ctenuchid moths produce clicking sounds in response to the ultrasonic cries of bats. Clicks were recorded from the two arctiid moth speciesArctia caja, the garden tiger, andPhragmatobia fuliginosa, the ruby tiger. The threshold for eliciting clicks was around 60 to 75 dB pe SPL in both species.A. caja produced single clicks, andP. fuliginosa bursts of clicks. The maximum intensity of the clicks was 90 to 94 dB pe SPL at 5 cm forA. caja and 85 dB pe SPL at 5 cm forP. fuliginosa. The clicks contain most energy in the frequency range from 40 to 80 kHz (Figs. 2, 3). 2. Pipistrelle bats (Pipistrellus pipistrellus) were trained to sit on a platform and discriminate the difference in range,Δd, to two targets. The minimum Δd the bats could discriminate with more than 75% success rate was 1.5 cm. 3. The targets had built-in electrostatic loudspeakers through which different sounds could be played back to the bat. Playback of arctiid moth clicks from both targets did not disturb the bat's discrimination accuracy. The success rate did not decrease at anyΔd, and the minimumΔ d in the presence of clicks was 1 cm. 4. The clicks played from both loudspeakers did not influence the acoustic behavior or discrimination behavior of the bats in any obvious way. In all trials the bats went through a period with long (3 ms) slowly repeated (12–15 pulses/s) cries, a period with shorter cries and increased PRR (20 pulses/s) in which the decision seemed to be made, and finally a period with very short cries (0.5 ms) repeated at rates of up to 150 pulses/s (Figs. 4 and 5). The cries were FM sweeps from 120 kHz to 55 kHz with a second harmonic, which was strongest in the short cries. 5. The bats' response to the playback of different sounds, such as noise and recorded bat cries, from either the left or right loudspeaker, suggested that the bats reacted to clicks as if they were noise. The playback of sounds from only one speaker at a time decreased the bats' success rate, since the bats were attracted to the sounds (Figs. 6 and 7). 6. A secretion from the cervical glands ofA. caja, which contains choline ester, was given to a bat if it crawled towards a clicking target. Both bats tested in this way learned to associate the clicks with a noxious reward and avoided the clicks after just one or two trials (Fig. 8). 7. These results suggest that the function of the garden tiger and ruby tiger clicks in nature is to warn the bat of the moth's distastefulness, and not to ‘jam’ the bat's sonar system.

Characterization of a protein toxin from dried specimens of the garden tiger moth ( Arctia caja L.)

A protein toxin was isolated from the female abdomen of dried specimens of the garden tiger moth, Arctia caja L. It is toxic to both the house fly and the white mouse. The toxin is labile to heat (60°C) and organic solvents; is unstable to low pH and freeze-drying; and is destroyed by proteolytic enzymes. Purification by molecular sieve and ion exchange Sephadex column chromatography showed that the toxin has a mol. wt of about 50,000. In polyacrylamide gel disc electrophoresis, it has an R f value of 0·4. The protein toxin has an isoelectric point of 6·0 as determined by isoelectrofocusing. The toxic symptom of the protein toxin to white mice is similar to that of the small mol. wt polypeptide previously isolated from fresh specimens by Rothschild et al. (1979), but the latter toxin was not found in a detectable amount in the dried specimens used in this study. This protein toxin resembles chemically the neurotoxin, leptinotarsin, from the Leptinotarsa species, but apparently has a quite different mode of action on both insects and mammals.

A study on the mode of action and composition of a toxin from the female abdomen and eggs of Arctia caja (L.) (Lep. Arctiidae): An electrophysiological, ultrastructural and biochemical analysis

Cajin, the toxic principle extracted from the female abdomen and eggs of the aposematic moth Arctia caja, was investigated by means of column chromatography, and its effects on tissues were studied by electrophysiology and electron microscopy. Partial purification suggests that one fraction is a polypeptide with a molecular weight (mol. wt) of about 1000. It is lethal to both mammals and insects if injected into the body, but inactive via the oral route. Crude extracts applied to insect muscles produce a slow contracture which lasts for over 1 1 2 hr and is irreversible. Fine structural analyses of insect tissues after 5 min toxin treatment reveal disruption of both internal membranous systems and mitochondria. Unlike many other toxins, cajin appears to act by stimulating the muscle directly. The results of experiments involving Ca 2+-free solutions plus cajin suggest that it may increase the permeability of the muscle membrane to Ca 2+, perhaps behaving as a calcium ionophore, or may act as an analogue of an insect neurotransmitter.

Storage of cannabinoids by Arctia caja and Zonocerus elegans fed on chemically distinct strains of Cannabis sativa

THE larvae of the warningly coloured tiger moth Arctia caja (L.) (Lepidoptera) and the grasshopper Zonocerus elegans (Thunberg) (Acridoidea) are polyphagous feeders with a predilection for poisonous food plants. These species can sequester and store various secondary plant substances such as cardiac glycosides and pyrrolizidine alkaloids1,2, which presumably function as predator deterrents. We report here that cannabinoids ingested with the leaves of Cannabis sativa L. are also stored by both insects.

Biochemical and Serological Studies of a Cytoplasmic Polyhedrosis Virus from Arctia caja: a Naturally-occurring Mixture of Two Virus Types

SUMMARY A cytoplasmic polyhedrosis virus (CPV) isolated from larvae of Arctia caja contained at least 12 RNA segments when these were fractionated by poly-acrylamide gel electrophoresis. When the virus RNA was compared with RNA isolated from Nymphalis io CPV and from Spodoptera exempta CPV, it appeared that A. caja CPV could be interpreted as a mixture of these two viruses. The structural polypeptides of virus particles of A. caja CPV also resembled a mixture of proteins derived from the other two virus types, but two classes of particles were not separated by size or density measurements. Virus particles of S. exempta CPV and N. io CPV were unrelated serologically using antisera that did not react with double-stranded RNA. Particles of A. caja CPV were resolved into two fractions using the antiserum specific for S. exempta CPV; particles containing RNA segments characteristic of S. exempta CPV and particles containing RNA segments characteristic of N. io CPV. This confirmed that the A. caja CPV isolate was a naturally-occurring mixture of two virus types.

Particles present in the haemolymph and defensive secretions of insects.

ABSTRACT Defensive fluids obtained from the Garden Tiger, Scarlet Tiger and Burnet Moths and from the Monarch Butterfly and the Seven-Spot Ladybird Beetle, haemolymphs taken from the wasp, the Burying Beetle and the Rat Flea, and fluids from the eggs of the Garden Tiger, Gypsy Moth and Oak Eggar Moth were examined in the electron microscope after negative staining. Except for the ladybird all the defensive fluids, haemolymphs and egg fluids contained particles 100–150 Å across which frequently had rectangular or square outlines. In some species the particles were occasionally arranged in groups of 2 and 4 and in the egg fluid of the Garden Tiger they were arranged in rows which were aligned side by side to form strands of considerable length. The particles are believed to be protein. They correspond in size to the 16 s component of the haemocyanins of Limulus and Homarus and the protein particles found in Calliphora by other workers.