Creatonotos Transiens Research Articles

How Do Moth Clicks Decrease the Capture Success of Horseshoe Bats?

Moths are among the most diverse and abundant animals. They have evolved a suite of acoustic defenses, such as producing ultrasound to guard against predation by low-duty-cycle bats. Recently, we found that the ultrasonic clicks of several moth species can also help decrease the capture success of high-duty-cycle bats. We tested whether moth clicks could advertise moth toxicity and/or jam the echolocation calls of high-duty-cycle bats. We examined the acoustic response of a hawkmoth (Cechenena minor) and a tiger moth (Creatonotos transiens) to free-flying horseshoe bats, Rhinolophus osgoodi. C. minor and C. transiens produced anti-bat ultrasonic clicks with an average duty cycle of 22.3% and 4.9%, respectively. The clicks of C. minor overlapped spectrally with the echolocation calls of R. osgoodi. C. minor occasionally emitted clicks immediately after the end of bat feeding buzzes. The clicks of C. transiens did not overlap spectrally with the echolocation calls of R. osgoodi. More than half the click sequences of C. transiens were produced before the emergence of bat feeding buzzes and did not overlap temporally with the feeding buzzes. Moreover, we found that C. minor was palatable and C. transiens was unpalatable to R. osgoodi. These results suggest that C. minor might be capable of jamming R. osgoodi and might also use ultrasonic clicks as warning signals. The clicks of C. transiens probably function to advertise moth toxicity. This study highlights the diversity of moth anti-bat sounds and illustrates the potential mechanisms of moth acoustic defense against high-duty-cycle bats.

Ultrastructure of Egg Chorion and Its Sculpture in Two Arctiids (Erebidae: Arctiinae)

The identification of moths has been always dependent on characters like wing maculation, wing venation, male and female genitalic features, but the ultrastructural characters like egg chorion patterns have been completely ignored. These are equally important for identification. In the present study, scanning electron microscope was used to inspect, characterize, and depict eggs of two tiger moth species i.e., Andala unifascia Walker, 1855 and Creatonotos transiens (Walker, 1855) referable to family Erebidae. On the eggshells of both these species, morphological features have been observed and these are of great taxonomic value at species as well as at genus levels. These characters will enable identifying moths at much earlier stages of their life histories i.e., eggs.

Preliminary study on the wing scales of moth, Creatonotus transiens Walker, 1855 (Lepidoptera: Erebidae)

Dimensions of different types of scales on the wings of the moth Creatonotos transiens Walker were analyzed using micrometry. A total of 65 morphologically distinct types of scales were investigated, including 35 from dorsal side and 30 from ventral portion. Dorsal side scales have a length range of 82.7 to 141.3? and width range of 55.1 to 78.8?. The length of scale on the ventral region ranged from 82.7 to 133.9? and width 63 to78.8?. On comparison with ventral side of wing most of the dorsal side scale forms are long narrow and dentate.

DNA barcoding unravels contrasting evolutionary history of two widespread Asian tiger moth species during the Late Pleistocene.

Populations of widespread pest insects in tropical areas are characterized by a complex evolutionary history, with overlapping natural and human-mediated dispersal events, sudden expansions, and bottlenecks. Here, we provide biogeographic reconstructions for two widespread pest species in the tiger moth genus Creatonotos (Lepidoptera: Erebidae: Arctiinae) based on the mitochondrial cytochrome c oxidase subunit I (COI) gene. The Asian Creatonotos transiens reveals shallow genetic divergence between distant populations that does not support its current intraspecific systematics with several local subspecies. In contrast, the more widespread Creatonotos gangis comprises at least three divergent subclades corresponding to certain geographic areas, i.e. Australia, Arabia + South Asia and Southeast Asia. With respect to our approximate Bayesian computation (ABC) model, the expansion of Creatonotos gangis into Australia is placed in the Late Pleistocene (~65–63 ka). This dating coincide with an approximate time of the earliest human migration into the continent (~65–54 ka) and the period of intervisibility between Timor and Australia (~65–62 ka). Our findings highlight that the drying Sunda and Sahul shelf areas likely support successful migrations of Asian taxa into Australia during the Pleistocene. The phylogeographic patterns discovered in this study can be used to improve the effectiveness of integrated pest control programs that is a task of substantial practical importance to a broad range of agricultural stakeholders.

Insect-synthesised Retronecine Ester Alkaloids: Precursors of the Common Arctiine (Lepidoptera) Pheromone Hydroxydanaidal

Many pyrrolizidine alkaloid (PA)-adapted insects convert PAs sequestered from their larval host plants into "insect-PAs" in which the acid components of the alkaloids are replaced by small, branched aliphatic 2-hydroxy acids of insect origin. It has been proposed that insect-PAs are precursors of the pheromone hydroxydanaidal in male Estigmene acrea moths, but it is not clear why they are specifically required or what the structural features or chemical properties are that make insect-PAs more suitable for conversion into hydroxydanaidal than superficially similar alkaloids of plant origin. Evidence is presented that insect-PAs are also precursors of hydroxydanaidal in the polyphageous arctiine, Creatonotos transiens, and a new biosynthetic pathway to hydroxydanaidal is proposed that has a mandatory requirement for insect-PAs as intermediates.

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.

Influence of Previous Feeding Regimes and Ambient Temperatures on Degradation and Storage of Pyrrolizidine Alkaloids in the Moth Species Creatonotos transiens (Lepidoptera: Arctiidae)

Larvae of the arctiid moth species Creatonotos transiens (Walker 1855) take up dietary pyrrolizidine alkaloids (PA) and store them predominantly in their integument. A substantial part of the ingested alkaloids is not stored but degraded into non-alkaloidal compounds which are excreted with the faeces. If larvae had previous feeding experience with dietary alkaloids, their capacity to store PA in the last larval stage (L 7 ) is markedly reduced. After eclosion, part of the stored alkaloids is redistributed: In MM, PA are either transferred to the spermatophore (PA serve as a «nuptial gift») or are metabolized into the pheromone 7R-hydroxydanaidal. In FF, PA are translocated into the ovaries and subsequently to the eggs, where they could function as chemical defence compounds. Transfer rates and translocation were optimal at ambient T of 21° C, but were reduced at 4°C or 30°C. Thus, nutritional conditioning and ambient T in addition to varying PA supplies by food plants influence PA storage and PA utilization in larvae and imagines of C. transiens

Insect pheromone biosynthesis: stereochemical pathway of hydroxydanaidal production from alkaloidal precursors in Creatonotos transiens (Lepidoptera, Arctiidae).

The mechanism by which the moth Creatonotos transiens produces its male pheromone, (7R)-hydroxydanaidal, from heliotrine, an alkaloidal precursor of opposite (7S) stereochemistry, was investigated. Specifically deuteriated samples of heliotrine and epiheliotrine were prepared and fed to C. transiens larvae, and the steps in the biosynthetic process were monitored by gas chromatography/mass spectrometry. These analyses indicate that heliotrine is initially epimerized to (7S)-epiheliotrine by oxidation to the corresponding ketone followed by stereospecific reduction. The order of the subsequent steps is (i) aromatization of the dihydropyrrole ring, (ii) ester hydrolysis, and (iii) oxidation of the resulting primary alcohol to the final aldehyde. The ecological implications of this insect's ability (and the inability of another moth, Utetheisa ornatrix) to use representatives of two stereochemical families of alkaloids as pheromone precursors are discussed.

The neuroanatomy of a pharmacophagous insect

The neuroanatomy of the supraoesophageal ganglion and suboesophageal ganglion of larval Creatonotos transiens (Lepidoptera: Arctiidae) was investigated to obtain a three-dimensional model of the brain. Central projections of antennal and maxillary sensory structures were traced using methods of cobalt diffusion. The majority of antennal axons project to the larval antennal centre in the supraoesophageal ganglion, whereas the major region to which the maxillary inputs project lies within the suboesophageal ganglion.

Molecular basis for the insensitivity of the Monarch ( Danaus plexippus) to cardiac glycosides

The Monarch ( Danaus plexippus) sequesters cardiac glycosides for its chemical defence against predators. Larvae and adults of this butterfly are insensitive towards dietary cardiac glycosides, whereas other Lepidoptera, such as Manduca sexta and Creatonotos transiens are sensitive and intoxicated by ouabain. Ouiabain inhibits the Na +,K +-ATPase by binding to its α-subunit. We have amplified and cloned the DNA sequence encoding the respective ouabain binding site. Instead of the amino acid asparagine at position 122 in ouabain-sensitive insects, the Monarch has a histidine in the putative ouabain binding site, which consists of about 12 amino acids. This change may explain the ouabain insensitivity.

Time-Course of Pyrrolizidine Alkaloid Processing in the Alkaloid Exploiting Arctiid Moth, Creatonotos transiens

Abstract The processing of dietary pyrrolizidine alkaloids by larvae and adults of the arctiid moth Creatonotos transiens was studied in time-course experiments: In larvae, pyrrolizidine alkaloid uptake is quickly followed by the transformation of the alkaloids into their N-oxides. Further- more, if 7 S-heliotrine is applied, a stereochemical inversion of the hydroxyl group at C 7 to 7 R-heliotrine can be observed within 48 h of feeding. The rate of this biotransformation is substantially higher in males which use the 7 R-form later as a precursor for the biosynthesis of 7 R-hydroxydanaidal, a pheromone. The resorbed pyrrolizidine alkaloids are deposited in the integument within 48 h, where they remain stored during the larval, pupal and partly also the imaginal stages. Virtually no alkaloids are lost during ecdysis. Some pyrrolizidine alkaloids can be recovered from the meconium which is released at eclosion by the imagines especially when disturbed. In the adults pyrrolizidine alkaloids are processed in different ways by the two sexes: In females, about 50-80% of total alkaloids are transferred from the integument to the ovaries and the eggs within 2 - 3 days after eclosion. If females mate with alkaloid-rich males they additionally receive with the spermatophore up to 290 jig pyrrolizidine alkaloid, which are further translocated to the eggs. A biparental endowment of eggs with acquired defence alkaloids is thus achieved. In males, 30-50% of pyrrolizidine alkaloids remain in the integu- ment; about 10 - 30% are transferred to the scent organ, the corema, where they are converted into 7 R-hydroxydanaidal. Another part (about 40%) is passed to the spermatophore. In the laboratory experiments, the sizes of the coremata and their respective 7 R-hydroxydanaidal contents are strongly dependent on the availability of dietary pyrrolizidine alkaloids during L6 and especially L7 stages. In the L7 stage even short-term feeding (4-6 h) on Senecio jaco- haea is sufficient to induce large coremata.

Organ Specific Storage of Dietary Pyrrolizidine Alkaloids in the Arctiid Moth Creatonotos transiens

Abstract Larvae of the arctiid moth Creatonotos transiens obtained each 5 mg of heliotrine, a pyrrolizidine alkaloid, via an artificial diet. 7 S-H eliotrine is converted into its enantiomer, 7 R1-heliotrine, and some minor metabolites, such as callimorphine. 7 S- and 7 R-heliotrine are present in the insect predominantly (more than 97%) as their N-oxides. The distribution of heliotrine in the organs and tissues of larvae, prepupae, pupae and imagines was analyzed by capillary gas-liquid chromatography. A large proportion of the alkaloid is stored in the integument of all developmental stages, where it probably serves as a chemical defence compound against predators. Female imagines had transferred substantial amounts of heliotrine to their ovaries and subsequently to their eggs; males partly directed it to their pheromone biosynthesis.

Transformation of plant pyrrolizidine alkaloids into novel insect alkaloids by Arctiid moths (Lepidoptera)

Two new pyrrolizidine alkaloids (PAs) were isolated from adults of Creatonotos transiens, the larvae of which had ingested retronecine or ester alkaloids. The structures were elucidated by GC-MS and 1H and 13C NMR spectroscopy as 0 9-(2- hydroxy-3- methylpentanoyl)- retronecine (creatonotine) and its isomer O 7-(2- hydroxy-3- methylpentanoyl)- retronecine (isocreatonotine). The 2-hydroxy-3-methylpentanoic acid obtained by hydrolysis of the creatonotines is the 2S,3S- stereoisomer . The creatonotines as well as accompanying trace amounts of callimorphine were shown to be synthesized by both sexes from dietary retronecine by esterification. If Creatonotos larvae had been fed with Gynura scandens as PA source, the insect PAs accounted for about 75% of total PAs isolated from adults, indicating that Creatonotos degraded plant PAs and subsequently re-esterified the resulting retronecine. This work provides definitive proof that an arctiid moth is able to hydrolyse plant ester alkaloids and re-esterify the resulting necine base with acids which are intermediates of insect metabolism. PAsisolated from Creatonotoswere exclusively present in the form of their N- oxides .

Dorsal ocelli and light-induced diurnal activity patterns in the arctiid moth Creatonotos transiens

The control of the dual mating system (both males and females produce pheromone) was investigated using continuous measurements of oxggen consumption. Luring activity started some time after the ambient light fell below a certain threshold and also when day-night cycles were shortened considerably. Two to three hours later the activity decreased and oxygen consumption returned to a rather constant resting level. Rates of oxygen consumption are compared with those of other animals. Occlusion of the dorsal ocelli induced a significant delay in onset of activity. This delay was different in both sexes, and their periodicity tended to level off at low light intensities. Periodical changes of the external light level are obviously the predominant entraining factor, as untreated moths showed rather weak indications for a free running periodicity under continuous light or darkness. Males with occluded ocelli could be re-synchronized by small light changes following permanent light.

Biosynthesis of Pyrrolidine Alkaloid-Derived Pheromones in the Arctiid Moth, Creatonotos transiens: Stereochemical Conversion of Heliotrine

Abstract In larvae and later developmental stages of Creatonotos transiens, which had been reared on the pyrrolizidine alkaloid 7S-heliotrine, a new major metabolite was detected by capillary GLC. The structure of this metabolite was determined by GLC-MS (EI, CI-MS) and 13C NMR to be 7Rheliotrine and 7R-heliotrine-N-oxide. 7R-Heliotrine is likely to be the direct precursor for the pheromone R( - )-hydroxydanaidal.

Stereochemical course of pheromone biosynthesis in the arctiid moth, Creatonotos transiens.

The biosynthetic conversion of a pyrrolizidine alkaloid (heliotrine, IV) to a male moth pheromone (hydroxydanaidal, III) is found to proceed with inversion of configuration at the remaining asymmetric center (C-7).