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Skin-piercing blood-sucking moths I: ecological and ethological studies on Calpe eustrigata (Lepid., noctuidae).

The Noctuid Calpe [Calyptral] eustrigata Hmps. was reported as a skin-piercing blood-sucking moth for the first time in Malaya (Bänziger, 1968) and is so far the only lepidopteran proved to suck blood by means of a piercing act. A few field observations and the description of the piercing behaviour of caged moths were given. Apart from a taxonomic study of the genus Calpe (Berio, 1956), a single record (Büttiker, 1969) and some notes on the moth's proboscis and possible evolutionary pathway (Bänziger, 1970, 1971, 1972) to our knowledge no other data have been published on the moth after its description as a new species (Hampson, 1926). The life cycle is completely unknown. From the scanty museum specimens available, it appears that the species inhabits South and Southeast Asia. A closely related, though less rare species, the fruit-piercing C. thalictri Bkh., has been used for a detailed study of the piercing mechanism likely to be adopted by Calpe (Bänziger, 1970); the feeding turned out to be as unusual as the feeding habits. Little or nothing is known about other Calpe species. C. eustrigata is not the only adult lepidopterous parasite of mammals. Lachryphagous ("eye-frequenting") moths feed as "marginal" parasites upon eye-secretions of ungulates, elephants and occasionally man (Shannon, 1928; Reid, 1954; Büttiker, 1964, 1967; Bänziger, 1966). Arcyophora species and the eulachryphagous Noctuid Lobocraspis graseifusa Hmps. which apparently feeds exclusively upon eye discharges, are suspected as vectors of eye diseases (Guilbride et al., 1959, Büttiker, 1964; Bänziger, 1972). While no lachryphagous moth is able to suck blood by a piercing act, there are a number of facultative lachryphagous moths which lick up the blood freely present at wounds, or that excreted anally by mosquitoes (Bänziger, 1969, 1972). Because of the scientific interest in C. eustrigata, research has been carried out to investigate different biological aspects of the species in Malaysia, Thailand. Laos and Indonesia (May 1971-May 1973). The first account presented here will be continued with a paper (in prep.) on the piercing mechanism and soon, it is hoped, with more information on the physiology, life cycle and medical importance of the moth.

Adaptation, Biological

Skin-piercing blood-sucking moths II: Studies on a further 3 adult Calyptra [Calpe] sp. (Lepid., Noctuidae).

1. Of the scarce Calyptra minuticornis, C. orthograpta and C. labilis, 51, 24, and 7 adults, respectively, were observed during some 600 night inspections at over 100 sites in 1965--1967 and 1971--1977. 2. Hitherto biologically completely unknown, and not recorded before in S.E. Asia, the latter two species flew in or near tropical monsoon forests in hilly regions (300--600 m) of N. Thailand (C. orthograpta also N. Laos). C. minuticornis was found in these and in tropical evergreen and semi-evergreen rain forests of S. Thailand and N.W. Malaysia. 3. In N. Thailand the three species were more common at the end of the cool season/start of the hot season and at the start of the rainy season. They were active mainly during the first half of the night 4. Flight and piercing behaviour, alighting, resting, enemies, and the lack of females, were similar to virtually identical with the "classical" skin-piercing blood-sucking C. eustrigata. 5. C. labilis was seen attacking elephant, C. orthograpta also water buffalo and sambar, C. minuticornis also zebu and tapir but not sambar. C. minuticornis settled on man also but did not pierce. 6. Through no piercing of hosts' skin has actually been seen in nature, indirect evidence suggests that the 3 moths are likely to be occasional blood-suckers. They pierced and sucked blood from the author's skin in experiments. 7. Reasons for lack of direct evidence may be: less developed hematophagy, less favoured hosts, lack of easy-to-pierce injured skin (which also trigger the piercing response), different climatic and phytoecological environment, fewer specimens than in the case of C. eustrigata. 8. Field observations and experiments indicate that the closely related, fruit-piercing Oraesia emarginata is not skin-piercing blood-sucking--a habit likely to be exhibited mainly in humid equatorial regions by a few Calyptra only.

Animals

Cytochemical studies on the PAS-positive and metachromatic substances in the cells of enteric epithelium of Achoea janata (Noctuidae: Lepidoptera).

Of the different polysaccharides present in the cells of insects the PAS-positive and metachromatic substances were studied in the cells of the enteric epithelium of the moth Achoea janata during its larval period and following metamorphosis. The amounts of both the substances progressively decrease in sequential pupal stages. The reaction intensity at the cell apex is higher than at the cell periphery. Reduction in the amount of carbohydrate material in the epithelial cells of the mid-gut is associated with change in intracellular localization (by vanishing from definite sites, not by migration). The loss of metachromatic substances is, however, more rapid than that of PAS-positive ones in the cells of the same region. It appears likely that there are simultaneous conversions of both kinds of substances into chitin precursors, independent of each other. No movement of these substances for the chemical change to be accomplished at specific sites in the cell is found. Association of PAS-positive substances with the formation of peritrophic membrane has been discussed.

Animals

2-Phenylethanol, a presumed sexual stimulant produced by the male cabbage looper moth, Trichoplusia ni.

A sex pheromone produced by male cabbage looper moths, Trichoplusia ni (Hübner), has been isolated from the genital scent brushes and identified as 2-phenylethanol. It is shown conclusively to elicit specific behavioural responses in the female (such as wing vibration and abdominal elevation), as determined by a novel behavioural laboratory bioassay. This is taken as further evidence that the male pheromone of T. ni acts as a sexual stimulant (aphrodisiac) prior to mating. 2-Phenylethanol represents the first identification of a genital scent brush pheromone in the family Noctuidae, and of a male pheromone in the subfamily Plusiinae.

Action Potentials

Genome-wide identification of olfactory receptor and odorant-binding protein gene families and their roles in Heliothine chemosensory evolution.

Chemosensory systems play key roles in the survival and reproductive success of insects. Two large and diverse chemosensory gene families, odorant receptors (ORs) and odorant-binding proteins (OBPs), play critical roles in insect chemosensation and mediate odour-guided behaviours. In the process of insect chemosensation, odorants from the environment pass through pores in the antennal sensilla and become soluble in the sensillar lymph, either directly on contact or by binding to an OBP. Solubilized odour molecules diffuse through the lymph until they reach and activate their cognate ORs, sending electrophysiological signals to the insect brain. To better understand the evolutionary roles of OR and OBP gene families among members of the Heliothinae, we systematically characterized these two gene families in Chloridea virescens (Lepidoptera: Noctuidae). A total of 81 ORs and 49 OBPs were identified genome-wide. Based on the number and positions of conserved cysteine residues, the OBPs were classified into three types: 34 Classic OBPs, 8 Minus-C OBPs and 7 Plus-C OBPs. Phylogenetic analyses identified potential gene duplications and losses within OR and OBP gene families among members of the Heliothinae, which may be associated with differences in their volatile sensation and olfactory behaviours. Further motif and structural analyses identified a conserved region that was unique among pheromone receptors and predicted as key residues of the binding pocket, implying its critical role in pheromone detection. Future work should focus on experimentally validating its function. Overall, our findings provide important insights into how chemosensory gene evolution contributes to ecological adaptation and reproductive isolation in the Heliothine moths.

Animals

Isolation of genotypic variants of Autographa californica nuclear polyhedrosis virus.

A nuclear polyhedrosis virus (MNPV) isolated from a lepidopteran (Noctuidae) insect, Autographa californica, was cloned by successive plaque purification using virions containing only one nucleocapsid per envelope as inoculum. The ability to clone the virus by this method was demonstrated by the isolation of nondefective, genotypic variants of the virus with similar but not identical restriction endonuclease fragment patterns. Five distinct variants were identified by genotypic analysis with HindIII, EcoRI, SalI, and Bam HI restriction endonucleases. The characteristic genotype of each variant was maintained upon passage in insect larvae. The isolation of these virus variants demonstrates (i) the heterogeneity of the uncloned virus preparation and (ii) the ability to clone MNPVs by plaque purification of media-derived nonoccluded virions. The A. californica MNPV is being considered for commercial use as a pesticide in the United States, and the cloning of the virus, in view of the heterogeneity detected, may be advisable. The cloning and genotype analyses are also significant with regard to understanding the genetic nature of multiply embedded NPVs (those NPVs containing more than one nucleocapsid per envelope in the occluded form of the virus) and indicate that further genetic analysis of these viruses is possible.

Animals

The genome sequence of the Autumnal Rustic, Eugnorisma glareosa (Esper, 1788).

We present a genome assembly from an individual male Eugnorisma glareosa (the Autumnal Rustic; Arthropoda; Insecta; Lepidoptera; Noctuidae). The genome sequence is 631.0 megabases in span. Most of the assembly is scaffolded into 30 chromosomal pseudomolecules, including the Z sex chromosome. The mitochondrial genome has also been assembled and is 15.39 kilobases in length. Gene annotation of this assembly on Ensembl identified 19,768 protein coding genes.

Autumnal Rustic

The genome sequence of the Six-striped Rustic, Xestia sexstrigata (Haworth, 1809).

We present a genome assembly from an individual female Xestia sexstrigata (the Six-striped Rustic; Arthropoda; Insecta; Lepidoptera; Noctuidae). The genome sequence is 638.3 megabases in span. Most of the assembly is scaffolded into 32 chromosomal pseudomolecules, including the W and Z sex chromosomes. The mitochondrial genome has also been assembled and is 15.36 kilobases in length. Gene annotation of this assembly on Ensembl identified 15,104 protein coding genes.

Lepidoptera

The genome sequence of the Alder Moth, Acronicta alni (Linnaeus, 1767).

We present a genome assembly from a male Acronicta alni (Alder Moth; Arthropoda; Insecta; Lepidoptera; Noctuidae). The assembly contains two haplotypes with total lengths of 470.37 megabases and 472.86 megabases. Most of haplotype 1 (98.95%) is scaffolded into 31 chromosomal pseudomolecules, including the Z chromosome. Haplotype 2 was assembled to scaffold level. The mitochondrial genome has also been assembled and is 15.38 kilobases in length.

Acronicta alni

Structure-response relationships in noctuid sex pheromone reception. An introductory report.

Electroantennogram (EAG) data reflecting response spectra of male pheromone receptors have been analyzed for 16 species of Noctuidae (Lepidoptera). The test compounds included 100 pheromone analogues, altered in chain length, in position and configuration of double bond(s), and in the functional end groups. On comparison of amounts of substance required to elicit an equivalent EAG response, a single compound was determined to be most effective on a given species: these structures, either known or proposed as the natural sex pheromones of the species, were cis-7-dodecen-1-y1 acetate, cis-7-tetradecen-1-y1 acetate, cis-9-tetradecen-1-yu acetate, trans-9-tetradecen-1-y1 acetate, cis-11-hexadecen-1-y1 acetate, cis-9, trans-12-tetradecadien-1-y1 acetate, cis-9-tetradecen-1-y1 formate, and cis-9-tetradecen-1-ol, respectively. Elongation (shortening) of the chain by 1 or 2 methylene groups, the movement of a double bond 1 carbon from the optimum, a change to the opposite geometrical isomer, or the introduction of a second double bond invariably reduced EAG responses to 1.8 to 56 times below that observed with the most stimulating compound, in all 16 species. Further alterations in chain length or in double bond position caused even greater reduction in activity, as did certain in end group (Tables I and II). A set of distinct rules could be derived from these structure-response relationships; one of these rules concerns the optimum position of the double bond(s) in relation to chain length, and another one the ratios in activity values produced by end group variations, irrespective of chain length. The same rules described here for 16 noctuid species held also for the structure-response relationships observed within various additional groups of Lepidoptera. From EAG values determined in this study, an attempt has been made to calculate physicochemical propteries of underlying acceptor structures.

Animals

Competition between species of the aestivo-autumnal group of birch pests for food in Transuralia.

The aestivo-autumnal group of birch pests includes 25 species belong to the Notodontidae, Geometridae, Noctuidae, and other families. The larvae of all its species hatch out in mid-July and feed until the end of August. On emerging from the eggs they spread from leaf to leaf, but as the food supply diminishes they crowd together and competition is intensified. The species structure of the group shows some variation over the territory, and only a few species dominate, different species in different places. It is suggested that improvement in the food supply leads to mass reproduction. Biochemical investigations confirmed this hypothesis: different species feeding on the same leaf assimilate different amino acids more completely, and their relative numbers on the leaves vary in different parts and at different times. The composition of secondary metabolites important for resistance of the plants also varies.

Ecology

Paradigm shift for cry gene expression in Bacillus thuringiensis.

In most Bacillus thuringiensis strains, the cry genes are transcribed by RNA polymerases containing sporulation-sigma factors E or K, leading to the formation of an insecticidal crystal within the mother cell along spore development. The kurstaki HD1 strain, a parent of commercial strains, also releases the insecticidal proteins Cry1I and Vip3A in the extracellular medium. vip3A expression is activated by the transcriptional regulator VipR at the onset of the stationary phase. Here, we expanded the VipR regulon in strain HD1 by identifying the VipR-binding box upstream from the cry2Aa, cry2Ab, and cry1Ia genes, and conducting transcription assays. Unexpectedly, a VipR box was located in the promoter of a putative N-acetylmuramoyl-l-alanine amidase (ami) gene upstream from cry1Ac in strain kurstaki HD73, closely related to the HD1 but devoid of vipR. Introduction of vipR in this strain led to the expression of the ami-cry1Ac operon, resulting in an early and increased production of Cry1Ac. We demonstrated that Cry1Ac was also produced in a VipR-dependent manner in an HD73 ∆spo0A mutant. Similarly, an HD1 ∆spo0A strain produces all the insecticidal proteins encoded in its genome, including cry2Ab, previously considered unexpressed. A genomic analysis also revealed the presence of putative VipR-binding sequences in lepidopteran-active strains, upstream from cry genes such as cry1E, cry1F, cry9D, and cry9E. Overall, our results break the dogma on the regulation of cry1A and cry2A genes and provide evidence of sporulation-independent Cry toxin production in biopesticidal Bt strains.IMPORTANCEBacillus thuringiensis is a remarkably efficient entomopathogen due to its ability to produce various insecticidal proteins, such as Cry or Vip. This property has made it a highly effective biopesticide used worldwide. Our work modifies the paradigm of cry1 and cry2 genes being regulated solely by sporulation-specific sigma factors and thus exclusively expressed during this process. Indeed, we demonstrated that the VipR regulator controls the transcription of vip3Aa, cry2Aa, cry2Ab, cry1Ia, and the ami-cry1A operons encoded by a strain closely related to that of commercial biopesticides and specifically turns on their expression from the onset of the stationary phase, leading to the production of insecticidal crystals independently of sporulation. By providing new knowledge on the regulation of insecticidal protein genes, these findings bring new insight for the genetic improvement of Bt strains used as commercial biopesticides.

Bacillus thuringiensis