Double-countershading as a means of camouflage in larvae of Orange-tip Anthocharis cardamines (Linnaeus, 1758) (Lepidoptera: Pieridae)

In Shaw & Otto (2020), Shaw described larvae of the butterfly, Orange-tip Anthocharis cardamines (Linnaeus, 1758), that were visually obvious yet apparently immune to bird predation. He speculated that mustard oils in the foodplants may render them distasteful to birds so that being conspicuous is of little consequence, allowing them to bask in sunshine possibly to aid digestion. In contrast, I argue that in certain lighting conditions larger larvae of Orange-tip can be very well camouflaged. These two different defence mechanisms are not mutually exclusive and each may come into play under different conditions of lighting, larval age and/or food-plant availability. For disguise the larvae make use of double-countershading in what Süffert (1932) called the 'two-surface effect'. Here I briefly describe its mechanism along with that of the better-known ordinary (single) countershading. Photographs are shown of both.

Chemical Profiling of Roasted Mustard Oils of Khokana, Nepal

Background: Khokana, commonly known as “the living museum” of Nepal is famous for “the roasted mustard oil”. People have been using oil for a long time ago and it is trusted that roasted mustard oil has many health benefits. Detail chemical profiling of roasted mustard oil of Khokana has not been reported yet. Objectives: Detail chemical profiling of roasted mustard oil and chemical variations in different seeds available for roasting. Methods: Three different roasted mustard oils (Nepali, Indian, and other origins seeds) were taken for chemical profiling of oil. The GC/MS of all samples was analyzed by the gas chromatography-mass spectrometer Shimadzu GCMS-QP2010 Ultra. Results: The GC/MS of all samples were carried out and the GC-MS analysis revealed that Nepali (brown seed) and other origins (yellow seed) sample showed erucic acid as a major compound with almost 40-50%. Nepali oil showed gamma-tocopherol (<1%) which is a potent antioxidant. Whereas Indian mustard (black seed) oil showed cis-oleic acid as a major compound with 50-60% and Erucic acid was below 1% in Indian seed oil.

Olfactory receptors tuned to volatile mustard oils in drosophilid flies

Plant toxins are effective defenses because they are aversive to enemies. The same molecules, however, are co-opted as host-finding cues by specialist herbivores. Although such behavioral shifts are central to our understanding of herbivorous insect diversification, it is not well understood how they evolve. We addressed this in Scaptomyza flava, a herbivorous drosophilid fly within a lineage that shifted to feeding on toxic mustard plants (Brassicales) <10 million years ago. S flava lost the ancestral attraction to yeast volatiles and the attendant chemoreceptors that detect these odors. Here we report that S. flava, but not its close microbe-feeding relatives Drosophila melanogaster and S. pallida, is attracted to mustard host-plant odors, including volatile mustard oils (isothiocyanates or ITCs). Our genomic analysis uncovered three S. flava paralogs of an olfactory receptor gene (Or67b) that likely experienced positive selection. We then tested whether these chemoreceptors could underlie the observed attraction to volatile ITCs. Our in vivo recordings revealed that two of the S. flava Or67b proteins (Or67b1 and Or67b3) – but not the homologous Ors from microbe-feeding relatives – responded selectively and sensitively to volatile ITCs. These Ors are the only ITC chemoreceptors other than TRP channel family members (e.g., the TrpA1 ‘wasabi’ receptor) known from animals. Remarkably, S. flava Or67b3 was sufficient to drive olfactory attraction toward butyl ITC when expressed in an attractive olfactory circuit. Our study illuminates that ancestrally aversive chemicals can be co-opted as attractants through gene duplication, leading to the origin of hedonic valence shifts in herbivorous insects.Significance StatementPlant toxins trigger aversive olfactory (volatile-mediated) and gustatory (contact-mediated) responses in animals. Paradoxically, toxic plants are colonized by specialist insects that co-opt toxins as host-plant finding cues. The mechanisms underlying these behavioral shifts, from indifference or repulsion, to attraction, remain unclear. To address this, we used a fly lineage, Scaptomyza flava, that switched from yeast-feeding to feeding on mustard plants less than 10 million years ago. We found that S. flava is attracted to mustard-plant odors and volatile mustard oils (isothiocyanates or ITCs) such as ‘wasabi’, a behavior enabled by the evolution of genes encoding odorant receptors highly sensitive to ITCs. Our study illuminates how insects colonize toxic host plants through duplication and ecological repurposing of genes encoding pre-existing chemoreceptors.

Evolution of herbivory remodels a Drosophila genome

ABSTRACTOne-quarter of extant Eukaryotic species are herbivorous insects, yet the genomic basis of this extraordinary adaptive radiation is unclear. Recently-derived herbivorous species hold promise for understanding how colonization of living plant tissues shaped the evolution of herbivore genomes. Here, we characterized exceptional patterns of evolution coupled with a recent (<15 mya) transition to herbivory of mustard plants (Brassicaceae, including Arabidopsis thaliana) in the fly genus Scaptomyza, nested within the paraphyletic genus Drosophila. We discovered a radiation of mustard-specialized Scaptomyza species, comparable in diversity to the Drosophila melanogaster species subgroup. Stable isotope, behavioral, and viability assays revealed these flies are obligate herbivores. Genome sequencing of one species, S. flava, revealed that the evolution of herbivory drove a contraction in gene families involved in chemosensation and xenobiotic metabolism. Against this backdrop of losses, highly targeted gains (“blooms”) were found in Phase I and Phase II detoxification gene sub-families, including glutathione S-transferase (Gst) and cytochrome P450 (Cyp450) genes. S. flava has more validated paralogs of a single Cyp450 (N=6 for Cyp6g1) and Gst (N=5 for GstE5-8) than any other drosophilid. Functional studies of the Gst repertoire in S. flava showed that transcription of S. flava GstE5-8 paralogs was differentially regulated by dietary mustard oils, and of 22 heterologously expressed cytosolic S. flava GST enzymes, GSTE5-8 enzymes were exceptionally well-adapted to mustard oil detoxification in vitro. One, GSTE5-8a, was an order of magnitude more efficient at metabolizing mustard oils than GSTs from any other metazoan. The serendipitous intersection of two genetic model organisms, Drosophila and Arabidopsis, helped illuminate how an insect genome was remodeled during the evolutionary transformation to herbivory, identifying mechanisms that facilitated the evolution of the most diverse guild of animal life.SIGNIFICANCE STATEMENTThe origin of land plants >400 million years ago (mya) spurred the diversification of plant-feeding (herbivorous) insects and triggered an ongoing chemical co-evolutionary arms race. Because ancestors of most herbivorous insects first colonized plants >200 mya, the sands of time have buried evidence of how their genomes changed with their diet. We leveraged the serendipitous intersection of two genetic model systems: a close relative of yeast-feeding fruit fly (Drosophila melanogaster), the “wasabi fly” (Scaptomyza flava), that evolved to consume mustard plants including Arabidopsis thaliana. The yeast-to-mustard dietary transition remodeled the fly’s gene repertoire for sensing and detoxifying chemicals. Although many genes were lost, some underwent duplications that encode the most efficient detoxifying enzymes against mustard oils known from animals.

Quality and vitamin A status assessment of different commercial edible oil

The present study was done to evaluate the quality and the vitamin A fortification status of 5 types of commercial edible oils sold in Dhaka city markets. The percentages of free fatty acid (FFA), peroxide value (POV), iodine value (IV) and fatty acid composition were estimated to evaluate the quality and vitamin A content were determined to evaluate the vitamin A fortification status of 25 commercial edible oils- soybean oil, sunflower oil, rice bran oil, mustard oil and palm olein (5 brands of each) . The results revealed that FFA, POV and IV of the commercial oils analyzed were within the BSTI standard limits. The highest saturated fatty acids (SFA) values ranging from 39.85 ± 0.005 to 46.97 ± 0.002 % was found in palm olein samples and the lowest SFA values ranging from 4.56 ± 0.031 to 6.97 ± 0.096 % was found in mustard oils. On the other hand, mustard oils contained highest monounsaturated fatty acids (MUFA) ranging from 69.30 ± 0.189 to 75.87 ± 0.069 % compared to other oils analyzed. Highest polyunsaturated fatty acids (PUFA) were recorded in sunflower oils 64.78 ± 0.035% followed by soybean oils 63.25 ± 0.245%. In addition, except sunflower and mustard oils, vitamin A was found in all the soybean and rice bran oils analyzed. On the contrary, vitamin A was found only in 60% of the palm olein samples analyzed and the content was much lower than the standard value (15-30 ppm). Bangladesh J. Sci. Ind. Res.54(1), 11-20, 2019