The Functional Morphology of the Bursa Copulatrix of a Butterfly That Does Not Digest Spermatophores (Leptophobiaaripa, Pieridae).

The bursa copulatrix of female Lepidoptera is a complex organ where crucial male-female reproductive interactions occur during and after copulation. The bursa copulatrix receives, stores, and digests the spermatophore and other substances transferred by the male during copulation, and is involved in changes in female receptivity, ovogenesis, and oviposition. Although females of the butterfly Leptophobia aripa do not digest the spermatophore, they possess a prominent signum. Since, in general, the function of the signum is considered to be the piercing or tearing of the spermatophore to initiate its digestion, its presence in L. aripa poses a conundrum. We undertook a microscopic study of the different components of the bursa copulatrix (ductus bursae and corpus bursae) and found structural differences that we interpreted in functional terms. We provide a detailed description of the signum and present experimental data regarding its effect on the spermatophore. Our observations led us to propose a novel hypothesis regarding the function of the signum.

Distal-less and spalt are distal organisers of pierid wing patterns.

Two genes, Distal-less (Dll) and spalt (sal), are known to be involved in establishing nymphalid butterfly wing patterns. They function in several ways: in the differentiation of the eyespot's central signalling cells, or foci; in the differentiation of the surrounding black disc; in overall scale melanisation (Dll); and in elaborating marginal patterns, such as parafocal elements. However, little is known about the functions of these genes in the development of wing patterns in other butterfly families. Here, we study the expression and function of Dll and sal in the development of spots and other melanic wing patterns of the Indian cabbage white, Pieris canidia, a pierid butterfly. In P. canidia, both Dll and Sal proteins are expressed in the scale-building cells at the wing tips, in chevron patterns along the pupal wing margins, and in areas of future scale melanisation. Additionally, Sal alone is expressed in the future black spots. CRISPR knockouts of Dll and sal showed that each gene is required for the development of melanic wing pattern elements, and repressing pteridine granule formation, in the areas where they are expressed. We conclude that both genes likely play ancestral roles in organising distal butterfly wing patterns, across pierid and nymphalid butterflies, but are unlikely to be differentiating signalling centres in pierids black spots. The genetic and developmental mechanisms that set up the location of spots and eyespots are likely distinct in each lineage.

Genetic analysis reveals three novel QTLs underpinning a butterfly egg-induced hypersensitive response-like cell death in Brassica rapa.

BACKGROUND: Cabbage white butterflies (Pieris spp.) can be severe pests of Brassica crops such as Chinese cabbage, Pak choi (Brassica rapa) or cabbages (B. oleracea). Eggs of Pieris spp. can induce a hypersensitive response-like (HR-like) cell death which reduces egg survival in the wild black mustard (B. nigra). Unravelling the genetic basis of this egg-killing trait in Brassica crops could improve crop resistance to herbivory, reducing major crop losses and pesticides use. Here we investigated the genetic architecture of a HR-like cell death induced by P. brassicae eggs in B. rapa. RESULTS: A germplasm screening of 56 B. rapa accessions, representing the genetic and geographical diversity of a B. rapa core collection, showed phenotypic variation for cell death. An image-based phenotyping protocol was developed to accurately measure size of HR-like cell death and was then used to identify two accessions that consistently showed weak (R-o-18) or strong cell death response (L58). Screening of 160 RILs derived from these two accessions resulted in three novel QTLs for Pieris brassicae-induced cell death on chromosomes A02 (Pbc1), A03 (Pbc2), and A06 (Pbc3). The three QTLs Pbc1-3 contain cell surface receptors, intracellular receptors and other genes involved in plant immunity processes, such as ROS accumulation and cell death formation. Synteny analysis with A. thaliana suggested that Pbc1 and Pbc2 are novel QTLs associated with this trait, while Pbc3 also contains an ortholog of LecRK-I.1, a gene of A. thaliana previously associated with cell death induced by a P. brassicae egg extract. CONCLUSIONS: This study provides the first genomic regions associated with the Pieris egg-induced HR-like cell death in a Brassica crop species. It is a step closer towards unravelling the genetic basis of an egg-killing crop resistance trait, paving the way for breeders to further fine-map and validate candidate genes.

Spatio-Temporal Evolutionary Patterns of the Pieridae Butterflies (Lepidoptera: Papilionoidea) Inferred from Mitogenomic Data.

Pieridae is one of the largest and almost cosmopolitan groups of butterflies, which plays an important role in natural ecosystems; however, to date, its phylogeny and evolutionary history have not been fully resolved. In this study, we obtained the complete or nearly complete mitochondrial genomes of 100 pierid taxa (six newly sequenced, sixty extracted from the whole-genome data, and thirty-four directly available from GenBank). At the same time, for the first time, we conducted comparative mitogenomic and phylogenetic analyses based on these mitogenomic data, to further clarify their spatio-temporal evolutionary patterns. Comparative mitogenomic analysis showed that, except for cox2, the GC content of each of the 13 protein-coding genes (PCGs) in the rapidly diverging subfamily Pierinae was higher than in its sister group Coliadinae. Moreover, the dN/dS values of nine genes (atp6, atp8, cox1, cox3, cob, nad1, nad3, nad5, and nad6) in Pierinae were also relatively higher than those in its sister group, Coliadinae. Phylogenetic analysis showed that all the resultant phylogenetic trees were generally in agreement with those of previous studies. The Pierinae family contained six clades in total with the relationship of (Leptosiaini + (((Nepheroniini + Arthocharidini) + Teracolini) + (Pierini + Elodini))). The Pieridae originated in the Palearctic region approximately 72.3 million years ago in the late Cretaceous, and the subfamily Pierinae diverged from this family around 57.9 million years ago in the Oriental region, shortly after the K-Pg mass extinction event; in addition, the spatio-temporal evolutionary patterns of Pierinae were closely correlated with geological events and environmental changes, as well as the host plant coevolutionary scenario in Earth's history. However, some incongruencies were observed between our results and those of previous studies in terms of shallow phylogenies for a few taxa, and should be further investigated.

Innate and learnt color preferences in the common green-eyed white butterfly (Leptophobia aripa): experimental evidence.

BACKGROUND: Learning abilities help animals modify their behaviors based on experience and innate sensory biases to confront environmental unpredictability. In a food acquisition context, the ability to detect, learn, and switch is fundamental in a wide range of insect species facing the ever-changing availability of their floral rewards. Here, we used an experimental approach to address the innate color preferences and learning abilities of the common green-eyed white butterfly (Leptophobia aripa). METHODS: In Experiment 1, we conducted innate preference choice-tests to determine whether butterflies had a strong innate color preference and to evaluate whether color preferences differed depending on the array of colors offered. We faced naïve butterflies to artificial flowers of four colors (quadruple choice-test): yellow, pink, white, and red; their choices were assessed. In Experiment 2, we examined the ability of this butterfly species to associate colors with rewards while exploring if the spectral reflectance value of a flower color can slow or accelerate this behavioral response. Butterflies were first trained to be fed from artificial yellow flowers inserted in a feeder. These were later replaced by artificial flowers with a similar (blue) or very different (white) spectral reflectance range. Each preference test comprised a dual-choice test (yellow vs blue, yellow vs white). RESULTS: Butterflies showed an innate strong preference for red flowers. Both the number of visits and the time spent probing these flowers were much greater than the pink, white, and yellow color flowers. Butterflies learn to associate colors with sugar rewards. They then learned the newly rewarded colors as quickly and proficiently as if the previously rewarded color was similar in spectral reflectance value; the opposite occurs if the newly rewarded color is very different than the previously rewarded color. CONCLUSIONS: Our findings suggest that common green-eyed white butterflies have good learning abilities. These capabilities may allow them to respond rapidly to different color stimulus.

Phylogenetic relationship and characterization of the complete mitochondrial genome of Colias fieldii (Lepidoptera: Papilionoidea: Pieridae).

Colias fieldii is a common seen diurnal butterflies in the fields and widely distributed in many provinces of China. In this study, we sequenced and analyzed the complete mitochondrial genome (mitogenome) of C. fieldii. This mitogenome was 15,150 bp long and encoded 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), and two ribosomal RNA unit genes (rRNAs). The overall base composition of the mitogenome was estimated to be A 39.8%, T 41.2%, C 11.4% and G 7.6%, with a high A + T content of 81.0%. Except for cox1 started with CGA, all other PCGs started with the standard ATN codons (seven ATG, four ATT and one ATC). Most of the PCGs terminated with the stop codon TAA or TAG, whereas cox1, cox2, nad5 and nad4 end with the incomplete codon T--. Phylogenetic analysis showed that C. fieldii is indeed the sister species of Colias erate with a high support value. All seven Coliadinae species formed one clade and was sister to Pierinae butterflies. Within Coliadinae, the relationships (Eurema + (Gonepteryx + (Catopsilia + Colias))) were highly supported.

Genotype-environment interaction reveals varied developmental responses to unpredictable host phenology in a tropical insect.

Understanding the genetic architecture of life history plasticity may inform resilience under environmental change, but relatively little is known for the inhabitants of unpredictable wet-dry tropical environments. Here, I explore the quantitative genetics of juvenile growth and development relative to hostplant phenology in the butterfly Eurema hecabe. Wet season generations of this species breed explosively on leguminous annuals whereas dry season generations subsist at low density upon an alternative perennial host. The wet-to-dry season transition is temporally unpredictable and marked by widespread host defoliation, forcing a large cohort of stranded larvae to either pupate prematurely or prolong development in the hope of renewed foliage production. A split-brood experiment demonstrated greater performance on high quality annual as opposed to perennial host foliage and a marked decline under the stressed conditions faced by stranded wet season larvae. Genetic variances for rates of growth and development were equivalent among high quality treatments but strikingly elevated under resource stress, and the associated cross-environment genetic correlations were indistinguishable from zero. The results demonstrate genotype-environment interaction involving both rank order and variance scale, thereby revealing genetic variance for norms of reaction that may reflect variable risk aversion given an unpredictable tropical host phenology.

Incomplete Sterility of Chromosomal Hybrids: Implications for Karyotype Evolution and Homoploid Hybrid Speciation.

Heterozygotes for major chromosomal rearrangements such as fusions and fissions are expected to display a high level of sterility due to problems during meiosis. However, some species, especially plants and animals with holocentric chromosomes, are known to tolerate chromosomal heterozygosity even for multiple rearrangements. Here, we studied male meiotic chromosome behavior in four hybrid generations (F1-F4) between two chromosomal races of the Wood White butterfly Leptidea sinapis differentiated by at least 24 chromosomal fusions/fissions. Previous work showed that these hybrids were fertile, although their fertility was reduced as compared to crosses within chromosomal races. We demonstrate that (i) F1 hybrids are highly heterozygous with nearly all chromosomes participating in the formation of trivalents at the first meiotic division, and (ii) that from F1 to F4 the number of trivalents decreases and the number of bivalents increases. We argue that the observed process of chromosome sorting would, if continued, result in a new homozygous chromosomal race, i.e., in a new karyotype with intermediate chromosome number and, possibly, in a new incipient homoploid hybrid species. We also discuss the segregational model of karyotype evolution and the chromosomal model of homoploid hybrid speciation.

Complex multi-modal sensory integration and context specificity in colour preferences of a pierid butterfly.

Innate colour preferences in insects were long considered to be a non-flexible representation of a floral 'search image' guiding them to flowers during initial foraging trips. However, these colour preferences have recently been shown to be modulated by multi-sensory integration of information. Using experiments on the butterfly Catopsilia pomona (common emigrant), we demonstrate that cross-modal integration of information not only affects colour preferences but also colour learning, and in a sex-specific manner. We show that spontaneous colour preference in this species is sexually dimorphic, with males preferring both blue and yellow while females prefer yellow. With minimal training (two training sessions), both males and females learned to associate blue with reward, but females did not learn green. This suggests that the aversion to green, in the context of foraging, is stronger in females than in males, probably because green is used as a cue to find oviposition sites in butterflies. However, females learned green after extensive training (five training sessions). Intriguingly, when a floral odour was present along with green during training, female colour preference during the subsequent choice tests resembled their innate preference (preference for yellow). Our results show that multi-sensory integration of information can influence preference, sensory bias, learning and memory in butterflies, thus modulating their behaviour in a context-specific manner.

Flower orientation in Gloriosa superba (Colchicaceae) promotes cross-pollination via butterfly wings.

BACKGROUND AND AIMS: Complex modifications of angiosperm flowers often function for precise pollen placement on pollinators and to promote cross-pollination. We explore the functional significance of the unusually elaborate morphology of Gloriosa superba flowers, which are divided into one hermaphrodite meranthium and five male meranthia (functional pollination units of a single flower). METHODS: We used controlled pollination experiments, floral measurements, pollen load analyses and visitor observations in four populations of G. superba in South Africa to determine the breeding system, mechanism of pollination and role of flower in the promotion of cross-pollination. KEY RESULTS: We established that G. superba is self-compatible, but reliant on pollinators for seed production. Butterflies, in particular the pierid Eronia cleodora, were the primary pollinators (>90 % of visitors). Butterflies brush against the anthers and stigma during nectar feeding and pollen is carried on their ventral wing surfaces. Butterfly scales were positively correlated with the number of pollen grains on stigmas. We demonstrate that the styles were orientated towards clearings in the vegetation and we confirm that the highest proportion of initial visits was to hermaphrodite meranthia pointing towards clearings. CONCLUSIONS: The flower morphology of G. superba results in effective pollen transfer on the wings of butterfly visitors. The style-bearing hermaphrodite meranthium of the flowers orientates towards open spaces in the vegetation, thus increasing the probability that butterflies land first on the hermaphrodite meranthium. This novel aspect of flower orientation is interpreted as a mechanism that promotes cross-pollination.

Plant responses to butterfly oviposition partly explain preference-performance relationships on different brassicaceous species.

The preference-performance hypothesis (PPH) states that herbivorous female insects prefer to oviposit on those host plants that are best for their offspring. Yet, past attempts to show the adaptiveness of host selection decisions by herbivores often failed. Here, we tested the PPH by including often neglected oviposition-induced plant responses, and how they may affect both egg survival and larval weight. We used seven Brassicaceae species of which most are common hosts of two cabbage white butterfly species, the solitary Pieris rapae and gregarious P. brassicae. Brassicaceous species can respond to Pieris eggs with leaf necrosis, which can lower egg survival. Moreover, plant-mediated responses to eggs can affect larval performance. We show a positive correlation between P. brassicae preference and performance only when including the egg phase: 7-day-old caterpillars gained higher weight on those plant species which had received most eggs. Pieris eggs frequently induced necrosis in the tested plant species. Survival of clustered P. brassicae eggs was unaffected by the necrosis in most tested species and no relationship between P. brassicae egg survival and oviposition preference was found. Pieris rapae preferred to oviposit on plant species most frequently expressing necrosis although egg survival was lower on those plants. In contrast to the lower egg survival on plants expressing necrosis, larval biomass on these plants was higher than on plants without a necrosis. We conclude that egg survival is not a crucial factor for oviposition choices but rather egg-mediated responses affecting larval performance explained the preference-performance relationship of the two butterfly species.

A mitogenomic phylogeny of pierid butterflies and complete mitochondrial genome of the yellow tip Anthocharis scolymus (Lepidoptera: Pieridae).

The yellow tip butterfly Anthocharis scolymus (Lepidoptera: Pieridae) has a circular mitochondrial genome of 15,230 bp in size. It consists 13 protein-coding genes, 22 tRNAs, two ribosomal RNA genes, and an AT-rich control region. Using whole mitogenome alignments, we reconstructed the phylogenetic relationships of 28 pierid butterflies. The maximum-likelihood (ML) tree topology was consistent with previous studies.

Phylogeography and population genetics of pine butterflies: Sky islands increase genetic divergence.

The sky islands of southeastern Arizona (AZ) mark a major transition zone between tropical and temperate biota and are considered a neglected biodiversity hotspot. Dispersal ability and host plant specificity are thought to impact the history and diversity of insect populations across the sky islands. We aimed to investigate the population structure and phylogeography of two pine-feeding pierid butterflies, the pine white (Neophasia menapia) and the Mexican pine white (Neophasia terlooii), restricted to these "islands" at this transition zone. Given their dependence on pines as the larval hosts, we hypothesized that habitat connectivity affects population structure and is at least in part responsible for their allopatry. We sampled DNA from freshly collected butterflies from 17 sites in the sky islands and adjacent high-elevation habitats and sequenced these samples using ddRADSeq. Up to 15,399 SNPs were discovered and analyzed in population genetic and phylogenetic contexts with Stacks and pyRAD pipelines. Low genetic differentiation in N. menapia suggests that it is panmictic. Conversely, there is strong evidence for population structure within N. terlooii. Each sky island likely contains a population of N. terlooii, and clustering is hierarchical, with populations on proximal mountains being more related to each other. The N. menapia habitat, which is largely contiguous, facilitates panmixia, while the N. terlooii habitat, restricted to the higher elevations on each sky island, creates distinct population structure. Phylogenetic results corroborate those from population genetic analyses. The historical climate-driven fluxes in forest habitat connectivity have implications for understanding the biodiversity of fragmented habitats.

The complete mitochondrial genomes of Aporia crataegi, Gonepteryx rhamni, and Appias remedios (Lepidoptera, Pieridae) and phylogenetic relationship of other Pieridae species.

Pieridae is a butterfly family whose higher classification has not yet been settled. In this research, we used completed mitochondrial genome sequence to identify and analyze the relationship of three subfamilies of Pieridae (Dismorphiinae, Coliadinae and Pierinae). We have sequenced the complete mitogenomes of Aporia crataegi, Gonepteryx rhamni, and Appias remedios, which are 15,148 bp, 15,118 bp and 15,223 bp in length, respectively. These three mitogenomes have a typical set of 37 genes and an A+T-rich region. The protein-coding genes, excluding the cox1 gene, in the three mitogenomes are initiated by the typical ATN codons. The putative initiation codon for the cox1 gene in the three species is CGA. tRNA genes in the three Pieridae mitogenomes show typical clover leaf structures, except tRNASer(AGN) which lacks the dihydrouridine (DHU) stem. The length of A+T-rich region varies in the three species, which leads to the variation in the mitochondrial genome size. The characterizations of the three mitogenomes enrich our knowledge on the Lepidopteran mitogenome and provide us genetic information to reconstruct the phylogenetic tree. Finally, the phylogenetic analyses using mitogenome data showed that the relationship among three subfamilies of Pieridae is (Dismorphiinae + (Coliadinae + Pierinae)).

The complete mitochondrial genome of Aporia crataegi L. (Lepidoptera: Pieridae).

The complete mitochondrial genome of Aporia crataegi is 15,147 bp long, and consists of 13 protein-coding genes (PCGs), 2 ribosomal RNA genes, 22 transfer RNA (tRNA) genes, and a putative control region (GenBank accession No. MN371463). The nucleotide composition is significantly biased (A, G, C, and T is 39.66%, 7.30%, 11.41%, and 41.63%, respectively) with A + T contents of 81.29%. All PCGs are initiated by ATG, ATT, and ATC codons. Seven PCGs use a common stop codon of TAA, whereas the remaining six terminated with a single T. The phylogenetic relationships based on maximum-likelihood phylogenetic tree method showed that A. crataegi is closely related to Aporia bieti, Mesapia peloria, and Aporia martineti.

Chorionic sculpture of eggs in the subfamily Dismorphiinae (Lepidoptera: Papilionoidea: Pieridae).

This is the second exploration, comparison, and analysis of the chorion of species (45 sspp.) of the subfamily Dismorphiinae (Pieridae). This study includes nearly 50% of the species of the subfamily, including six of the seven genera in its two subtribes: Leptidea (Leptideini), Enantia, Pseudopieris, Lieinix, Moschoneura, and Dismorphia (Dismorphiini). The material studied originates from more than three dozen localities in six different countries on three continents (America, Asia, and Europe) and two biogeographical regions, the Palearctic and Neotropical, over the last 20 years. We have corrected and added information regarding several morphological aspects of the chorion. The precision of the citriform configuration and the elimination of the meloniform shape in the egg of Dismorphiini were determined with detailed observations on the maturation of the chorion in the ovarioles where each stage appears in a linear sequence. We discerned that the meloniform states correspond to incompletely differentiated or immature eggs. This was confirmed by the study of new samples of Dismorphia amphione, D. eunoe, and D. lewyi. The chorion of Dismorphiinae is basically plesiomorphic with respect to those of Coliadinae and Pierinae because it lacks several typical synapomorphies of these subfamilies, such as the presence of micro-grid and/or perimicropylar and apex differentiation, respectively. The eggs of each Dismorphiinae genus can be diagnosed by a combination of chorionic features, although sometimes by one or more plesiomorphies or apomorphies in each genus, with respect to the form or character states in axes, ribs, and poles in the grid of the three regions of the egg - two polar regions and one equatorial (basal, medial, and apical). Leptidea and Enantia show the most generalized grid pattern; however, two genera retain several plesiomorphies with respect to the undifferentiated axes or a small number of short axes (Pseudopieris), as well as many equidistant ribs (Lieinix). The chorionic grid of Moschoneura, although practically lacking short axes, shows the fewest number of axes in the entire subfamily (eight aligns it with Pseudopieris). The chorionic grid in Dismorphia is highly diverse, as it shows the most derived states; however, it comprises symplesiomorphies or atavisms in two groups of species, which aligns them closer to Lieinix or Pseudopieris, but we do not take them into account in some cases where they are convergences or structural parallelisms. It seems that the combination of the shape and its length:width ratio is correlated with the alar configuration (design, sexual dimorphism, and coloring patterns) and separates three groups of species in Dismorphia, and often correlates with the number of ribs. This also coincides with the Batesian participation in the number of mimetic complexes in which a subgroup of species and their stenoecy are integrated within the primary forests. Finally, two schemes are presented that synthesize and illustrate the changes or progression of the form and chorionic grid in the genera of the subfamily.

Discovery of a rare and striking new pierid butterfly from Panama (Lepidoptera: Pieridae).

We here describe and name a distinctive new pierid species in the subfamily Pierinae, Catasticta sibyllae Nakahara, Padrón MacDonald, n. sp. from western Panama. Catasticta. sibyllae n. sp. is known from only two male specimens collected at two sites which are approximately 130 km apart in western Panama. This new species is the only species in the genus without markings in the median area of both surfaces of forewing and hindwing, and our molecular data suggest that the Peruvian species C. lisa Baumann Reissinger, 1969 is its sister species.

ß-Cyanoalanine Synthases and Their Possible Role in Pierid Host Plant Adaptation.

Cyanide is generated in larvae of the glucosinolate-specialist Pieris rapae (Lepidoptera:Pieridae) upon ingestion of plant material containing phenylalanine-derived glucosinolates as chemical defenses. As these glucosinolates were widespread within ancient Brassicales, the ability to detoxify cyanide may therefore have been essential for the host plant shift of Pierid species from Fabales to Brassicales species giving rise to the Pierinae subfamily. Previous research identified ß-cyanoalanine and thiocyanate as products of cyanide detoxification in P. rapae larvae as well as three cDNAs encoding the ß-cyanoalanine synthases PrBSAS1-PrBSAS3. Here, we analyzed a total of eight species of four lepidopteran families to test if their cyanide detoxification capacity correlates with their feeding specialization. We detected ß-cyanoalanine synthase activity in gut protein extracts of all six species tested, which included Pierid species with glucosinolate-containing host plants, Pierids with other hosts, and other Lepidoptera with varying food specialization. Rhodanese activity was only scarcely detectable with the highest levels appearing in the two glucosinolate-feeding Pierids. We then amplified by polymerase chain reaction (PCR) 14 cDNAs encoding ß-cyanoalanine synthases from seven species. Enzyme characterization and phylogenetic analysis indicated that lepidopterans are generally equipped with one PrBSAS2 homolog with high affinity for cyanide. A second ß-cyanoalanine synthase which grouped with PrBSAS3 was restricted to Pierid species, while a third variant (i.e., homologs of PrBSAS1), was only present in members of the Pierinae subfamily. These results are in agreement with the hypothesis that the host shift to Brassicales was associated with the requirement for a specialized cyanide detoxification machinery.

Toxicity and residual effects of insecticides on Ascia monuste and predator Solenopsis saevissima.

BACKGROUND: Investigating the impact of pesticides on non-target organisms is essential for sustainable integrated pest management programs. We therefore assessed the toxicity of ten insecticides to the brassica caterpillar Ascia monuste and its ant predator Solenopsis saevissima and examined the effect that the insecticide synergists had on toxicity to the predator. We also assessed the residual period of control and impact of the insecticides during the brassica growing cycle. RESULTS: All insecticides except flubendiamide exhibited mortality above the threshold required by Brazilian legislation (80%). Chlorantraniliprole, cyantraniliprole, indoxacarb and spinosad exhibited lower toxicity to the ant predator than they did to the brassica caterpillar. The results obtained for synergized insecticides suggest that selectivity to the predator was due the involvement of cytochrome P450-dependent monooxygenases. Chlorfenapyr and cyantraniliprole exhibited the highest residual periods of control to the brassica caterpillar, whereas malathion had the greatest impact on the predator. CONCLUSION: Most of the insecticides efficiently controlled the brassica caterpillar, but not all exhibited selectivity to the predator. Therefore, due to the distinctive responses of organisms with respect to residual periods of control and the impact of the insecticides, spraying frequency must be strongly considered in integrated pest management programs. © 2017 Society of Chemical Industry.

Complete genome of Pieris rapae, a resilient alien, a cabbage pest, and a source of anti-cancer proteins.

The Small Cabbage White ( Pieris rapae) is originally a Eurasian butterfly. Being accidentally introduced into North America, Australia, and New Zealand a century or more ago, it spread throughout the continents and rapidly established as one of the most abundant butterfly species. Although it is a serious pest of cabbage and other mustard family plants with its caterpillars reducing crops to stems, it is also a source of pierisin, a protein unique to the Whites that shows cytotoxicity to cancer cells. To better understand the unusual biology of this omnipresent agriculturally and medically important butterfly, we sequenced and annotated the complete genome from USA specimens. At 246 Mbp, it is among the smallest Lepidoptera genomes reported to date. While 1.5% positions in the genome are heterozygous, they are distributed highly non-randomly along the scaffolds, and nearly 20% of longer than 1000 base-pair segments are SNP-free (median length: 38000 bp). Computational simulations of population evolutionary history suggest that American populations started from a very small number of introduced individuals, possibly a single fertilized female, which is in agreement with historical literature. Comparison to other Lepidoptera genomes reveals several unique families of proteins that may contribute to the unusual resilience of Pieris. The nitrile-specifier proteins divert the plant defense chemicals to non-toxic products. The apoptosis-inducing pierisins could offer a defense mechanism against parasitic wasps. While only two pierisins from Pieris rapae were characterized before, the genome sequence revealed eight, offering additional candidates as anti-cancer drugs. The reference genome we obtained lays the foundation for future studies of the Cabbage White and other Pieridae species.