Pieris Rapae Research Articles

Butterfly species vary in sex‐specific sodium accumulation from larval diets

Abstract Sodium is essential for animals, and its heterogeneous distribution can cause a range of phenomena, from sodium‐seeking behaviours to impacting their performance. Although sodium content in soils and plants is relatively well documented, data for higher trophic levels are limited. Knowledge of the variation in sodium in lower trophic levels could have implications for understanding the behaviour and physiology of species at higher levels. We investigated the variation in tissue sodium concentration between males and females of four butterfly species. Puddling behaviour of Lepidoptera suggests sodium needs of males are generally greater than females, thus, we predicted males would accumulate more sodium than females on a given diet. Larvae were reared on plants (for Battus philenor, Chlosyne lacinia and Danaus plexippus) and an artificial diet (for Pieris rapae) under Low Na (no added sodium) and High Na (sodium added) conditions. Among species and sexes, we quantified and compared adult absolute tissue sodium concentrations and bioconcentration factors, which indicate net sodium accumulation or excretion relative to individuals' diets. On average, individuals on low‐sodium diets had higher bioconcentration values across all species. Male butterflies accumulated significantly higher sodium concentrations than females in two sodium treatments for B. philenor, and P. rapae and only in the High Na treatment for C. lacinia. However, in D. plexippus, individuals accumulate sodium in the High Na treatment, but males and females responded in the same way. Our study revealed sex‐ and species‐specific patterns of butterfly sodium accumulation, which could be linked to variations in behaviour and/or performance. Differences in sodium content across species have implications for variation in predation and trophic‐level interactions, an interesting avenue for future ecological and evolutionary research.

Important Insect Pests on Cabbage in Lao PDR

This study was conducted in Xiengkhouang province, Vientiane province, Saravane province, Champasak province, Vientiane Capital, and Plant Protection Center, from January to March 2017. The aims of study were to investigate to major insect pests on cabbage and compared the efficacy of Jeevatu, Jeevatu+botanical pesticide and chemical pesticide to control Diamondback moth in laboratory condition. The study was divided into two treatments: 1) survey important insect pests of cabbage in 3 purposive sampling areas (field)/village, 10 points/rai, and 3 cabbages/point to identify insect pests and survey the life cycle of Diamondback moth of cabbage, and 2) conduct the efficacy experiment of Jeevatu, Jeevatu+botanical pesticide and chemical pesticide to Diamondback moth in laboratory. The experiment was done by Completely Randomized Design (CRD) with 5 treatments and 4 replications. The survey showed that there are 8 species of insect pests on cabbage and the most important species is Diamondback moth (Plutella xylostella) which was found in all provinces that had been survey than followed by striped flea beetle (Phyllotreta striolata), cabbage aphid (Brevicoryne brassicae), cabbage butterfly (Pieris rapae), taro caterpillar (Spodoptera litura), cabbage webworm (Hellula undalis), cabbage looper (Trichoplasia ni) and flea beetle (phyllotreta cruciferae). Life cycle of Diamondback moth was investigated in that laboratory, and it showed that the total of life cycle took about 14-21 days that included 3-5 days for egg stage, 8-12 days for lavae stage, 3-4 days for pupae stage, and 13-31 days of bebeing mature. The efficacy of Jeevatu+Sugar apple leaf extracts, Jeevatu+Neem extracts, and Jeevatu with water for control Diamondback moth indicated that after 5 days sprayed, the mortality percentage was up to 90%, 80% and 57% respectively. For chemical sprayed for 2 days, the mortality percentage was up to 100%. The results of this study showed that the Jeevatu+botanical pesticide can be used as a substitute for substituting chemical in preventing the control Diamondback moth.

Caterpillar-parasitoid interactions: species-specific influences on host microbiome composition.

There is increasing evidence that host-parasitoid interactions can have a pronounced impact on the microbiome of host insects, but it is unclear to what extent this is caused by the host and/or parasitoid. Here, we compared the internal and external microbiome of caterpillars of Pieris brassicae and Pieris rapae parasitized by Cotesia glomerata or Cotesia rubecula with nonparasitized caterpillars. Additionally, we investigated the internal and external microbiome of the parasitoid larvae. Both internal and external bacterial densities were significantly higher for P. brassicae than P. rapae, while no differences were found between parasitized and nonparasitized caterpillars. In contrast, parasitism significantly affected the composition of the internal and external microbiome of the caterpillars and the parasitoid larvae, but the effects were dependent on the host and parasitoid species. Irrespective of host species, a Wolbachia species was exclusively found inside caterpillars parasitized by C. glomerata, as well as in the corresponding developing parasitoid larvae. Similarly, a Nosema species was abundantly present inside parasitized caterpillars and the parasitoid larvae, but this was independent of the host and the parasitoid species. We conclude that parasitism has pronounced effects on host microbiomes, but the effects depend on both the host and parasitoid species.

DNA Repair and Mutagenesis of ADP-Ribosylated DNA by Pierisin.

Pierisin is a DNA-targeting ADP-ribosyltransferase found in cabbage white butterfly (Pieris rapae). Pierisin transfers an ADP-ribosyl moiety to the 2-amino group of the guanine residue in DNA, yielding N2-(ADP-ribos-1-yl)-2'-deoxyguanosine (N2-ADPR-dG). Generally, such chemically modified DNA is recognized as DNA damage and elicits cellular responses, including DNA repair pathways. In Escherichia coli and human cells, it has been experimentally demonstrated that N2-ADPR-dG is a substrate of the nucleotide excision repair system. Although DNA repair machineries can remove most lesions, some unrepaired damages frequently lead to mutagenesis through DNA replication. Replication past the damaged DNA template is called translesion DNA synthesis (TLS). In vitro primer extension experiments have shown that eukaryotic DNA polymerase κ is involved in TLS across N2-ADPR-dG. In many cases, TLS is error-prone and thus a mutagenic process. Indeed, the induction of G:C to T:A and G:C to C:G mutations by N2-ADPR-dG in the hypoxanthine phosphoribosyltransferase gene mutation assay with Chinese hamster cells and supF shuttle vector plasmids assay using human fibroblasts has been reported. This review provides a detailed overview of DNA repair, TLS and mutagenesis of N2-ADPR-dG induced by cabbage butterfly pierisin-1.

Biochemical and genetic mechanisms in Pieris rapae (Lepidoptera: Pieridae) resistance under emamectin benzoate stress

Pieris rapae (Lepidoptera: Pieridae) poses a significant threat to Brassicaceae crops, leading to substantial losses annually. Repeated insecticide applications are widely used to protect crops and increase the resistance of P. rapae. Exploring the biochemical and molecular basis of insecticide tolerance in P. rapae is crucial for achieving effective insect suppuration and implementing resistance control strategies. In our research, emamectin benzoate (EBZ) resistance was developed in P. rapae strain through selective pressure over 15 generations. Moreover, the biochemical mechanisms underlying resistance to EBZ and its potential cross-resistance to other insecticides were studied. Additionally, the expression levels of cytochrome P450 (CYP450) and glutathione-s-transferase (GST) genes in P. rapae were quantitatively assessed upon exposure to EBZ using real-time PCR. Our data exhibited that the LC50 value of susceptible strain (Sus) and EBZ resistance strain (EBZ-R) were 0.009 and 8.09 mg/L, with a resistance ratio (RR) reaching 898.8-fold. The EBZ-R stain displayed notably low cross-resistance to lambda-cyhalothrin, spinetoram, and cypermethrin. However, it demonstrated a moderate level of cross-resistance to deltamethrin. Conversely, no cross-resistance was noted to chlorantraniliprole and indoxacarb. Notably, enzyme inhibitors of detoxification enzymes revealed that piperonyl butoxide (PBO) and diethyl maleate (DEM) enhanced the EBZ toxicity to the resistant strain, indicating the potential involvement of CYP450 and GST in avermectin resistance. A remarkable enhancement in CYP450 and GST activity was observed in the EBZ-R stain. CYP450 and GST genes are upregulated in the EBZ-R stain compared to the Sus strain, which serves as a basis for comprehending the mechanism behind P. rapae resistance to EBZ. The molecular docking analysis demonstrated that EBZ has a high binding affinity with CYP6AE120 and PrGSTS1 with docking energy values of −20.19 and −22.57 kcal/mol, respectively. Our findings offer valuable insights into crafting efficient strategies to monitor and manage resistance in P. rapae populations in Egypt.

Oviposition strategies in Pieridae butterflies and the role of an egg-killing plant trait therein.

Most herbivorous insects are host-plant specialists that evolved detoxification mechanisms to overcome their host plant's toxins. In the evolutionary arms-races between Pieridae butterflies and Brassicaceae plants, some plant species have evolved another defence against the pierids: egg-killing. Underneath the eggs, leaves develop a so-called hypersensitive response (HR)-like cell death. Whether some butterflies have evolved oviposition strategies to counter-adapt against egg-killing remains to be studied. In this study, we assessed the oviposition site location of Pieridae butterflies on their natural host plants. We described the plant tissue on which we located the eggs of the most common Pieridae in the Netherlands: Gonepteryx rhamni, Anthocharis cardamines, Pieris rapae, P. napi, P. brassicae and P. mannii. Additionally, we assessed expression of HR-like cell death in response to the deposited butterfly eggs. We found that both A. cardamines and G. rhamni mainly oviposited on the floral stem and the branch, respectively, and oviposited on host plants from lineages not expected to kill pierid eggs. Accordingly, no HR-like cell death was seen. All Pieris eggs found were located on leaves of their host, the only tissue found to express HR-like cell death. Furthermore, each Pieris species was found to at least occasionally oviposit on Brassica nigra. This was the only plant species in this survey that expressed HR-like cell death in response to the eggs of P. rapae, P. napi and P. brassicae. Our observations demonstrate that HR-like cell death remains an effective defence strategy against these Pieris species and as such did not find evidence for the hypothesized counterstrategies. Surveying certain key species and disentangling the micro-evolution of oviposition strategies within a species would allow us to further investigate potential counter-adaptations that evolved against HR-like cell death. This study provides the basis for further investigation of potential counter-adaptations to egg-killing defences.

Too hot to handle: temperature-induced plasticity influences pollinator behaviour and plant fitness.

Increased temperature can induce plastic changes in many plant traits. However, little is known about how these changes affect plant interactions with insect pollinators and herbivores, and what the consequences for plant fitness and selection are. We grew fast-cycling Brassica rapa plants at two temperatures (ambient and increased temperature) and phenotyped them (floral traits, scent, colour and glucosinolates). We then exposed plants to both pollinators (Bombus terrestris) and pollinating herbivores (Pieris rapae). We measured flower visitation, oviposition of P. rapae, herbivore development and seed output. Plants in the hot environment produced more but smaller flowers, with lower UV reflectance and emitted a different volatile blend with overall lower volatile emission. Moreover, these plants received fewer first-choice visits by bumblebees and butterflies, and fewer flower visits by butterflies. Seed production was lower in hot environment plants, both because of a reduction in flower fertility due to temperature and because of the reduced visitation of pollinators. The selection on plant traits changed in strength and direction between temperatures. Our study highlights an important mechanism by which global warming can change plant-pollinator interactions and negatively impact plant fitness, as well as potentially alter plant evolution through changes in phenotypic selection.

Unraveling the efficacy and reproductive potential of two native isolates of entomopathogenic nematodes against cabbage butterfly (Pieris brassicae (L.) (Lepidoptera: Pieridae)

Unraveling the efficacy and reproductive potential of two native isolates of entomopathogenic nematodes against cabbage butterfly (Pieris brassicae (L.) (Lepidoptera: Pieridae)

Pierisin, Cytotoxic and Apoptosis-Inducing DNA ADP-Ribosylating Protein in Cabbage Butterfly.

Pierisin-1 was serendipitously discovered as a strong cytotoxic and apoptosis-inducing protein from pupae of the cabbage butterfly Pieris rapae against cancer cell lines. This 98-kDa protein consists of the N-terminal region (27 kDa) and C-terminal region (71 kDa), and analysis of their biological function revealed that pierisin-1 binds to cell surface glycosphingolipids on the C-terminal side, is taken up into the cell, and is cleaved to N- and C-terminal portions, where the N-terminal portion mono-ADP-ribosylates the guanine base of DNA in the presence of NAD to induce cellular genetic mutation and apoptosis. Unlike other ADP-ribosyltransferases, pieisin-1 was first found to exhibit DNA mono-ADP-ribosylating activity and show anti-cancer activity in vitro and in vivo against various cancer cell lines. Pierisin-1 was most abundantly produced during the transition from the final larval stage to the pupal stage of the cabbage butterfly, and this production was regulated by ecdysteroid hormones. This suggests that pierisn-1 might play a pivotal role in the process of metamorphosis. Moreover, pierisin-1 could contribute as a defense factor against parasitization and microbial infections in the cabbage butterfly. Pierisin-like proteins in butterflies were shown to be present not only among the subtribe Pierina but also among the subtribes Aporiina and Appiadina, and pierisin-2, -3, and -4 were identified in these butterflies. Furthermore, DNA ADP-ribosylating activities were found in six different edible clams. Understanding of the biological nature of pierisin-1 with DNA mono-ADP-ribosylating activity could open up exciting avenues for research and potential therapeutic applications, making it a subject of great interest in the field of molecular biology and biotechnology.

Resistance and susceptibility of different Barbarea (Brassicaceae) species and types to cabbage whitefly (Hemiptera: Aleyrodidae) and cabbage white butterfly (Lepidoptera: Pieridae)

Several Barbarea spp. (Brassicaceae) have been tested as trap crops for the diamondback moth Plutella xylostella L. (Lepidoptera: Plutellidae). The use of trap crops can be affected by their susceptibility to other pests, especially if the purpose is to reduce insecticide use. Barbarea rupicola Moris, B. verna (Mill.) Asch., and B. vulgaris Aiton (types G and P) (Brassicaceae) were tested for their susceptibility to the cabbage whitefly Aleyrodes proletella L. (Hemiptera: Aleyrodidae). The percentage of plants showing infestation by cabbage whiteflies ranged from 50% in G-type B. vulgaris and 8.3% in B. verna to no infestation at all in B. rupicola and P-type B. vulgaris. On the other hand, 95.8% of P-type plants showed symptoms of powdery mildew, Erysiphe cruciferarum Opiz ex L. Junell (Erysiphales: Erysiphaceae), while the G type and the other Barbarea spp. were unaffected by this pathogen. Additionally, the G and P types were used in two-choice oviposition preference tests to compare their attractiveness to the small white butterfly Pieris rapae L. (Lepidoptera: Pieridae). No significant differences in total oviposition per plant were found between the two types, but within-plant differences show that the small white butterfly prefers to oviposit on the adaxial leaf side in the P type. This study indicates that in locations where the cabbage whitefly is an economic pest, B. verna, which can also be used as a dead-end trap crop for the diamondback moth, could be chosen over G-type B. vulgaris.

Butterfly wing-inspired microstructured film with high reflectivity for efficient passive radiative cooling

Radiative cooling is a passive cooling technology that radiates heat to outer space without any energy input thus such technology is of great significance for alleviating environmental pollution and consumption of energy. However, achieving cooling during the daytime normally requires a series of complex structural designs that are economically inefficient and unscalable fabrication process. In this work, inspired by the nanostructure of Pieris rapae butterfly wings, we fabricate a double-layered polymeric film with a bead-like structure which can scatters incident light intensely for passive radiative cooling. Through optical characterization, it was demonstrated that the film can provide a high solar reflectivity of ∼92.4 % and a high atmospheric window emissivity of ∼93.2 %. In field tests, the film can achieve a maximum temperature drop of 6.5 °C and an average temperature drop of 3.8 °C under direct sunlight, and theoretically producing an effective cooling power of 123.8 W m−2. The as-prepared film could be fabricated through a low-cost template process, and our work presents a new approach to the application of radiative cooling technology in the field of building cooling.

Quantifying direct and indirect effects of early‐season herbivory on reproduction across four brassicaceous plant species

Abstract Insect herbivores can directly affect plant reproduction by feeding on reproductive tissues, or indirectly by feeding on vegetative tissues for which plants are unable to compensate. Additionally, early arriving herbivores may have cascading effects on plant reproduction by altering the later arriving community. However, the dynamic interplay between plant development and the assembly of herbivore communities remains underexplored. Hence, it is unclear whether non‐outbreak levels of ambient herbivory early in the development of plants can impact plant fitness and to what extent these effects are mediated through changes in plant development and subsequent herbivory. By excluding the herbivore community in an exclosure experiment and by manipulating early‐season herbivory in a common garden field experiment replicated across four Brassicaceae species and 2 years, we tested whether early‐season herbivory by caterpillars (Pieris rapae) or aphids (Myzus persicae) affected development, reproduction, and the herbivore communities associated with individual plants. In addition, we tested a causal hypothesis to assess the relative importance and temporal interplay between variation in herbivore communities and variation in plant development in determining plant reproduction. Early‐season herbivory affected plant reproduction in the exclosure experiment, with effects being highly dependent on the plant species, the herbivore species and the year. However, we found no such effects in the field experiment. The exploratory path analysis indicated that variation in plant reproduction is best predicted by variation in plant development, explaining 80% of the total effect on seed production. This suggests early‐season herbivory had limited effects on later plant development, and plants were able to attenuate the impact of early‐season herbivory. However, no clear compensatory mechanism could be identified. While early‐season herbivory has the potential to affect plant reproduction through changes in plant development or the subsequent development of the associated community, these effects were small and varied across closely related species. This suggests that plant species may be exposed to different levels of natural selection by early‐season herbivores through plant‐ or community‐mediated effects on reproduction. Read the free Plain Language Summary for this article on the Journal blog.

Resource-based trade-offs and the adaptive significance of seasonal plasticity in butterfly wing melanism.

Phenotypic plasticity is the ability of an organism to alter its phenotype in response to environmental cues. This can be adaptive if the cues are reliable predictors of impending conditions and the alterations enhance the organism's ability to capitalize on those conditions. However, since traits do not exist in isolation but as part of larger interdependent systems of traits (phenotypic integration), trade-offs between correlated plastic traits can make phenotypic plasticity non- or maladaptive. We examine this problem in the seasonally plastic wing melanism of a pierid (Order Lepidoptera, Family Pieridae) butterfly, Pieris rapae L. Several wing pattern traits are more melanized in colder than in warmer seasons, resulting in effective thermoregulation through solar absorption. However, other wing pattern traits, the spots, are less melanized during colder seasons than in warmer seasons. Although spot plasticity may be adaptive, reduced melanism of these spots could also be explained by resource-based trade-offs. Theory predicts that traits involved in resource-based trade-offs will be positively correlated when variation among individuals in resource acquisition is greater than variation among individuals in resource allocation strategies, and negatively correlated when variation in allocation is greater than variation in acquisition. Using data from both field studies and laboratory studies that manipulate dietary tyrosine, a melanin precursor, we show that when allocation to thermoregulatory melanism (ventral hindwing, and basal dorsal fore- and hindwing "shading") varies substantially this trait is negatively correlated with spot melanism. However, when there is less variation in allocation to thermoregulatory melanism we find these traits to be positively correlated; these findings are consistent with the resource-based trade-off hypothesis, which may provide a non- or maladaptive hypothesis to explain spot plasticity. We also show that increased dietary tyrosine results in increased spot melanism under some conditions, supporting the more general idea that melanism may involve resource-based costs.

Entomocomplex of Radish in Open-field Cultivation in the Central Part of the Right-Bank Forest-Steppe of Ukraine

Goal. To specify the species composition of insect pests affecting radish (Raphanus sativus (L.) convar. radicula (Pers) Sazon.) in open-field cultivation conditions in the central part of the Right-Bank Forest-Steppe of Ukraine.
 Methods. The study was conducted following commonly accepted methods in entomology and vegetable growing. From 2008 to 2022, we investigated the species diversity of insects, dominant species, their abundance, and the structure of the harmful entomocomplex in radish crops grown in open-field conditions on household plots and farms in the Cherkasy region.
 Results. In the entomological complex of radish, 59 species of phytophagous insects from 20 families and 8 orders were identified: Coleoptera — 29%, Lepidoptera — 27%, Homoptera — 15%, Diptera — 10%, Orthoptera — 9%, Thysanoptera — 5%, Hemiptera — 3%, Hymenoptera — 2%. Sixteen dominant species of phytophagous insects were found in radish crops, including diamondback moth (Plutella maculipennis Curt.), crucifer flea beetles (Phyllotreta cruciferae Goeze), striped flea beetle (Phyllotreta undulata Kutsch.), cabbage white butterfly (Pieris brassicae L.), turnip moth (Agrotis segetum Denis&Schiff.) and owlet moth (Lacanobia oleracea L.), crucifer shield bug (Eurydema ventralis Kol.), cabbage aphid (Brevicoryne brassicae L.), spring root maggot (Delia brassicae Bouche) and summer root maggot (Delia floralis Fallen), seedcorn maggot (Delia platura Mg.), sawfly (Athalia rosae L.), stem weevil (Ceutorrhynchus quadridens Panz.), tobacco thrips (Thrips tabaci Lindeman), turnip sawfly (Entomoscelis adonidis Pallas), and crucifer webworm (Evergestis extimalis Scop.). Through multi-year studies, the periods of insect damage corresponding to radish developmental stages were determined. The most critical damage to radish plants by harmful insects occurred during the initial stages of development (ВВСН 0—9) and from emergence to the growth and formation of the root crop (BBCH 42—48).
 Conclusions. It was found that among the identified phytophagous insects in radish crops, the most economically significant damage was caused by the cabbage aphid, crucifer flea beetles, striped flea beetle, spring cabbage fly, and seedcorn maggot. On average over the research period (2008—2022), the largest areas of radish crops were infested by the diamondback moth, crucifer flea beetles, and striped flea beetle, cabbage white butterfly, winter and owlet moths, cabbage shield bug, and cabbage aphid, ranging from 5% to 80%, reaching a maximum in some years up to 60—100% of the area.

Formulation and Validation of Organic Insect Pest Management Module for Pests of Cabbage and Cauliflower in Valley and Foot Hills Region, Manipur, India

During the rabi seasons from 2017 to 2020 in the valley and foothill regions of Imphal, Manipur, a study was conducted to design and test three different organic insect pest management modules M1, M2 and M3 for cabbage and cauliflower. The focus was on three major pests: cabbage butterfly, diamondback moth, and cabbage aphid. Module three (M-3) emerged as the most effective strategy, incorporating various organic practices. This included seed treatment with Trichoderma harzianum at 10g/kg seed and soil drenching in nursery plots at 25g/100 m2, intercropping with mustard, application of anonnin extract at 5 ml/litre, Spinosad 45% SC (biopesticide) at 3ml/10 litres, and Verticillium lecanii at 10 ml/litre. Additionally, the module incorporated the installation of yellow sticky traps for aphids and pheromone traps for diamondback moths for monitoring and mass trapping. The results indicated that Module 3 performed well than other modules and the control group in reducing insect pest incidence on cabbage and cauliflower with the number of cabbage butterfly ranging from 0.07 to 0.11, in both cabbage and cauliflower, where as 0.06 to 0.04 in case of Diamond back moth and 0.21 to 0.47 number of cabbage aphid per square inch leaf area with B:C ratio of 1:12.4 and 1:12.7 for cabbage and 1:6:39 and1:6.41 for cauliflower at lamphel and lanol fields, respectively. Moreover, it contributed to an increased yield, demonstrating its superiority in organic insect pest management for both valley and foothill regions. This underscores the effectiveness of a holistic and integrated approach to pest management in organic farming practices.

Genome-wide association analysis reveals genes controlling an antagonistic effect of biotic and osmotic stress on Arabidopsis thaliana growth.

While the response of Arabidopsis thaliana to drought, herbivory or fungal infection has been well-examined, the consequences of exposure to a series of such (a)biotic stresses are not well studied. This work reports on the genetic mechanisms underlying the Arabidopsis response to single osmotic stress, and to combinatorial stress, either fungal infection using Botrytis cinerea or herbivory using Pieris rapae caterpillars followed by an osmotic stress treatment. Several small-effect genetic loci associated with rosette dry weight (DW), rosette water content (WC), and the projected rosette leaf area in response to combinatorial stress were mapped using univariate and multi-environment genome-wide association approaches. A single-nucleotide polymorphism (SNP) associated with DROUGHT-INDUCED 19 (DI19) was identified by both approaches, supporting its potential involvement in the response to combinatorial stress. Several SNPs were found to be in linkage disequilibrium with known stress-responsive genes such as PEROXIDASE 34 (PRX34), BASIC LEUCINE ZIPPER 25 (bZIP25), RESISTANCE METHYLATED GENE 1 (RMG1) and WHITE RUST RESISTANCE 4 (WRR4). An antagonistic effect between biotic and osmotic stress was found for prx34 and arf4 mutants, which suggests PRX34 and ARF4 play an important role in the response to the combinatorial stress.

Ecological and economic analysis of insecticidal control of fall armyworm

Fall Armyworm (FAW), Spodoptera frugiperda (Lepidoptera: Noctuidae) , is a significant pest causing substantial economic losses worldwide, particularly in Sub-Saharan Africa. The prevalent strategy for managing FAW involves insecticide applications, ranging from synthetic to botanical and microbial agents. However, the ecological and economic impacts of these interventions often remain unassessed. This study scrutinizes the ecological and economic viability of two insecticidal treatments: one based on emamectin benzoate and another comprising a combination of Pieris rapae granulovirus (PrGV) and Bacillus thuringiensis subsp. kurstaki (Btk) with varied application timings and frequencies. Our findings indicate that both insecticide types were effective in reducing FAW larval populations and the associated crop damage. From an ecological standpoint, the PrGV|Btk treatment enhanced parasitism rates, especially when applied only at the early stage of the crop. However, this approach did not significantly lower crop damage compared to a "targeted" strategy, where insecticide application was contingent upon observed injury levels. Remarkably, the "targeted" strategy led to increased FAW larval parasitism, particularly at the V7 growth stage of the crop. Economically, the "targeted" insecticide application emerged as both effective and efficient, minimizing the need for multiple sprays and thus recommended for managing FAW infestations while considering cost and ecological balance.

Enhanced dispersal capacity in edge population individuals of a rapidly expanding butterfly.

Natural range shifts offer the opportunity to study the phenotypic and genetic changes contributing to colonization success. The recent range shift of the Southern small white butterfly (Pieris mannii) from the South to the North of Europe offers a prime example to examine a potential dispersal syndrome in range-expanding individuals. We compared butterflies from the core and edge populations using a multimodal approach addressing behavioral, physiological, and morphological traits related to dispersal capacity. Relative to individuals from the core range (France), individuals from the edge (Germany) showed a higher capacity and motivation to fly, and a higher flight metabolic rate. They were also smaller, which may enhance their flight maneuverability and help them cope with limited resource availability, thereby increasing their settlement success in novel environments. Altogether, the behavioral, physiological, and morphological differences observed between core and edge populations in P. mannii suggest the existence of a dispersal syndrome in range-expanding individuals. Whether these differences result from genetic and/or phenotypic responses remains, however, to be determined.

Determination of Phenethyl Isothiocyanate, Erucin, Iberverin, and Erucin Nitrile Concentrations in Healthy and Pieris rapae-Infected Broccoli Tissues Using Gas Chromatography-Mass Spectrometry

Cruciferous vegetables (Brassicaceae family) are a rich source of phytochemicals, in particular glucosinolates (GLS) and their hydrolysis products, isothiocyanates and nitriles. These phytochemicals may act as chemosensors, attracting insects, such as Pieris rapae, and stimulating oviposition. There is a lack of information on the concentrations of isothiocyanates and nitriles when an insect affects a Brassicaceae plant. In the current study, some GLS hydrolysis products were determined in healthy and Pieris rapae-infected organic cultivated broccoli plants, as well as the infesting insects’ larvae, using gas chromatography-mass spectrometry (GC-MS). This study investigated the following phytochemicals: phenethyl isothiocyanate (PEITC), erucin (ER), 3-(methylthio)propyl isothiocyanate (3MIC), and 1-cyano-4-(methylthio)butane (5MITN). All these components were quantified in the aerial and underground parts of the plants and were found in high concentrations in the roots. Among the phytochemicals studied, 5MITN presented the highest concentration in all the broccoli samples but was especially high in the stalks of the infected plants. Moreover, the analysis of a sample of Pieris rapae larvae, fed from the hosted broccoli, revealed the presence of PEITC and ER. These findings indicate that the infestation of broccoli with Pieris rapae may affect the distribution of PEITC, ER, 3MIC, and 5MITN throughout the plant. An extension of our study to conventional cultivated broccoli showed that the roots are indeed rich in GLS hydrolysis products.

Transcriptome-based analysis reveals a crucial role of the 20E/HR3 pathway in the diapause of Pieris rapae

Pieris rapae is among the most damaging pests globally, and diapause makes it highly resistant to environmental stresses, playing a crucial role in the survival and reproduction of P. rapae while exacerbating the challenges of pest management and control. However, the mechanisms of its diapause regulation remain poorly understood. This research used RNA sequencing to profile the transcriptomes of three diapause phases (induction and preparation, initiation, maintenance) and synchronous nondiapause phases in P. rapae. During each comparison phase, 759, 1045, and 4721 genes were found to be differentially expressed. Among these, seven clock genes and seven pivotal hormone synthesis and metabolism genes were identified as having differential expression patterns in diapause type and nondiapause type. The weighted gene co-expression network analysis (WGCNA) revealed the red and blue modules as pivotal for diapause initiation, while the grey module was identified to be crucial to diapause maintenance. Meanwhile, the hub genes HDAC11, METLL16D, Dyw-like, GST, and so on, were identified within these hub modules. Moreover, an ecdysone downstream nuclear receptor gene, HR3, was found to be a shared transcription factor across all three phases. RNA interference of HR3 resulted in delayed pupal development, indicating its involvement in regulating pupal dipause in P. rapae. The further hormone assays revealed that the 20-hydroxyecdysone (20E) titer in diapause type pupae was lower than that in nondiapause type pupae, which exhibited a similar trend to HR3. When 20E was injected into diapause pupae, the HR3 expression levels were improved, and the pupal diapause were broken. These results indicate that the 20E/HR3 pathway is a critical pathway for the diapause regulation of P. rapae, and perturbing this pathway by ecdysone treatment or RNAi would result in the disruption of diapause. These findings provide initial insights into the molecular mechanisms of P. rapae diapause and suggest the potential use of ecdysone analogs and HR3 RNAi pesticides, which specifically target to diapause, as a means of pest control in P. rapae.