Synergistic effect of naturally occurring Granulosis virus isolates (PbGV) with phagostimulants against the cabbage butterfly, Pieris brassicae (L.) for its eco-friendly management

Background To manage the cabbage butterfly, Pierisbrassicae (L.) (Lepidoptera: Pieridae), it is not wise to use insecticides on leafy vegetables which are eaten mostly fresh. During the past decades, the efforts to manage the pest, through chemical insecticides have raised serious health. Investigations were carried out to isolate naturally occurring GVs (PbGV) as a potent biopesticide against P.brassicae and to explore their efficacy with the application of phagostimulants. Results Among the four naturally occurring isolates obtained from Northwestern Himalayas, Sudhmahadev isolate was found to be the most promising based on virulence and speed of kill against all the instars tested in the laboratory, showing the natural incidence of PbGV infection in field conditions. In concentration and time–response bioassay, all the isolates of P.brassicae Granulosis virus were found high virulent against second instar larvae of cabbage butterfly. Therefore, for enhanced efficacy of PBGV, its combined application with phagostimulants (Lepidiumsativum + Teepol + jaggery) or sticker (Teepol + jaggery), applied in field trials, resulted into greater mortality of larval instars than the single one. Overall, the results indicated that the introduction of a more isolates PBGV strain into populations of P.brassicae could be of vital importance for eco-friendly suppression of this pest globally with the combination of phagostimulants. The application virus alone with the pre-standardized concentration of 1 × 1012 OBs/ha did not reduce the larval population density to the desirable extent in the greenhouse chamber and therefore was not included in field experiments. Overall, the most promising treatments in reducing the larval population of the pest were PbGV + Teepol + B.thuringiensis (93.49 and 91.39%) and PbGV + Teepol + L.sativum (88.79 and 86.97%) over control in both greenhouse and field trials, respectively. Conclusions In this study, the native isolates of PbGV from different target locations to test their efficacy against different instars of P.brassicae were explored. Using native PBGV isolates with phagostimulant combinations played an important role for regulating the pest effectively. These phagostimulants not only protected the OBs from degradation in the presence of sunlight but also increased the speed of killing. The biocontrol potential of PbGV in both laboratory and field conditions indicated that baculoviruses are sustainable alternative to chemical insecticides.

Effectiveness of biological protection of cabbage against pests in the conditions of the Primorsky Territory

The results of the use of entomophages and biological products to regulate the number of cabbage pests (cabbage moth Mamestra brassicae L., cabbage butterfly Pieris brassicae L., turnip butterfly Pieris rapae L., diamondback moth Plutella xylostella L.) are presented. The study was carried out in the Primorsky Territory in 2018-2020. The efficiency of Trichogramma ussuricum Sorokina applications was assessed on cabbage varieties. The effectiveness of the entomophage against the cabbage moth varied from 33.3 to 66.6%, against the turnip butterfly - from 32.6 to 70.2%. In field experiments the effectiveness of biological products Fitoverm EC (0.09 l/ha), Akarin EC (1.6 l/ha), Proclaim WG (0.3 kg/ha), Bitoxibacillin (10 l/ha), Bitoxibacillin P (2 kg/ha), Lepidocid SC (2 l/ha), Lepidocid P (2 kg/ha) against diamondback moth are studied. Cabbage plants were sprayed with the preparations once. Pest counts were carried out before treatment and after treatment on the 5th, 10th and 15th day in accordance with the approved methods. Bioinsecticide Proclaim showed a high efficiency of 93.0-100% on the 5-10th day. The effectiveness of preparations based on aversectin C and avertin N was 65.0-88.6%. Using the biological product Bitoxibacillin and Lepidocid a decrease the number of diamondback moth relative to the control by 61.2-97.5 и 65.0-78.0% was registered.

Seguimiento plurianual (2013-2016) del vuelo invernal de mariposas (Lepidoptera: Papilionoidea) en el campus de la Universidad Pablo de Olavide, de Sevilla (sur de España)

Durante los inviernos 2013/2014, 2014/2015 y 2015/2016 y la primera mitad de la primavera que siguió a cada uno de ellos, fue estudiada la fenología de la fase adulta de las mariposas diurnas presentes en el campus de la Universidad Pablo de Olavide, de Sevilla (España). El número de especies observadas a lo largo de esos inviernos (12), la abundancia de cada una de ellas y los cambios en la diversidad fueron analizados. Ejemplares de Artogeia rapae, Vanessa atalanta, Vanessa cardui, Pieris brassicae, Colias crocea, Tomares ballus y Zerynthia rumina fueron observados todos los inviernos. Por último, para todas las especies halladas en este estudio ha sido realizado un estudio comparativo entre el inicio del periodo de vuelo aquí registrado y aquél que aparece recogido en la bibliografía consultada.

Parasitism by endoparasitoid wasps alters the internal but not the external microbiome in host caterpillars

Background The microbiome of many insects consists of a diverse community of microorganisms that can play critical roles in the functioning and overall health of their hosts. Although the microbial communities of insects have been studied thoroughly over the past decade, little is still known about how biotic interactions affect the microbial community structure in and on the bodies of insects. In insects that are attacked by parasites or parasitoids, it can be expected that the microbiome of the host insect is affected by the presence of these parasitic organisms that develop in close association with their host. In this study, we used high-throughput amplicon sequencing targeting both bacteria and fungi to test the hypothesis that parasitism by the endoparasitoid Cotesia glomerata affected the microbiome of its host Pieris brassicae. Healthy and parasitized caterpillars were collected from both natural populations and a laboratory culture. Results Significant differences in bacterial community structure were found between field-collected caterpillars and laboratory-reared caterpillars, and between the external and the internal microbiome of the caterpillars. Parasitism significantly altered the internal microbiome of caterpillars, but not the external microbiome. The internal microbiome of all parasitized caterpillars and of the parasitoid larvae in the caterpillar hosts was dominated by a Wolbachia strain, which was completely absent in healthy caterpillars, suggesting that the strain was transferred to the caterpillars during oviposition by the parasitoids. Conclusion We conclude that biotic interactions such as parasitism have pronounced effects on the microbiome of an insect host and possibly affect interactions with higher-order insects.

The genome sequence of the large white, Pieris brassicae (Linnaeus, 1758)

We present a genome assembly from an individual female Pieris brassicae (the large white; Arthropoda; Insecta; Lepidoptera; Pieridae). The genome sequence is 292 megabases in span. The majority of the assembly is scaffolded into 16 chromosomal pseudomolecules, with the W and Z sex chromosome assembled. Gene annotation of this assembly on Ensembl has identified 12,229 protein coding genes.

Bio-efficacy of entomopathogenic nematodes, Steinernema feltiae and Heterorhabditis bacteriophora against the Cabbage butterfly (Pieris brassicae [L.]) under laboratory conditions

Background Entomopathogenic nematodes (EPNs) have the potential to supersede larvicidal activity for the management of various insect pests. Result Lab experiments were conducted to test the pathogenicity of 2 EPNs local species; Steinernema feltiae and Heterorhabditis bacteriophora at different (IJs/cm2) concentrations against the cabbage butterfly, Pieris brassicae (L.). The native isolate was obtained from soil samples, collected from Rajgarh, Hamachi Pradesh, India. Petri dish bioassay used the EPNs species (S. feltiae HR1 and H. bacteriophora HR2) at the concentrations (0, 10, 20, 40, 80, 160 IJs/cm2). Based on the pathogenicity of the strains, only 2 isolates effectively showed larvicidal activity. The highest (%) (72.08 and 67.42%), at the 2nd instar larval mortality was recorded in the treatments with H. bacteriophora and S. feltiae at160 IJs/cm2, respectively. At the 4th instar larvae, respective larval mortality (85.38, 69.50%) was recorded in treatment with H. bacteriophora, and S. feltiae, respectively, at160 IJs/cm2. In case of pupae, the mortality rates were (62.12, 58.58%) for H. bacteriophora and S. feltiae, respectively, at 160 IJs/cm2; (74 and 12%) for both the tested EPNs, respectively, at 80 IJs/cm2. Percent of P. brassicae larval mortality treated with the tested EPN isolates was significantly higher than the untreated control. Results revealed that the percent of larval mortality significantly increased with the increase in time periods, being maximum at 72 h. S. feltiae and H. bacteriophora, strains showed potent larvicidal activity at low concentration even at 48 and 72 h of exposure. Conclusion This study revealed that the local strains of EPNs (S. feltiae HR1 and H. bacteriophora HR2) were found as a biocontrol agent against P. brassicae.

Sphingolipids are involved in Pieris brassicae egg-induced cell death in Arabidopsis thaliana

In Brassicaceae, hypersensitive-like (HR-like) cell death is a central component of direct defenses triggered against eggs of the large white butterfly Pieris brassicae. The signaling pathway leading to HR-like in Arabidopsis is mainly dependent on salicylic acid (SA) accumulation, but downstream components are unclear. Here, we found that treatment with P. brassicae egg extract (EE) trigger changes in expression of sphingolipid metabolism genes in Arabidopsis and Brassica nigra. Disruption of ceramide synthase activity led to a significant decrease of EE-induced HR-like whereas SA signaling and reactive oxygen species levels were unchanged, suggesting that ceramides are downstream activators of HR-like. Sphingolipid quantifications showed that ceramides with C16-0 side-chains accumulated in both species, and this response was independent on SA accumulation. Finally, we provide genetic evidence that the modification of fatty acyl chains of sphingolipids modulates HR-like. Altogether, these results show that sphingolipids play a key and specific role during insect egg-triggered HR-like.

Environmentally acquired chemical camouflage affects Pieris brassicae L. host plant selection and orientation behaviour of a larval parasitoid

Environmentally acquired chemical camouflage is a phenomenon, where a plant growing close to a strong volatile organic compound (VOC) emitter will adsorb and re-emit the VOCs produced by the neighbouring plant. The re-emitted volatile bouquet may resemble more the VOC composition of the neighbour than plant’s own typical odour, and thus act as chemical camouflage against insect detection, potentially simultaneously providing associational resistance towards herbivory. We exposed a pest-sensitive horticultural crop, Brassica oleracea var. italica (broccoli) cv. Lucky, to the volatiles emitted by Rhododendron tomentosum [RT] twigs and assessed the host selection by ovipositing females and larval instars of the major caterpillar pest Pieris brassicae between RT-exposed and control plants. Potential impact of RT exposure on herbivore natural enemies was studied using behavioural tests with a parasitoid wasp Cotesia glomerata. P. brassicae females laid significantly less eggs and egg clusters were fewer on RT-exposed plants at both night-time (6 °C) and daytime (22 °C) temperatures. Larvae preferred leaves from control plants over RT-exposed plants at both temperatures. Preceding RT-exposure did not disturb orientation of parasitoid wasp Cotesia glomerata females towards B. oleracea plants damaged by its host P. brassicae. However, host-damaged control plants were favoured by the parasitoid over RT-exposed, host-damaged plants. Our results suggest that companion plant based chemical camouflage as a mechanism of pest suppression could be developed as an additional tool for the integrated pest management toolbox in agriculture.

Pieris brassicae (large cabbage white).

P. brassicae is an oligophagous insect that feeds on members of family Brassicaceae (Lal and Ram, 2004; Younas et al., 2004; Hwang et al., 2008; Hasan and Ansari, 2010; 2011). Damage to cabbage heads has been reported to be as high as 70-98% (Prasad, 1961; 1963).