Single-step novel biosynthesis of silver nanoparticles: a potent and eco-friendly mosquitocides

Mosquito-borne diseases like malaria, dengue, chikungunya, filariasis, and Japanese encephalitis cause thousands of deaths per year. Mosquito control is to enhance the health and quality of life of county residents and visitors through the reduction of mosquito populations. Mosquito control is of serious concern in developing countries like India due to the lack of general awareness, development of resistance, and socioeconomic reasons. Insecticides of botanical origin may serve as suitable alternative biocontrol techniques in the future. In view of the recently increased interest in developing plant origin insecticides as an alternative to chemical insecticide, In this research, we biosynthesized silver nanoparticles (Ag NP) using the Sida acuta leaf extract as reducing and stabilizing agent. The biosynthesis of Ag NP was confirmed analyzing the excitation of surface plasmon resonance using ultraviolet–visible (UV–vis) spectrophotometry. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed the clustered and irregular shapes of Ag NP. The presence of silver was confirmed by energy dispersive X-ray (EDX) spectroscopy. Fourier transform infrared (FTIR) spectroscopy investigated the identity of secondary metabolites, which may also act as Ag NP capping agents. The acute toxicity of S.acuta leaf extract and biosynthesized Ag NP was evaluated against larvae of Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus. Compared to the leaf aqueous extract, biosynthesized Ag NP showed higher toxicity against Ae. aegypti,                             An. stephensi, and Cx.quinquefasciatus with the LD50 values of 35.12, 39.53 and 41.44 µg/mL, respectively. This result suggests that the leaf extract have the potential to be used as an ideal eco-friendly approach for the control of vector mosquitoes

Effect of simple processing on selected pesticide residues in cottonseed (Gossypium spp.)

Food processing techniques reduce pesticide residue accumulation in food components. The present study investigated the effectiveness of simple processing techniques such as roasting, soaking, autoclaving and storage conditions on twenty-seven selected pesticides belonging to the classes of organophosphates (OPs), organochlorines (OCPs) and pyrethroids (PPs) in pesticide-fortified cottonseed (Gossypium spp.). The residue concentration was analysed by GC–MS/MS from the extract of different treated samples as untreated and pesticide free (T1), pesticide treated (T2) and pesticide treated cum processed (R1- Roasting 5 min; R2-Roasting 10 min; S1-Soaking 6 hours; S2-Soaking 12 hours; AC1-Autoclaving 5 min; AC2-Autoclaving 10 min; ST-Storage) cottonseed. The recovery values of the residues ranged from 78.20 to 114% with the application of 1, 5 and 10 μg/g pesticide in pesticide-free cottonseed. The concentration of pesticide residues is presented for nondetected levels in pesticide-free samples. Otherwise, pesticide-treated samples contained all pesticide residues ranging from 856 to 1138 ng/g OP, 782 to 1058 ng/g OCPs and 857 to 1140 ng/g PP, which are higher than the maximum residue limits (MRLs) set by The Japan Food Chemical Research Foundation (FFCR). Among the different processing methods, autoclave samples had fewer residues detected (3 compounds), followed by stored (5 compounds), soaked (7 compounds) and roasted (8 compounds) samples. The stored cottonseeds contained residues for phorate, total lindane excluding δ-lindane and deltamethrin at the end of storage. Nevertheless, the residue from phorate, δ-lindane and deltamethrin exceeded the concentration of MRLs. This finding indicated that the most effective method for reducing pesticide residues was autoclaved treatment from the respective pesticide-fortified cottonseed sample

Dynamic behaviour of woven bio fiber composite

The effect of weaving pattern and natural filler addition on the dynamic properties of composite structure was investigated. The reinforcement effect of plain, basket, and twill weave were compared with randomly oriented natural fiber in short form. An experimental modal analysis was used to determine the fundamental natural frequency and modal damping factor of composite structure. The results for a woven reinforced composite were compared with those of a randomly oriented short fiber composite. Reinforcement with woven form enhanced the fundamental natural frequency, while randomly oriented short fiber enhanced the damping factor of composite material. In addition, mechanical properties, such as tensile and flexural behavior, were examined to understand the effect of reinforcement on the composite material. The sisal bio fiber with woven form enhanced the properties of the composite material

Enthralling genetic regulatory mechanisms meddling insecticide resistance development in insects: role of transcriptional and post-transcriptional events

Insecticide resistance in insects severely threatens both human health and agriculture, making insecticides less compelling and valuable, leading to frequent pest management failures, rising input costs, lowering crop yields, and disastrous public health. Insecticide resistance results from multiple factors, mainly indiscriminate insecticide usage and mounted selection pressure on insect populations. Insects respond to insecticide stress at the cellular level by modest yet significant genetic propagations. Transcriptional, co-transcriptional, and post-transcriptional regulatory signals of cells in organisms regulate the intricate processes in gene expressions churning the genetic information in transcriptional units into proteins and non-coding transcripts. Upregulation of detoxification enzymes, notably cytochrome P450s (CYPs), glutathione S-transferases (GSTs), esterases [carboxyl choline esterase (CCE), carboxyl esterase (CarE)] and ATP Binding Cassettes (ABC) at the transcriptional level, modification of target sites, decreased penetration, or higher excretion of insecticides are the noted insect physiological responses. The transcriptional regulatory pathways such as AhR/ARNT, Nuclear receptors, CncC/Keap1, MAPK/CREB, and GPCR/cAMP/PKA were found to regulate the detoxification genes at the transcriptional level. Post-transcriptional changes of non-coding RNAs (ncRNAs) such as microRNAs (miRNA), long non-coding RNAs (lncRNA), and epitranscriptomics, including RNA methylation, are reported in resistant insects. Additionally, genetic modifications such as mutations in the target sites and copy number variations (CNV) are also influencing insecticide resistance. Therefore, these cellular intricacies may decrease insecticide sensitivity, altering the concentrations or activities of proteins involved in insecticide interactions or detoxification. The cellular episodes at the transcriptional and post-transcriptional levels pertinent to insecticide resistance responses in insects are extensively covered in this review. An overview of molecular mechanisms underlying these biological rhythms allows for developing alternative pest control methods to focus on insect vulnerabilities, employing reverse genetics approaches like RNA interference (RNAi) technology to silence particular resistance-related genes for sustained insect management

In vitro Assessment of Neonicotinoids and Pyrethroids against Tea Mosquito Bug, Helopeltis antonii Sign. (Hemiptera: Miridae) on Guava

The tea mosquito bug (TMB), Helopeltis antonii, is an emerging pest of horticultural crops, specially on guava and moringa. Insecticides are indispensable component for the management of insect pests. Exploration of new molecules with shortest waiting period may pave way for managing TMB in fruit and vegetable crops with nil/low residue. Until now there are no recommended insecticides available under Central Insecticides Board & Registration Committee (CIB&RC) against TMB on guava. In view of the above facts, new molecules with a low waiting period and are recommended by CIB&RC on tea, viz., Clothianidin 50% WDG, Thiacloprid 21.7% SC, Bifenthrin 10% EC, and Thiamethoxam 12.60% + Lambda-Cyhalothrin 9.5% ZC, were chosen and evaluated against TMB under in vitro condition. Clothianidin 50% WDG recorded the highest mortality of 100.00 per cent at 72 hours after treatment (HAT), and the lowest LC50 value (0.328 ppm, fiducial limits: 0.144-0.515 ppm) and LT50 value (10.49 h, fiducial limits: 5.444-14.551 h), followed by Thiamethoxam 12.60% + Lambda-Cyhalothrin 9.5% ZC, Thiacloprid 21.7% SC, and Bifenthrin 10% EC. The results showed that the Clothianidin 50% WDG and Thiamethoxam 12.60% + Lambda-Cyhalothrin 9.5% ZC, were highly effective, with the lowest LC50 and LT50 values. Since TMB occurs from new flushing to fruiting stage of guava, a minimum of two sprays are mandatory to have quality fruit yield. Hence, application of Clothianidin 50% WDG followed by Thiamethoxam 12.60% + Lambda-Cyhalothrin 9.5% ZC on need basis will help to reduce the impact of TMB on guava

Commercial Mosquito Repellents and Their Safety Concerns

Mosquitoes are serious vectors of diseases threading millions of humans and animals worldwide, as malaria, filariasis, and important arboviruses like dengue, yellow fever, chikungunya, West Nile virus, and Zika viruses. The swift spread of arboviruses, parasites, and bacteria in conjunction with the development of resistance in the pathogens, parasites, and vectors represents a great challenge in modern parasitology and tropical medicine. Unfortunately, synthetic insecticides had led to some serious health and risk concerns. There are no vaccines or other specific treatments for arboviruses transmitted by mosquitoes. Accordingly, avoidance of mosquito bites remains the first line of defense. Insect repellents usually work by providing a vapor barrier deterring mosquitoes from coming into contact with the skin surface, and this chapter focused on assets and liabilities, mechanism of action, improving efficacy, safety, and future perspective of synthetic and natural repellents that could potentially prevent mosquito-host interactions, thereby playing an important role in reducing mosquito-borne diseases when used correctly and consistently

Fast Evolution and Lineage-Specific Gene Family Expansions of Aphid Salivary Effectors Driven by Interactions with Host-Plants

Effector proteins play crucial roles in plant-parasite interactions by suppressing plant defenses and hijacking plant physiological responses to facilitate parasite invasion and propagation. Although effector proteins have been characterized in many microbial plant pathogens, their nature and role in adaptation to host plants are largely unknown in insect herbivores. Aphids rely on salivary effector proteins injected into the host plants to promote phloem sap uptake. Therefore, gaining insight into the repertoire and evolution of aphid effectors is key to unveiling the mechanisms responsible for aphid virulence and host plant specialization. With this aim in mind, we assembled catalogues of putative effectors in the legume specialist aphid, Acyrthosiphon pisum, using transcriptomics and proteomics approaches. We identified 3,603 candidate effector genes predicted to be expressed in A. pisum salivary glands (SGs), and 740 of which displayed up-regulated expression in SGs in comparison to the alimentary tract. A search for orthologs in 17 arthropod genomes revealed that SG-up-regulated effector candidates of A. pisum are enriched in aphid-specific genes and tend to evolve faster compared with the whole gene set. We also found that a large fraction of proteins detected in the A. pisum saliva belonged to three gene families, of which certain members show evidence consistent with positive selection. Overall, this comprehensive analysis suggests that the large repertoire of effector candidates in A. pisum constitutes a source of novelties promoting plant adaptation to legumes

Two new species of Clypeocaenis (Ephemeroptera: Caenidae) from Western Ghats, Southern India

Muthukatturaja, Marimuthu, Balasubramanian, Chelliah, Murugan, Alagumalai (2020): Two new species of Clypeocaenis (Ephemeroptera: Caenidae) from Western Ghats, Southern India. Zootaxa 4722 (4): 361-370, DOI: https://doi.org/10.11646/zootaxa.4722.4.

Negative Effects of <i>Phthorimaea absoluta</i>-Resistant Tomato Genotypes on the Zoophytophagous Biocontrol Agent, <i>Orius laevigatus</i> (Fieber) (Hemiptera: Anthocoridae)

Complex interactions between host plant resistance (HPR) and biological control agents, particularly omnivorous predators, can shape the outcome of an integrated pest management (IPM) program. However, such interactions are seldom explored during plant breeding programs. Therefore, in the present study, we compared the performance of the omnivorous biological control agent Orius laevigatus on six tomato genotypes with different levels of resistance to the tomato leaf miner Phthorimaea absoluta. We found that the O. laevigatus fitness components (i.e., egg deposition, egg hatching rate, and duration of egg, early nymphal, late nymphal stages, and their survival) were inferior on the wild resistant genotypes (LA 716 and LA 1777) in comparison to the resistant domesticated genotype EC 620343 and the susceptible genotypes (EC 705464 and EC 519819). It appears that the adverse effects of tomato genotypes on O. laevigatus are determined mainly by glandular and non-glandular trichome densities on the leaves. Comparison of O. laevigatus response to the tested tomato cultivars to that of P. absoluta revealed significant positive correlations in duration of the egg stages, development time of early and late larval stages, and overall immature mortality in both species. It appears, therefore, that defensive plant traits operate in a similar way on the pest and its predator in the system. Overall, the present study of the tomato-P. absoluta-O. laevigatus system provides experimental evidence for the need to optimize pest management by employing intermediate levels of crop resistance together with biological control agents