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Fabrication, characterization and evaluation of the larvicidal potential of novel silk protein (sericin)-based silver nanoparticles (Se-AgNPs) were the prime motives of the designed study. Furthermore, investigation of the sericin as natural reducing or stabilizing agent was another objective behind this study. Se-AgNPs were synthesized using sonication and heat. Fabricated Se-AgNPs were characterized using particle size analyzer, UV spectrophotometry, FTIR and SEM which confirmed the fabrication of the Se-AgNPs. Size of sonication-mediated Se-AgNPs was smaller (7.49 nm) than heat-assisted Se-AgNPs (53.6 nm). Being smallest in size, sonication-assisted Se-AgNPs revealed the significantly highest (F 4,10  = 39.20, p = .00) larvicidal activity against fourth instar lab and field larvae (F 4,10  = 1864, p = .00) of dengue vector (Aedes aegypti) followed by heat-assisted Se-AgNPs and positive control (temephos). Non-significant larvicidal activity was showed by silver (without sericin) which made the temperature stability of silver, debatable. Furthermore, findings of biochemical assays (glutathione-S transferase, esterase, and acetylcholinesterase) showed the levels of resistance in field strain larvae. Aforementioned findings of the study suggests the sonication as the best method for synthesis of Se-AgNPs while the larvicidal activity is inversely proportional to the size of Se-AgNPs, i.e., smallest the size, highest the larvicidal activity. Conclusively, status of the sericin as a natural reducing/stabilizing agent has been endorsed by the findings of this study. RESEARCH HIGHLIGHTS: Incorporation of biocompatible and inexpensive sericin as a capping/reducing agent for synthesis of Se-AgNPs. A novel sonication method was used for the fabrication of Se-AgNPs which were thoroughly characterized by particle size analyzer, UV-visible spectrophotometry, SEM and FTIR. Analysis of enzymatic (GSTs, ESTs) levels in field and lab strains of Aedes aegypti larvae for evaluation of insecticides resistance., (© 2023 Wiley Periodicals LLC.)

Aedes aegypti (Linnaeus, 1762) is a major vector responsible for dengue transmission. Insecticides are being used as the most effective tool to control vector populations in Lahore, Pakistan. Control of Ae. aegypti is threatened by the development of resistance against insecticides. The current status of insecticide resistance was evaluated against pyrethroids (deltamethrin, cypermethrin, and lambda-cyhalothrin) in different populations of Lahore (Model Town, Mishri Shah, Sadar Cantt, Walton, and Valencia). The susceptibility of the larval and adult populations was tested following the standard WHO guidelines. Moderate to high levels of resistance were found against pyrethroids in the larval (RR50: 3.6-27.2 and RR90: 5-90) and adult populations (percentage mortality < 98%). Biochemical assays revealed a statistically significant increase in the enzyme level in all field populations compared to the laboratory strain. The value of esterase was one-fold higher, monooxygenase was 3.9- to 4.7-fold higher, and glutathione S-transferases was 1.9- to 2.6-fold higher in field populations compared to the laboratory strain. These results depict the presence of resistance against deltamethrin, cypermethrin, and lambda-cyhalothrin in field populations of Lahore mediated by metabolic enzymes i.e. esterases, monooxygenases, and glutathione S-transferase., (© The Author(s) 2021. Published by Oxford University Press on behalf of Entomological Society of America.All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Elevated levels of insecticides detoxifying enzymes, such as esterases, glutathione S-transferases (GSTs), and cytochrome P-450 monooxygenases, act in the resistance mechanisms in insects. In the present study, levels of these enzymes in the insecticide-resistant ground spider Pardosa sumatrana (Thorell, 1890) were compared with a susceptible population (control) of the same species. Standard protocols were used for biochemical estimation of enzymes. The results showed significantly higher levels of nonspecific esterases and monooxygenases in resistant spiders compared to controls. The activity of GSTs was lower in the resistant spiders. Elevated levels of nonspecific esterases and monooxygenases suggest their role in metabolic resistance in P. sumatrana. The reduced levels of total protein contents revealed its possible consumption to meet energy demands., (© 2016 Wiley Periodicals, Inc.)

Sucking pests of cotton (Gossypium hirsutum L.), such as thrips, or Thrips tabaci Lindeman, and jassid, or Amrasca biguttula Ishida, are among the most threatening insect pests to young cotton plants in Pakistan. New chemical insecticides have been trialed to control their damage in commercial fields. Formulations that show good suppression of these pest's populations, while sparing bio-controlling agents, are always preferred for obtaining better crop yield. Six different commercially available insecticides, namely Fountain® (fipronil and imidacloprid), Movento Energy® (spirotetramat and imidacloprid), Oshin® (dinotefuran), Concept Plus® (pyriproxyfen, fenpyroximate, and acephate), Maximal® (nitenpyram), and Radiant® (spinetoram) were evaluated in the present study to shortlist the best available insecticide against targeted pests. Harmful impacts of selected insecticides were also evaluated against naturally occurring predators, such as spiders and green lacewings (Chrysoperla carnea). Radiant® (spinetoram) and Movento Energy®, respectively, were best at controlling thrips (with 61% and 56% mortality, respectively) and jassid (62% and 57% mortality, respectively) populations during 2018 and 2019. Radiant® proved itself as the best option and showed minimal harmful effects on both major arthropod predators of cotton fields i.e., spiders (with 8–9% mortality) and green lacewings (with 12–16% mortality). Movento Energy® also showed comparatively less harmful effects (with 15–18% mortality) towards natural predatory fauna of cotton crops, as compared to other selective insecticides used in the study. The findings of current study suggest that the judicious use of target-oriented insecticides can be an efficient and predator-friendly management module in cotton fields. However, the impact of these chemicals is also depended on their timely application, keeping in consideration the ETL of pests and the population of beneficial arthropods. [ABSTRACT FROM AUTHOR]

The wolf spider Lycosa terrestris (Araneae: Lycosidae) is a well known arthropod containing toxic compounds. It has significant predatory potential in addition to its uses in medicinal and insecticidal formulation. Current investigations were aimed to extract and partially characterize the venom of L. terrestris and the susceptibility tests to evaluate antibacterial potential of venom supernatant and venom pellets against four pathogenic bacterial strains i.e., Gram negative Acinetobacter sp. and Pasteurella sp. and Gram Positive Staphylococcus sp. and Streptococcus sp. Results of this study revealed that the venom of L. terrestris contained six relatively high molecular weight peptides ranging from 125 kDa to 35 kDa. Moreover, results of the susceptibility test confirmed the bacteriostatic action of venom supernatant against aerobic Gram negative Acinetobacter sp. in dose dependent manner. A reduced trend of bacteriostatic inhibition was also observed for venom pellets against Acinetobacter sp. [ABSTRACT FROM AUTHOR]

Abstract: The effectiveness of three botanical insecticides (neem, datura and bitter apple), and three new chemistry synthetic insecticides (acephate, spirotetramat and spinetoram) against onion thrips (Thrips tabaci) was evaluated in experimental field plots at university of Sargodha, Pakistan. The influence of these botanical and chemical insecticides on natural predators and crop yield was simultaneously investigated. All the botanicals and chemical insecticides tested caused significant reductions (45–70%) in thrips populations; the botanicals gave more than 60% control of thrips, while among chemical insecticides, acephate was found to be the most effective followed by spirotetramat and spinetoram, respectively, and these insecticides gave better control than the botanicals. The adverse effects of the botanicals on predator populations were negligible compared to the chemical insecticides. All chemical treatments resulted in a significantly higher yield compared to the untreated control. The botanicals and chemical insecticides became less effective by 7 days after treatment. Therefore, it is recommended that treatment with botanical or chemical insecticides should be repeated weekly consecutively at least three times to keep thrips populations below economic injury levels until crop maturity. [Copyright &y& Elsevier]

The present study was undertaken to compare the activities of nonspecific esterases (i.e., a-esterases and (3-esterases) in chiorpyrifos-treated and control groups of Musca domestica. Higher activities of esterases were found in chiorpyrifos-treated flies, both for males and females as compared to the control flies. Higher activities of nonspecific esterases are reliable indicators for the future development of chlorpyrifos resistance in M. domestica in the area. [ABSTRACT FROM AUTHOR]