Fast-acting Insecticides Research Articles

Assessing the Impact of Onion Juice on the Levels of Leutinizing Hormone and Follicle Stimulating Hormone in Female Mice Exposed to Transfluthrin Smoke

Assessing the Impact of Onion Juice on the Levels of Leutinizing Hormone and Follicle Stimulating Hormone in Female Mice Exposed to Transfluthrin Smoke

Biodegradation of Synthetic Pyrethroid Insecticide Deltamethrin by Stenotrophomonas maltophilia Strain DRNB1

: Deltamethrin is one of the most used pyrethroid insecticide in different regions of the world. It is the fastacting insecticide that disrupts the cellular sodium channels. The deltamethrin residues are highly retained in environments, particularly in soil and water and have inevitable side effects on natural resources and human health. The most efficient, economical, and environmentally beneficial way of removing deltamethrin from contaminated sites is bioremediation. Bacteria are the most used biological agents in biodegradation studies. Thus, in this study deltamethrin-degrading bacteria Stenotrophomonas maltophilia strain DRNB1 was isolated and characterised. The bacterial growth was analysed by UV-spectrophotometer and deltamethrin degradation was studied by GC-MS analysis. S. maltophilia strain DRNB1 used deltamethrin as the sole carbon source for growth. Deltamethrin degradation efficiency of DRNB1 was 89.2% in insecticide supplemented media and 93% in presence of additional glucose in mineral media. These results implies that S. maltophilia strain DRNB1 could be used as a bioremediation technology for deltamethrin contaminated environments.

Infertility: A product of smoke emanating from Transfluthrin coated insecticide paper (TCIP)

Transfluthrin is a fast-acting insecticide used in household and hygiene products, mainly against flying insects, such as mosquito and flies, and in agriculture material pests. Its uses in these areas have not been without health risk to humans and the ecosystem. Therefore, the current study was designed to investigate the effect of smoke emanating from Transfluthrin Coated Insecticide Paper (TCIP) on adult Wistar rats’ testicular functions. The rats were grouped into three. Group A was exposed to normal environmental air. Group B and C rats were exposed via whole-body inhalation to smoke emanating from 6 g and 12 g of TCIP every day for 8 weeks. The entire groups contained eight rats each. At the end of the exposure, body and organs weight, semen analysis, biochemical assay and histological examination were evaluated and determined. The results show that the exposure significantly altered the testicular cytoarchitecture, sperm quality, hormonal profile and oxidative parameters with an increase in exposure to TCIP. This study revealed that exposure to transfluthrin is detrimental to the reproductive functions of male rats.

Arthropod Abundance and Biomass in Response to Pinus taeda L. Trunk Height

The trunks of southeastern pines provide vital habitat for many invertebrates that are, in turn, available as prey for bark-foraging birds. Knowing how these arthropods are distributed vertically on tree trunks is important and may allow for a rapid assessment of prey response to forest management practices. In this study, we used a fast-acting insecticide to sample the arthropods on the lower (0–3 m) and upper (3–9 m) bole sections of nine loblolly pine, Pinus taeda L., trees. We collected over 1,600 arthropods representing 15 orders and 66 families. Ants (Hymenoptera: Formicidae) were the most abundant group collected, and wood cockroaches (Blattodea: Blattellidae) accounted for the greatest overall biomass. Abundance and biomass of arthropods per m2 were greater on the lower trunk, but these values were strongly correlated with those from the upper trunk. Nonmetric multidimensional scaling and permutational multivariate analysis of variance showed that arthropod community composition differed significantly between the two trunk positions. Additionally, indicator species analysis found four flightless taxa to be significantly associated with the lower trunk (Araneae, Zygentoma, Hymenoptera, and Pseudoscorpiones) but none with the higher trunk position. These findings show that bark-dwelling arthropods are generally more abundant near the bases of trees and that there is a strong relationship between abundance and biomass between lower and upper trunk sections. Knockdown insecticides offer an effective tool for rapidly assessing the availability of invertebrate prey for bark-foraging birds.

Chronic Flubendiamide Exposure Induces Oxidative Stress in Water Buffalo (<i>Bubalus bubalis</i>) Calves

Flubendiamide is a recently introduced, fast-acting insecticide with an excellent residual effect. In an unpublished study, it was reported not to cause any genotoxic, carcinogenic and neurotoxic effects in mammals. However, recent studies suggest that it is toxic for fish and Chinese tiger frog. Alterations in leukogram, erythrocytic indices and aspartic acid concentration in cerebrospinal fluid in water buffalo following its chronic exposure to flubendiamide have also been recorded in our laboratory.

Toxicity of butene-fipronil, in comparison with seven other insecticides, in Leptinotarsa decemlineata and Drosophila melanogaster

The speed of toxic action of an insecticide is an indicator for control efficacy and has considerable practical importance. For agricultural pest control, fast-acting is an important feature for an insecticide to consistently reduce the amount of feeding damage. Butene-fipronil is a novel compound obtained via the structural modification of fipronil. However, information about the toxicity and speed of toxic action is still limited. In the present paper, we compared the toxic feature of butene-fipronil with seven other insecticides, of which imidacloprid and abamectin are slow-acting insecticides, and acephate, endosulfan, methomyl, α-cypermethrin and spinosad are fast-acting insecticides. We found that the contact and stomach toxicities of butene-fipronil were among the highest ever estimated to Leptinotarsa decemlineata and Drosophila melanogaster. The speed of toxic action of butene-fipronil was determined using median lethal time (LT50) at a dose (concentration) equivalent to LD80 values. For L. decemlineata, the values for butene-fipronil, imidacloprid, abamectin, acephate, endosulfan, methomyl, cypermethrin and spinosad were calculated to be 39.9, 36.5, 37.5, 20.2, 22.4, 23.8, 16.4 and 23.1 h, respectively. Those for D. melanogaster were 29.8, 31.5, 29.4, 14.0, 20.3, 18.1, 13.5, and 20.1 h, respectively. ANOVA analysis showed that butene-fipronil, imidacloprid, abamectin had similar LT50 values, whereas acephate, endosulfan, methomyl, spinosad and cypermethrin had comparable LT50 values. Thus, butene-fipronil belongs to slow-acting insecticides. Our results provide more empirical information for butene-fipronil potential application.

Disrupting Mosquito Reproduction and Parasite Development for Malaria Control.

The control of mosquito populations with insecticide treated bed nets and indoor residual sprays remains the cornerstone of malaria reduction and elimination programs. In light of widespread insecticide resistance in mosquitoes, however, alternative strategies for reducing transmission by the mosquito vector are urgently needed, including the identification of safe compounds that affect vectorial capacity via mechanisms that differ from fast-acting insecticides. Here, we show that compounds targeting steroid hormone signaling disrupt multiple biological processes that are key to the ability of mosquitoes to transmit malaria. When an agonist of the steroid hormone 20-hydroxyecdysone (20E) is applied to Anopheles gambiae females, which are the dominant malaria mosquito vector in Sub Saharan Africa, it substantially shortens lifespan, prevents insemination and egg production, and significantly blocks Plasmodium falciparum development, three components that are crucial to malaria transmission. Modeling the impact of these effects on Anopheles population dynamics and Plasmodium transmission predicts that disrupting steroid hormone signaling using 20E agonists would affect malaria transmission to a similar extent as insecticides. Manipulating 20E pathways therefore provides a powerful new approach to tackle malaria transmission by the mosquito vector, particularly in areas affected by the spread of insecticide resistance.

DNA Insecticides: Application of the Iap-2 Gene Single-stranded Fragments from Three Different Nucleopolyhedroviruses against Second Instar Gypsy Moth Larvae

We discovered that the external application of a solution containing one single-stranded DNA fragment, 18 nucleotides long, either from the BIR domain of the AcMNPV IAP-2 gene or the RING domain of the TnSNPV IAP-2 gene, induces a significantly higher mortality of gypsy moth larvae compared to a solution of distilled water. The results show the insecticidal potential of viral DNA fragments that can be used to create safe, relatively inexpensive and fast-acting insecticides to control quantity of pest insect populations. In our opinion, insecticidal effect may depend on the specific sequence of double and triple hydrogen bonds in a single-stranded DNA fragment or on a sequence of a few nitrogenous bases at specific sites of an oligonucleotide. The results suggest that small single-stranded viral DNA fragments may have practical applications as DNA insecticides.

Bioassay method for toxicity studies of insecticide formulations to Tuta absoluta (meyrick, 1917)

Chemical control is the main method for controlling the tomato leafminer, Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae). Reported techniques for the evaluation of insecticide toxicity to the tomato leafminer are not in agreement with field conditions and do not allow us to verify whether doses used in the field are efficient for control. Thus, the objective of this work was to develop a bioassay methodology to study the toxicity of insecticide formulations to T. absoluta that represent field conditions for fast-acting insecticides (neurotoxics and inhibitors of respiration) and slow-acting insecticides (Bacillus thuringiensis and insect growth regulators). The leaf-dip method was the most efficient method for toxicity studies of insecticides formulations to T. absoluta. We verified that bioassays with fast-acting insecticides should be performed with glass Petri dishes containing one tomato foliole from the 4th leaf from the plant apex infested with 10 larvae of 3rd instar and these bioassays can last 48 hours. Conversely, bioassays with slow-acting insecticides should be performed with two-liter transparent PET bottles containing the 4th leaf from the plant apex, with their petioles immersed in a glass bottle containing 120 mL of water, and this leaf should be infested with 10 larvae of 2nd instar and this bioassays can last seven days.

Insecticide resistance in Anopheles gambiae from south-western Chad, Central Africa

BackgroundIndoor residual spraying and insecticide-treated nets (ITN) are essential components of malaria vector control in Africa. Pyrethroids are the only recommended compounds for nets treatment because they are fast-acting insecticides with low mammalian toxicity. However, there is growing concern that pyrethroid resistance may threaten the sustainability of ITN scaling-up programmes. Here, insecticide susceptibility was investigated in Anopheles gambiae sensu lato from an area of large scale ITN distribution programme in south-western Chad.MethodsSusceptibility to 4% DDT, 0.05% deltamethrin, 0.75% permethrin, 0.1% bendiocarb and 5% malathion was assessed using the WHO standard procedures for adult mosquitoes. Tests were carried out with two to four days-old, non-engorged female mosquitoes. The An. gambiae Kisumu strain was used as a reference. Knockdown effect was recorded every 5 min and mortality scored 24 h after exposure. Mosquitoes were identified to species and molecular form by PCR-RFLP and genotypes at the kdr locus were determined in surviving specimens by Hot Oligonucleotide Ligation Assay (HOLA).ResultsDuring this survey, full susceptibility to malathion was recorded in all samples. Reduced susceptibility to bendiocarb (mortality rate of 96.1%) was found in one sample out of nine assayed. Increased tolerance to pyrethroids was detected in most samples (8/9) with mortality rates ranging from 70.2 to 96.6% for deltamethrin and from 26.7 to 96.3% for permethrin. Pyrethroid tolerance was not associated with a significant increase of knock-down times. Anopheles arabiensis was the predominant species of the An. gambiae complex in the study area, representing 75 to 100% of the samples. Screening for kdr mutations detected the L1014F mutation in 88.6% (N = 35) of surviving An. gambiae sensu stricto S form mosquitoes. All surviving An. arabiensis (N = 49) and M form An. gambiae s.s. (N = 1) carried the susceptible allele.ConclusionThis first investigation of malaria vector susceptibility to insecticides in Chad revealed variable levels of resistance to pyrethroid insecticides (permethrin and deltamethrin) in most An. gambiae s.l. populations. Resistance was associated with the L1014F kdr mutation in the S form of An. gambiae s.s.. Alternative mechanisms, probably of metabolic origin are involved in An. arabiensis. These results emphasize the crucial need for insecticide resistance monitoring and in-depth investigation of resistance mechanisms in malaria vectors in Chad. The impact of reduced susceptibility to pyrethroids on ITN efficacy should be further assessed.

Indirect Effect of Insecticides on Convergent Lady Beetle (Coleoptera: Coccinellidae) in Pecan Orchards

Indirect toxicity through feeding on insecticide-treated prey was determined for five insecticides at two concentrations each to larvae and adults of convergent lady beetle, Hippodamia convergens Guerin-Meneville. Endosulfan (0.375 and 0.75 g [AI]/liter), carbaryl (1.2 and 2.4 g [AI]/liter), phosmet (0.375 and 0.75 g [AI]/liter), methomyl (0.225 and 0.45 g [AI]/liter), and esfenvalerate (0.015 and 0.03 g [AI]/liter) were toxic to larvae and adults when convergent lady beetles were fed insecticide-treated yellow pecan aphids, Monelliopsis pecanis Bissell. Esfenvalerate was a fast-acting insecticide, killing all tested convergent lady beetle life stages 1 h after feeding on treated yellow pecan aphids. Carbaryl and phosmet were slow-acting insecticides, causing the greatest mortality after 48 h. Methomyl was the only insecticide that did not cause 100% mortality to adult convergent lady beetles 48 h after feeding on insecticide-treated yellow pecan aphids, at both rates tested.