Bioactivities of Lamiaceae, Myristicaceae, and Myrtaceae plant oils against Nilaparvata lugens Stâl. (Hemiptera: Delphacidae)

Essential oil (EO) plants have properties as botanical insecticides. Some of them come from the families of Lamiaceae, Myristicaceae, and Myrtaceae. A plant belonging to the Lamiaceae includes patchouli (Pogostemon cablin), while the Myristicaceae includes nutmeg (Myristica fragrans), and the Myrtaceae includes clove (Syzygium aromaticum) and cajuput (Melaleuca cajuput subsp. cajuputi). This research aimed to evaluate toxicity, feeding inhibition, and oviposition deterrent from four EO plants from the Lamiaceae, Myristicaceae, and Myrtaceae to brown rice planthopper Nilaparvata lugens (Hemiptera: Delphacidae), the main pest of rice. The results showed that cajuput and patchouli oil gave more potent toxicity to N. lugens with LC50 and LC95 were 0.016% and 4.87% for cajuput oil and 0.019% and 5.25% for patchouli oil. Cajuput oil at 0.002% deterred oviposition 51.74% and inhibited feeding on 0.016% as many as 71.52% with strong enough criteria to the fourth instar nymphs of N. lugens. Patchouli oil deterred oviposition from 0.002% as much as 61.15% and inhibited feeding on 0.019% as many as 68.73% with strong enough criteria. The highest oviposition deterrent was 83.2% on patchouli oil at the concentration of 0.188%, whereas the highest feeding inhibition was 82.78% on cajuput oil at the concentration of 0.169%.

The First GLP Compliant Study in Africa for the Evaluation of LLIN’s; Efficacy of SafeNet® and SafeNet NF®

Background: To attain and sustain the universal Long-Lasting Insecticidal Nets (LLINs) coverage, cheap nets that provides equivalent or better protection than the standard LLINs, are required. While it is essential to follow the World Health Organization (WHO) guidelines for the evaluation of LLINs, adherence to the Good Laboratory Practice (GLP) is necessary to generate reliable and reproducible data that will facilitate efficient LLINs to be speedy registered. Adherence to GLP obviate the need to duplicate the assessment and ensures substandard LLINs are not reaching the market. This study aimed to evaluate efficacy of SafeNet NF® and SafeNet® LLIN in accordance to the WHO Pest Evaluation Scheme (WHOPES) and the GLP guidelines. Both candidate LLINs were manufactured with less fabrics to cut down manufacturing costs, motivated by the need for cheaper LLINs to achieve universal coverage. Materials & Methods: SafeNet NF® and SafeNet® LLIN, were assessed in experimental huts against wild, pyrethroid-resistant Anopheles arabiensis mosquitoes. Efficacy in terms of mosquito blood-feeding inhibition and mortality, was compared with Interceptor® LLIN and an untreated net. All nets were washed and artificially holed to simulate a used torn net. The GLP guidelines were followed throughout this study.Results: The mortality of mosquitoes exposed to SafeNet NF® and SafeNet® LLIN were equivalent to that of the reference net. Blood-feeding inhibition was only evident in Interceptor® LLIN. Adherence to GLP was observed throughout the study.Conclusions: Step-wise procedures to conduct LLIN evaluation in compliance to both WHOPES and GLP guidelines are elaborated in this study. SafeNet NF® and SafeNet® LLIN offers equivalent protection as Interceptor® LLIN and can facilitate universal LLIN coverage due to its low manufacturing cost. However, further research is needed to understand durability, acceptability and residual efficacy of these nets in field environments.

Effects of Insect Growth Regulators on Mortality, Survival, and Feeding of Euprosterna elaeasa (Lepidoptera: Limacodidae) Larvae

The potential of insecticides that affect the growth and insect development to control Euprosterna elaeasa was evaluated. Fenoxycarb, methoxyfenozide, pyriproxyfen, and tebufenozide were assessed against E. elaeasa larvae for toxicity, survivorship, and feeding inhibition in the laboratory, and mortality in semifield conditions. Concentration–mortality bioassays demonstrated that insect growth regulators (IGRs) have a lethal effect on this insect, with pyriproxyfen (LC50 = 0.141 g L−1) being the most effective, followed by fenoxycarb (LC50 = 0.199 g L−1), methoxyfenozide (LC50 = 0.233 g L−1), and tebufenozide (LC50 = 0.259 g L−1). The survival rate was 99.8% in the control group, compared to 44.6%, 42.9%, 42.2%, and 39.5% in insects treated with pyriproxyfen, fenoxycarb, methoxyfenozide, and tebufenozide, respectively. IGRs caused feeding inhibition in E. elaeasa larvae 3 h after exposure. Furthermore, mortality in semifield conditions was similar to the results found in the laboratory. Our findings suggest that fenoxycarb, methoxyfenozide, pyriproxyfen, and tebufenozide are effective against E. elaeasa and, therefore, we confirm the potential of these IGRs for the control of this pest.

TOKSISITAS EKSTRAK n-HEKSANA KULIT KAYU GEMOR (Nothaphoebe cariacea Kosterm)TERHADAP LARVA Spodoptera exiguaHubner SECARA LABORATORIS

One of the problems in shallots is the infestation of Spodoptera exigua. Currently, pest control using phyto-pesticides is being carried out intensively, because it can reduce the negative impact on the environment. Nothaphoebe cariacea Kosterm is a plant that haspotential as a phyto-pesticides. Evaluation of the potential of N. cariacea bark (NCB) biolarvicide in S. exiguawas applied to this study in a laboratory.Ten test larvae were fed with leaves that had been applied with n-hexane extract with a concentration of 0.25%; 0.50%; 0.75%; 1.00%; 1,25% and positive control (active ingredientSipermetrin).Observations were made every 12 hours after application for 72 hours on the mortality of larvae and the area of leaves consumed.The results showed that the NCBn-hexane extract had an extract content of 0.34% with the active ingredients contained were triterpenoids andsteroids.Bio-assay showed that NCB n-hexane extract had the ability to kill tested larvae close to positive control (mortality: 74% -86%) and (feeding inhibition: 47% -53%).Although not as potent as synthetic pesticides, NCB n-hexane extract has potential as a phyto-pesticides for S. exiguaS. exigua.

New mosquito repellency bioassay for evaluation of repellents and pyrethroids using an attractive blood-feeding device

Background With the increasing threat of the worldwide spread of mosquito-borne infectious diseases, consumer interest in anti-mosquito textiles that protect against mosquito bites is also increasing. Accordingly, repellent- or insecticide-treated textiles are gaining popularity. The standardization of commercial textile products is, therefore, indispensable for an authentic and objective evaluation of these products. Here we report a textile testing method using an artificial blood-feeding system that does not involve human volunteers or live animals, which aligns with the policy of protecting human and animal welfare. Methods The attractive blood-feeding device (ABFD) was designed using the Hemotek® membrane feeding system. The repellency of DEET, icaridin and permethrin was assayed using unfed female adults of Aedes albopictus (Skuse) under two different test conditions, namely choice and no-choice tests. The choice test consisted of two feeding units, one chemically treated and untreated, that were installed on the ABFD; mosquitoes attracted to and resting on the feeding units were counted and the overall blood-feeding rates recorded. The no-choice test consisted of two feeding units treated with the same chemical that were installed on the ABFD; mosquitoes attracted to and resting on the feeding units were counted and the blood-feeding rates were recorded. A control test was conducted using two feeding units, both sides of which were untreated. Results In the choice test, high repellency (> 95% inhibition of resting on the treated surface) of 1% DEET and 2% icaridin was observed, whereas 2% permethrin was not an effective repellent. Also, high blood-feeding inhibition (> 95%) was observed for 2% DEET and 2% icaridin. In the no-choice test, high repellency was observed for 1% DEET and 2% icaridin, whereas the repellency of 2% permethrin was low. Also, high blood-feeding inhibition was observed for 2% DEET, 4% icaridin and 2% permethrin. Conclusions The accuracy and reproducibility of the developed method demonstrate that the ABFD may be widely used for fundamental experiments in the field of mosquito physiology, for the development of new repellent chemicals and in evaluation studies of mosquito repellent products, such as anti-mosquito textiles. The further development of the membrane and feeding unit systems will enable a more practical evaluation of mosquito repellents and blood-feeding inhibitors, such as pyrethroids.

The effects of organic matter and flooding on the ecotoxicity of pore water in soils developed in the sites of historical arsenic mining: application of biological tests with crustacean zooplankton

<p>Arsenic is a trace metalloid, potentially toxic for humans, animals and for plants. The problem of soil pollution with arsenic occurs in Poland only on a local scale, but in the Sudetes and in their foreland, there are several sites were arsenic was mined in the past. Particularly high concentrations of As in soils were confirmed in Złoty Stok, formerly the main European centre of arsenic industry. Decomposing forest litter as well as flooding can affect mobilization of As and other toxic elements, change their speciation in pore water and influence the toxicity to biota. This study examined the chemistry and ecotoxicity of pore water acquired from two soils that developed in a former As mining site: from the “Orchid dump” and from a nearby forest. Soils used in the experiment  contained very high concentrations of As: 2020 and 19600 mg/kg.  An unpolluted soil was used as a control. Soil samples were incubated in various moisture conditions (70%  of water holding capacity and 100% flooding), in the presence and absence of organic matter introduced with forest litter collected from a beech stand. Soil pore water was collected three times (after 7, 21 and 90 days) with MacroRhizon suction samplers. Chemical analysis of pore water involved the measurements of concentrations of As and potentially toxic metals, including Mn and Fe, as well as the concentrations of P. Ecotoxicity of pore water was examined in two bioassays: THAMNOTOXKIT F and RAPIDTOXKIT F. The Thamnocephalus platyurus toxicity test is a 24h bioassay based on the mortality of the test organisms (freshwater crustaceans). The sublethal effects were determined using RAPIDOTOXKIT, based on ISO standard 2011. This procedure measures the feeding inhibition of the juveniles of T. platyurus. A very high toxicity to T. platyurus was confirmed in the pore water of the soil richer in As, where all the organisms died. High mortality of crustaceans > 83,33 % was found in the pore water of soil collected from the Orchid dump, in particular after a longer incubation period. The addition of beech litter, as well as soil flooding, caused an increased mortality of test organisms that reached 100%, regardless of the time of incubation. In the pore water of less polluted soil, collected from the forest site in Złoty Stok, an increased mortality of crustaceans was observed upon the addition of beech litter. The RAPIDOTOXKIT test turned out less sensitive to high concentrations of As and other toxic components present in soil pore water. The feeding inhibition did not correspond directly with the concentrations of As. However, in the case of samples with the highest As concentration (130 mg/L), found in pore water of the Orchid dump soil treated with beech litter and fully flooded, the feeding inhibition reached 100%.</p><p>This research was funded by the National Science Centre of Poland; Project No. 2016/21/B/ST10/02221</p>

Efficacy of indoor residual spraying with broflanilide (TENEBENAL), a novel meta-diamide insecticide, against pyrethroid-resistant anopheline vectors in northern Tanzania: An experimental hut trial

Novel chemistry for vector control is urgently needed to counter insecticide resistance in mosquitoes. Here a new meta-diamide insecticide, broflanilide (TENEBENALTM), was evaluated in East African experimental huts in Moshi, northern Tanzania. Two consecutive experimental hut trials with broflanilide 50WP were conducted; the first evaluating the efficacy of three concentrations, 50 mg/m2, 100 mg/m2, and 200 mg/m2 using a prototype formulation, and the second trial evaluating an improved formulation. The IRS treatments were applied on both mud and concrete surfaces and efficacy was monitored over time. The mortality, blood-feeding inhibition and exiting behaviour of free-flying wild mosquitoes was compared between treatment arms. Additionally, cone assays with pyrethroid-susceptible and resistant mosquito strains were conducted in the huts to determine residual efficacy. The first trial showed a dosage-mortality response of the prototype formulation and 3–8 months of residual activity, with longer activity on concrete than mud. The second trial with an improved formulation showed prolonged residual efficacy of the 100 mg/m2 concentration to 5–6 months on mud, and mosquito mortality on the concrete surface ranged between 94–100% for the full duration of the trial. In both trials, results with free-flying, wild Anopheles arabiensis echoed the mortality trend shown in cone assays, with the highest dose inducing the highest mortality and the improved formulation showing increased mortality rates. No blood-feeding inhibition or insecticide-induced exiting effects were observed with broflanilide. Broflanilide 50WP was effective against both susceptible and pyrethroid-resistant mosquito strains, demonstrating an absence of cross resistance between broflanilide and pyrethroids. The improved formulation, which has now been branded VECTRONTM T500, resulted in a prolonged residual efficacy. These results indicate the potential of this insecticide as an addition to the arsenal of IRS products needed to maintain both control of malaria and resistance management of malaria-transmitting mosquitoes.

Increased prevalence of insecticide resistance in Anopheles coluzzii populations in the city of Yaoundé, Cameroon and influence on pyrethroid-only treated bed net efficacy

In Cameroon, pyrethroid-only long-lasting insecticidal nets (LLINs) are still largely used for malaria control. The present study assessed the efficacy of such LLINs against a multiple-resistant population of the major malaria vector, Anopheles coluzzii, in the city of Yaoundé via a cone bioassay and release-recapture experimental hut trial. Susceptibility of field mosquitoes in Yaoundé to pyrethroids, DDT, carbamates and organophosphate insecticides was investigated using World Health Organization (WHO) bioassay tube tests. Mechanisms of insecticide resistance were characterised molecularly. Efficacy of unwashed PermaNet® 2.0 was evaluated against untreated control nets using a resistant colonised strain of An. coluzzii. Mortality, exophily and blood feeding inhibition were estimated. Field collected An. coluzzii displayed high resistance with mortality rates of 3.5% for propoxur (0.1%), 4.16% for DDT (4%), 26.9% for permethrin (0.75%), 50.8% for deltamethrin (0.05%), and 80% for bendiocarb (0.1%). High frequency of the 1014F west-Africa kdr allele was recorded in addition to the overexpression of several detoxification genes, such as Cyp6P3, Cyp6M2, Cyp9K1, Cyp6P4 Cyp6Z1 and GSTe2. A low mortality rate (23.2%) and high blood feeding inhibition rate (65%) were observed when resistant An. coluzzii were exposed to unwashed PermaNet® 2.0 net compared to control untreated net (p < 0.001). Furthermore, low personal protection (52.4%) was observed with the resistant strain, indicating reduction of efficacy. The study highlights the loss of efficacy of pyrethroid-only nets against mosquitoes exhibiting high insecticide resistance and suggests a switch to new generation bed nets to improve control of malaria vector populations in Yaoundé.

Effectiveness Test of Piper methysticum Extract Against Crocidolomia pavonana larvae

Application synthetic insecticide with high frequency and continuously can give to negative impact. Alternative control which secures is botanical insecticide. This research aimed to effectiveness tests of P. methysticum plant against C. pavonana larvae using root and leaves this plant. The tested insecticide activity including mortality and feeding inhibition tests. The extract was tested at five concentration levels and repeated five times. The results showed that P. methysticum root extract was able to cause C. pavonana larvae mortality of 94% with a concentration of 419.7 gram/100 ml in water meanwhile, the testing using leaves extract causes mortality 98% from concentration 342 gr/100 ml in water. The feeding inhibition test showed the P. methysticum roots extract give effect with very weak criteria at some concentrations used a no choice method while Leaves extract P. methysticum does not show feeding inhibition.