Insecticide Combinations Research Articles

Field Tests of Three Alternative Insecticides with Protein Bait for the Development of an Insecticide Rotation Program to Control Melon Flies, Zeugodacus cucurbitae (Coquillett) (Diptera: Tephritidae).

Simple SummaryMelon flies in Hawaii have developed high levels of resistance to a widely used insecticidal bait containing the active ingredient spinosad. Since farmers relied heavily on this product and have few alternatives, we tested three other insectides mixed with a bait spray called Nu-Lure. The three products (Agri-Mek SC, Mustang Maxx, and Malathion 5EC) were all found to be effective in either decreasing melon fly numbers or suppressing the growth of the population in the field. When used one-by-one in rotation for two weeks per product at one-week intervals on a commercial zucchini farm, melon fly populations were dramatically reduced and the yield of zucchinis harvested was substantially increased.High levels of resistance to the spinosad-based insecticidal protein bait GF-120 have been detected in some populations of melon fly, Zeugodacus cucurbitae (Coquillett) (Diptera: Tephritidae), in Hawaii in 2017. To provide cucurbit farmers in Hawaii with alternative insecticides, we field-tested the effectiveness of Agri-Mek SC (a.i., abamectin), Mustang Maxx (a.i., zeta-cypermethrin), and Malathion 5EC (a.i., malathion), added to a protein bait spray (Nu-Lure Insect Bait). The insecticide and protein bait combinations were applied to the roosting plants of Z. cucurbitae around the perimeter of the cucurbit fields at one-week intervals. When individually tested, all three insecticides in combination with protein bait significantly reduced or suppressed the numbers of female flies caught in torula yeast traps. A two-week rotation of weekly applications of the three insecticides and GF-120 significantly reduced Z. cucurbitae numbers on a commercial zucchini farm on Maui. The percentage of marketable fruits harvested increased from 51% to 98% after implementing the insecticide rotation. Our findings will be used to provide cucurbit farmers with additional products to control Z. cucurbitae. The future focus will be on educating cucurbit farmers to use the insecticide rotation strategy to prevent or delay resistance development.

Effect of sublethal concentrations of insecticides associated with NaCl and KCl on feeding behavior and mortality of Euschistus heros and Diceraeus melacanthus (Hemiptera: Pentatomidae)

Stink bugs are important pests of highly profitable agricultural crops worldwide, and the use of insecticides remains the main strategy for their control. The objectives of this study were to evaluate the behavioral aspects of Euschistus heros and Diceraeus melacanthus through feeding after exposure to chloride solutions (NaCl and KCl), as well as the control efficacy of insecticides in combination with salt. Two bioassays were performed with stink bugs exposed to treated substrate: i) feeding preference by salivary sheath counting in a free choice test for chloride solutions, using bean pod or corn seedling as counting substrate for newly emerged E. heros and D. melacanthus adults, respectively; and ii) comparative efficiency of five synthetic insecticides associated with NaCl or KCl in the mortality of 4th instar nymphs (N4). Pre-determined sublethal (LC25) and median lethal (LC50) concentrations of commercially available insecticides (Lfn), buprofezin (Bpf), pyriproxyfen (Ppx), chlorantraniliprole (Ctn) and spinosad (Spn) were used. For each species and insecticide, the treatments were pure LC25, LC25 + NaCl 5% m/m, LC25 + KCl 5% m/m, pure LC50, and distilled water (dH2O) as the control. Corn seedlings treated with 5% NaCl saline solution had reduced salivary sheaths from D. melacanthus. Ctn LC25 (0.63 mL L-1) + 5% NaCl and pure Ctn LC50 (1.16 mL L-1) were similar and more efficient in terms of mortality of D. melacanthus N4s than any other treatment. The association of Spn LC25 (0.37 mL L-1) + 5% NaCl and Spn LC50 only (0.90 mL L-1) was similar to that of E. heros N4s compared to other treatments. The insecticide concentrations used in this study have potential for stink bug pest control, thus the association of insecticides with commercially available, easy-to-find, and low-cost chloride salts may represent a good strategy for stink bug control.

Evaluation of pesticide combinations against brown planthopper and sheath blight in rice

Field experiment was conducted at Regional Agricultural Research Station, Maruteru, West Godavari (A.P.) during two kharif seasons of 2019 and 2020 to evaluate the compatibility of combinations of insecticides and fungicides against brown planthopper and sheath blight in rice. The results revealed that pymetrozine and triflumezopyrim as sole treatments are highly effective against brown planthopper (BPH), Nilaparvata lugens (Stal) by registering over 90% reduction in BPH population. While, pymetrozine and triflumezopyrim in combination with azoxystrobin and azoxystrobin + tebuconazole are highly effective against BPH and sheath blight, Rhizoctonia soloni Kuhn in by registering over 90% and >50% reduction in BPH population and sheath blight severity, respectively and registered 64.23% to 73.03% higher grain yields than untreated control. It was also found that there was no adverse effect of fungicides on the efficacy of insecticides or vice versa. The insecticides tested were physically compatible with fungicides and no phytotoxic symptoms observed on rice crop when pesticides were applied in combination. Thus, pymetrozine and triflumezopyrim are compatible with test fungicides and can be safely used as tank mix for the simultaneous management of BPH and sheath blightin rice.

Seed Treatment with Diamide and Neonicotinoid Mixtures for Controlling Fall Armyworm on Corn: Toxicity Evaluation, Effects on Plant Growth and Residuality.

The diamides, chlorantraniliprole (CHL) and cyantraniliprole (CYA), have been used as seed treatment agents against the fall armyworm (FAW), Spodoptera frugiperda in China. However, large-scale application of these two insecticides is prohibited because of their high cost. The neonicotinoid insecticides, clothianidin (CLO) and thiamethoxam (THI), are cheaper and widely used. In this study, we tested the efficacy of CHL + CLO and CYA + THI as seed treatment agents against FAW larvae both in laboratory and field conditions. Laboratory experiments showed that the two binary mixtures (both 240 g.a.i.100 kg−1 corn seeds) caused FAW mortality exceeded 84.00% at 14 days after seedling emergence (DAE). The mortality of the binary mixtures were similar to either CHL (300 g.a.i.100 kg−1corn seeds) or CYA (144 g a.i.100 kg−1corn seeds), but higher than CLO (120 g.a.i.100 Kg−1corn seeds) or THI (180 g a.i.100 kg−1corn seeds). Two independent field experiments showed that both binary mixtures resulted in above 68.00% control efficacy at 14 DAE, suggesting that these insecticidal combinations could effectively control FAW over a relative long period. In addition, both binary mixtures showed no negative effects on the growth and development of corn seedlings. The residues of binary mixtures in corn leave were also lower at 28 DAE as compared to residues in CHL or CYA alone. Most importantly, the costs of CHL + CLO were reduced up to 50% and CYA + THI up to 20% when compared to singly used chemical. Totally, our results indicated that CHL + CLO and CYA + THI had the same control efficacy as CHL or CYA alone, but with much lower cost.

Efficacy of a New Combination Insecticide Against Rice Brown Planthopper <i>Nilaparvata Lugens</i> (Stal)

Efficacy of a new combination insecticide against rice brown plant hopper (BPH) Nilaparvata lugens Stal revealed that among all the treatments, significant reduction in the incidence (76.91% reduction over control) and higher grain yield (5.37 ton/ ha) was obtained with buprofezin 24%+ fipronil 40%SC (MAIRM-10) @ 875 ml/ ha. It was at par with buprofezin 24%+ fipronil 40%SC (MAIRM-10) @ 750 ml/ ha followed by buprofezin 25%SC @ 800 ml/ ha. Although maximum grain yield was obtained from buprofezin 24%+ fipronil 40%SC (MAIRM-10) @ 875 ml/ ha, maximum cost benefit in term of ICBR was observed with buprofezin 24%+ fipronil 40%SC (MAIRM-10) @ 750 ml/ ha (1:6.11) besides considering the environmental effect. Buprofezin 24%+ fipronil 40%SC (MAIRM-10) @ 750 ml/ ha was found to be most optimum one for BPH management.

Resistance intensity status of Anopheles gambiae s.l. species at KOLOKOPE, eastern plateau Togo: A potential site to assess new vector control tools

According to WHO recommendations, the deployment of the next generation of Long-Lasting Insecticidal Nets (LLINs) for malaria vector control requires appropriate investigations on the insecticide resistance profile of the vector. Most of the next generation of LLINs are impregnated with a combination of pyrethroid insecticides and piperonyl butoxide (PBO), a synergist with an additional impact on the increase in the mortality rate of Anopheles gambiae s.l. (Diptera: Culicidae). Kolokopé is a cotton-growing area in the central region of Togo characterized by an intensive use of agricultural pesticides and insecticides where there is a phase II experimental hut station. For the characterization of the site, WHO susceptibility tests using diagnostic doses of ten insecticides, PBO synergist assays and intensity assays of three pyrethroids (5x and 10x) were conducted on adult female mosquitoes obtained from larvae collected around the site. Anopheles gambiae s.l. from Kolokopé showed high resistance to pyrethroids and DDT, but to a lesser extent to carbamates and organophosphates. Likewise, high intensity of resistance to pyrethroid was observed with less than 40% mortality at 10x deltamethrin, 52 and 29% mortality at 10x permethrin and 10x alphacypermethrin, respectively. Also, PBO treatment resulted in increased mortality which was higher than the mortality rate at 10x doses of pyrethroids. The high pyrethroid intensity resistance recorded at Kolokopé could be mainly due to the selection pressure on An. gambiae s.l. caused by the excessive use of insecticide in agriculture. These results can be used to assess the next generation of LLINs either in experimental hut or at a community trial.

Synergistic and Additive Interactions of Zhongshengmycin to the Chemical Insecticide Pymetrozine for Controlling Nilaparvata lugens (Hemiptera: Delphacidae).

Management of the rice brown planthopper Nilaparvata lugens Stål is challenging because it can rapidly adapt to new pesticides within several generations. Combined use of chemical insecticides and antimicrobials was proposed as an alternative strategy to control N. lugens. Our previous experiments identified two effective agents (chemical insecticide: pymetrozine and antimicrobial: zhongshengmycin) that act on different targets in N. lugens. However, conditions and effectiveness of combinations of antimicrobials and insecticides against N. lugens are still unknown. Here, we evaluated separate and combined effects of pymetrozine and zhongshengmycin on third instar nymphs of N. lugens under laboratory and greenhouse conditions. Results showed that zhongshengmycin exerts significant inhibitory effects on the three endosymbionts Pichia guilliermondii, Cryptococcus peneaus, and Pichia anomala cultured in vitro of N. lugens. Combinations of pymetrozine and zhongshengmycin under laboratory conditions produced additive or synergistic effects on N. lugens and caused higher mortality in third instar nymphs than either of them used alone. Experiments under greenhouse conditions further demonstrated that effective component quality ratio of pymetrozine to zhongshengmycin of 1:10 and 1:40 with co-toxicity coefficients of 221.63 and 672.87, respectively, also produced significant synergistic effects against N. lugens. Our results indicated that chemical insecticides combined with antimicrobials may provide a potential novel strategy for controlling N. lugens by inhibiting its endosymbionts.

The synergistic effects of rosehip oil and matrine against Icerya aegyptiaca (Douglas) (Hemiptera: Coccoidea) and the underlying mechanisms.

Icerya aegyptiaca (Douglas) is an important agricultural pest that has a protective wax shell. Insecticides generally fail to achieve the desired control of I. aegyptiaca because of difficulties penetrating this wax shell. Plant essential oils are rich in terpenoids and have strong penetrability and expansibility, which can enable the rapid penetration and absorption of insecticides, thereby improving the control effect. Matrine is a botanical insecticide with contact and stomach toxicity, low toxicity toward non-target organisms and is environmentally friendly. In this study, we tested the insecticidal activity of rosehip oil (Ro)/matrine combinations and revealed the synergistic mechanism of Ro and its components with matrine in terms of physiology and biochemistry. Ro/matrine combinations have strong penetrating power, enabling matrine to quickly penetrate the wax shell of I. aegyptiaca and enter the insect body. This improves the insecticidal activity and enhances inhibition of acetylcholinesterase activity. Ro and its main chemical constituents, cineole and (+)-camphor, showed synergistic effects on matrine with synergic ratios of 4.79, 3.49 and 4.21, respectively. Combinations of Ro, cineole and (+)-camphor with matrine have good insecticidal effects on I. aegyptiaca while remaining safe to the environment. These combinations of biological insecticides have excellent development prospects and provide a new reference for the pest management of scale insects. © 2022 Society of Chemical Industry.

Control of Sitophilus granarius and Sitophilus oryzae on stored wheat using low-rate combinations of natural zeolite with three insecticides

The insecticidal potential of three insecticides (chlorpyrifos-methyl (CH), deltamethrin (DE), spinosad (SP)), zeolite (ZE) and their low-rate combinations was tested against Sitophilus granarius (L.) and Sitophilus oryzae (L.) adults. The application rates were: CH at 0.1, 0.5 and 1.0 mg/kg, DE at 0.2, 0.5, 1.0 and 2.0 mg/kg, SP at 0.1, 0.25, 0.5 and 1.0 mg/kg, and ZE at 100 and 500 mg/kg. Individual treatments with CH, DE or SP at 1.0 mg/kg induced 100, 83.9 and 76.2% mortality of S. granarius, and 95.5, 69.3 and 88.2% mortality of S. oryzae after 21 days, respectively. Treatment with ZE alone at 500 mg/kg caused 43.5 and 50.3% mortality of S. granarius and S. oryzae, respectively, after 21 days. The combined treatments of insecticides and ZE showed higher adult mortality than treatments with each insecticide or ZE alone. Combined treatments of CH (0.5 mg/kg) + ZE (100 mg/kg), CH (0.1 mg/kg) + ZE (500 mg/kg), CH (0.5 mg/kg) + ZE (500 mg/kg) and SP (1.0 mg/kg) + ZE (500 mg/kg) induced 100% adult mortality of both insects after 21 days. In addition, a mixture of DE (1.0 mg/kg) + ZE (500 mg/kg) caused 100% mortality of S. oryzae after 21 days. Progeny of both insects decreased significantly in all treatments compared by untreated wheat grain. The mixtures, CH (0.5 mg/kg) + ZE (500 mg/kg), DE (1.0 mg/kg) + ZE (500 mg/kg, SP (1.0 mg/kg) + ZE (100 mg/kg) and SP (1.0 mg/kg) + ZE (500 mg/kg), induced remarkable progeny reduction (≈100%) and complete protection of wheat grain (weight loss = 0.0%) against damage caused by insects for 90 days. Our results indicate that the combination of insecticides with ZE at low rates is a promising approach for the control of S. granarius and S. oryzae on stored wheat.

Economic returns on seed treatment combinations in Louisiana rice

The use of multiple insecticidal seed treatments in combination to control a greater spectrum of pests has been increasing in rice production in the U.S. Mid-South. The economic benefits of individual seed treatments in rice are well documented, but returns on investment (ROI) on combinations are unknown. Efficacy and economic returns of insecticidal seed treatments alone and in combination were evaluated through a series of five field trials conducted in Louisiana from 2018 to 2020. In all trials, treatments containing chlorantraniliprole or cyantraniliprole provided the best control of rice water weevil, Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae), and control was not significantly improved by the addition of a second insecticide. Insecticidal control of L. oryzophilus by all seed treatments was reduced in late-planted rice fields relative to rice planted within the recommended planting window. Control of the Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), did not improve rice yields. Fungicidal seed treatments generally protected rice yields over treatments without fungicides despite having no effect on early-season plant populations. All seed treatments provided returns on investment which ranged from $94.30 (fungicide only 2018) to $519.75/ha (chlorantraniliprole + thiamethoxam + fungicides in 2019–2020). Increased yields resulting from the use of multiple insecticides in combination appears to justify the added expense. Collectively, results demonstrate the immense value of insecticidal seed treatments to rice production in Louisiana and throughout the U.S. Mid-South. Future research efforts should aim to assess returns on seed treatments across a range of rice production conditions and to quantify the impacts of sporadic pests on rice yields.

Combinations of insecticides with carbon dioxide for the management of Sitophilus oryzae (Linnaeus 1763) on stored wheat: An approach to reduce the application rates of insecticides

Efficacy of insecticides chlorpyrifos-methyl (CH), deltamethrin (DE) and spinosad (SP) was evaluated alone and in binary combinations with carbon dioxide (CA) against Sitophilus oryzae (L.). Mortality of S. oryzae adults was recorded after 3, 7 and 14 days, and progeny production and wheat weight loss were assessed after 90 days for all treatments. In individual treatments, the mortality of S. oryzae adults was 69.5, 79.8, 50.7 and 61.4% after 14 days of exposure to the highest concentration of CA (30%), CH (0.5 mg/kg), DE (1.0 mg/kg) and SP (0.5 mg/kg), respectively. Mortality of S. oryzae adults was higher in combined treatments at all tested rates than individual treatments. Mortality of adults of 100% was obtained in combined treatments of CH (0.5 mg/kg) + CA (30%) after 3 days and DE (1.0 mg/kg) + CA (30%) after 14 days of exposure. Combinations of SP + CA were more effective than CH + CA and DE + CA as 100.0% mortality was achieved in combined treatments of SP at 0.25 mg/kg with CA at 20 and 30%, and SP at 0.5 mg/kg with CA at 20 and 30% after 3 days of exposure. Progeny production of S. oryzae was decreased significantly in all treatments compared with untreated wheat grains after 90 days of exposure. High rates induced progeny reduction of 100% and complete protection of wheat grains against damage caused by S. oryzae after 90 days. Moreover, germination percentages of wheat seeds treated with CH at 0.5 mg/kg, DE at 1.0 mg/kg, CA at 30% and CH at 0.5 mg/kg + CA at 30% were 90.6, 86.7, 86.7 and 90.0, respectively. Our results indicate that the combination of insecticides with CA appears promising as an approach for the control of S. oryzae.

Comparison of Mineral Oil, Insecticidal, and Biopesticide Spraying Regimes for Reducing Spread of Three Potato virus Y Strains in Potato Crops.

In-field management of Potato virus Y (PVY) faces challenges caused by the changing availability and environmental acceptability of chemical agents to control aphid vectors of the virus and by proliferation of PVY strains with different symptoms and rates of spread. From 2018 to 2020, foliar spray treatments were compared in field experiments in New Brunswick, Canada, to measure effectiveness at reducing spread of PVYO, PVYN:O, and PVYNTN strains. Mineral oil, insecticide, combined oil and insecticide spray, and a biopesticide (i.e., LifeGard WG) were compared. Insecticide-only and mineral oil-only treatments were not effective, but several combined oil and insecticide treatments and biopesticide treatments significantly reduced PVY spread. The biopesticide was proportionately more effective with recombinant PVYN:O and PVYNTN strains, possibly by exciting the plant's hypersensitive resistance response, caused naturally only in cultivar 'Goldrush' by PVYO. Pesticide residue analysis showed that mineral oil increased the retention of pyrethroid insecticide in the potato foliage longer than with insecticide applied alone, which may explain the beneficial synergistic effect of combined sprays for reducing PVY spread. Tuber yields were generally unchanged in chemical insecticide treatments but were slightly lower in biopesticide treatment. The cost per PVY treatment was competitive across all effective treatments, including biopesticide; however, there was some revenue loss from lower yield with the biopesticide. This biopesticide is certified organic, however, and thus a small premium on the price for organic production could offset this yield deficit.

Bio-efficacy of insecticide and fungicide mixtures against leaf folder, stem borer, BPH and sheath blight of rice

Bio-efficacy assessment with four insecticides and two fungicides was carried out in Agricultural College farm, Naira during kharif, 2019 against leaf folder, stem borer, brown plant hopper (BPH) and sheath blight of rice. The treatments include four insecticides [Flonicamide 50 WG (0.4 g/l), Pymetrozine 50 WG (0.6 g/l), Chlorantraniliprole 18.5 SC (0.3 g/l), Acephate 75 SP (1.5 g/l)], two fungicides [(Difenoconazole 25 EC (0.5 ml/l), Azoxystrobin 23 EC (0.75 ml/l] and Untreated Control. Results indicated that treatment Chlorantraniliprole 18.5 SC (0.3 g/l) was effective against leaf folder (per cent leaf folder damage: 3.29) and stem borer (% DH: 1.17, % WE: 2.11) which was on par to both of its fungicide combinations viz., Azoxystrobin 23 EC (0.75 ml/l) (per cent leaf folder damage: 3.02, % DH: 1.29, % WE: 2.51) and Difenoconazole 25 EC (0.5 ml/l) (3.85, 1.76, 2.64). Against brown planthopper, treatment Pymetrozine 50 WG + Difenoconazole 25 EC (0.6 g/l + 0.5 ml/l) (reduction over control- 92.95%) was effective and pertinent to sheath blight, treatment chlorantraniliprole + azoxystrobin (PDI: 5.14) along with all the four test insecticide combinations of azoxystrobin proved their best.

Annual bluegrass weevil (Listronotus maculicollis) and paclobutrazol control annual bluegrass (Poa annua) in creeping bentgrass fairways

AbstractThe annual bluegrass weevil (ABW) is a pest of fine turfgrass, but recent research has found that withholding insecticides for ABW control can reduce annual bluegrass cover. The objective of this research was to evaluate threshold-based insecticide and paclobutrazol programs for annual bluegrass control. The effect of three insecticide programs (preventive, threshold, and no insecticide) and four rates of paclobutrazol (0, 70, 105, or 210 g ha−1 applied monthly) were evaluated. Replicate experiments were conducted from April to November in both 2018 and 2019 on a mixed creeping bentgrass and annual bluegrass fairway in North Brunswick, NJ. By the conclusion of both experiments, all paclobutrazol programs exhibited reduced annual bluegrass cover compared with the nontreated plots. In threshold and no-insecticide programs, reduction in annual bluegrass cover was enhanced by paclobutrazol applied at 105 g ha−1 in both years, and at 70 g ha−1 in the 2019 experiment. Paclobutrazol at 210 g ha−1 resulted in annual bluegrass cover of <20% regardless of insecticide program. In 2019, threshold-based ABW control without paclobutrazol provided similar annual bluegrass control as monthly applications of paclobutrazol at 70 and 105 g ha−1 with the preventive insecticide program. A reduction in turfgrass quality from threshold-based insecticide programs persisted for a shorter duration than the no-insecticide program, regardless of paclobutrazol treatment. Threshold-based ABW insecticide programs that allow ABW feeding damage to occur can result in reduced annual bluegrass cover. These reductions were further enhanced by paclobutrazol applications. The combination of threshold-level insecticide with moderate rates of paclobutrazol (70 to 105 g ha−1) provided reductions in annual bluegrass cover that were similar to the highest rate of paclobutrazol (210 g ha−1) without ABW damage. Turfgrass managers who integrate the threshold-level insecticide approach and monthly paclobutrazol applications may achieve greater annual bluegrass control than either strategy alone if temporary reductions in turf quality can be tolerated.

Interaction of Insecticides and Fungicides in Bees.

Honeybees and wild bees are among the most important pollinators of both wild and cultivated landscapes. In recent years, however, a significant decline in these pollinators has been recorded. This decrease can have many causes including the heavy use of biocidal plant protection products in agriculture. The most frequent residues in bee products originate from fungicides, while neonicotinoids and, to a lesser extent, pyrethroids are among the most popular insecticides detected in bee products. There is abundant evidence of toxic side effects on honeybees and wild bees produced by neonicotinoids, but only few studies have investigated side effects of fungicides, because they are generally regarded as not being harmful for bees. In the field, a variety of substances are taken up by bees including mixtures of insecticides and fungicides, and their combinations can be lethal for these pollinators, depending on the specific group of insecticide or fungicide. This review discusses the different combinations of major insecticide and fungicide classes and their effects on honeybees and wild bees. Fungicides inhibiting the sterol biosynthesis pathway can strongly increase the toxicity of neonicotinoids and pyrethroids. Other fungicides, in contrast, do not appear to enhance toxicity when combined with neonicotinoid or pyrethroid insecticides. But the knowledge on possible interactions of fungicides not inhibiting the sterol biosynthesis pathway and insecticides is poor, particularly in wild bees, emphasizing the need for further studies on possible effects of insecticide-fungicide interactions in bees.

Repellent Effect of the Pandanus (Pandanus amaryllifolius Roxb.) and Neem (Azadirachta Indica) Against Rice Weevil Sitophilus oryzae L. (Coleoptera, Curculionidae)

Sitophilus oryzae is the main and highly destructive pest on storage products, such as rice, wheat, and cereal grains around the world. The substances that are safe and envi- ronmentally friendly are still being sought for managing this pest. One of the ingredients that are continuously being developed as an insecticide is natural plant susbtances. Hence, this research was conducted in the laboratory to evaluate the effect of Pandanus and Neem leaves powder on rice weevil. The repellency and mortality effects of PW and Neem to trice weevil were recorded. The repellency and mortality were caused by the treatment of 10 grams of pandan leaf powder and 10 grams of neem leaf powder. The treatment without a combination of insecticides in this study had a higher repellency and mortality effect than the combination. The aim of this study was to determine the effect of Pandanus (Pandanus amaryllifolius Roxb.) and Neem (Azadirachta indica) leaves powder on the repellency, mortality, and weight loss of grains due to Sitophilus oryzae. The methodes of this study used a completely randomized design (CRD) with 7 treatments and 4 replications. The results of this study indicate that the best treatment in terms of causing repellency was the treatment of 10 grams of pandanus with a percentage of 87.5%, while the best treatment in terms of causing pest mortality and was also able to reduce the risk of rice weight loss due to Sitophilus oryzae was treatment 10 gram of neem with a mortality percentage of 76.25% and weight loss of rice 3.14%. This research showed that neem leaf com- pounds are better in terms of causing mortality, while Pandanus compounds are better in terms of causing mortality of Sitophilus oryzae.

Impact assessment of CDC bottles treated with a combination of insecticide and synergist on insecticide-resistant Anopheles gambiae populations in Benin

Impact assessment of CDC bottles treated with a combination of insecticide and synergist on insecticide-resistant Anopheles gambiae populations in Benin

Studies on Pesticide Use Behavior of Non-IPM Farmers of Rice Ecosystem in Southern Districts of Tamil Nadu

Rice is the major crop cultivated in southern India and farmers resort to using pesticides intensively to realize higher productivity. The present study aimed to monitor the pesticide use behavior of the farmers, mainly relies on pesticides as a key component in pest management. This study was carried out in four southern districts of Tamil Nadu, where paddy is grown for almost two seasons in a year and a total of 75 farmers who rely on pesticide for their pest management were identified through the local pesticide dealers for the study. Rice stem borer (100%) and leaf folder (93.33%) are the key pests in the region and in all the districts surveyed, 92 percent of the farmers have indicated the rice earhead bug as a major problem during the reproductive phase for which 20 percent of them continue to take-up spraying across milking and grain maturing stages of the crop. It is apparent that the farmers in this area have the habit of using a tank mixture of pesticides and 72 per cent of the farmers interviewed use insecticides in combination with fungicides. They also use synthetic pyrethroids, which are not recommended in rice crops. Most of them (72.33%) throw the used pesticide container in open space, and 24 per cent use the containers for household and farm use. The study indicates an urgent need for creating awareness among this pesticide intense farmers to have sensible use of pesticides form minimizing pesticide residue preserving the rice ecosystem.

Sensitivity, Optimal Control, and Cost-Effectiveness Analysis of Intervention Strategies of Filariasis

In this work, sensitivity, optimal control, and cost-effectiveness of several intervention strategies of filariasis are discussed. We study the intervention strategies that are related to bednet use, insecticide, and the combination of bed-net use and insecticide. We use Pontryagin’s maximum principle to characterize the optimal controls. The Average Cost-Effectiveness Ratio (ACER) and Infection Averted Ratio (IAR) are used to identify the most cost-effective strategy. We also determine the basic reproduction number and investigate the sensitivity of the basic reproduction number on the parameters that are related to bed-net use and insecticide. Based on the ACER values, the most cost-effective strategy to control filariasis is insecticide intervention. On the other hand, the IAR values indicates that bed-net use intervention is the most cost-effective strategy. Furthermore, it is also the most effective strategy to eliminate filariasis. The sensitivity analysis results show that the control parameter related to bed net use and treatment have a central role in reducing the basic reproduction number and filariasis spread.

Diversity of indigenous Bacillus thuringiensis isolates toxic to the diamondback moth, Plutella xylostella (L.) (Plutellidae: Lepidoptera)

BackgroundToxins from the Bacillus thuringiensis (Bt) bacterium are employed as an alternative to synthetic pesticides in pest management. The greatest threat to the long-term viability of Bt toxins is resistance evolution in the target pests. Genetic diversity and toxicity of Bt isolates were studied in this work in order to find Bt isolates with novel cry genes.ResultsIn terms of colony morphology, among a total of 60 isolates, 51 isolates had off-white colour colonies with typical fried egg appearance, irregular shape, flat and undulate margin. Different crystal shapes, viz. spherical (88.13%), bipyramidal (49.15%), cuboidal (42.37%), rectangular, and crystals attached to spores (3.38%) were observed among Bt isolates. SDS-PAGE analysis of spore crystal mixture showed the presence of proteins with various molecular weights ranging from 124 to 26 kDa. PCR screening with cry1, cry2, cry9 and vip3A1 primers showed isolates with varied insecticidal gene combinations. Bt isolates containing cry1 genes were found to be abundant (30), followed by cry2 (9) and vip3A1 (9). Cry9 was absent in all the 60 isolates tested. Insecticidal activity of spore crystal mixtures ranged from 0 to 100% mortality. Furthermore, 12 isolates were found to be highly toxic against the larvae of diamondback moth, Plutella xylostella (L.) (Plutellidae: Lepidoptera) with 100% mortality, at 25 µg/ml in leaf disc bioassay.ConclusionsThe present work established the diversity of Bt isolates and confirmed the importance of continuous exploration of new Bt isolates for novel genes. Further, research needs to be carried out to unveil the hidden potential of these toxic isolates.