Neem Application Research Articles

The integrated use of entomopathogenic fungus, Beauveria bassiana with botanical insecticide, neem against Bemisia tabaci on eggplant

In a previous experiment, sweetpotato whitefly was found to be difficult to control with either neem or Beauveria bassiana alone. This earlier research also reported that the combined application of neem and B. bassiana increased mortality of whitefly nymphs when both of these products were applied to eggplant foliage; but a higher concentration of neem (more than 0.5%) was slightly toxic for young eggplant. Therefore, the present research was undertaken with these two products in which neem was applied as soil drench and B. bassiana was applied to foliage. Three concentrations of neem- 0.25, 0.5 and 1.0%; and three concentrations of B. bassiana- 106, 107 and 108 conidia/ml were used to investigate the combined efficacy against sweet potato whitefly, Bemisia tabaci. The results demonstrate that maximum nymph mortality (92.3%) occurred when 1.0% neem was combined with 108 conidia/ml of B. bassiana. The highest (14.3) mortality ratio (N/Bb; mortality caused by neem/mortality caused by B. bassiana) occurred when 1.0% neem was combined with 106 conidia/ml of B. bassiana; and the lowest mortality ratio (5.7) occurred when 0.25% neem was combined with 108 conidia/ml of B. bassiana. The results showed that neem was compatible with B. bassiana; and suggest that soil application of neem along with foliar application of B. bassiana might be useful for the control of B. tabaci. Key words: Botanical insecticide, compatibility, eggplant, entomopathogenic fungus, integrated pest management (IPM).

Management of Leucinodes Orbonalis Guenee on Eggplants During the Rainy Season in India

Management of Leucinodes Orbonalis Guenee on Eggplants During the Rainy Season in India Leucinodes orbonalis Guenee (Pyraustidae: Lepidoptera) is a fruit and shoot borer which is the key pest of eggplant (also known as brinjal and aubergine). L. orbonalis causes broad-based problems in eggplant cultivation. An effort was made to control the borer during the Indian rainy season, as this is the time when the problem is at its worst. The impact of treatments on natural enemies as well as pollinators was also assessed. Integration of phytosanitation, mechanical control and prophylactic application of neem seed kernel extract (NSKE) exerted a satisfactory impact on the incidence and damage of L. orbonalis. After two need-based applications of new generation pesticide molecules like flubendiamide or rynaxypyr or emamectin benzoate, fairly good, healthy yields were produced. A ready-mix formulation (triazophos 40% + cypermethrin 4%), and carbofuran also offered good protection against the borer but both were found highly toxic and unsafe for predators i.e. predatory coccinellids and spiders and pollinating bees. Flubendiamide and rynaxypyr appeared comparatively more unsafe for bees than emamectin benzoate, while both allowed a substantial proportion of coccinellids and spiders to survive. Naturolyte, with the active ingredient emamectin benzoate, was found safe for predators and bees and on par with the untreated check.

Effect of Tillage Practices and Neem Leaves(Azadirachta indica A. Juss) on the Incidence and Severity of Termites on Cassava(Manihot esculenta Crantz) in Owerri

Termites have been identified as one of the major pests of cassava in Nigeria especially on infested soils. Effect of different tillage practices and rates of neem leaves on the incidence and severity of termites on cassava field was investigated in this study. Field experiment was conducted in 2007 at the teaching and research Farm of the Federal University of Technology, Owerri. The experiment was laid out in a 3x3 factorial in a randomized complete block design(RCBD) with three replications. The TMS 4(2)1425 was the cassava cultivar used. Treatments comprised three tillage methodsnamely: zero, flats and mounds, and neem leaves at 0 (control), 20 and 30 tons/ha. Results show that mounds and control plots significantly recorded highest termites incidence and severity on Cassava stems, while neem application at 30 tons/ha suppressed termites incidence and severity most. On the other hand mounds and neem leaves at 30 tons/ha produced highest fresh tuber and stem cutting yields .

Effect of neem and willow aqueous extracts on fusarium wilt disease in tomato seedlings: Induction of antioxidant defensive enzymes

Fusarium wilt disease is one of the major plant diseases that affect tomato production. The effects of neem (Azadirachta indica) and willow (Salix babylonica) aqueous extracts on fusarium wilt disease in tomato seedlings were investigated. Four weeks old tomato seedlings were treated with 10% of either neem and willow aqueous extracts and then infected with Fusarium oxysporum after 4days of treatment. The results showed that the percentage of disease incidence was increased in non treated tomato seedlings in time dependent manner and reached the maximum level (65%) after 6weeks of infection. Treatments of tomato plants with neem and willow aqueous extracts reduced the percentage of disease incidence to the level of 25.5% and 27.8% after 6weeks of infection respectively. The results show that infection of tomato seedling with Fusarium oxysporum led to many morphological and biochemical changes including, reducing the growth of tomato shoot and root, increasing the level of lipid peroxidation and marked increase in the activities of antioxidant defensive enzyme i.e. POX, CAT, and SOD. Treatment with neem and willow aqueous extracts significantly exhibited a growth promotion of tomato shoot and root in infected or non infected seedling. Moreover, application of neem and willow aqueous extracts with fusarium, significantly reduce the level of lipid peroxidation and induce high activities of antioxidant defensive enzymes after 3 and 7days of infection. Electrophoretic pattern of POX demonstrated that Fusarium oxysporum caused up regulation of several POX isoenzymes. It could be concluded that neem and willow aqueous extracts reduced the disease incidence of fusarium wilt in tomato seedlings by increasing the activities of antioxidant defensive enzymes and decreasing the level of lipid peroxidation

Comparative effect of integrated pest management and farmers' standard pest control practice for managing insect pests on cabbage (Brassica spp.)

Studies were conducted on experimental cabbage plantings in 2009 and on experimental and commercial plantings in 2010, comparing farmers' current chemical standard pesticide practices with an integrated pest management (IPM) program based on the use of neem (Aza-Direct) and DiPel (Bacillus thuringiensis). In experimental plantings, the IPM program used six or eight applications of neem and DiPel on a rotational basis. The standard-practice treatments consisted of six or eight applications of carbaryl and malathion or control treatment. The IPM treatments reduced pest populations and damage, resulting in a better yield than with the standard chemical or control treatment. When IPM treatment included three applications of neem plus three applications of DiPel (on a rotational basis in experimental fields), it again reduced the pest population and damage and produced a better yield than the standard practice. The lower input costs of the IPM program resulted in better economic returns in both trials. The IPM components neem and DiPel are suitable for use in an IPM program for managing insect pests on cabbage (Brassica spp.).

Use of plant products and copepods for control of the dengue vector, Aedes aegypti

The efficacy of plant extracts (neem tree, Azadirachta indica A. Juss.; Meliaceae) and copepods [Mesocyclops aspericornis (Daday)] for the control of the dengue vector Aedes aegypti L. was tested in the laboratory. Neem Seed Kernel Extract (NSKE) at 25, 50, 100, 200 and 400 ppm caused significant mortality of Ae. aegypti larvae. Lethal concentrations (LC50 and LC90) were worked out. The LC50 and LC90 values for I to IV larval instars were 111.98, 138.34, 158.93, 185.22 ppm and for pupae was 146.13 ppm, respectively. The LC90 value of I instar was 372.95 ppm, II instar was 422.77 ppm, III instar was 440.63 ppm, IV instar was 456.96 ppm, and pupae was 476.92 ppm, respectively. A study was conducted to test the whether the predatory efficiency of copepods on first instars changed in the presence of NSKE. The percentage of predatory efficiency of copepod was 6.80% in treatments without NSKE and the percentage of predatory efficiency increased up to 8.40% when copepods were combined with NSKE. This increase in predation efficiency may caused by detrimental effects of the neem active principle compound (Azadirachtin) on the mosquito larvae. Our results suggest that the combined application of copepods and neem extract to control Aedes populations is feasible. Repeated application of neem does not cause changes in copepod populations, because neem is highly degradable in the environment.

Application of Neem and Karanjia Oils as Natural Pesticide Microemulsion Systems

Abstract Microemulsions are preferred over conventionally used pesticide systems for their long term thermodynamic stability, low viscosity, cost economy and aesthetic appeal. Such systems provide a method for preparing an isotropic mixture of oil and water. Neem and Karanjia isolates have proven activities. Therefore, uses of these oils provide a biologically and environmentally acceptable pesticide formulation. The present investigation deals with the systematic study to arrive at the economical composition for formulating microemulsion systems using these oils. These microemulsions, when diluted with water, formed macroemulsions which were stable over an extended period of time.

Influence of neem on susceptibility of Beauveria bassiana and investigation of their combined efficacy against sweetpotato whitefly, Bemisia tabaci on eggplant

A study on the compatibility of the entomopathogenic fungus Beauveria bassiana with neem was conducted against sweetpotato whitefly, Bemisia tabaci, on eggplant. Initially, three concentrations of neem (0.25%, 0.5% and 1.0%) were used to investigate the physiological responses of B. bassiana. Thereafter, above three concentrations of neem along with three concentrations of B. bassiana (10 6, 10 7 and 10 8 conidia/ml) were used to investigate combined deterrence index, DI under two application methods (foliar and soil) of B. tabaci. Significant differences were observed among neem concentrations on all variables- germination percentage, vegetative growth, number of conidia, amount of biomass and proteolytic activity of B. bassiana. The reduction percentage of germination, vegetative growth, sporulation, biomass production and proteolytic activity of B. bassiana were as high as 12%, 13%, 35%, 38%, and 34%, respectively, to neem. Significant differences were also observed on deterrence index, DI (adult and oviposition) of B. tabaci. The current study investigated that the highest adult DI (80.15) and oviposition DI (88.25) occurred when 1.0% neem was combined with 10 8 conidia/ml of B. bassiana. As the results show, neem is compatible with B. bassiana; and soil application of neem along with foliar application of B. bassiana might be useful for the control of B. tabaci.

INTEGRATED MANAGEMENT OF PAPAYA RING SPOT VIRUS (PRSV) IN AGRO ECOLOGICAL CONDITIONS OF BIHAR

Over the last decade Papaya ring spot virus (PRSV) has been identified as a major threat of papaya production resulting in heavy reduction in area under this crop. In an attempt to combat the disease, a field trial was conducted to manage PRSV through integrated approach. Seven treatments viz. 1. Raising of papaya seedlings under Nylon net (40-60 mesh) and spraying of Dimethoate (1.05%) 3 days before planting; 2. Use of two rows of maize as a border crop (Maize sown 15 days ahead of planting); 3. Application of neem seed kernel extract (2%) at 15 days interval (30 days after planting); 4. Application of Dimethoate (1.05%); 5. Application of neem oil 1% + Dimethoate (1.05%); 6. Two rows of maize as a border crop + application of Zn (0.5%) and B (0.1%); and 7. Control without any treatment was evaluated in randomised block design (RBD) with 12 plants/treatment with spacing of 1.8×1.8 m/plant during 2005-2006 and 2006-07. All the treatments were replicated thrice. Observation on PRSV incidence was recorded starting from 60 to 210 days after planting (DAP) at monthly interval. Initially at 60 to 150 DAP there were significant differences among various treatments in relation to their effect on the incidence of PRSV. The most effective treatment was application of neem oil 1 % + Dimethoate 1.05% with least disease incidence (6.66%) and 41.66% respectively at 60 and 150 DAP. This was followed by application of Dimethoate 1.05% with 16.33 and 56.66% PRSV incidence while the untreated (control) plants registered 68.33 and 90% incidence respectively at 60 and 150 DAP. But after 210 days all the treatments were at par in relation to their effect on disease. However the treatment comprising of neem oil 1 % + Dimethoate 1.05% showed the minimum disease incidence (76.66%) as compared to the control showing 100% incidence at 210 DAP. Growth and yield characters of papaya i.e. plant height at first flowering, plant height at first harvest, stem girth at harvest and number of fruits were significantly affected by the treatments while mean fruit weight was not affected markedly. Likewise some quality parameters of fruits i.e. TSS and central cavity diameter did not show notable difference due to the treatments although other quality parameters like average fruit weight, fruit length, fruit diameter and hundred seeds weight were appreciably affected by the treatments.

Cost-benefit of using some plant extracts in controlling cercospora leaf spot of groundnut in the Sudan savanna of Nigeria

Field trials were conducted to evaluate the economics of controlling cercospora leaf spot of groundnut using different plant extracts. The experiments were laid out in a completely randomized block design (CRDB) with three replications at the Teaching and Research farm of the Department of Crop Protection, University of Maiduguri, Sudan savanna of Nigeria during the 2002 and 2003 cropping seasons. Five plant extracts, namely, neem seed, garlic clove, onion bulb, ginger rhizome and pawpaw leaf extracts and a fungicide ridomil were applied as foliar sprays while the controls were left untreated. The application of the plant extracts led to about 3–10% reduction in the disease incidence and 10–15% reduction in disease severity and gave higher seed and haulm yields than the control. Ridomil gave about 16% reduction in disease incidence and 19% reduction in disease severity. The cost-benefit analysis revealed positive returns per hectare from use of the plant extracts for controlling the disease in the study area. Application of neem seed extract, for instance, gave 43.82% seed yield increase over the control which translated into a mean (two years) net profit of N198 730.56 Nigerian Naira equivalent to $1987.31 per hectare. Even the least effective of the plant extracts (ginger rhizome) gave seed yield increase of 24.17% over the control which translated into a mean (two years) net profit of N167 247.00 equivalent to $1672.47 per hectare for the two seasons. The control gave mean net profit of N134 121.21 equivalent to $1341.21 per hectare which is lower than those realized from the plant extracts. The profit from the sell of haulms which is an additional income to the farmer amounted to N50 944.56, equivalent to $509.45 per hectare following application of neem seed extract. These returns are attractive particularly to the farmers in the study area who grow the high yielding, cercospora susceptible Ex-Dakar groundnut variety.

Comparative evaluation of modified neem leaf, wood ash and<br>neem leaf extracts for seed treatment and pest control in maize<br>(Zea mays L.)

An experiment was conducted at Akure, rainforest zone of Nigeria to evaluate theeffectiveness of neem leaf, wood ash extracts, modified neem leaf extract, Apron star 42WS andKarate 720EC as seed treatment and pest control in maize. The organic treatment extracts namelyneem leaf extract, wood ash extract applied at 1200ml per hectare and modified neem leaf extract(1:1 ratio 600ml wood ash + 600ml neem leaf extract) were compared with Apron star 42WS (seedtreatment), Karate 720EC and control treatment (no neem leaf, wood ash extracts nor Karate),replicated four times and arranged in randomized complete block design. The results showed thatthere were significant differences (P < 0.05) in the germination counts, insect population, numberof damaged leaves, growth and yield parameters of maize under different treatments compared tothe control treatment. The modified neem leaf extract performed better in germination counts,reduction of damaged leaves, insect population and yield of maize than the sole application ofneem leaf and wood ash. For percentage germination counts, Apron star 42WS had 65% followedby modified neem leaf extract (57%), wood ash extract (51%), neem leaf extract (47%)respectively. Modified neem leaf extract increased the leaf area, plant height and stem girth ofmaize by 8%, 5% and 7% respectively compared to the neem leaf (sole) extract. Generally,modified neem leaf extract had the best values of maize growth parameters followed by Karate,neem leaf and wood ash extracts respectively. Modified neem leaf extract decreased significantlythe insect population, number of damaged leaves and number of holes per plant in maize by 33%,70% and 30% respectively compared to the neem leaf extract (sole). When compared to modifiedneem extract, Karate decreased the number of damaged leaves per sample plot by 33%. However,there was no significant difference between karate and modified neem extract for insectpopulation. For yield parameters, modified neem leaf extract significantly increased the maizeyield gains by 15%, 14% and 2% compared to neem leaf, wood ash extracts and karate treatmentsrespectively. However, wood ash and neem leaf extracts did not affect significantly the maizeyield. Therefore, the modified neem leaf extract applied at 1200L/ha (3L/25m2) was mosteffective for pest control and seed treatment in maize crop.

Neem-based integrated approaches for the management of tea mosquito bug, Helopeltis theivora Waterhouse (Miridae: Heteroptera) in tea

Despite continuous use of synthetic insecticides during last two decades, the tea mosquito bug, Helopeltis theivora Waterhouse (Miridae: Heteroptera), has become the most destructive sucking pest of tea in North East India. In order to reduce the load of the synthetic chemicals in tea vis-a-vis their deleterious effect, integration of biopesticide, synthetic pesticides along with effective spraying strategies, have been attempted. The anti-insect property of “neem”, Azadirachta indica A. Juss. (Meliaceae), has been used to solve many pest problems. In this study, different azadirachtin concentrations were evaluated at different doses against the H. theivora to find out their controlling efficacy. At 50,000 ppm azadirachtin concentration 65% control of infestation could be attained, whereas at 3,000 and 10,000 ppm, gave 30–43% reduction and 300 and 1,500 ppm <30% control was possible. Further in case of 3,000 and 10,000 ppm, azadirachtin concentration 30–43% reduction was registered. Therefore, azadirachtin concentration and its dilutions are the major criteria for getting desired bioactivity. Treatments with combined formulations viz. “neem + endosulfan” or “neem + deltamethrin” recorded significant reduction in H. theivora incidence even at reduced doses, as compared to sole application of neem or synthetic insecticide at recommended doses. Effective combinations and dose of the insecticides along with their formulations in controlling H. theivora have been presented and discussed.

Management of Tomato Root-knot Nematode Meloidogyne incognita by Plant Extracts and Essential Oils

The effect of plant extracts of eucalyptus (Eucalyptus chamadulonsis), garlic (Allium sativium), marigold (Tagetes erecta) and neem (Azadirachta indica) and essential oils were tested on the suppression of root-knot nematode Meloidogyne incognita under greenhouse and field conditions. In vitro study, all tested treatments had nematicidal effect on nematode juveniles after 24 and 48 hours from exposures. The highest percentage of nematode mortality was achieved by application of neem extract (65.4%), essential oils (64.4%) and marigold extract (60.5%), followed by garlic and eucalyptus extracts (38.7-39.5%). Under greenhouse and field conditions, neem extract and essential oils treatments were more effective in reducing population numbers of the M. incognita in soil and root gall index compared to other treatments. In field experiments, the maximum protection of tomato plant against root-knot nematode was obtained by application of neem and essential oil treatments, 44.2 and 32.6%, respectively.

Studies on loss of bio-efficacy of two indirect neem application over time (seed and soil) against Bemisia tabaci (Homoptera: Aleyrodidae) under semi-field conditions

In a choice test, loss of bio-efficacy (1–30 days) of neem (seed and soil application) were studied in a naturally ventilated and lighted greenhouse (semi-field conditions) using a commercial neem product (NeemAzal-U 17%) against Bemisia tabaci Gennadius (Hom., Aleyrodidae) on tomatoes. The fresh neem residue had the strongest effects in all parameters (adult colonisation behaviour, eggs deposition, eggs hatch and immature mortality). This effect decreased gradually over the time. The bio-efficacy loss of neem applied through seed treatment was rapid, and tomato plants grown from seed soaked in neem effectively managed B. tabaci only until the 15-day post application. Soil application was a more stable method to prolong the bio-efficacy of neem against B. tabaci under greenhouse conditions. The bio-efficacy of soil neem application were recorded daily for 1–7-day and during this period, the immature mortality, which was 88.20% for the first day reduced to almost half i.e. 45.01%. The results of the experiments are discussed in context of potential use of neem-based pesticides for Integrated Pest Management of sucking insect-pests in open field or in greenhouse conditions.

Effects of soil application of neem (NeemAzal®-U) on different life stages of Liriomyza sativae (Diptera: Agromyzidae) on tomato in the humid tropics

NeemAzal®-U, a formulation containing 17% azadirachtin developed for soil treatments, was tested in air conditioned laboratories and net greenhouses in Thailand to control Liriomyza sativae Blanchard (Diptera: Agromyzidae) on tomatoes (Lycopersicon esculentum). The substrates of potted tomato plants were drenched with set volumes of neem solutions of altered concentrations. All tested neem concentrations had very low effects on oviposition and egg hatching. Strong systemic effects however were recorded in the larval stages attaining mortalities up to 100% when high dose drenching solutions containing 3 g NeemAzal®-U l−1 water equivalent to 0.5 g l−1 azadirachtin A were implemented. First instar larvae were found to be most susceptible to all dosages tested. Activity of NeemAzal®-U was persistent since application of even seven days before infestation resulted in mortalities extending between 40 to 70%. Leafminer late 3rd instar surviving on treated plants and moving as so called prepupa to pupate in treated soils endured a very high mortality during pupal stage ensuing in few adult emergences even when the lowest NeemAzal®-U concentration of 0.75 g l−1 water was used. The direct effects of soil treatment were elucidated by rearing leafminers on untreated plants but treating the substrate used for pupal development. Significant mortalities were only obtained when soil treatment was performed immediately before prepupa moved to the soil.

Nutrient Mineralization from Deoiled Neem Seed in a Savanna Soil from Nigeria

The mineralization of nutrients from deoiled neem seed (neem seed cake), the residue left after oil extraction, was examined in a typical savanna soil with a view to determining its potential for fertility improvement. The neem seed cake (NSC) application rates were 0, 2.5, and 5.0 g kg−1 soil (0, 5, and 10 tons ha−1). The concentrations of ammonium‐nitrogen (NH4‐N) and nitrate (NO3)‐N mineralized from the neem‐amended soil were two to three times greater than the control. Similarly, exchangeable potassium (K), magnesium (Mg), and cation exchange capacity were significantly greater than the control. The neem‐amended soil maintained organic carbon (OC) at the pre‐incubation level, whereas OC in the control soil declined to significantly less than the pre‐incubation concentration. The electrolytic conductivity of the soil saturation extract with neem application was 8–10 times greater than the control soil. However, the NSC increased exchange acidity markedly and decreased the soil pH significantly. Thus, the benefits of NSC in increasing the concentrations of N, K, and Mg and maintaining OC of the soil must be weighed against the consequences of soil acidity, though it is unlikely that NSC can acidify the soil to the same extent under field conditions as it did in this closed‐system incubation study.

English

The effect of topical application of neem seed extract on sheep infested with tickAblyomma variegatum&nbsp;was examined for acaricidal and repellant activity. The seed extract showed acaricidal activity at 5.0, 2.5 and 1.0% concentration&nbsp;in vitro. The extract had no acaricidal activity&nbsp;in vivo. However, it showed a repellant activity against ticks at 5.0 and 2.5% concentration. The activity of the extract seems to be concentration dependent. The extract appears to have some potentials as a repellant or antifeedant and could provide an inexpensive integrated pest management resource for farmers. &nbsp; Key words:&nbsp;Acaricidal, repellant, ticks.

Effect of topical application of neem seed (Azadiracta indica) extract on sheep infested with Amblyomma variegatum

The effect of topical application of neem seed extract on sheep infested with tick Ablyomma variegatum was examined for acaricidal and repellant activity. The seed extract showed acaricidal activity at 5.0, 2.5 and 1.0% concentration in vitro. The extract had no acaricidal activity in vivo. However, it showed a repellant activity against ticks at 5.0 and 2.5% concentration. The activity of the extract seems to be concentration dependent. The extract appears to have some potentials as a repellant or antifeedant and could provide an inexpensive integrated pest management resource for farmers.

Control of legume pod borer,Maruca vitrataFab. and coreid bug,Clavigralla tomentosicollisStal on Cowpea,Vigna unguiculata(L.) Walp using different concentrations and spraying regimes of aqueous extracts from Neem,Azadirachta indica(A. Juss) seed

The effect of three rates (5, 10 and 20% w/v) and different spraying schedules (2, 4 and 6 weekly applications) of aqueous neem, Azadirachta indica (A. Juss) seed extracts was tested on legume pod borers, Maruca vitrata Fab. and the coreid bugs, Clavigralla tomentosicollis Stal on cowpea under field conditions in two cropping seasons in the northern Guinea savanna of Nigeria. Legume pod borers (LPB) were better controlled at 20% and 6 applications of neem seed extract compared with other plant material treatments and the untreated check but its values were not significantly different to the synthetic insecticide treatment. Although, at similar rate of neem seed extract, its control of the coreid bugs was inferior to the synthetic insecticide treatment but was superior to 10% and 5% rates of neem seed extracts at all application schedules. Cowpea pods were adequately protected from damage by the pests and grain yields were significantly higher at 10 and 20% extract rates with four or six application schedu...

Application of neem seed kernel extracts result in mouthpart deformities and subsequent mortality in Nezara viridula (L.) (Hem: Pentatomidae)

Abstract: The effect of topical application of neem seed kernel aqueous suspension (NSKAS) and neem seed kernel hexane extract (NSKHE) on 2‐day‐old fourth instar nymphs of Nezara viridula (L.) was studied under laboratory conditions. The applications resulted in loosening of the proboscis, along with separation and deformation of mouthparts, predominantly in the stylets in fifth instar nymphs, adults and in inter‐stadial moults. This rendered the insects incapable of feeding and led them to death. Application of NSKAS at 2.5% concentration led to 100% mortality, of which 40% was due to mouthpart deformities. Application of NSKHE at 2.5% concentration led to only 70% mortality, of which 3.33% was due to mouthpart deformities. At 5% concentration, mortality was again 100% for NSKAS and reached close to 100% for the NSKHE application. Dose‐dependent mortality was observed for both the applications. However, dose‐dependent mouthpart deformities were observed only for NSKAS, the highest being 60% at the 5% concentration. Moreover, for both the applications, more than 50% of the total mortality was observed up to the fifth instar at almost all the concentrations. The LC50 values for NSKAS and NSKHE applications, for mortality up to the fifth instar were 0.36% and 5.22%, and for mortality to the adult stage (10 days old) they were 0.23% and 1.32% respectively. The percentage of bugs showing mouthpart deformities and toxicity was higher for NSKAS than NSKHE, and indicated that NSKAS was more potent than NSKHE.