Neem-based Insecticide Research Articles

Bio-efficacy of bio-rationals against citrus leaf miner (Phyllocnistis citrella) in acid lime (Citrus aurantiifolia)

The field experiment was conducted during winter (rabi) 2020–21 and rainy (kharif) season of 2021–22 at College of Agriculture (University of Agricultural Sciences, Dharwad), Vijayapura, Karnataka to evaluate efficacy of bio-rationals against citrus leaf miner (Phyllocnistis citrella Stainton). The experiment was conducted in a randomized block design (RBD) with 8 treatments, viz. bio digester solution (10%); pongamia leaf extract (5%); Prosopis juliflora leaf extract (5%); Beauveria bassiana (2 × 108 conidia/g) (1 kg/ha); Bacillus thuringiensis 8 L (1 L/ha); neem-based insecticide (10000 ppm) (1.5 L/ha); thiamethoxam 25 wg (125 ml/ha) (standard check); and untreated control (water spray), replicated thrice. Among the selected bio-rationals, two application of neem (Azadirachta indica)-based insecticide recorded significantly lesser number of live mines/shoot followed by bio-digester solution (10%) and these treatments were found superior in controlling citrus leaf miner on acid lime [Citrus aurantiifolia (Christm.) Swingle]. The pongamia leaf extract, Bacillus thuringiensis 8 L and Beauveria bassiana were proved to be moderately affective against this pest. The bio-rationals found effective can be used in integrated management of citrus leaf miner on acid lime.

Neem's promise: The way to a sustainable future and eco-friendly biopesticides

Modern agriculture must include pest management since pests can seriously harm crops and lower yields, resulting in considerable financial losses. Conventional chemical insecticides have been used as the main method of pest management, but their detrimental effects on the environment and human health have inspired the quest for new environmentally friendly options. In this situation, Azadirachta indica showed promise as a sustainable and eco-friendly biopesticide. This research shows many aspects for Azadirachta indica as an environment friendly biopesticide. Neem is well known for having antiviral, antiseptic, and antifungal characteristics, which make it a crucial component in remedies for many illnesses, skin disorders, and mouth care. It is also beneficial to the environment. When added to the soil, its seeds and leaves help increase the fertility of the soil and structure. Additionally, the tree's large root system helps stop soil erosion. Azadirachta indica, is a great asset in the field of pest control and agricultural sustainability due to its repellent and antifeedant qualities. These characteristics are a result of neem's bioactive substances, known as Azadirachtin which has been the subject of in-depth study and use because of its function as a natural repellent and antifeedant Azadirachtin is a potent natural insect growth regulator because it interferes with beetle feeding, molting, and reproduction. Furthermore, the eco-friendliness of azadirachtin and its safety for people and non-target animals highlight its essential function in sustainable pest management techniques, aiding in the advancement of environmentally friendly and healthier agricultural systems. The neem plant is a unique botanical gem that has enormous medicinal, farming, and cultural significance. Its adaptability and environmental friendliness make it an important resource for sustainable agriculture and human well-being. Three commercialized neem-based formulations were tested aphid, Myzus persicae, including Azatrol, Triple Action Neem Oil (70% neem oil), and Pure Neem Oil (100% neem oil) in greenhouse and laboratory settings. A bioassay using a leaf disc choice test indicated that of the established neem-based insecticides tested were effective against the aphid at the recommended concentrations. However, a doubling in the quantity of Azatrol and Triple Action Neem Oil resulted in a 50% decrease in the number of aphids landing on handled leaf tissue compared to untreated leaf tissue.

Residual Toxicity of Neem-Based Insecticides against Egg Parasitoid <i>Trichogrammatoidea bactrae</i> Nagaraja

A study was carried out with neem-based insecticides, viz., azadirachtin (0.03%EC, 0.15%EC, 0.3%EC, 1%EC), neem seed oil (1, 2 and 3%), neem seed extract 5% and dashparni ark (ten plant leaf extract) 4%, on Trichogrammatoidea bactrae Nagaraja (Hymenoptera: Trichogrammatidae) adults using the thin film residue method under laboratory conditions. After coating glass vials with neem-based insecticides, the adults of T. bactrae were released on the first, fifth, and tenth days of coating and the mortality was assessed. Among all neem-based insecticides, azadirachtin 1%EC was observed to be harmful to adults of T. bactrae on the first, fifth and tenth days. In contrast, neem seed extract 5% and dashparni ark 4% were found safe.

Survival Analysis of the Green Lacewing, Chrysoperla externa (Hagen) Exposed to Neem-Based Products

Brazil is the country which has produced the most coffee for over 150 years, and to achieve high productivity, pesticides are the most common control measure for pests. Due to the need to adopt less impactful control practices, natural enemies or insecticides of botanical origin have been studied as alternatives to synthetic insecticides. However, botanical pesticides can negatively affect some natural enemies, and the effect depends on the formulation and concentration. The objective of this study was to estimate the survival of green lacewing larvae, Chrysoperla externa (Hagen), exposed to different doses of neem-based products, whose active ingredient is azadirachtin (Azamax®: 0 (control treatment with distilled water), 12, 24, 36, 48, 60, 72, 84, 96, and 108 mg a.i. L−1; Organic neem®: 0, 3.3, 6.6, 9.9, 13.2, 16.5, 19.8, 23.1, and 26.4 mg a.i. L−1; Natuneem®: 0, 3.8, 7.5, 10.5, 15.0, 18.8, 22.5, 26.3, 30.0, and 33.8 mg a.i. L−1), using a parametric approach. Predator larvae were exposed to neem-based insecticides and evaluated for 20 days. Survival curves estimated by the models—Log-logistic for Azamax®, Weibull for Organic neem®, and Log-normal for Natuneem®—demonstrated an inverse relationship between increasing doses and survival time. These concluded that the application dose should be less than 84 mg a.i. L−1 for Azamax®, 19.8 mg a.i. L−1 for Organic neem®, and 26.3 mg a.i. L−1 for Natuneem® to keep 50% of the green lacewings alive for 13 days, which is the average time for the larval cycle of C. externa.

Laboratory bioassay of fall armyworm (Spodoptera frugiperda) larva using various insecticides

Fall armyworm (FAW), Spodoptera frugiperda J.E. Smith, is a polyphagous invasive pest that seriously affects the maize crop. Various insecticides such as Spinosad, Chlorantraniliprole, Imidacloprid, Emamectin benzoate, Spinetoram and Neem-based insecticides are recommended to control this pest. However, their efficacy is not well studied in Nepal. Hence, a study was performed to evaluate the efficacy of the above-mentioned insecticides for FAW management in laboratory experiments. Seven different treatments (six insecticides such as Spinosad 45% SC, Chlorantraniliprole 18.5% SC, Imidacloprid 17.8% SL, Emamectin benzoate 5% SC, Spinetoram 11.7% SC, Neem-based pesticide (Azadirachtin 1500 ppm) and control (water spray) were evaluated in three replicated CRD design. Spinosad and Spinetoram were found effective for the FAW mortality in which > 50% mortality of the larva was obtained in twelve hours and > 90 % mortality in twenty-four hours. Likewise, Emamectin benzoate and Chlorantraniliprole also caused > 90% mortality within twenty-four hours. Azadirachtin and Imidacloprid were not as effective as other pesticides that caused only 17% larval mortality in the first twelve hours and 68% mortality in sixty hours. Similarly, Imidacloprid caused 8% larval mortality in twelve hours and 59% mortality in sixty hours. There was no mortality in water spray (control). This information gives an idea of all pesticides are not equally effective and efficient. Such information’s are important to the farmers to select the right insecticides for the control of FAW in maize crops.

Neem-Based Insecticides Deter Oviposition Activity in Spotted Wing Drosophila (Diptera: Drosophilidae) in Sweet Cherries.

Spotted wing drosophila, Drosophila suzukii (Matsumura), is an important invasive insect pest in the United States. Spotted wing drosophila females have serrated ovipositor that enables them to deposit eggs inside healthy, ripening softskinned fruits. In many berry and fruit crops, spotted wing drosophila is primarily controlled using synthetic insecticides in the organophosphate, pyrethroid, and spinosyn groups. However, alternative, reduced-risk insecticides with short residuals are necessary to minimize the possibilities of insecticide resistance and address other negative effects of synthetic insecticides. Neem-based products as alternative plant-based insecticides have antifeedant, repellent, antiovipository, and molting interference effects on insects and have been shown to affect the oviposition activities of some tephritid flies. We conducted laboratory studies to evaluate the oviposition deterrent activities of selected neem-based insecticides that contain either azadirachtin, or CHENO, or a combination of both, on spotted wing drosophila using sweet cherry in California. The results of the study showed that some of the neem oil products could reduce the degree of spotted wing drosophila oviposition by half compared with the control.

Integration of Repellency Effect of Neem-Based Insecticide and Pheromone Bio-Trap® with Beauveria bassiana (Hypocreales: Cordycipitaceae) to Control the Red Palm Weevil, Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae)

To control adults of the red palm weevil (RPW), Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae), a pheromone Bio-Trap® containing the commercial formulation of Beauveria bassiana (Broadband™) was integrated with neem-based insecticide, (azadirachtin). Beauveria bassiana at 40 ml suspension of 1 × 109 spores/ml caused 100% mortality of RPW. The LC50 of neem-based insecticide, (azadirachtin) to RPW by direct spraying was 1810.3 ppm, whereas that by feeding was 2117.80 ppm. The lowest concentration of neem that was 100 % repellent to RPW was 800 ppm. The repellency effect of neem was integrated with the pheromone Bio-Trap in three net houses (5 × 5 m), each planted with five offshoots of palm trees (height, 1–1.5 m). In two of the net houses, wounds were made on offshoots and sprayed weekly with 800 ppm neem, and a pheromone Bio-Trap was introduced. The third net house was the control, in which wounds were made on the offshoots without the spraying of neem and a pheromone non-Bio-Trap (without fungus) was introduced. Thirty adults were introduced, and after 30 days in the net houses with the pheromone Bio-Trap, all RPW died because of contamination by fungi. The repellency of neem prevented the insects from laying eggs in the wounded offshoots, and no larvae were found. However, in the control net house, only 60 % of the adults were trapped and killed in the pheromone non-Bio-Trap, and two of the five offshoots were infested with 26–34 larvae.

Can the botanical azadirachtin replace phased-out soil insecticides in suppressing the soil insect pest Diabrotica virgifera virgifera?

BackgroundDue to recent bans on the use of several soil insecticides and insecticidal seed coatings, soil-dwelling insect pests are increasingly difficult to manage. One example is the western corn rootworm (Diabrotica virgifera virgifera, Coleoptera: Chrysomelidae), a serious root-feeder of maize (Zea mays). We investigated whether the less problematic botanical azadirachtin, widely used against above-ground insects, could become an option for the control of this soil insect pest.MethodsArtificial diet-based bioassays were implemented under standard laboratory conditions to establish dose response curves for the pest larvae. Then, potted-plant experiments were implemented in greenhouse to assess feasibility and efficacy of a novel granular formulation of azadirachtin under more natural conditions and in relation to standard insecticides.ResultsBioassays in three repetitions revealed a 3-day LD50 of 22.3 µg azadirachtin/ml which corresponded to 0.45 µg/neonate of D. v. virgifera and a 5-day LD50 of 19.3 µg/ml or 0.39 µg/first to second instar larva. No sublethal effects were observed. The three greenhouse experiments revealed that the currently proposed standard dose of a granular formulation of 38 g azadirachtin/hectare for in-furrow application at sowing is not enough to control D. v. virgifera or to prevent root damage. At 10× standard-dose total pest control was achieved as well as the prevention of most root damage. This was better than the efficacy achieved by cypermethrin-based granules and comparable to tefluthrin-granules, or thiamethoxam seed coatings. The ED50 for suppressing larval populations were estimated at 92 g azadirachtin/ha, for preventing heavy root damage 52 g/ha and for preventing general root damage 220 g/ha.ConclusionsThere seems clear potential for the development of neem-based botanical soil insecticides for arable crops such as maize. They might become, if doses are increased and more soil insecticides phased out, a promising, safer solution as part of the integrated pest management toolkit against soil insects.

Evaluation of ipm modules against whitefly bemisia tabaci (Gennadius) in cotton

On-farm trials were conducted for the evaluation of IPM modules in cotton against the whitefly Bemisia tabaci (Gennadius) by the Krishi Vigyan Kendra, Bathinda and Mansa at five locations during 201718 and 2018-19. The modules included neem-based insecticides along with detergent powder, darek (Melia azedarach L.) extract and the University recommended insecticides compared with that of farmers’ practice of mixing of non-recommended insecticides. The data revealed significantly maximum reduction (80.0- 85.1% and 80.9- 85.4%) in the incidence of adults compared to the University recommended practice (Mj) at Bathinda and Mansa, respectively. This was followed by module (Mj) comprising use of home-made darek extract (54.4 to 63.3% at Bathinda and 58.0 to 72.5% at Mansa). Module (M3) comprising of addition of detergent powder in neem-based spray solution remained on a par with M with 55.8 to 62.7 and 57.4 to 71.9% reduction in incidence over untreated check. Farmers’ practice of spraying non-recommended insecticides resulted in minimum reduction in incidence (16.7 to 23.1% and 23.6 to 36.3%, at Bathinda and Mansa, respectively). The trend in yield was similar to the above, with maximum being in M4 followed by Mj and M3 with the least yield being with the module comprising of use of non-recommended sprays by the farmers. Maximum number of spray applications (5-6) were given in M4 (farmer’s practice). Maximum and minimum B: C ratio was obtained with the modules M4 (1.3 to 1.5) and M4 (0.8 to 1.2), respectively.

Botanical and synthetic pesticides alter the flower visitation rates of pollinator bees in Neotropical melon fields

The ecological and economic contributions of pollinator bees to agricultural production have been threatened by the inappropriate and excessive use of pesticides. These pesticides are often applied in areas with ecological peculiarities (e.g., the Neotropical savannah-like region termed as Cerrado) that were not considered during the product development. Here, we conducted field experiments with melon (i.e., Cucumis melo L.) plants cultivated under Brazilian Cerrado conditions and evaluated the impacts of botanical (i.e., neem-based insecticide) and synthetic (i.e., the pyrethroid insecticide deltamethrin and the fungicides thiophanate-methyl and chlorothalonil) pesticides on the flower visitation rates of naturally occurring pollinator bees. Our results revealed that both honey bees (i.e., Apis mellifera L.) and non-Apis bees visited melon flowers and the intensity of bee visitation was moderately correlated with yield parameters (e.g., number of marketable fruits and fruit yield). Pesticide treatments differentially affected bee species. For instance, Plebeia sp. bees were not affected by any pesticide treatment, whereas both A. mellifera and Halictus sp. bees showed reduced visitation intensity after the application of deltamethrin or neem-based insecticides. Fungicide treatment alone did not influence the bee's visitation intensity. Deltamethrin-treated melon fields produced significantly lighter marketable fruits, and the melon yield was significantly lower in melon fields treated with the neem-based insecticide. Thus, our findings with such pollinator bees reinforce the idea that field applications of botanical pesticides may represent as risky as the applications of synthetic compounds, indicating that these alternative products should be submitted to risk assessments comparable to those required for synthetic products.

Integration of Cotton Plant Resistance With Selected Organic Boll Weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae) Control Tactics

The boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), is one of the key pests and limiting factors to cotton production in conventional and organic systems. We assessed the use of resistant and susceptible cotton cultivars, a neem-based insecticide (Natuneem), and trapping with an A. grandis grandis aggregation pheromone as possible control tactics. In the first of two growing seasons we evaluated resistance of colored fiber cotton cultivars BRS 200, BRS Rubi, BRS Safira, and BRS Verde, and white fiber cotton BRS Aroeira, against A. grandis grandis attack. In the second growing season we assessed three colored cotton cultivars grown in and without close association of BRS Aroeira, and two control tactics: the neem-based pesticide and trapping. Because BRS Aroeira showed resistance against A. grandis grandis in the first growing season, it was selected to be planted in close association with more susceptible colored cultivars in the second growing season. Field plots with white and colored cotton cultivars reduced the need to control A. grandis grandis using the neem-based pesticide. Control by the neem-based pesticide and by trapping were of comparable value although the traps provided measurable control during early cotton growth stages and the neem-based pesticide provided measurable control during later cotton growth stages.

Responses of the Whitefly <i>Bemisia tabaci</i> (Hemiptera: Aleyrodidae) to Biologically Based Insecticides

The effects of three bio-insecticides Azatrol [neem: 1.2% azadirachtin A and B], Molt-X [neem: 3% azadirachtin], and Conserve SC [spinosad; 11.6% spinosyn A and spinosyn D], applied at different concentrations were evaluated on Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) under both laboratory and greenhouse conditions. Laboratory bioassays demonstrated that both neem-based insecticides were repellent to adult whiteflies in a dose-dependent manner. The amounts and frequency of honeydew excretion were significantly reduced up to 0.95 by foliar application of these insecticides at the labeled rate, as compared to untreated plants, with the neem products displaying greater effects on food uptake than spinosad. Reduced fecundity and egg hatch also were associated with these bio-insecticides. The bio-insecticides decreased significantly the survival of nymphs, egg hatch and adult emergence when applied systemically via the roots. However, the impacts of neem-based insecticides on all parameters tested were greater than that of spinosad. The results indicate that the biologically based formulations tested were effective in suppressing whitefly abundance and acting as an efficient repellent, though they were not able to completely inhibit food intake. The repellent and antifeedant activities of such natural products render plants unattractive to B. tabaci , thus potentially reducing the incidence of viral diseases transmitted by this pest. The systemic properties of these formulated biopesticides minimize their rapid degradation by strong ultraviolet light and their adverse effects on non-target organisms.

Toxicity of botanical and synthetic formulations to the maize weevil, Sitophilus zeamais (Coleoptera: Curculionidae)

Maize is attacked by various pest species, including the key-pest of stored maize, Sitophilus zeamais (Coleoptera: Curculionidae). This study determined the LC50 and LD50 of neem-based insecticides (AzaMax® and Natuneem®) in comparison to a synthetic pyrethroid insecticide (Decis® 25 CE) to S. zeamais. The bioassays consisted of insects’ exposure alone (topical application with microsyringe) and exposure of both insects and seeds treated simultaneously. The final bioassays used four to six concentrations of each formulation per bioassay, diluted in distilled water. The bioassays were run with the use of 10 non-sexed adults of S. zeamais per replication and mortality was assessed after 48 h of exposure. The data regarding concentration and dose-mortality were analyzed by probit analysis. Both LC50 and LD50 were used to calculate LCR and LDR’s and their respective confidence interval (CI). After using topical application, the bioassays yielded LD50-values of 51.32, 76.76 and 42.75 μL of AzaMax, Natuneem and Decis/g of insects, respectively. The bioassays with simultaneous exposure of both insects and seeds yielded LC50-values of 4.01, 4.46 and 0.41 μL of AzaMax, Natuneem and Decis/g of seeds, respectively. Regarding the fact that there were no significant differences between the LC50-values of the botanical insecticides, both of them can be used to manage S. zeamais infesting stored corn. The cost to treat maize and to obtain effective control of S. zeamais is cheapest for Decis<Natuneem<Azamax. The LC50-values found in our study would be equivalent to use 8.02, 8.92 and 0.82 L of AzaMax, Natuneem and Decis/ton of seeds.

Preimaginal exposure to azadirachtin affects food selection and digestive enzymes in adults of Drosophila melanogaster (Diptera: Drosophilidae)

Among the plant derived product, azadirachtin, a neem-based insecticide, is exceptional in having a broad range of bioactivity including toxicity, growth, development and reproduction effects, repellency and antifeedancy. If considerable progress on the physiological and biological activities and agricultural application of azadirachtin has been achieved, its exact mechanism of action remains uncertain. In this study, we aimed at assessing the lethal and sublethal behavioral and physiological effects of azadirachtin on Drosophila melanogaster Meigen, 1830 (Diptera: Drosophilidae) as biological model. Azadirachtin was applied topically at two doses LD25 (0.28μg) and LD50 (0.67μg) on early third instar larvae. Results showed that flies preferentially ingested control medium rather than azadirachtin-treated medium. Pre-imaginal exposure (L3) to azadirachtin increased aversion to this substance suggesting a memorability of the learned avoidance. In addition, all tested flies revealed a clear preference for solvent odour rather than azadirachtin odour. Moreover, azadirachtin treatment decreased significantly the amount of food intake in the adults of both sexes. Finally, azadirachtin was found to affect digestive enzyme activities in the midgut of flies. Indeed, an inhibition of α-amylase, chitinase, and protease activities and an increase of lipasic activity were noted. These results may reflect interference of azadirachtin with regulation of feeding and metabolism, and provide some evidence of a long term antifeedancy and delayed effects through developmental stage which may reinforce the insecticidal activity of this bioinsecticide.

English

The management of Neoleucinodes elegantalis (Guenee) (Lepidoptera: Crambidae) with neem-based and registered insecticides most applied on tomato crops in the Agreste region on N. elegantalis (eggs, pre-pupae and pupae) were evaluated in this study; methomyl, chlorpyrifos, lambda-cyhalothrin, beta-cypermethrin, deltamethrin, etofenprox, chlorantraniliprole and the neem-based insecticides (azadirachtin A/B and emulsifiable neem oil) were used for studying the repellent effect on oviposition. Lufenuron, deltamethrin and indoxacarb associated with 2.5% sucrose were used as toxic baits on tomato plants. Regarding the ovicidal effect, etofenprox and methomyl had the highest egg mortality, reducing larval survival and fruit damage. Etofenprox had the highest average mortality: 50% in pupae and 38% in pre-pupae. As for repellency, all insecticides tested reduced significantly the number of eggs when compared to the control, except for azadirachtin and chlorantraniliprole. Lufenuron and deltamethrin decreased the number of eggs, showing great potential for use in toxic baits, while indoxacarb stimulated oviposition, thus not being recommended for this purpose. The appropriate use of synthetic insecticides can maximize their potential of control, as long as their use is directed to the stage of the pest that causes higher damage to the crop, or exploring their potential as oviposition deterrent, as well as their use in toxic baits. Key words: Toxic bait, ovicidal effect, repellence, integrated management.

DETERMINAÇÃO DA CL50 DOS INSETICIDAS À BASE DE NIM E THIAMETHOXAN E SEUS EFEITOS NA BIOLOGIA DE Aphis gossypii GLOVER (HEMIPTERA: APHIDIDAE) EM TRÊS CULTIVARES DE ALGODOEIRO

DETERMINAÇÃO DA CL50 DOS INSETICIDAS À BASE DE NIM E THIAMETHOXAN E SEUS EFEITOS NA BIOLOGIA DE Aphis gossypii GLOVER (HEMIPTERA: APHIDIDAE) EM TRÊS CULTIVARES DE ALGODOEIRO

Effects of Neem-Based Insecticides on Consumption and Utilization of Food in Larvae ofSpodoptera eridania(Lepidoptera: Noctuidae)

Neem-based insecticides, which have many biological properties, were evaluated for effects on growth, food intake, survival, and nutritional indices of Spodoptera eridania (Stoll), an important pest of crops in the western hemisphere. Short-term consumption of food treated with neem-derived insecticides by second-instar larvae resulted in suppressed feeding, retarded weight gain, and prolonged development time after the treated larvae had been transferred to untreated synthetic insect diet. Relative consumption rate, efficiency of conversion of ingested food, relative growth rate, approximate digestibility, and assimilation rate of food were reduced after treatment with neem products, especially by the higher concentrations of neem. Efficiency of conversion of digested food was not affected. Also, application of pure neem oil and Azatrol at high concentrations induced 20 and 13.3% larval mortality, respectively, whereas mortality caused by the lower concentrations of both chemicals did not exceed 3.3%. Larvae of S. eridania were more sensitive to pure neem oil than to Azatrol. These observations may reflect interference of neem with regulation of feeding and metabolism, as well as with anatomy and function of midgut tissues.

Systems of organic farming in spring vetch II: Biological response of Aeolothrips intermedius Bagnall and Coccinella septempunctata L.

The effects of four systems of organic farming of spring vetsch on Aeolothrips intermedius Bagnall (Thysanoptera: Aeolothripidae) and Coccinella septempunctata L. (Coleoptera: Coccinellidae) population density and the toxicity of several products on predatory insects were studied. The variants were: Control (without using any biological products); combined treatment with Polyversum (biological foliar fertilizer) and Biofa (biological plant growth regulator); treatment with NeemAzal T/S (biological insecticide, a.i. azadirachtin) and treatment with a combination of NeemAzal with Polyversum and Biofa. Variant V was a conventional farming system in which a combination of Nurelle D (synthetic insecticide), Masterblend (foliar fertilizer) and Flordimex 420 (growth regulator) was used as a standard treatment. In the organic farming system that included treatment of plants with the biological insecticide NeemAzal (azadirachtin), the reduction in A. intermedius abundance was 20.7% when it was applied alone and 24.6 % in combination with the organic products Polyversum and Biofa. NeemAzal achieved a lower reduction in the counts of predatory ladybirds C. septempunctata, from 14.9% (alone) to 21.9% (combination). The biological insecticide, applied alone or in combination, was mostly harmless and rarely harmful to A. intermedius. NeemAzal manifested harmlessness to C. septempunctata as its toxic action did not exceed 25%. An analysis of variance regarding product toxicity to A. intermedius and C. septempunctata demonstrated that the type of treatment (the application of insecticides alone or in combination) had the strongest effect on product toxicity. ?he use of neem-based insecticides can be a substantial contribution towards preservation of biodiversity in ecosystems.

Integration between Steinernema feltiae and some of environmental friendly compounds to control Spodoptera littoralis (Lepidoptera: Noctuidae)

The efficacy of different concentrations of the commercial neem-based insecticide, Nimbicidine® and the ecdysone agonist compound Methoxyfenozide (RH-2485), was evaluated against larvae of Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae). RH-2485 and Nimbicidine® significantly (p < 0.001) reduced adult longevity by 2.7 and 1.9 d at the higher concentrations tested, respectively, but no significant differences were observed at low concentration. The tested compounds strongly affected the reproduction of S. littoralis by producing a high percentage of sterility. Fecundity and fertility were significantly affected by both insecticides. No egg laying has been recorded with the higher concentration 0.5% of Nimbicidine® and 0.1 ppm of RH-2485, while no significant (p > 0.05) difference was noticed on total number of eggs laid by the female when lower concentration 0.0001 ppm of RH-2485 was applied in the same stage as compared to the control. In the second part of this study, the invasion rate of Steinernema feltiae was affected by the addition of both Nimbicidine and RH-2485 to the diet of experimental host. At higher concentration of both compounds, the invasion rate was decreased despite the infection rate, while the percentage of invading nematodes increase to 56.7% with the combination treatment indicating a considerable improvement in the efficacy of S. feltiae nematode applied in combination with the lower concentration of Nimbicidine® over that of nematode alone. On the other hand, the invasion of S. feltiae to the insects that were fed on the diet with the addition of ecdyson compound was strongly decreased with increasing concentration of RH-2485 in host diet.

Toxic effects of neem-based insecticides on Pieris brassicae (Linn.)

Four neem-based insecticides, Neemix ® (0.25% EC @ 20 mg azadirachtin/liter), Ecozin ® (3% EC @ 20 mg azadirachtin/liter), Agroneem ® (0.15% EC @ 4.8 mg azadirachtin/liter) and Neem oil (0.25% EC azadirachtin @ 20 mg azadirachtin/liter) and a non-commercial neem leaf powder, were evaluated for oviposition deterrence, antifeedant effect to larvae and toxicity to eggs and larvae of Pieris brassicae (Linn.) on cabbage leaves in the laboratory. The concentrations tested were with in the ranges of recommended field rates. Oviposition deterrence in no-choice, two-choice and six-choice assays, was observed for all the treatments. They exhibited significant ( P < 0.01) oviposition deterrence on P. brassicae when compared with a non-treated control. Cabbage leaves treated with the neem-based insecticides were used as an egg-laying substrate. Numbers of eggs oviposited by P. brassicae adults on treated cabbage leaves were significantly lower then those treated with water, but no significant differences were detected among the neem insecticides. They also deterred feeding by Pieris larvae and exhibited significant antifeedant effects. Larvae of P. brassicae on treated leaves stopped feeding and dropped from the leaf, resulting in no or minimal damage. Direct contact with neem-based insecticides decreased the survival of eggs. Survival of larvae fed for 9 days on leaves treated with neem-based insecticides was reduced to 51%, 49%, 48%, 24% and 18% in the Neem oil, Neemix, Agroneem, Ecozin and neem leaf powder treatments, respectively. Therefore, it can be concluded from the present investigations that neem-based insecticides had oviposition deterrence, antifeedant and toxic effect to P. brassicae.