Synthetic Chemical Insecticides Research Articles

Nematicidal and ovicidal activity of Bacillus thuringiensis against the zoonotic nematode Ancylostoma caninum

Ancylostoma caninum is a gastrointestinal parasite that affect dogs and humans, considered a worldwide public health problem. The control of these parasitosis is increasingly difficult due to the development of multi-drug resistance. Bacillus thuringiensis is an insecticidal, spore forming bacterium, often species specific. The strain GP526 of B. thuringiensis has toxic effect on the cestode Dipylidium caninum and the trematode Centrocestus formosanus, both of them zoonotic parasites. The high degrees of specificity and environment safe make B. thuringiensis suitable for use against pathogen parasites, especially those resistant to synthetic chemical insecticides. The objective of the current work was to evaluate the in vitro effect of B. thuringiensis on Ancylostoma caninum. Spore-crystal mixture of the strains was co-incubated with 120 adult nematodes (males, non-pregnant females and pregnant females) or with 4800 eggs. GP526 showed a nematicidal effect with an LT50 of 35.8 h and an LC50 of 60 μg/ml. It also showed an ovicidal effect with an LC50 of 94.9 μg/ml. Histological analyses showed detachment of the cuticle and of the uterus in adult females, and vacuolization with destruction of the eggs. The effects of GP526 strain were comparable to those of albendazole, allowing us to propose GP526 for A. caninum control, in both, the adult stage at a gastrointestinal level, and in egg stage in the environment. In addition, GP526 can be proposed as a potential broad spectrum antiparasitic drug.

Bioactivity of essential oils of Cymbopogon citratus (DC) Stapf and Cymbopogon nardus (L.) W. Watson from Benin against Dinoderus porcellus Lesne (Coleoptera: Bostrichidae) infesting yam chips

Dinoderus porcellus L. (Coleoptera: Bostrichidae) is a most abundant and damageable pest of stored yam chips in West Africa. In view of the negative effects related to the use of synthetic chemical insecticide, it is important to develop alternative eco-friendly methods of control, such as the use of plant essential oils. The chemical composition and biological effects (repellent, antifeedant, contact and fumigant toxicity) of essential oils from Cymbopogon citratus (DC) Stapf and Cymbopogon nardus (L.) W. Watson were evaluated for the first time against D. porcellus. The chemical composition of C. citratus essential oil revealed that neral (24.64%), geranial (23.46%), and beta-pinene (21.90%) were the predominant compounds whereas citronellal (37.87%), nerol (19.88%) and citronellol (9.11%) were identified in C. nardus essential oil. Data showed that both essential oils were more effective as repellents and fumigant than the commercial insecticide Actellic 50 EC. The results also revealed the low contact toxicity of C. citratus and C. nardus essential oils against D. porcellus. However, similarly to Actellic 50 EC, C. citratus essential oil presented good antifeedant activity against D. porcellus and reduced yam chips weight loss. The results obtained suggest the good potential of C. citratus as both antifeedant and fumigant toxic agent against D. porcellus. While, C. nardus essential oil could be recommended as repellent. However, further studies are required to evaluate the insecticidal activity of both Cymbopogon essential oils under farmers’ storage conditions and to develop a good formulation as biopesticide.

Composition and toxicity of rough lemon (Citrus jambhiri Lush.) rind essential oil against red flour beetle

One of the most destructive beetles attacking stored grain products in the tropics is red flour beetle, Tribolium castaneum Herbst (Coleoptera: Tenebrionidae). The ecological problems associated with using synthetic chemical insecticides have strongly necessitated the need to search for biorational alternatives. The aim of this experiment was to evaluate the chemical composition and the insecticidal potentials of rough lemon (Citrus jambhiri Lush.) fruit rind essential oil (EO) against the pest. The EO obtained via hydrodistillation was assayed against T. castaneum at 27, 53, 80 and 107 mL/L air. Chlorpyrifos was used as a positive control. The EO was subjected to Gas chromatography-Mass spectrometry. A total of 51 compounds, predominated by oxygenated monoterpenes, were identified. The predominant ones included α-Terpineol (8.03%), Lemonol (7.67%) Citral (7.00%), 4-Terpineol (6.52%), n-hexadecanoic acid (4.70%), Caryophellene (4.58%), Citronellol (4.38%) and β-Bisabolene (4.01%), α-Bergamotene (3.74%), and Precocene I (3.33%). Application of the EO at 80–107 mL/L air evoked toxicity (53.75–100.00%) which compared with what was observed in insects treated with Chlorpyrifos (70.00–100.00%). The median lethal time (LT50) observed when the EO was applied at the rate of 80 μL/L air [1.11 (0.00–2.48 h)] was not significantly different from 0.70 (0.16–1.12) h observed when the EO was applied at 107 μL/L air and 0.62 (0.39–1.39) h observed when Chlorpyrifos was applied. The results of this study indicate the potential of the EO as an alternative to over-dependence on synthetic pesticides in the management of red flour beetle.

Evaluation of botanical powders and extracts from Nigerian plants as protectants of maize grains against maize weevil, Sitophilus zeamais (Motschulsky) [Coleoptera: Curculionidae

Toxicities of leaf powders and extracts of Acanthus montanus, Acanthospermum hispidum, Alchornea laxiflora and Argyreia nervosa against maize weevil (Sitophilus zeamais) were evaluated. Powders were tested at dose 3.0g/20g while extracts were tested at concentration 3%/20g of maize grains. Mortality, oviposition, and adult emergence rates as well as weight loss, seeds damage and weevil perforation index (WPI) were evaluated. Phytochemical constituents of the experimental plants were also carried out. The results showed that Acanthus montanus powder was the most potent with 65% adult mortality after 24 h of treatment. This is followed by Argyreia nervosa powder that evoked 52.5% weevil mortality. The least toxic to S. zeamais was Acanthospermum hispidum powder with 32.5% adult mortality. Extracts were more toxic than the powders of the tested plants. Acanthus montanus extract was the most toxic since it promoted 80% adult mortality after 24 h of treatment. Acanthus montanus, Alchornea laxiflora and Argyreia nervosa leaf powders and extracts completely prevented oviposition by adult insect, adult emergence, weight loss and seeds damaged. The phytochemicals present in Acanthus montanus were alkaloids (3.67 mg/g), saponin (3.33 mg/g), tannin (3.00 mg/g) and flavonoid (2.67 mg/g) contents. Acanthospermum hispidum had the least alkaloid (2.67 mg/g), saponin (1.67 mg/g), tannin (1.33 mg/g) and flavonoid (1.00 mg/g) contents. Acanthus montanus, Argyreia nervosa, Alchornea laxiflora and Acanthospermum hispidum were efficacious against S. zeamais instead of synthetic chemical insecticides that have environmental health hazards and they can be used in integrated pest management by farmers and foods merchants.

Efficacy of nano-formulated certain essential oils on the red flour beetle Tribolium castaneum and confused flour beetle, Tribolium confusum (Coleoptera: Tenebrionidae) under laboratory and storage conditions

AbtractBackgroundThe confused flour beetles Tribolium confusum (Jacquelin) and red flour beetle Tribolium castaneum (Herbst) are widespread insects found in the stores and homes that attack many stored foods in several commodities. They are controlled by synthetic chemical insecticides. The natural oils give good results in controlling these pests and decreasing its infestations. The natural essential oils have a low effect on the human, non-target insects, and do not pollute the environments. This research is an alternative approach to naturally control these two stored product pests.MethodsNano-formulations of four essential oils, namely, coriander, black seed, caraway oil, and Janesville were tested against T. confusum and T. castaneum in the laboratory and stored conditions. Encapsulation method by the technology of polymerization was followed. The nano-oils were tested at the concentrations of 0.5% against the 3rd larval instars. Cumulative percentages of mortality was determined after 7 days of the first applications. The effect of nano-oils on oviposition was carried out by spraying 2 g of foams of the tested oils and their nano-formulations mixed with 100 g of wheat.ResultsThe results obtained showed that the percentage of larval mortality of T. confusum and T. castaneum increased with an increase in the treatment concentrations. Larvae of T. confusum were more susceptible to the treatments than T. castaneum larvae. Nano Janesville oil was more effective than that of coriander or black seed oil. Fecundity and adult emergence percentage are highly suppressed by nano-formulations of coriander, black seed, or Janesville oils under storage conditions, compared to those of the controls or non-nano-oils.The results suggested that nano Janesville can be used as a valuable tool in pest management programs of T. confusum and T. castaneumConclusionThe results of this work indicate that some essential oils might be helpful management of pests in the stores because of their fumigant and odor action. Essential oils of plant origin contain active ingredients that are effective against many insects. Nano-formulations of essential oils, through controlled release, prevent rapid vaporization and degradation and increase the stability of the oils. Treated foam, using coriander, Janesville, caraway, and black seed (habat al Baraka) oils, gave protection against the red flour beetles Tribolium castaneum and confused flour beetle Tribolium confusum.

Evaluation of Five Medicinal Plant Extracts on Aphis craccivora (Hemiptera: Aphididae) and Its Predator, Chrysoperla carnea (Neuroptera: Chrysopidae) under Laboratory Conditions.

Botanical insecticides that degrade rapidly are safer than persistent synthetic chemical insecticides, less harmful to the environment, decrease production costs and are not likely to cause insecticide resistance among pests. This study aimed to evaluate the effect of five different botanical extracts on the bean aphid, Aphis craccivora and the 2nd larval instar of the green lacewing, Chrysoperla carnea under laboratory conditions. Also, the flavonoids in the methanolic extracts of these tested plants were detected using HPLC analysis. The data from the HPLC analysis indicated that the tested plants differed in their flavonoid components. The total flavonoids were 869.4, 1125.6, 721.4, 1667.8 and 2025.9 mg/kg in Psiadia penninervia, Salvia officinalis, Ochradenus baccatus, Pulicaria crispa and Euryops arabicus, respectively. Moreover, there were many variations among these plants in the amount of each compound. The lethal concentration (LC50) value of P. penninervia extract on aphids was the lowest among all of the plants (128.546 µg/mL) followed by O. baccatus (626.461 µg/mL). Also, the LC50 value of P. penninervia extract on the 2nd larval instar of C. carnea (232.095 µg/mL) was significantly lower than those of all other four plant species extracts, while the other four plants did not show significant differences among them according to relative median potency analyses. Accordingly, O. baccatus extract had a strong effect on aphids and was safest for the predator. This finding suggests that O. baccatus could be exploited and further developed as an effective plant extract-based insecticide to be utilized in integrated pest management (IPM) programs against A. craccivora.

Interaction of thiamethoxam with DNA: Hazardous effect on biochemical and biological parameters of the exposed organism

In the present scenario, insecticides/pesticides are used intensively to control the various insect pests. Indiscriminate use of these insecticides/pesticides affects the structure and function of the ecosystem. In this context, a thorough toxicological study of each insecticide/pesticide is a must to understand the hazardous effect of these chemicals on the target and non-target organisms. The present study was aimed to understand the hazardous effect of thiamethoxam against the Spodoptera litura. Different concentrations (20–80 μg/mL) of thiamethoxam were prepared, and fourth instar larvae of S. litura were allowed to feed for 12–72 h. We first examined the interaction of thiamethoxam with DNA. Next, treated and non-treated larvae were assessed for different biological parameters such as mortality, emergence, fecundity, fertility, longevities, and biochemical parameters. Our result showed that thiamethoxam directly interacts with the DNA and significantly influenced the different biological and biochemical parameters of exposed the organisms. We observed a significant change in stress enzymes such as SOD, CAT, and GST. A similar observation was also made with the oxidative marker for lipid damage, MDA and DNA damage, 8-OHdG, respectively. In conclusion, our results suggest that improper use of synthetic chemical insecticides influenced both biological and biochemical parameters through oxidative stress and probably damage the genetic material.

LARVICIDAL EFFICACY OF NIGELLA SATIVA SEEDS OIL AND IT’S NANOPARTICLES AGAINST CULEX PIPIENS AND MUSCA DOMESTICA

Extensive and continuous use of synthetic chemical insecticides led to environmental hazards to non-target organisms, and development of insect’s resistance. The present study evaluated essential oil of Nigella sativa seeds as a friendly larvicidal measure for Culex pipiens and Musca domestica vectors of infectious diseases. The N. sativa components essential oil was analyzed by GC-MS. Sixteen components were identified. The selenium nanoparticles (SeNPs)with N. sativa essential oil were prepared to form N. sativa SeNPs and proved by UV-Spectrophotometer, FT-IR, and SEM. The droplet size of nanoemulsion was 65±11.4 nm. The bioassay showed that N. sativa essential oil and its nanoparticles were more effective against larvae of Cx. pipiens than those of M. domestica.

Application of Beauveria bassiana (Bals.) Vuil. (Hypocreales: Cordycipitaceae) in rice seed and its effect on mortality of green leaf hopper, Nephotettix virescens (Distant) (Homoptera: Cicadellidae)

The use of synthetic chemical insecticides in controlling rice pest insects has various negative impacts. Chemical insecticides can stimulate pest resistance, the emergence of secondary pests, killing of useful organisms and natural enemies, and contamination of residues in food, soil and water. Another potential effective control alternative is the use of entomopathogenic fungus Beauveria bassiana (Bals.) Vuil. (Hypocreales: Cordycipitaceae). The effectiveness of B. bassiana application by spraying on plants or pests directly, can decrease due to the influence of high temperatures, low humidity, and exposure to ultra violet light. The study of the application of B. bassiana by treatment of rice seeds was carried out to determine the cumulative mortality of green leaf hopper, which was carried out in two-time periods at the Bioecology Laboratory for Natural Pests and Enemies, Department of Plant Pests and Diseases, Faculty of Agriculture, Hasanuddin University. The first series of studies used B. bassiana collection culture of Bioecology Laboratory, and the second series used the commercially available B. bassiana formulation. Completely Randomized Design (CRD), with each of the 4 treatments and 5 replications was used in this study. The results showed that, coating or soaking rice seeds with entomopathogenic fungi B. bassiana was able to cause mortality to green leafhoppers. Although the mortality is lower than spraying on rice plants or penetrating the body of green leafhoppers, however, with the covering or soaking rice seeds, the mortality of green leafhoppers is significantly higher than control without the application of B. bassiana. This indicates basic potential that requires a study for development of rice seed coating and immersion techniques to increase its effectiveness in controlling green leafhoppers.

Evaluation of Plants Extracts from Capsicum annum and Allium sativum against Aphis craccivora Attacking Cowpea Plant in Kano, Nigeria

The efficacy of Capsicum annum fruits and Allium sativum cloves methanolic crude extracts were evaluated on field for the control of Aphis craccivora attacking cowpea plants. Two cowpea genotypes (IAR-48 and IT97K-499-35) were planted separately in a randomized block design, for a cowpea genotype an experimental plots measured 5m x 3m with 1.5m space between plots was demarcated. The plot contained four subplots each measured 1.67m x 3m and replicated three times, given the total of twelve subplots. Within a subplot are three pairs of ridges (70cm apart) tallied with the three different concentrations (200, 600 and 1000ppm) for the plant extracts treatments application. Plant extract treatments along side with synthetic chemical insecticide (Magic force) as positive control were applied to the subplots using Knapsack sprayer 15 days after sowing. The results showed that the population scores of A. craccivora after treatments application on susceptible genotype IAR-48 was reduced significantly (p <0.05) when compared with untreated control subplot. The least population scores of this insect on genotype IAR-48 was recorded in plants treated with A. sativum at 600ppm concentration level which was effective over positive control (synthetic chemical). The genotype IT97K-499-35 recorded no population aphid in plants treated with A. sativum at 200ppm concentration level which is also effective over the positive control. There is critical need to enhance the use of plant extracts scientifically on field as part of Integrated Pests Management for safe food production.

Chemical composition and insecticidal effect of essential oils from Illicium verum and Eugenia caryophyllus on Callosobruchus maculatus in cowpea

The cowpea weevil Callossobruchus maculatus Fabr. (Coleoptera: Chrysomelidae: Bruchinae) is the major pest in stored cowpea, especially in subtropical countries. Thus, the present study aimed to evaluate the insecticidal potential of the essential oils of Illicium verum Hook. F. and Eugenia caryophyllus Spreng on adults of C. maculatus. The components of the essential oils were obtained and identified, the contact toxicity and the repellent and fumigant effect were determined. In the contact and fumigation test the lethal concentrations LC50 and LC95 were determined, the lethal concentrations determined in the contact test were used in the repellency test. For contact and repellency tests, the number of eggs and adults emerged were counted. According to the chemical analysis of the oils, E-anethole (88.85 %) and eugenol (74.31 %) for I. verum and E. caryophyllus, respectively, were the compounds in greater quantity. The values of lethal concentrations LC50 and LC95 in the contact test were estimated at 9.62 and 32.78, 1.27 and 11.95 μL/20 g, respectively, for the oils of I. verum and E. caryophyllus. The essential oil of E. caryophyllus presented higher toxicity for both lethal concentrations, being 5.44 and 2.74 times more toxic than I. verum for LC50 and LC95, respectively. In contact and repellency tests both oils reduced the number of eggs and insects emerged. The LC95 concentration for both oils was repellent to C. maculatus. The essential oils of E. caryophyllus and I. verum presented a potential fumigant effect on C. maculatus with relatively low lethal concentration (LC50) (22.36 and 20.27 μL/L of air for I. verum and E. caryophyllus, respectively), thus being an alternative to synthetic chemical insecticides for the control of stored grain pests.

COMPARISON OF IPM PACKAGES ON FLOWER THRIPS AND POD BORERS MANAGEMENT OF MUNGBEAN WITH RECOMMENDED PRACTICE

Effectiveness of integrated management approaches using blue sticky trap, pheromone trap, bio and synthetic insecticides were evaluated against major insects, like flower thrips and pod borers of mungbean at Regional Agricultural Research Station, Rahmatpur, Barishal and Pulses Research Centre, Ishurdi, Pabna, Bangladesh, respectively, during two consecutive years of 2018 and 2019. All of the management packages significantly reduced flower infestation, thrips population and pod borer infestation in mungbean. The highest percentage of reduction of flower infestation, thrips population and pod borer infestation was found in IPM package-3: installing blue sticky trap + two spraying of chlorfenapyr (Intrepid 10 EC) @ 1 ml/l + third spraying with (chlorantraniliprole + thiamethoxam), i.e. Virtako 40 WG) @ 0.15 g/l, followed by IPM package-1, IPM package-2 and recommended practice (spraying imidacloprid, i.e. Imitaf 20 SL @ 0.5 ml/l). The highest yield was also recorded from IPM package-3, which was statistically similar to IPM package-1, followed by IPM package-2 and recommended practice. Although the IPM package-3 provided the highest yield and return, followed by IPM package-1, but recommended practice (farmer’s practice) gave the highest benefit because of higher cost of IPM components brought down the profit margin of IPM packages. The components of IPM package-1, i.e. biopesticides, are ecologically safer than that of IPM package-3 (synthetic chemical insecticides). So, considering environment friendliness, the IPM package-1: installation of blue sticky trap and pheromone trap + two spraying of azadiractin (Biomeem plus 1EC) @ 1 ml/l + third spraying with spinosad (Success 2.5 EC) @ 1.2 ml/l would be the best package for controlling flower thrips and pod borers of mungbean with higher yield in the insects prone areas, without harming the ecosystem.

COMPARISON OF IPM PACKAGES ON FLOWER THRIPS AND POD BORERS MANAGEMENT OF MUNGBEAN WITH RECOMMENDED PRACTICE

Effectiveness of integrated management approaches using blue sticky trap, pheromone trap, bio and synthetic insecticides were evaluated against major insects, like flower thrips and pod borers of mungbean at Regional Agricultural Research Station, Rahmatpur, Barishal and Pulses Research Centre, Ishurdi, Pabna, Bangladesh, respectively, during two consecutive years of 2018 and 2019. All of the management packages significantly reduced flower infestation, thrips population and pod borer infestation in mungbean. The highest percentage of reduction of flower infestation, thrips population and pod borer infestation was found in IPM package-3: installing blue sticky trap + two spraying of chlorfenapyr (Intrepid 10 EC) @ 1 ml/l + third spraying with (chlorantraniliprole + thiamethoxam), i.e. Virtako 40 WG) @ 0.15 g/l, followed by IPM package-1, IPM package-2 and recommended practice (spraying imidacloprid, i.e. Imitaf 20 SL @ 0.5 ml/l). The highest yield was also recorded from IPM package-3, which was statistically similar to IPM package-1, followed by IPM package-2 and recommended practice. Although the IPM package-3 provided the highest yield and return, followed by IPM package-1, but recommended practice (farmer’s practice) gave the highest benefit because of higher cost of IPM components brought down the profit margin of IPM packages. The components of IPM package-1, i.e. biopesticides, are ecologically safer than that of IPM package-3 (synthetic chemical insecticides). So, considering environment friendliness, the IPM package-1: installation of blue sticky trap and pheromone trap + two spraying of azadiractin (Biomeem plus 1EC) @ 1 ml/l + third spraying with spinosad (Success 2.5 EC) @ 1.2 ml/l would be the best package for controlling flower thrips and pod borers of mungbean with higher yield in the insects prone areas, without harming the ecosystem.

TOXICITY OF DIFFERENT PLANT EXTRACTS AND GREEN SILVER NANOPARTICLES AGAINST PLUTELLA XYLOSTELLA (LEPIDOPTERA: PLUTELLIDA)

The diamondback moth, Plutellaxylostella (Lepidoptera; Plutellidae) is one of the most notorious and cosmopolitan insect pests of brassica crops around the world. P. xylostella may causes 90% yield losses in brassica crops. Various control measures have been adopted to manage this pest; however, the most effective control method is the use of synthetic chemical insecticides. Overuse of insecticides have many adverse effects including insecticide resistance, hazardous to environment, long persistency, interfere with food chain. There is an urgent need for alternative control measures which should be effective, environmental friendly and economically safer. Bio pesticides include plant extracts and green synthesized nano-based insecticides are among these measures, which can be useful for the management of P. xylostella. Less work has been carried out on the use of green synthesized plant products against P. xylostella. Therefore, current study has been planned to evaluate the toxicity of plant extracts and green synthesized nano-based plant products against P. xylostella. Eight plants extract (neem, bakain, bitter-gourd, clove, eucalyptus, dathura, garlic and ginger) and their nano-based products (green synthesis silver nanoparticles) were applied in different concentrations against 3rd larval instars of P. xylostella. Mortality were recorded after 24, 48 and 72 hours of application of treatments. Corrected mortality was calculated using Abbot’s formula and LC50 values were calculated.

A REVIEW ON FUTURE OF BACULAVIRUSES AS A MICROBIAL BIO CONTROL AGENT

Pesticides driven from Plants, animals, and microbes such as (bacteria fungi, viruses, algae, nematodes and protozoa are replacing traditional chemical pesticides throughout the world. Bio pesticides reduce environmental risks and are target specific. Bio pesticide promotes sustainable agriculture development by reducing the environmental pollution. Various products have been registered and released, that play important role in the agro-market. Regulation of many insect populations in nature happen by Baculoviruses (entomopathogenic viruses). The pesticide based on baculovirus particles has been formed to control pest and their use is beneficial to reduce the risk of synthetic chemical insecticides. The present status and increase use of baculovirus based bio pesticides as replacement of chemical pesticides, its role in integrated pest management, have been discussed in this review.

Cuminum cyminum methanolic extract – Fe3O4 nanocomposite: A novel and efficient insecticide against the potato tuber moth (Lepidoptera: Gelechiidae) to protect potatoes

Phthorimaea operculella is a significant insect pest of cultivated potatoes in tropical and subtropical regions such as Iran. Since the potato is one of the most valuable sources of human food, non-chemical control of potato pests is essential. Application of medicinal plant extracts is a low-risk alternative method to synthetic chemical insecticides. Hence, the present study was conducted to investigate a potential strategy to improve the insecticidal activity of plant extracts for efficient management of P. operculella. The insecticidal efficacy of pure methanolic extract (PME) and Fe3O4@methanolic extract (FME) of Cuminum cyminum were evaluated against the potato tuber moth under laboratory conditions. The morphological characteristics of Fe3O4@Cumin were investigated by scanning electron microscope. Magnetic properties of the samples were determined using a vibration sample magnetometer. XRD was used to prove the crystalline structure of Fe3O4@Cumin. SEM, FTIR, XRD, and VSM analyses confirmed that the methanolic extract was loaded on Fe3O4. The toxicity of PME and Fe3O4@Cumin were evaluated on one-day-old eggs and penetration the first instar larvae of P. operculella into potato tubers and leaves. The LC50 values of Cumin extract and Fe3O4@ Cumin were 961.07 and 601.48 and 496.84 and 268.82 ppm for penetrating neonate larvae to tubers and leaves, and 874.90 and 595.16 ppm for eggs, respectively. Bioassays revealed that Fe3O4@Cumin was more toxic than non-formulated Cumin methanolic extract against eggs and neonate larvae of P. operculella. The formulated methanolic extract was significantly more repellent against the pest. Our results suggested that the prepared nanocomposite could be used as a new effective tool for P. operculella management strategies to protect potatoes.

Evaluation of Ovicidal Effect of Extracts from Hop, Oregano, Lemon Balm and Clove on the Sunn Pest, Eurygaster maura L. (Hemiptera: Scutelleridae)

Botanical insecticides may be an alternative to minimize or replace the use of synthetic chemical insecticides against pests of agricultural importance. In this search, the ovicidal effects of four plant extracts Lemon Balm Melissa officinalis L, Hop Humulus lupulus L, Oregano Origanum vulgare L. and clove Syzygium aromaticum (L.) were tested against Eurygaster maura L. (Hemiptera:Scutelleridae) under laboratory conditions. One to three-day-old eggs were dipped in plant extracts. The effects of three concentrations of plant extracts 2.5, 5 and 10% were studied. It was observed that as the concentration increased, the inhibition of egg hatchability increased. Lemon Balm extract didn't show significant ovicidal effect. On the other hand, Oregano and clove extracts moderately showed ovicidal effect. Hop extract revealed the best result in inhibiting egg hatchability (57.49%) at 10% concentration. It can be concluded that hop extract may be used as supportive in an integrated pest management programme aimed at controlling E.maura .

Insecticidal Activity of an Indian Botanical Insecticide ULTRA ACT&#174 against the Olive Pest <i>Bactrocera oleae</i> (Diptera: Tephritidae) in Tunisia

Bactrocera oleae is the most economically damaging insect of olive in the Mediterranean. As a reliable alternative to synthetic chemical insecticides, botanical pesticides from plant extracts are also considered natural control methods safe for the environment and human health. In practical applications up to date, studies demonstrating toxically effects of biological control agents on the insect have been carried out in organic farming systems based on some industrial microbial formulations. But much less attention has been given to botanical insecticides against B. oleae. Thus, a certified botanical insecticide issue from various plants and approved per Indian and International organic standards was tested against larvae and pupae of the olive pest Bactrocera oleae in the east of Tunisia under laboratory conditions. The experiments were conducted with 3 normal treatments and 1 control. Two techniques were used for larvae and pupae: direct contact using concentration from 0.5; 0.750; 1 and 1.5 mg/l and fumigation treatment using 2 mg/l conducted in rectangular boxes (25&#176C - 27&#176C, 75% - 85% RH and 14:10 LD photo period). For larval stages, LC50 and LC90 values for Ultra-Act were 0.45 and 1.22 mg/L in direct contact and 1.5 - 2 mg/l with fumigation, respectively. For pupal stage, the ID25 and ID50 values were estimated to be 0.71 mg and 1.26 mg respectively corresponding to the inhibition of emergence of 25% and 50% of B. oleae adults from pupa. Our results indicate that sprayed Ultra-Act product has the potential to control the three olive fly instar larvae. Pupal emergency was decreased significantly with fumigation treatment. In conclusion, Ultra-Act is a promising botanical insecticide against B. oleae that could be used as a successful alternative for chemicals in integrated control methods of this pest in Tunisia.

Formulation of plant based insecticides, their bio-efficacy evaluation and chemical characterization

The aim of this study was to develop Emulsifiable Concentrate (EC) formulations from seed oils of Pongamia pinnata L., Pachyrhizus erosus L. and Annona squamosa L. Insecticidal efficacy of developed formulations was tested in-vitro against cabbage aphid (Brevicoryne brassicae L.) and in-vivo against aubergine aphid (Aphis gossypii G.) and whitefly (Bemisia tabaci G.). EC formulations comprising of seeds extract (40%) were prepared using bio-degradable solvents (50%) and emulsifier blends (10%) with hydrophilic-lypophilic balance (HLB) value (12.54) suitable for the seed oils formulation. Among nine EC formulations prepared from seed oils of each plant, EC-1 type performed well in terms of emulsion stability, cold test, accelerated storage and flash point test indicating feasibility for their commercial production. In-vitro study of A. squamosa 40 EC at 1% dose caused the maximum mortality of 80.7% (LC50 = 0.08%) against B. brassicae at 72 h after the treatment. The bio-efficacy was comparable with the synthetic insecticide dimethoate 30 EC at 0.1% dose. Besides A. squamosa, the 40 EC formulation of P. pinnata at 1% dose having 70.6% mortality at 72 h after treatment (LC50 = 0.19%) was also found promising. In-vivo studies in brinjal also indicated the maximum reduction of aphids (67.3–72.3%) and whiteflies (67.5–75.6%) within 5–14 days after application of A. squamosa 40 EC formulation at 1.0% dose followed by P. pinnata 40 EC. The total flavonoids and phenolic content in all the crude seed extracts varied from 20.9 to 53.9 mg QE/g and 5.8–9.5 mg GAE/g, respectively. Further analysis of the extracts by GC-MS revealed some bioactive constituents belonging to fatty acids, esters, aldehyde, phenols, etc. The study unveiled its significance in developing herbal insecticidal formulations as an alternative to harmful synthetic chemical insecticides and a step forward towards development of a promising eco-friendly technology in crop protection.

TOXICOLOGICAL AND BIOCHEMICAL EFFECTS OF PRECOCENE II AGAINST COTTON LEAFWORM, SPODOPTERA LITTORALIS (BOISD.)

The cotton leafworm, Spodoptera littoralis (Boisd.) is very polyphagous insect against the most economic plants all over the world. The traditional synthetic chemical insecticides had dramatic effect on the living organisms including man. Anti-juvenile hormones; precocene II effect on the cotton leafworm, Spodoptera littoralis were assayed under laboratory conditions. (PrecoceneII (6,7-dimethoxy-2,2dimethylchromene) was the main constituent isolated from Ageratum houstonianum plant. The compound caused toxicity against the larvae with (LC10 was 5.59 mg/l), (LC25 was 24.69 mg/l) and (LC50 was 128.53 mg/l). There was some morphogenic effect obtained due to effect of precoceneII on larvae, pupae and adult stages. On the other hands the biochemical analysis of the cotton leafworm revealed that precocene II caused significant increase in chitinase, protease and total carbohydrates with (17.32, 50.17 and 36.85 %), respectively comparison to control.