Modern Insecticides Research Articles

Recent trends of modern bacterial insecticides for pest control practice in integrated crop management system.

Food security and safety are the major concern in ever expanding human population on the planet earth. Each and every year insect pests cause a serious damage in agricultural field that cost billions of dollars annually to farmers. The loss in term of productivity and high cost of chemical pesticides enhance the production cost. Irrespective use of chemical pesticides (such as Benzene hexachloride, Endosulfan, Aldicarb, and Fenobucarb) in agricultural field raised several types of environmental issues. Furthermore, continuous use of chemical pesticides creates a selective pressure which helps in emerging of resistance pest. These excess chemical pesticide residues also contaminate the environment including the soil and water. Therefore, the biological control of insect pest in the agricultural field gains more importance due to food safety and environment friendly nature. In this regard, bacterial insecticides offer better alternative to chemical pesticides. It not only helps to establish food security through fighting against insect pests but also ensure the food safety. In this review, we have categorized insect pests and the corresponding bacterial insecticides, and critically analyzed the importance and mode of action of bacterial pesticides. We also have summarized the use of biopesticides in integrated pest management system. We have tried to focus the future research area in this field for the upcoming scientists.

Economics of Crop Cultivation in Himachal Pradesh: Facts from Cost of Cultivation Data

Agricultural economy plays a significant role in the rural livelihood of Himachal Pradesh as about 90 per cent the population of the state resides in rural areas (highest in country in terms of (percentages) and nearly 70 per cent of the working population directly or indirectly depends on it to eke out its livelihood. Keeping in view the preponderance of agriculture in the state economy, the present study also provide a detailed economic analysis of costs, returns and profitability of principal crops namely, Maize, Paddy, Wheat and Potato by using the cost of cultivation data for the period 2012–13 through different cost concepts developed by the CACP. The result shows that different crop systems studied in this research vary with the magnitude of inputs (land, labor, bullock labor, seed etc.) and crop output. The study highlights that family labour has predominant role in the accomplishment of various crop operations. In respect of net returns and profitability, only paddy and potato crops are bearing positive returns over cost C and in terms of net profit per quintal, all crops are bearing profits though it is too low. The production of these crops are not viable at least from farmers ’point of view. In order to make agriculture a viable and sustainable occupation, an integrated development strategy encompassing effective modern extension services, transfer of production technology & technical know-how to the farmers, use of modern inputs (certified seeds, balanced fertilizer (N+ P +K), insecticides & pesticides, improved agricultural implements and machinery), access to institutional credit, development of adequate storage and warehousing facilities, watershed management, livestock policy, linking of MSP to the costs of cultivation, creation of irrigation potential and its optimum utilization is of primary importance.

Residual Acute Toxicity of Some Modern Insecticides Toward Two Mirid Predators of Tomato Pests.

The successful integration of chemical and biological control strategies for crop pests depends on a thorough evaluation of the effects of pesticides on the natural enemies of pests. A case-by-case review is difficult to achieve because of the many combinations of pests, natural enemies, and crops that need to be tested. Within this framework, we tested and compared seven insecticides representative of four different modes of action (MoAs) groups on closely related predators (Miridae): flubendiamide, spirotetramat, metaflumizone, and sulfoxaflor on Nesidiocoris tenuis Reuter and flubendiamide, spiromesifen, indoxacarb, and imidacloprid on Macrolophus basicornis (Stal). We follow the standardized methodology of the International Organization for Biological Control, a sequential testing exposure scheme. The lethal effect of each insecticide was evaluated in adults after three days of contact with treated surfaces in the laboratory, extended laboratory, and semifield tests (inert substrate, tomato leaves, and tomato plant as the treated surface, respectively). Flubendiamide, spiromesifen, and spirotetramat were classified as harmless (class 1), metaflumizone was slightly harmful (class 2) but persistent, indoxacarb was harmless (class 1), and sulfoxaflor and imidacloprid were toxic (class 4) and exhibited a long residual activity. Our results suggest similarities in the acute toxicities of insecticides from the same MoA group on related species of natural enemies.

A brief review of most widely used modern insecticides and prospects for the creation of DNA insecticides

The need for insecticides cannot be questioned but many of them cause great harm to the environment. This warrants further research aimed at the development of safe preparations. Understanding the structure and mode of action of the modern insecticides as well as the risks associated with their use is important for the development of effective and selective insecticides. The most marketable preparations will be those combining the best properties of the existing insecticides. In our opinion, this condition is met by DNA insecticides, preparations based on nucleic acids. They have some unique features, such as a topical application, the small size of oligonucleotides, the use of single-stranded DNA molecules, and the use of viral anti-apoptotic genes. These features distinguish DNA insecticides from other post-genomic means of plant protection that are currently under development. DNA insecticides can combine the best characteristics of modern insecticides, namely, affordability, fast action of chemical insecticides, and selectivity of biological preparations.

Are Mummies and Adults of Eretmocerus mundus (Hymenoptera: Aphelinidae) Compatible With Modern Insecticides?

The parasitic wasp Eretmocerus mundus (Mercet) is an important natural enemy of the widespread key pest Bemisia tabaci (Gennadius). The toxicity of 11 modern insecticides applied at their maximum field recommended rate in Spain was tested in two life stages of E. mundus: adults and mummies. Laboratory and persistence tests were conducted and effects assessed not only in terms of mortality but on reproductive performance as well. Some insecticides caused the same effect to both life stages: flubendiamide, methoxyfenozide, spiromesifen, and flonicamid were harmless, while spinosad and sulfoxaflor were harmful. The last two insecticides cannot be used jointly with E. mundus under any condition because they were highly persistent. The rest of tested insecticides (spirotetramat, metaflumizone, deltamethrin, abamectin, and emamectin) caused some direct mortality to one or both life stages and/or affected reproduction of the parasitic wasp and their harmful effect in the field ranged from short lived (metaflumizone and spirotetramat) to slightly persistent (emamectin) and to moderately persistent (abamectin and deltamethrin). Therefore, they could be recommended for use in integrated pest management programs together with the natural enemy if appropriate safety intervals after insecticide application are observed.

A short history of insecticides

AbstractThis review contains a brief history of the use of insecticides. The peculiarities, main advantages, and disadvantages of some modern insecticides are described. The names of the discoverers of some of the most popular insecticide preparations on the world market, are listed. The tendencies to find new insecticides to control the quantity of phytophagous insects are discussed. Special attention is paid to the perspective of creating preparations based on nucleic acids, in particular DNA insecticides. The use of insect-specific, short single-stranded DNA fragments as DNA insecticides, is paving the way in the field of “intellectual” insecticides that “think” before they act. It is worth noting, though, that in the near future, the quantity of produced insecticides will increase due to the challenges associated with food production for a rapidly growing population. It is concluded, that an agreeable interaction of scientists and manufacturers of insecticides should lead to the selection of the most optimal solutions for insect pest control, which would be safe, affordable, and effective at the same time.

Comparative relative toxicity of some modern insecticides against Spodoptera litura fabricius on groundnut

Investigation on comparative relative toxicity of some modern insecticides against S. litura revealed that emamectin benzoate was the most toxic and effective insecticide as its LC 50 value was 0.000954. Notably, emamectin benzoate proved very effective in laboratory, as evident from its low LC 50 values against S. litura . As emamectin benzoate is a novel semi-synthetic derivative of the natural product was found to be most toxic. On the other hand, spinosad found to be the least toxic in which the LC 50 value was worked out to the tune of 0.0158.

Ecological life table and relative toxicity of insecticides against leaf eating caterpillar,Spodoptera lituraFab. on groundnut

The life table and key mortality factors of Spodoptera litura Fabricius revealed that the mortality in the younger group larvae was 1.56 per cent due to bacterial infection and unknown reasons. Mortality in the older group larvae was 19.8 per cent due to diseases like NPV, N. rileyi, B. bassiana and parasites like Cotesia spp., and Tachinid maggot. Mortality in the pupal and adult stage was 7.98 & 2.15 per cent due to NPV and unknown reasons, respectively. Generation survival (SG) was worked out and it was 0.70. Value of trend index (I) was calculated to the tune of 0.018. Comparative relative toxicity of some modern insecticides against S. litura revealed that Emamectin benzoate was the most toxic and effective insecticide as its LC50 value was 0.000954, however, Spinosad was found to be the least toxic in which the LC50 value was worked out to the tune of 0.0158 in comparision to Chlorpyriphos, Flubendiamide, Rynaxypyr and Novaluron.

Laboratory tests on sorption and transformation of the insecticide flubendiamide in Japanese tea field soil

Flubendiamide belongs to the modern insecticides applied in Japanese tea cultivation to control smaller tea tortrix and tea leaf roller. Since fate and behavior in soil have been only monitored sparsely and fragmentarily until today, laboratory tests were performed on sorption, leaching, biotransformation and photo-induced biotransformation of flubendiamide in two different soils. In batch equilibrium tests, Kd and KOC values were 15 and 298Lkg−1 for the Japanese tea field soil as well as 16 and 1610Lkg−1 for the German arable field soil classifying flubendiamide to be moderately mobile and slightly mobile, respectively. The affinity to the tea field soil was additionally confirmed by soil column tests where flubendiamide was predominantly retarded in the topsoil layers resulting in a percolate contamination of only 0.002mgL−1. In the aerobic biotransformation tests, flubendiamide did not substantially disappear within the 122-d incubation period. Due to DT50>122 d, flubendiamide was assessed very persistent. Supplementary, photo-induced impacts on biotransformation were studied in a special laboratory irradiation system. Despite a 14-d irradiation period, photo-induced biotransformation in the tea field soil was not identifiable, neither by HPLC/DAD nor by LC/MS/MS. 3-d irradiation tests in photosensibilizing acetone, however, showed that the primary photo-transformation product desiodo-flubendiamide was formed. How far this photochemical reaction may also occur in soil of perennial tea plant stands, however, has to be checked in field studies.

Insecticide resistance mechanisms in three sucking insect pests of tea with reference to North-East India: an appraisal

Tea is prepared from the tender leaves and buds of Camellia sinensis (L.). In sub-Himalayan tea plantations of North-East India, different management practices are followed to protect the tea crop against different sucking insect pests such as Helopeltis theivora (Hemiptera: Miridae), Empoasca flavescens (Homoptera: Cicadellidae) and Scirtothrips dorsalis (Thysanoptera: Thripidae). Most plantations are managed conventionally through the use of different organo-synthetic insecticides, whereas some are managed organically by using herbal and microbial insecticides. In conventional tea plantations, organo-synthetic insecticides of different functional groups (organochlorines, organopho- sphates, synthetic pyrethroids and neonicotinoids) are routinely applied round the year to keep the sucking insect pest populations under control. A variety of defence mechanisms, including enzymatic detoxification systems (carboxylesterases, glutathione S-transferases and cytochrome P450 monooxygenases), physiological tolerance and behavioural avoidance, protect insect herbivores from these hazardous compounds. Insect pests have evolved mechanisms to degrade metabolically (enzymatically) or otherwise circumvent the toxic effect of many types of chemicals synthesized as modern insecticides. The extent to which insects can metabolize and thereby degrade these toxic or otherwise detrimental chemicals is of considerable importance for their survival in an unfriendly chemical environment. These mechanisms continue to evolve as insects attempt to colonize new plant species or encounter newer molecules of synthetic insecticides. The level and type of detoxifying mechanisms differs greatly, which, therefore, results in varying toxicity among different stages, species and populations. Variation in detoxifying enzyme activity is responsible, in part, at least for the selective toxicity of different insecticides, the development of resistance to insecticides and the selection of host plants. Overexpression of these detoxifying enzymes, capable of metabolizing insecticides, can result in higher levels of metabolic tolerance/resistance to synthetic insecticides.

Modern insecticides for potato pest control

The results are given of the past five years’ investigations to assess the biological efficacy of new insecticides from the chemical classes of pyrethroids, neonicotinoids, and anthranilamides in controlling a complex of potato pests in different potato-growing zones of the country. Ecologically low-hazard use regulations and technologies of using these insecticides are determined.

Comparative acute toxicity of twenty-four insecticides to earthworm, Eisenia fetida

In this study, we used two different types of bioassay, a contact filter paper toxicity bioassay and a soil toxicity bioassay, to compare the acute toxicity of twenty-four insecticides belonging to six chemical categories on earthworm species, Eisenia fetida. Results of the contact filter paper toxicity bioassay indicated that neonicotinoids were super toxic to E. fetida (48h-LC50 value ranged from 0.0088 to 0.45μgcm−2), pyrethroids were very toxic (48h-LC50 values ranged from 10.55 to 25.7μgcm−2) and insect growth regulators (IGRs) were moderately toxic (48h-LC50 values ranged from 117.6 to 564.6μgcm−2) to the worms. However, antibiotics, carbamates and organophosphates induced variable toxicity responses in E. fetida, and were very to extremely toxic (48h-LC50 values ranged from 3.64 to 75.75μgcm−2). Results of the soil toxicity bioassays showed a different pattern of toxicity except that neonicotinoids were the most toxic even under the soil toxicity bioassay system. The acute toxicity of neonicotinoids was higher than those of antibiotics, carbamates, IGRs and organophosphates. In contrast, pyrethroids were the least toxic to the worms under the soil toxicity bioassay system. It was concluded that irrespective of bioassay systems, earthworms were more susceptible to neonicotinoids than other modern synthetic insecticides.

WHEAT AND BARLEY SEED SYSTEM IN SYRIA: FARMERS, VARIETAL PERCEPTIONS, SEED SOURCES AND SEED MANAGEMENT

A total of 206 wheat and 200 barley farmers were interviewed in northeastern Syria to understand farmer perceptions and practice relating to modern varieties, seed sources and seed quality. Wheat farmers had better awareness and grew modern varieties (87%), applied fertilizers (99.5%), herbicides (93%), seed treatment (90%) or insecticides (41%). In contrast barley growers had low awareness (36%) and use (0.5%) of modern varieties, herbicides (4%), insecticides (3%) and fertilizers (56%). Grain yield, grain size, food quality and tolerance to lodging, drought and frost were the agronomic characteristics farmers sought from new wheat varieties. For barley, grain yield, grain size, grain color, feed quality, marketability and tolerance to diseases and drought were the key traits sought. The informal sector-seed retained from the previous harvest or obtained from neighbors or local traders/markets-was the main source of seed for both wheat and barley. Most farmers practiced onfarm seed selection, cleaning, treatment, separate storage or quality assessment of seed that was obtained locally. Farmers’ perceptions and preferences of new varieties/technologies and their seed sources and seed management practices must be taken into account in any efforts to develop or to strengthen seed sector development.

Identification of ion channel genes in the Acyrthosiphon pisum genome.

Aphids are major pests of crops, causing hundreds of millions of dollars worth of damage annually. Ion channel proteins are often the targets of modern insecticides and mutations in ion channel genes can lead to resistance to many leading classes of insecticides. The sequencing of the pea aphid, Acyrthosiphon pisum, genome has now allowed detailed in silico analysis of the aphid ion channels. The study has revealed significant differences in the composition of the ion channel families between the aphid and other insects. For example A. pisum does not appear to contain a homologue of the nACh receptor alpha 5 gene whilst the calcium channel beta subunit has been duplicated. These variations could result in differences in function or sensitivity to insecticides. The genome sequence will allow the study of aphid ion channels to be accelerated, leading to a better understanding of the function of these economically important channels. The potential for identifying novel insecticide targets within the aphid is now a step closer.

Looking Straight at Them! Understanding the Big Bug Movies of the 1950s

Giant insects, from the ants of Them! to the locusts in Beginning of the End, featured prominently in Hollywood's postwar science fiction boom. Critics and historians have invariably interpreted these cinematic big bugs as symbolic manifestations of Cold War era anxieties, including nuclear fear, concern over communist infiltration, ambivalence about science and technocratic authority, and repressed Freudian impulses. This essay argues that Hollywood's mammoth arthropods should be taken more literally, less as metaphors than as insects, and that the big bug genre should be analyzed in the context of actual fears of insect invasion and growing misgivings about the safety and effectiveness of modern insecticides in 1950s and early 1960s America. In movies like Them!, worries about real-life insects on the loose, notably gypsy moths and imported fire ants, and uneasiness about pesticides like DDT were refracted through a cultural lens colored by superpower rivalries, nuclear proliferation, and a wide range of social tensions.

Molecular pharmacology of insect ion channels and implications for insect toxicology

Safe insecticides are essential if agriculture is to generate adequate supplies of high quality food, maintain the health of farm animals and ensure that human populations secure effective control of major disease vectors. Insect central and peripheral nervous systems contain important molecular targets of chemicals used to control insects. Insecticides with new modes of actions are under development, and several major new target molecules are emerging. Meanwhile, resistance to the current generation of insecticides continues to develop, restricting the long-term utility of these valuable chemicals. Also, methods for investigating the mechanisms of action, safety, and resistance are advancing at an accelerated pace. Modern insecticides offer improved selectivity for the target organism and understanding the mechanisms responsible may yield a future generation of effective control chemicals with reduced environmental impact. The 11th International Congress of Pesticide Chemistry (ICPC), which took place in Kobe, Japan from 6 to 11 August in 2006, chose this year as an opportune time to revisit current developments at the leading edge of research on the molecular pharmacology of ion channels targeted by insect control chemicals. This was the 2nd ICPC meeting to be held in Japan. An earlier symposium was held in Kyoto in 1982. Thus, two of us (Kazuhiko Matsuda of Kinki University, Nara and Yoshihisa Ozoe of Shimane University, Matsue) planned to invite world-leading scientists to Kinki University School of Agriculture (Fig. 1) for a satellite symposium entitled ‘‘Frontiers in Molecular Neurotoxicology’’ on August 4 prior to the start of ICPC 2006. The venue for the meeting, Kinki University School of Agriculture, is located about 6 miles west of the historical city of Nara. The city was built as the capital of Japan in 710 and still today contains many World Heritage sites, notably Todai-ji Temple, Kofukuji Temple, Kasuga-Taisha-Shrine, Gango-ji Temple, Yakushi-ji Temple, Toshodai-ji Temple, Nara Palace Site and Kasugayama Primeval Forest. Kinki University consists of 11 schools and 44 departments and was founded as the Osaka Technical College in 1925. The University started with the School of Engineering and the School of Commerce, both of which have grown to become the modern School of Business and Economics. Its strong links with Agriculture were developed in the second half of the twentieth century and the School of Agriculture was introduced in 1958. In 1989, the location of the School of Agriculture moved from Higashi Osaka to Nara. The aim of the 2006 symposium was to enhance our understanding of the current status and future perspectives in the field of molecular pharmacology of primarily insect ion channels. Authors have adopted various approaches, often in combination, and these K. Matsuda (&) Department of Applied Biological Chemistry, School of Agriculture, Kinki University, 3327-204, Nakamachi, Nara 631-8505, Japan e-mail: kmatsuda@nara.kindai.ac.jp

Comparative effectiveness of chemical insecticides against the chilli thrips, Scirtothrips dorsalis Hood (Thysanoptera: Thripidae), on pepper and their compatibility with natural enemies

The chilli thrips, Scirtothrips dorsalis Hood, is a significant pest of various vegetable tropical fruit and ornamental crops. Originally from south Asia, this pest is becoming widely distributed in tropical, subtropical and temperate areas, and in 2003 was found for the first time in the Western Hemisphere established on St. Lucia and St. Vincent in the insular Caribbean. Since there is a paucity of information on the effectiveness of modern insecticides in managing S. dorsalis populations, we evaluated the efficacy of the following insecticides for their control of this pest on ‘Scotch Bonnet’ pepper on St. Vincent: spinosad, imidacloprid, chlorfenapyr, novaluron, abamectin, spiromesifen, cyfluthrin, methiocarb, and azadirachtin. Irrespective of the number of applications and use of surfactant, chlorfenapyr was the most effective in reducing the densities of S. dorsalis adults and larvae followed by spinosad and imidacloprid. The performance of other insecticides in controlling S. dorsalis populations was inconsistent. Nevertheless, all of the above insecticides if applied repeatedly were effective in suppressing of S. dorsalis populations. Addition of the surfactant-sticker, Nu-Film 17™, improved the performance of all insecticides somewhat. Spinosad was slightly harmful and chlorfenapyr was moderately harmful to Cryptolaemus sp. predators.

Enantioselectivity in environmental safety of current chiral insecticides.

Chiral pesticides currently constitute about 25% of all pesticides used, and this ratio is increasing as more complex structures are introduced. Chirality occurs widely in synthetic pyrethroids and organophosphates, which are the mainstay of modern insecticides. Despite the great public concerns associated with the use of insecticides, the environmental significance of chirality in currently used insecticides is poorly understood. In this study, we resolved enantiomers of a number of synthetic pyrethroid and organophosphate insecticides on chiral selective columns and evaluated the occurrence of enantioselectivity in aquatic toxicity and biodegradation. Dramatic differences between enantiomers were observed in their acute toxicity to the freshwater invertebrates Ceriodaphnia dubia and Daphnia magna, suggesting that the aquatic toxicity is primarily attributable to a specific enantiomer in the racemate. In field sediments, the (-)enantiomer of cis-bifenthrin or cis-permethrin was preferentially degraded, resulting in relative enrichment of the (+)enantiomer. Enantioselective degradation was also observed during incubation of sediments under laboratory conditions. Enantioselectivity in these processes is expected to result in ecotoxicological effects that cannot be predicted from our existing knowledge and must be considered in future risk assessment and regulatory decisions.

Toxicity and pharmacokinetics of insect growth regulators and other novel insecticides on pupae of Hyposoter didmator (Hymenoptera: Ichneumonidae), a parasitoid of early larval instars of lepidopteran pests.

Susceptibility of the lepidopteran parasitoid Hyposoter didymator (Thunberg) to seven modern insecticides, azadirachtin, diflubenzuron, halofenozide, methoxyfenozide, pyriproxyfen, tebufenozide, and spinosad, was tested in the laboratory. Pupae were exposed to different doses of each compound by direct topical application. At the field recommended doses, methoxyfenozide and tebufenozide had no effect on H. didymator. Halofenozide had a low effect on both adult emergence and adult survival but the progeny size and parasitism capacity were not affected. Diflubenzuron was moderately toxic to the parasitoid, while azadirachtin, pyriproxyfen and spinosad were very toxic, affecting all its life parameters. In the pyriproxyfen and spinosad treatments, no progeny was obtained. As a second approach of this study, we determined the rate of penetration through the pupal cocoon and absorption in the parasitoid body as pharmacokinetic parameters important for toxicity. Most of the radioactivity was retained in the silken cocoon, indicating a low accumulation in the parasitoid body. Among all compounds tested, diflubenzuron exhibited the highest absorption in the parasitoid body, followed by pyriproxyfen. For halofenozide, methoxyfenozide and tebufenozide, low absorption (<2%) was found. In addition, we tested for the presence of molting hormone receptors in Hyposoter tissues using a monoclonal antibody 9B9. Our data suggest that the use of diflubenzuron azadirachtin, pyriproxyfen, halofenozide, and spinosad in combination with H. didymator in integrated pest management (IPM) programs should be carefully evaluated. Methoxyfenozide and tebufenozide could be considered safe for this parasitoid.

Effects of three modern insecticides, pyriproxyfen, spinosad and tebufenozide, on survival and reproduction of Chrysoperla carnea adults

SummaryThree novel insecticides, pyriproxyfen, spinosad and tebufenozide, were evaluated for their effect on survival and reproduction of Chrysoperla carnea adults using two methods of exposure: direct contact and ingestion. Pyriproxyfen and tebufenozide proved to be harmless to adult survival, whereas spinosad 72 h after treatment reduced the number of adults by 39.8% and 87.2% in topical and ingestion treatment at the maximum concentration recommended (800 mg a.i. litre−1). Fecundity was not affected irrespective of the insecticide or time of application (before or after the onset of oviposition). Concerning fertility, only pyriproxyfen exerted a negative effect on hatching when the eggs were deposited by females treated by ingestion in the post‐oviposition period at the highest concentration tested (150 mg a.i. litre−1).