Pesticides Occurrence in Water Sources and Decontamination Techniques

Pesticides are essential in crop protection as they keep the plants safe from insects, weeds, fungi, and other pests in order to increase crop production and feed billions of people throughout the world. There are more than 500 pesticide molecules currently in use all around the world. Their non-judicious use has noticeably contaminated the environment and caused negative effects on humans and other life forms. The rainfall or irrigation water takes away the pesticide residues to nearby surface water bodies through runoff or to the groundwater sources through leaching. The occurrence of pesticides in water resources could have multiple consequences. Exposure of pesticides through contaminated water becomes the cause of acute and chronic health problems in people of all ages. Pesticide residues have the potential to disrupt the ecosystem equilibrium in water bodies. Contaminated irrigation water can contaminate other crops as well as their environment. This chapter will discuss the major exposure routes of pesticides in water bodies mainly from agricultural sectors and their effect on the ecosystem. The chapter will also discuss decontamination techniques to eliminate pesticide contaminants from water bodies

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Not AvailableToxicity and repellency activity of Cleistanthus collinus (Roxb.) (CC) leaf extracts were evaluated against rice weevil, Sitophilus oryzae (L.) and red flour beetle, Tribolium castaneum (Herbst) under laboratory condition. Five concentration(s) (1%, 1.5%, 2%, 2.5% and 4%) with two controls (acetone and water) treatments along with deltamethrin were used for direct and contact residual toxicity. The insect that survived after CC exposure were transferred to an untreated feeding substrate and the population buildup of subsequent two generation were recorded after 30 (F1) and 60 days (F2). In the contact residual toxicity, highest CC concentration (4%) produced 75% mortality in S. oryzae and 62.5% mortality in T. castaneum during 7 days of exposure, whereas in direct toxicity the mortality were 81% and 58% respectively, for S. oryzae and T. castaneum. The long term effect of CC was apparent in both the insect species, where F2 populations were significantly decreased in the CC treatments. CC treatment at 4% produced similar adult mortality in comparison to deltamethrin at 1%. In addition, repellent activity of CC extracts was observed against both S. oryzae and T. castaneum. This is the first step towards assessing the scientific basis for the understanding the effectiveness of CC extracts against stored grain pests and it could be a viable eco-friendly option for stored grain insect pest management.ICAR-National Rice Research Institute, Cuttack 753006, Indi

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Not AvailableToxicity and repellency activity of Cleistanthus collinus (Roxb.) (CC) leaf extracts were evaluated against rice weevil, Sitophilus oryzae (L.) and red flour beetle, Tribolium castaneum (Herbst) under laboratory condition. Five concentration(s) (1%, 1.5%, 2%, 2.5% and 4%) with two controls (acetone and water) treatments along with deltamethrin were used for direct and contact residual toxicity. The insect that survived after CC exposure were transferred to an untreated feeding substrate and the population buildup of subsequent two generation were recorded after 30 (F1) and 60 days (F2). In the contact residual toxicity, highest CC concentration (4%) produced 75% mortality in S. oryzae and 62.5% mortality in T. castaneum during 7 days of exposure, whereas in direct toxicity the mortality were 81% and 58% respectively, for S. oryzae and T. castaneum. The long term effect of CC was apparent in both the insect species, where F2 populations were significantly decreased in the CC treatments. CC treatment at 4% produced similar adult mortality in comparison to deltamethrin at 1%. In addition, repellent activity of CC extracts was observed against both S. oryzae and T. castaneum. This is the first step towards assessing the scientific basis for the understanding the effectiveness of CC extracts against stored grain pests and it could be a viable eco-friendly option for stored grain insect pest managementNot Availabl

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Not AvailableToxicological screening of Swietenia mahagoni Jacq. (Meliaceae, West Indies Mahogany) against the lepidopteran pest Spodoptera litura was examined. Phytochemical screening through GC-MS analysis revealed nine peaks with prominent peak area % in Bis (2-ethylhexyl) phthalate (31.5%) was observed. The larvae exposed to discriminating dosage of 100 ppm deliver significant mortality rate compare to other treatment concentrations. The lethal concentrations (LC50 and LC90) was observed at the dosage of 31.04 and 86.82 ppm respectively. Sub-lethal concentrations (30 ppm) showed higher larval and pupal durations. However, pupal weight and mean fecundity rate reduced significantly. Similarly, the adult longevity reduced significantly in dose dependent manner. Midgut histology studies showed that the methanolic extracts significantly disturbs the gut epithelial layer, lumen and brush border membrane compare to the control. The soil assay on a non-target beneficial organism, the soil indicator earthworm Eudrilus eugeniae, with extracts from S. mahagoni (200 mg/kg) showed no toxicity compared to Monocrotophos at the dosage of 10 ppm/kg. Current results suggest that this bio-rational plant product from S. mahagoni displays a significant effect to reduce lepidopteran pests with low toxicity to other beneficial species.Not Availabl

Multigenerational Insecticide Hormesis Enhances Fitness Traits in a Key Egg Parasitoid, <i>Trichogramma chilonis</i> Ishii

Hormesis for the intractable pests can be dreadful, but for natural enemies of pests, it is a puissant strategy in optimizing their mass rearing. We report multigenerational stimulatory effects of widely used insecticide, imidacloprid, on the demographic traits of an important egg parasitoid Trichogramma chilonis Ishii. The study investigated the consequences of sublethal (LC5), low lethal (LC30), and median lethal (LC50) concentrations, as well as a control, for five continuous generations (F1 to F5). The initial bioassay experiments revealed imidacloprid exhibiting the highest toxicity for the parasitoid with a LC50 of 2 µg·L−1, whereas LC5 and LC30 were 0.07 µg·L−1 and 0.6 µg·L−1, respectively. Among biological traits, compared to the F1 individuals, a substantial increase in the fecundity of T. chilonis was observed in the F5 individuals by 54.92% and 46.81% when exposed to LC5 and LC30, respectively (p 5 individuals at both these concentrations. Considering the population traits, along with gross reproductive rate (GRR), net reproductive rate (R0) was also enhanced by both LC5 and LC30 in F5 individuals than F1; whereas the intrinsic rate of increase (r) and finite rate of increase (λ) were enhanced only at LC30 upon comparing with control. On the other hand, LC50 exposure to T. chilonis did not result in notable differences in biological or population traits when compared across generations (F1 and F5). Low and sublethal concentrations of imidacloprid did not have a major influence on demographic traits of T. chilonis at initial generations of exposure but can induce hormetic effects in the subsequent generations. Overall, imidacloprid-induced hormesis stimulating the development of T. chilonis might be helpful under circumstances of mild exposure of imidacloprid in fields and could be leveraged for its mass rearing

Multigenerational Insecticide Hormesis Enhances Fitness Traits in a Key Egg Parasitoid, Trichogramma chilonis Ishii

Hormesis for the intractable pests can be dreadful, but for natural enemies of pests, it is a puissant strategy in optimizing their mass rearing. We report multigenerational stimulatory effects of widely used insecticide, imidacloprid, on the demographic traits of an important egg parasitoid Trichogramma chilonis Ishii. The study investigated the consequences of sublethal (LC5), low lethal (LC30), and median lethal (LC50) concentrations, as well as a control, for five continuous generations (F1 to F5). The initial bioassay experiments revealed imidacloprid exhibiting the highest toxicity for the parasitoid with a LC50 of 2 &micro;g&middot;L&minus;1, whereas LC5 and LC30 were 0.07 &micro;g&middot;L&minus;1 and 0.6 &micro;g&middot;L&minus;1, respectively. Among biological traits, compared to the F1 individuals, a substantial increase in the fecundity of T. chilonis was observed in the F5 individuals by 54.92% and 46.81% when exposed to LC5 and LC30, respectively (p &lt; 0.00001). Further, there was a significant enhancement in the adult longevity as well as oviposition days of the F5 individuals at both these concentrations. Considering the population traits, along with gross reproductive rate (GRR), net reproductive rate (R0) was also enhanced by both LC5 and LC30 in F5 individuals than F1; whereas the intrinsic rate of increase (r) and finite rate of increase (&lambda;) were enhanced only at LC30 upon comparing with control. On the other hand, LC50 exposure to T. chilonis did not result in notable differences in biological or population traits when compared across generations (F1 and F5). Low and sublethal concentrations of imidacloprid did not have a major influence on demographic traits of T. chilonis at initial generations of exposure but can induce hormetic effects in the subsequent generations. Overall, imidacloprid-induced hormesis stimulating the development of T. chilonis might be helpful under circumstances of mild exposure of imidacloprid in fields and could be leveraged for its mass rearing

Performance of Trichogramma japonicum under field conditions as a function of the factitious host species used for mass rearing

Not AvailableDifferent factitious hosts were used to mass rear Trichogramma japonicum Ashmead in different parts of the globe because thorough details were lacking in both the laboratory and the field. The objective of this study was to compare, parasitoid, T. japonicum reared in different factitious hosts. Three commonly used factitious host eggs, Corcyra cephalonica (Stainton), Ephestia kuehniella Zeller and Sitotroga cerealella Olivier were tested under laboratory conditions and then in the field over a yellow stem borer, Scirpophaga incertulus (Walker) of rice. The highest parasitism by T. japonicum was observed on E. kuehniella eggs. The parasitoid’s highest emergence (88.99%) was observed on S. cerealella eggs at 24 h exposure, whereas at 48 h it was on E. kuehniella eggs (94.66%). Trichogramma japonicum females that emerged from E. kuehniella eggs were significantly long-lived. The days of oviposition by hosts and the host species were significant individually, but not their interaction. Higher proportions of flying T. japonicum were observed when reared on E. kuehniella and C. cephalonica eggs. Field results showed that T. japonicum mass-reared on E. kuehniella showed higher parasitism of its natural host, S. incertulus eggs. Hence, by considering these biological characteristics and field results, E. kuehniella could be leveraged for the mass rearing of quality parasitoids of T. japonicum in India, the Asian continent and beyond.Not Availabl

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Not AvailableDamage caused by insect herbivores, notably Asian rice gall midge, Orseolia oryzae is more prevalent in the rice-growing belts of India's southern and north-eastern states. As a prelude to resistant cultivar development, the identification of genomic regions for resistance in the source population is crucial. In the present investigation, 202 rice genotypes were phenotyped and assayed with genomic markers reported for gall midge resistance. Positive skewness and platykurtic distribution of response scores suggested the inheritance of gall midge resistance in the study population. The marker gm3del3 contributed the most genetic variation, followed by RM28574 and marker RM22709 explained minimal variation. A marker-trait association analysis with a single marker-trait linear regression approach was performed to discover gall midge resistant genomic region/genes. The marker RM17480 on chromosome 4 reported to be linked with gm3 gene was found significantly associated with the gall midge resistance genomic region with allelic effects in a negative direction favouring resistance reaction. The allelic effects of significantly associated markers were correlated significantly with the phenotypic variation of gall midge damage scores. Genes identified in the vicinity of this marker contribute to stress response reactions in rice plants. The 200 bp allele of the marker was associated with susceptibility, while the 250 bp allele was associated with resistance expression. This allelic association with trait variation suggests the importance of associated marker for utilisation in marker-assisted selection programmes to incorporate resistance alleles into elite rice genotypes.Not Availabl