Pesticides: An alarming detrimental to health and environment

Pesticides are chemical substances of natural or synthetic origin that are used to eradicate pests and insects. These are indispensable in the agricultural processes for better crop production. Pesticide use aims to promote crop yield and protect the crops from diseases and damage. Pesticides must be handled carefully and disposed of appropriately because they are dangerous to people and other species by default. Environmental pollution occurs when pesticide contamination spreads away from the intended plants. Older pesticides such as lindane and dichlorodiphenyltrichloroethane (DDT) may remain in water and soil for a longer time. These accumulate in various parts of the food chain and cause damage to the ecosystem. Biological techniques in the management of pest control such as importation, augmentation, and conservation, and the accompanying procedures are more efficient, less expensive, and ecologically sound than other ways. This review mainly focuses on the consequences on the targeted and non-targeted organisms including the health and well-being of humans by the use of pesticides and their toxicity. The side effects that occur when a pesticide's LD50 exceeds the accepted limit through oral or skin penetration due to their binding to various receptors such as estrogen receptors, GABA, EGFR, and others. These pesticide classes include carbamates, pyrethroids, organochlorides, organophosphorus, and others. The current study seeks to highlight the urgent requirement for a novel agricultural concept that includes a major reduction in the use of chemical pesticides.

Strategies for mitigation of pesticides from the environment through alternative approaches: A review of recent developments and future prospects

Chemical-based peticides are having negative impacts on both the healths of human beings and plants as well. The World Health Organisation (WHO), reported that each year, >25 million individuals in poor nations are having acute pesticide poisoning cases along with 20,000 fatal injuries at global level. Normally, only ∼0.1% of the pesticide reaches to the intended targets, and rest amount is expected to come into the food chain/environment for a longer period of time. Therefore, it is crucial to reduce the amounts of pesticides present in the soil. Physical or chemical treatments are either expensive or incapable to do so. Hence, pesticide detoxification can be achieved through bioremediation/biotechnologies, including nano-based methodologies, integrated approaches etc. These are relatively affordable, efficient and environmentally sound methods. Therefore, alternate strategies like as advanced biotechnological tools like as CRISPR Cas system, RNAi and genetic engineering for development of insects and pest resistant plants which are directly involved in the development of disease- and pest-resistant plants and indirectly reduce the use of pesticides. Omics tools and multi omics approaches like metagenomics, genomics, transcriptomics, proteomics, and metabolomics for the efficient functional gene mining and their validation for bioremediation of pesticides also discussed from the literatures. Overall, the review focuses on the most recent advancements in bioremediation methods to lessen the effects of pesticides along with the role of microorganisms in pesticides elimination. Further, pesticide detection is also a big challenge which can be done by using HPLC, GC, SERS, and LSPR ELISA etc. which have also been described in this review.

A review on biology and possible management strategies of tomato leaf miner, Tuta absoluta (Meyrick), Lepidoptera: Gelechiidae in Nepal

Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), Tomato Leaf Miner (TLM) moth, is one of the notorious oligophagous pests of solanaceous crops that mines primarily on mesophyll of leaves as well bore tomato fruits. In Nepal, T. absoluta, the pest that has a potential to create loss up to 100%, was detected in 2016 in a commercial tomato farm at Kathmandu. So, the farmers and researchers must heed for effective management contrivance to improve the yield of tomato in Nepal. The devastating nature of T. absoluta causes its unusual proliferation so that it needs dire study of its host range, potential damage and sustainable management strategies. We discussed the data and information on T. absoluta available in several research papers comprehensively and provided succinct information on occurrence of T. absoluta in the world, its biology, life cycle, host plants, yield loss due to T. absoluta and several novel control tactics which helps farmers, researchers, policy makers to sustainably rise the tomato production in Nepal as well as in global context to attain food security. Sustainable pest management strategies such as Integrated Pests Management (IPM) approaches incorporating and prioritizing biological control methods with usage of chemical pesticides with less toxic active ingredient can be encouraged to the farmers for controlling the pests sustainably.

Respiration, predatory behavior and prey consumption by Podisus nigrispinus (Heteroptera: Pentatomidae) nymphs exposed to some insecticides

Podisus nigrispinus Dallas (Heteroptera: Pentatomidae) preys on insect pests in eucalyptus plantations where it can be exposed to insecticides used in pest control. The effect of insecticides on non-target natural enemies requires further study. The objective of the present study was to evaluate the side-effects of Bacillus thuringiensis (Bt), permethrin, tebufenozide and thiamethoxam on third instar nymphs of the predator P. nigrispinus in the laboratory. The toxicity of insecticides for this insect was determined by estimating their lethal concentrations. Podisus nigrispinus behavior after exposure to insecticides was analyzed using a video tracking system and the respiratory rate with a respirometer. Prey/nymph consumption was assessed after 24 h of starvation. The preference of P. nigrispinus nymphs, for prey treated or not with the insecticides, was evaluated in free choice tests. The insecticides Bt [LC₅₀ = 1.10(0.83-1.46) mg mL^-1], permethrin [LC₅₀ = 0.25(0.17-0.34) mg mL^-1], tebufenozide [LC₅₀ = 5.71(4.17-7.57) mg mL^-1] and thiamethoxam [LC₅₀ = 0.04(0.02-0.06) mg mL^-1] are toxic to P. nigrispinus nymphs. Bt and the insecticides tebufenozide, permethrin and thiamethoxam reduced the respiratory rate of P. nigrispinus. The insecticides permethrin, tebufenozide and thiamethoxam affect the locomotion of this insect's nymphs. Prey treated with Bt, permethrin and thiamethoxam are less preferred by P. nigrispinus. The survival of the nymphs of this predator was 93.3%, 66.7%, 56.6%, 0% and 0% in the control, tebufenozide, Bt, permethrin and thiamethoxam treatments, respectively. In addition, the reduction of prey consumption, treated with neurotoxic insecticides, reduces the predatory potential of this natural enemy. Bt and tefubenozide present low toxicity for P. nigrispinus, but the neurotoxic products have low compatibility with this natural enemy and, therefore, are not recommended, with this predator in the management of forest insect pests.

Drivers of farmers' intention to use integrated pest management: Integrating theory of planned behavior and norm activation model

Integrated pest management (IPM) has been promoted as an environmentally friendly pest control approach, but its adoption by farmers, particularly in developing countries, is low. The main purpose of the current study was to examine factors affecting the intention of farmers to use IPM practices in Iran. The research model was developed using the Theory of Planned Behavior (TPB) and the Norm Activation Model (NAM) and was empirically tested using data obtained from structured interviews with 327 tomato producers in Zanjan Province in northwestern Iran. Structural Equation Modeling (SEM) analysis indicated that all three components of attitude, perceived behavioral control (PBC), and subjective norm significantly influenced intention in the original TPB, while subjective norm had no statistically significant effect on intention in the integrative TPB-NAM. Despite this fact, subjective norm significantly impacted attitude, PBC, and personal norm in the integrative model. The study also supported the significant effect of awareness of consequences (AC) on personal norm, ascription of responsibility (AR), attitude, and subjective norm as well as the significant effect of AR on personal norm. Overall, personal norm was the most salient determinant of farmers' intention to use IPM practices in the integrative model. Most notably, integrating the constructs of TPB and NAM and particularly adding the interrelationships among the volitional, moral, and cognitive dimensions of the two models significantly enhanced the predictive power, utility, and comprehensiveness of the proposed framework for explaining farmers' intention to use IPM practices. The findings of this research provide a clearer understanding of factors driving the promotion of IPM among farming community and can be a basis for developing IPM policy interventions in Iran and other developing countries.

Predicting aquatic toxicities of chemical pesticides in multiple test species using nonlinear QSTR modeling approaches

In this study, we established nonlinear quantitative-structure toxicity relationship (QSTR) models for predicting the toxicities of chemical pesticides in multiple aquatic test species following the OECD (Organization for Economic Cooperation and Development) guidelines. The decision tree forest (DTF) and decision tree boost (DTB) based QSTR models were constructed using a pesticides toxicity dataset in Selenastrum capricornutum and a set of six descriptors. Other six toxicity data sets were used for external validation of the constructed QSTRs. Global QSTR models were also constructed using the combined dataset of all the seven species. The diversity in chemical structures and nonlinearity in the data were evaluated. Model validation was performed deriving several statistical coefficients for the test data and the prediction and generalization abilities of the QSTRs were evaluated. Both the QSTR models identified WPSA1 (weighted charged partial positive surface area) as the most influential descriptor. The DTF and DTB QSTRs performed relatively better than the single decision tree (SDT) and support vector machines (SVM) models used as a benchmark here and yielded R(2) of 0.886 and 0.964 between the measured and predicted toxicity values in the complete dataset (S. capricornutum). The QSTR models applied to six other aquatic species toxicity data yielded R(2) of >0.92 (DTF) and >0.97 (DTB), respectively. The prediction accuracies of the global models were comparable with those of the S. capricornutum models. The results suggest for the appropriateness of the developed QSTR models to reliably predict the aquatic toxicity of chemicals and can be used for regulatory purpose.