Pest Dynamics Research Articles

The Influence of Regional Specialization in Agriculture on Farmers’ Pest Control Behaviors Based on a Dual Examination of Control Strategies and Control Costs

The pest control behaviors of agricultural producers are crucial not only for effectively managing pests and diseases but also for ensuring the sustainable development of agricultural production and the environment. Regional specialization in agriculture, as a typical method to optimize planting structure, influences farmers’ control behaviors through dual mechanisms. However, existing research has largely overlooked this issue. This paper systematically examines the influence and mechanisms of agricultural regional specialization on farmers’ pest control strategies and costs. Using village tracking research data and farmer data from the Jiangsu, Sichuan, and Jilin provinces of China over 15 years, the study employs fixed-effects models and the instrumental variable method to provide empirical evidence. The research results indicate that by reducing biological diversity, which exacerbates the occurrence and damage of pests and diseases, and increasing the homogeneity of cropping structures, the development of regional specialization in agriculture prompts farmers to shift their control strategy from “ex post treatment” to “ex ante prevention” and has increased the control costs. The policy implication is that farmers should be encouraged to practice moderate crop rotation in rapidly increasing regional specialization. Additionally, strengthening real-time monitoring of pest and disease dynamics is essential to guide farmers in early prevention and timely control.

Climate Change as an Existential Threat to Tropical Fruit Crop Production—A Review

Climate change is an emerging threat to global food and nutritional security. The tropical fruits such as mango, bananas, passionfruit, custard apples, and papaya are highly sensitive to weather changes especially; changes of monsoon onset and elevated temperature are influencing crop growth and production. There is a need for more specific studies concerning individual crops and regional variations. Long-term effects and interactions of weather parameters and increased concentration of greenhouse gases, especially carbon dioxide, with phenological stages of the plant, pests, and diseases remain understudied, while adaptation strategies require further exploration for comprehensive understanding and effective mitigation. Few researchers have addressed the issues on the effect of climate change on tropical fruits. This paper focuses on the impact of abiotic (temperature, rainfall, humidity, wind speed, evaporation, carbon dioxide concentration) and biotic (pest and pathogens dynamics) factors affecting the fruit crop ecosystem. These factors influence flowering, pollination, fruit set, fruit yield and quality. This review paper will help develop adaptive strategies, policy interventions and technological innovations aimed at mitigating the adverse effects of climate change on tropical fruit production and safeguarding global food and nutritional security.

Life history traits of the target pest and transmission routes of the biocide are critical for the success of the boosted Sterile Insect Technique

The sterile insect technique (SIT) is an environmentally friendly pest control strategy that consists of inundative releases of mass-reared sterilized males over defined areas, where they mate with wild females, resulting in no offspring and a declining pest population. The technique has effectively managed many crop pests and vector-borne diseases worldwide. A new approach, called boosted SIT, has been proposed to gain efficiency. It combines SIT with the contamination of wild females by sterile males previously coated with biocides. The present study investigated to what extent life history traits of the target pest and biocides can make the boosted SIT more efficient than the classical SIT. We built a generic agent-based model (SIT++) that simulates the population dynamics of insect pests. We then explored parameters related to the mating system, spermatic competition, and fecundity, taking examples from the biology of three well-known Dipteran pest species (Bactrocera dorsalis, Ceratitis capitata, and Glossina palpalis gambiensis). We found that for boosted SIT to be more beneficial than SIT, horizontal transmission of the biocide to the same generation and to the progeny must be very high. Female fecundity was the other key parameter behind the success of boosted SIT, which was more efficient with insect pests having low reproduction rates. In particular, vertical transmission and late killing time were critical parameters. We also observed that a high level of virulence can help, but only when the boosted SIT is already advantageous; otherwise, it becomes detrimental. The boosted SIT might be advantageous depending on the life history traits of the target pest and transmission routes. For a more extensive exploration, the model can easily be tailored to pests with very different life history traits.

Assessment of Lepidopteran Pest Dynamics in Maize: Dominance of Spodoptera frugiperda and Implications for Targeted Management in Himachal Pradesh, India

Maize (Zea mays L.) plays a crucial role in the agricultural economy of India, particularly in Himachal Pradesh, where it serves as a vital crop for food, feed, and fodder. This study assessed the distribution, and relative abundance of lepidopteran pests infesting maize during the kharif, 2022-23 across two agro-climatic zones of Himachal Pradesh. Surveys identified five key lepidopteran pests: Spodoptera frugiperda, Chilo partellus, Mythimna separata, Agrotis ipsilon, and Euproctis spp. Among all, S. frugiperda is the only pest occurring among the major three crop stages of maize. The findings revealed that S. frugiperda was the most dominant pest, with relative abundance values of 19.57 per cent in Zone I and 18.94 per cent in Zone II during the seedling stage, increasing to 30.87 per cent and 30.40 per cent during the vegetative stage, respectively. In contrast, other pests like C. partellus, M. separata, A. ipsilon, and Euproctis spp. exhibited variable distribution patterns, with some showing limited occurrence. In conclusion, this study underscores the necessity for targeted pest management strategies to address dominant and subdominant lepidopteran pests in maize cultivation in Himachal Pradesh. The results offer valuable insights that can inform focused pest control efforts, with the potential to significantly enhance sustainable maize production, crop resilience and overall productivity in the region.

Urban Entomology: Navigating the Intersection of Pests and Human Environments

Urban entomology, a distinct discipline within entomology, focuses on pests in human environments, addressing a wide range of species from insects to vertebrates. First coined by A.H. Waters in 1884 and popularized by W. Ebeling's 1975 book, urban entomology gives an idea about arthropods' interactions with humans, pets and structures. As urbanization accelerates, with a projected 68% of the global population living in cities by 2050, understanding pest dynamics becomes increasingly critical. Factors like invasive species, pesticide resistance and public health concerns underscore the need for effective pest management strategies, emphasizing Integrated Pest Management (IPM) approaches. This review explores urban entomology's history, key pest groups and modern management challenges, while highlighting the industry's evolution in response to urbanization. It also discusses the roles of various stakeholders, including researchers, pest management professionals and regulatory bodies, in addressing urban pest issues. Ultimately, the review calls for collaborative efforts to enhance pest control practices, leveraging biological control methods and sustainable strategies to mitigate the impacts of urban pests on public health and infrastructure.

Climate Change Impact on Fruit Crops and Mitigation through Climate-Smart Production Practices

Climate change poses significant threats to fruit crops worldwide, affecting growth, development, and productivity. Warmer temperatures disrupt flowering patterns, reduce fruit set, and increase pollination failures, leading to lower yields and decreased fruit quality. Climate change also alters suitable production areas, chilling hours, and pest dynamics, further exacerbating the issue. To address these challenges, this study highlights the importance of implementing climate resilience strategies, such as cultivating climate-ready crops, adopting low-chill and drought-tolerant varieties, selecting suitable rootstocks, and utilizing agro-techniques like fruit bagging and mulching. Additionally, specific chemicals like chitosan and the Bordeaux mixture can help mitigate the negative impacts of climate change on fruit crops. By adopting these strategies, fruit producers can enhance crop resilience, reduce physiological disorders, and promote sustainable productivity in the face of climate change.

Adaptation and carry over effects of extreme sporadic heat stress in Culex mosquitoes

Mosquitoes, as temperature-sensitive ectothermic vectors, exhibit temperature-dependence. This study investigates Culex pipiens pallens (Cx. pallens) responses to abrupt temperature increases and their implications on mosquito physiology.First instar larvae (24hr post hatching) and newly enclosed adults (24hr post emergence) were separately exposed to heat shock regimes of 33 °C, 37 °C, and 42 °C for 3 days alongside a control temperature of 27 °C. Results showed that mortality was triggered at 42 °C within a day. Adult male mosquitoes were less tolerant to all temperatures than larvae and adult females (p < 0.05). Exposing larvae to constant temperatures for 3 days significantly decreased larvae's development time, growth rate and adult emergence (p < 0.05). Reproductive fitness was significantly reduced (p < 0.05) in males emerging from larvae exposed to 37 °C. Life table parameters showed significant increased mortality rate, kill power and decreased life expectancy at the embryonic stage (p < 0.05). Furthermore, heatwaves deactivated the Transient receptor protein ankyrin 1 at 37 °C (p < 0.05) in larvae but not adults. Calmodium, Heat shock protein 90, and small heat shock protein expression were significantly decreased in larvae at 37 °C (p < 0.05) as compared to larvae raised at 33 °C and 27 °C.In conclusion, we classified the heat waves into three categories: adaptable (33 °C), critical (37 °C), and fatal (42 °C). Prolonged exposure of Culex pallens larvae to extreme heat affects the male reproductive output. These findings may serve as an important reference for forecasting vector and pest dynamics and used to tailor mosquito prevention and control measures.

Mathematical Modelling of Spatially Inhomogeneous Non-Stationary Interaction of Pests with Transgenic and Non-Modified Crops Considering Taxis

Introduction. This paper addresses a unified spatially inhomogeneous, non-stationary model of interaction between genetically modified crop resources (corn) and the corn borer pest, which is also present on a relatively small section of non-modified corn. The model assumes that insect pests influence both types of crops and are capable of independent movement (taxis) towards the gradient of plant resources. It also considers diffusion processes in the dynamics of all components of the unified model, biomass growth, genetic characteristics of both types of plant resources, processes of crop consumption, phenomena of growth and degradation, diffusion, and mutation of pests. The model allows for predictive calculations aimed at reducing crop losses and increasing the resistance of transgenic crops to pests by slowing down the natural mutation rate of the pest. Materials and Methods. The mathematical model is an extension of Kostitsin’s model and is formulated as an initial-boundary value problem for a nonlinear system of convection-diffusion equations. These equations describe the spatiotemporal dynamics of biomass density changes in two types of crops — transgenic and non-modified — as well as the specific populations (densities) of three genotypes of pests (the corn borer) resulting from mutations. The authors linearized the convection-diffusion equations by applying a time-lag method on the time grid, with nonlinear terms from eachequation taken from the previous time layer. The terms describing taxis are presented in a symmetric form, ensuring the skew-symmetry of the corresponding continuous operator and, in the case of spatial grid approximation, the finite-difference operator. Results. A stable monotonic finite-difference scheme is developed, approximating the original problem with second-order accuracy on a uniform 2D spatial grid. Numerical solutions of model problems are provided, qualitatively corresponding to observed processes. Solutions are obtained for various ratios of modified and non-modified sections of the field. Discussion and Conclusion. The obtained results regarding pest behavior, depending on the type of taxis, could significantly extend the time for pests to acquire Bt resistance. The concentration dynamics of pests moving in the direction of the food gradient differs markedly from the concentration of pests moving towards a mate for reproduction.

Population dynamics and diversity of pests and natural enemies in various organic rice regimes across different phenological stages in rice

A field study was conducted at the ICAR-Indian Institute of Rice Research to investigate insect pest populations and their natural enemies in different organic rice modules during the rabi 2020 season. Three organic rice regimes, farmers’ practice and untreated control were compared across three phenological stages in rice for the population dynamics of pests and natural enemies of Hemiptera and Hymenoptera. Sampling was done fortnightly for three months using various methods such as visual counting, sticky traps, sweep netting, and D-net. Pest and predator populations peaked during the vegetative stage, while parasitoids peaked during the reproductive stage. Pest population means were highest in untreated control during the reproductive and ripening stages exhibiting the impact of treatments. The predator population was highest in untreated control during the vegetative and reproductive stage, while parasitoid population size was highest in Pseudomonas treatment in the vegetative and reproduction stages of the crop and the Trichoderma treatment in the ripening stage. Predator diversity was highest in untreated control during vegetative and reproductive stages of the crop while parasitoid diversity was maximum during reproductive and ripening stage. Pearson’s correlation coefficient between the population of pests and natural enemies was found to be positive and highly significant.

Impact of Weather Parameters on the Population Fluctuation of Major Sucking Pest in Summer Mung Bean [Vigna radiata (L.) Wilczek

Background: Mungbean may be grown in an extensive range of agro climatic zones in India and across the world. It is a crucial component of our diet. Because of its capacity to fix nitrogen, it also plays a vital role in managing soil fertility. Mung beans are one of the most significant crops for farmers as a cash crop. In order to implement control measures effectively and on schedule, it is crucial to monitor the population dynamics of major sucking pests, such as aphids, jassids and whiteflies in relation of weather parameters. Methods: PDM-139 (Samrat) variety seeds were manually planted 5-7cm deep in the ground. Weekly observations were made from 10 randomly chosen plants Split cage methods were used to record the observations of jassids and whiteflies and aphids from the top and bottom surfaces of the first three trifoliate plants were tallied. Averages population were computed. Result: The incidence of pest population start on the 14-15th standard meteorological weeks which attain their peak population in 19th SMW. The insect-pest population was established positive correlation with the max and min temperature whereas population was negatively correlated with R.H. and Rainfall.

Population dynamics of major insect pest on mustard Brassica juncea in Vidarbha region and its correlation with weather parameters

Population dynamics of major insect pest on mustard Brassica juncea in Vidarbha region and its correlation with weather parameters

Potential distribution of rice thrips (Stenchaetothrips biformis) in India under changing climate

Sudden outbreaks of agricultural pests are increasing in India due to the growing prominence of environmental issues like global warming, the occurrence of weather extremes, and hydrological extremes. Climate change impacts the developmental rates and population dynamics of agricultural pests. As rice is a staple food widely used in India, it often suffers intensive damage by various pests, leading to a considerable decrease in crop yield. One of the most common pests in rice fields in India and neighboring countries is the rice thrips (Stenchaetothrips biformis). However, the degree of pest infestation of rice crops under climate change scenarios is poorly known. Therefore, this study aimed to understand the potential geographical distribution of the rice thrips in India for future scenarios using the MaxEnt modeling framework. Future projections from global climate models (GCMs), such as HadGEM3-GC31 and MPI-ESMI-2, are used to predict the most affected regions in 2050 under three greenhouse gas emission scenarios: SSP1-2.6, SSP3-4.5, and SSP5-8.5. The results from the MaxEnt indicate that the southern and northeastern parts of India will be highly affected by rice thrips in 2050. The affected number of districts are found to be 256, 330 and 313 under SSP1-2.6, SSP3-4.5, and SSP5-8.5 scenarios, respectively. It has been observed that the maximum temperature is the most influential climatic parameter for the geographical distribution of rice thrips, followed by the annual mean and minimum temperatures. It can be concluded from these results that the elevated temperature enhances the growth and distribution of rice thrips.

Assessing the Impact of Weather Parameters on the Population Dynamics of Insect Pests in Cucurbit Vegetables under Mid-Hill Conditions of Himachal Pradesh

A study focusing on population dynamics of sucking and leaf-eating some insect pests along with their correlation with weather parameters in cucurbits was conducted at research field, Department of Entomology, Dr. YSPUHF, Solan, H.P., India from June-October, 2019 and 2020. The results revealed that Amrasca biguttula biguttula (I), Trialeurodes vaporariorum (W), Aulacophora foveicollis (L), Henosepilachna vigintioctopunctata (F), Liriomyza trifolii (B), Aulacophora sp., were recorded as the major insect pests. In bitter gourd, maximum population of jassids recorded was (2.33/leaf) in first week of August while, maximum whitefly population in bottle gourd (2.96/leaf) during last week of August and in ridge gourd during last week of July (3.76/leaf). The maximum red pumpkin beetle population on bitter gourd (2.4 beetles/plant) and bottle gourd (2.6 beetles/plant) was observed during last week of August while, hadda beetle attained peak population during first and third week of August in ridge gourd (1.0/plant) and bitter gourd (1.1 adults/plant), respectively. Maximum leaf miner infestation (2.7 mines/leaf) in bottle gourd and ridge gourd was observed during first and third week of August. All pest attained maximum population between 30 to 32 SMW when weather parameters values were Tmax: 27.50 to 28.90; Tmin: 20.60 to 20.80 oC; RH: 79 to 80 %; Rainfall: 25.80 to 30.20 mm. Relative humidity and rainfall played major role with non-significant positive influence on the population build-up of these pests in cucurbit crops along with temperature. The present findings on weather-driven pest dynamics can inform strategies to boost crop yields and reduce farmers' economic losses in similar environments.

Prospect and Challenges of Litchi Cultivation in Northeast Region of India

The dynamics of pests affecting litchi crops have undergone changes over time, with litchi mites and bugs becoming less economically significant. However, insect pest infestations have emerged as a major constraint, causing substantial economic losses for growers. Litchi trees need to complete their post-harvest vegetative flush in a timely manner to produce a second flush in winter, which will then flower. Litchi fruit is highly perishable and temperature-sensitive, making it difficult to transport to distant markets without adequate cool chain infrastructure. The cumulative effect of biotic and abiotic factors compromises the agricultural value of this cash crop. Investigating natural defense mechanisms in litchi may uncover opportunities to enhance or induce antifungal compounds through defense elicitors. Further research could explore the applicability of these techniques in other countries, although registration issues may arise. Alternatively, other chemicals with similar benefits and lower health risks could be investigated. Additionally, the long-term effects of cincturing on fruit set and tree health warrant further investigation.

Water and Irrigation Needs of Tuber Crops in Coastal Climates: A Review

One of the most essential elements for plant growth is water. Large amounts of it are required by plants constantly throughout their life cycle. It significantly affects agricultural activities like irrigation, soil management, crop production, and chemical spraying environments, as well as plant processes like photosynthesis, respiration, absorption, transport, and use of mineral nutrients. This review examines the impacts of climate change on root and tuber crops, including rising temperatures, altered rainfall patterns, extreme weather events, and changes in pest and disease dynamics. These changes significantly affect root and tuber crop production, leading to lower yields, compromised quality, increased susceptibility to pests and diseases, and limited access to water resources. Adaptation strategies encompass various approaches, such as agronomic practices, crop diversification, improved water management, breeding for climate resilience, and agro ecological methods. In the world, the most significant root and tuber crops are cassava, sweet potatoes, and potatoes. Water will produce maximum production for root crops; however, water stress during critical stages might adversely affect the final output of root crops. The purpose of this article of review is to understand the water and irrigation needs of tuber crops (sweet potato, greater and lesser yams, aerial yams, elephant foot yams, xanthosoma, and cassava) that are effectively produced in Maharashtra's coastal climate. This review emphasizes the urgent need to address climate change impacts on tropical root and tuber crops. It highlights the critical role of adaptive measures in ensuring long-term sustainability and food security in a changing climate.

Seasonal Variations in Population Dynamics of Insect Pests in Tiruvallur District, Tamil Nadu, India

Understanding the complex relationship between seasonal changes and pest dynamics is essential for establishing effective protection methods in contemporary agriculture and guaranteeing long-term agricultural sustainability and food security. The study was conducted in the Tiruvallur District of Tamil Nadu, India, which is characterized by a tropical climate with distinct wet and dry seasons [1]. Shannon-Wiener Index and Simpson's Index biodiversity indices reflected the moderate to high pest diversity of species in the region. Values for Shannon-Wiener indexes ranged between about 1.93-1.95 for different species of insect pests, and Simpson's indexes were found to range between about 0.85-0.86. All these indices indicate a well-balanced insect pest community with high species richness and even distribution, which is necessary to maintain ecological resilience. The findings enrich our understanding of pest ecology in tropical agriculture and provide valuable insights applicable to other regions facing similar issues. The observed seasonal patterns emphasize the importance of ongoing monitoring and adaptive management to tackle the challenges posed by insect pests amid climate variability and agricultural intensification. Additionally, this research offers a thorough framework for comprehending and managing insect pest populations in the Tiruvallur District.

In-depth analysis of Bt cotton adoption: farmers' opinions, genetic landscape, and varied perspectives—a case study from Pakistan

BackgroundBt technology has played significant role in controlling bollworms and increasing cotton yield in earlier days of its introduction, a subsequent decline in yield became apparent over time. This decline may be attributed to various environmental factors, pest dynamics, or combination of both. Therefore, the present biophysical survey and questionnaire were designed to evaluate the impact of Bt cotton on bollworms management and its effect on reducing spray costs, targeting farmers with varied landholdings and educational backgrounds. Additionally, data on farmers' cultivated varieties and the prevalence of bollworms and sucking insects in their fields were recorded. Subsequently, about eleven thousand cotton samples from farmer fields were tested for Cry1Ac, Cry2Ab and Vip3A genes by strip test.ResultsIn this analysis, 83% of the farmers planting approved varieties believe that Bt technology control bollworms, while 17% hold contradictory views. Similarly, among farmers cultivating unapproved varieties, 77% agree on effectiveness of Bt technology against bollworms, while 23% disagree. On the other hand, 67% of farmers planting approved varieties believe that Bt technology does not reduce spray costs, while 33% agree with the effectiveness. Similarly, 78% of farmers cultivating unapproved varieties express doubt regarding its role to reduce spray costs, while 22% are in favour of this notion. Differences in opinions on the effectiveness of Bt cotton in controlling bollworms and reducing spray cost between farmers planting unapproved and approved varieties may stem from several factors. One major cause is the heavy infestation of sucking insects, which is probably due to the narrow genetic variation of the cultivated varieties. Additionally, the widespread cultivation of unapproved varieties (21.67%) is also an important factor to cause different opinions on the effectiveness of Bt cotton.ConclusionBased on our findings, we propose that the ineffective control of pests on cotton crop may be attributed to large scale cultivation of unapproved varieties and non-inclusion of double and triple transgene technologies in country’s sowing plan. On the basis of our findings, we suggest cotton breeders, regulatory bodies and legislative bodies to discourage the cultivation of unapproved varieties and impure seed. Moreover, the adoption of double and triple Bt genes in cottons with a broad genetic variation could facilitate the revival of the cotton industry, and presenting a promising way forward.

Population dynamics of major insect pest of lentil and correlation with weather factors

Population dynamics of major insect pest of lentil and correlation with weather factors

Seasonal Patterns and Abiotic Influences on Fall Armyworm Dynamics in Chhattisgarh's Maize Agroecology

The fall armyworm Spodoptera frugiperda (J. E. Smith), an invasive pest in India, exhibits variations in population dynamics and incidence levels compared to its native regions. Understanding these variations is crucial for developing effective management strategies. Given India's diverse agroecosystems and climatic conditions, continuous watch on pest dynamics is essential. In this context a fixed plot experiment for comprehensive analysis of fall armyworm population dynamics, incidence patterns across seasons, and damage potentials in the maize crop ecosystem of the Chhattisgarh plains, India was conducted across three seasons of the year 2022-23. The year-round activity of the pest and its potential to cause huge losses in the early stages of maize was reported. Specifically, the study provided insights into the comparative incidence of fall armyworm in the different maize growing seasons of the area with a maximum incidence in the rainy season (0.58 larvae/plant) followed by winter (0.56 larvae/plant) and summer (0.53 larvae/plant) seasons. Moreover, the incidence trends of fall armyworm in different growing stages of maize were analysed by considering egg laying pattern, leaf damage, larval incidence and plant damage parameters, which highlighted the plant age-dependent response of fall armyworm. The impact of various weather parameters in shaping the damage and population fluctuations was analysed, where the influence of temperature was significant. Results obtained in this study are crucial in devising ETL levels and developing integrated pest management strategies against fall armyworm.

Population Dynamics of Major Insect Pests and Natural Enemies in Tomato

An experiment on major insect pests and natural enemies of tomato was conducted during rabi, 2022-23 at the experimental farm for PG research, Biswanath College of Agriculture, Sonitpur. Results revealed eleven insect pests; whitefly, Bemisia tabaci (Gennadius); aphid, Aphis craccivora Koch; leafminer, Lyriomyza trifolii (Burgess); fruitborer, Helicoverpa armigera (Hubner); jassid, Amrasca biguttula biguttula (Ishida); semilooper, Trichoplusia ni (Hubner) were found to be the most dominant species. Two coccinellid predators viz., Micraspis discolor(F) and Cheilomenes sexmaculata (F) and two spiders Lycosa tista Tikader, Anyphaena accentuata (Walckenaer) were recorded as natural enemies. It was observed that the incidence of B. tabaci, A. craccivora and A. biguttula biguttula showed significant negative correlation with both maximum and minimum temperature. B. tabaci population registered a positive significant correlation with morning relative humidity. Both L. trifolii and H. armigera exhibited significant negative correlation with bright sunshine hour. Furthermore, T. ni showed significant negative correlation with maximum temperature and bright sunshine hour. As regards coccinellids, a significant negative correlation existed with maximum and minimum temperature, and rainfall and significant positive correlation with morning relative humidity. A significant positive correlation of aphids was also observed with coccinellids.