Pest Abundance Research Articles

INSECT BIODIVERSITY AND ASSESSMENT OF POST-HARVEST GRAIN LOSSES IN STORED COWPEA (Vigna aunguiculata L.)

Insect pests cause huge economic losses to stored grain cereals and pulses in tropical and subtropical areas around the globe. The level of damage and losses caused by different insect pests varies depending upon the infesting species, type of food materials, duration of storage and structures. The information about the diversity of infesting species, their dispersal and abundance are key for devising effective pest management techniques against storage insect pests. The present study aimed to collect information on the distribution, relative abundance and biodiversity of major insect pests of stored cowpeas in Dera Ismail Khan (Khyber Pakhtunkhwa) and its adjoining Punjab province areas of Pakistan. The areas selected for biodiversity studies were Paniala, Mankera, Bhakkar, Paharpur, Kulachi, Ramak, Dera Ismail Khan, Darya Khan, Notak and Behal. A vast survey of godowns was conducted to find out the population dynamics of insect pests of stored cowpeas and to explore the % grains damage and weight losses in the mentioned areas. For the collection of samples, a spear sampler was used to collect 500-gram samples from the top, middle and bottom portions of the bags. Samples were preserved in plastic containers and after 30 days, were sieved out with the help of a 2mm mesh sieve to remove different types of dead and alive insects. A total of five species representing two distinct orders i.e., Coleoptera and Lepidoptera. Coleopterans are Callosobruchus maculatus, Tribolium castaneum, Oryzaephilus surinamensis, Trogoderma granarium belonged to four families including Chrysomelidae, Tenebrionidae, Silvanidae, Dermestidae and Lepidopteron are Sitotroga cerealella belonging to family Gelechidae. The most abundant species among all the recorded insect pests of cowpea was C. maculatus (53.60%) followed by T. castaneum (18.60%), S. cerealella (16.97%), O. surinamensis (6.49%) and T. granarium (04.34%). The maximum infestation (26.98%) and weight loss (28.91%) of cowpea was recorded in Darya Khan followed by Dera Ismail Khan (22.70% and 26.33%), whereas; minimum % infestation and weight losses were recorded in Bhakkar (16.91% and 17.14%) area showing significant differences between the surveyed areas. The C. maculatus is the most abundant specie of the stored cowpea grains in the surveyed areas and needs management tactics to minimize the post-harvest grains losses. The population of C. maculatus starts to build up during the month of March (23.30⁰C and 56.25% RH) and reaches at peak in May (35.32⁰C and 68.88% RH). Special measures should be taken during these months to minimize the infestation and losses caused by C. maculatus.

Seasonal Abundance of Important Pests of Mango and their Correlation with Weather Parameters

The investigation was carried out at the Instructional Farm, ASPEE College of Horticulture and Forestry, Navsari Agricultural University (N.A.U.), Navsari, Gujarat, India during 2021-2022. The leaf webber, leafhopper, fruit fly, shoot borer, and thrips were found abundant, whereas the mealybug and stone weevils were very less. The leaf webber population exhibited a significant negative correlation with minimum temperature (r= -0.488*) and evaporation (r=-0.483*). The leafhopper population had a highly significant positive correlation with wind velocity (r= 0.577**) and rainfall (r= 0.823**) and a significant negative correlation with minimum temperature (r=-0.495*) and morning relative humidity (r= -0.414*). Fruit fly population exhibited a highly significant positive correlation with minimum temperature (r= 0.761**), wind velocity (r= 0.646**), and evaporation (r= 0.524**). There was a significant negative correlation of shoot borer population with minimum temperature (r= -0.804**), evening relative humidity (r= -0.467*), and wind velocity (r= -0.437*). Thrips population had a highly significant negative correlation with minimum temperature (r= -0.690**), evening relative humidity (r= -0.879**), wind velocity (r= -0.567**), and rainfall (r= - 0.541**) and a significant positive correlation with sunshine hours (r= 0.684**) and maximum temperature (r= 0.438*). Among natural enemies, ants, mantids, spiders, and chrysopa were found in the orchard and none of the parasitoids were reported.

YOLO_MRC: A fast and lightweight model for real-time detection and individual counting of Tephritidae pests

Tephritidae pests severely affect the quality and safety of various melons, fruits and vegetable crops. However, many agricultural managers lack an adequate understanding of the level of pest occurrence, resulting in the misuse of pesticides, which ultimately leads to environmental pollution and economic loss. Therefore, real-time detection and counting of Tephritidae pests are important for timely pest spotting and control. This work helps quickly determine the distribution and abundance of pests in the current environment, thus providing data on pest conditions for agricultural management to optimize pesticide use. Nevertheless, the fast speed, high accuracy, and lightweight performance of real-time detection and counting are difficult to balance. To address this problem, based on the YOLOv8n model, this paper takes Bactrocera cucurbitae pests as the detection target and proposes a fast and lightweight real-time detection and individual counting model for Tephritidae pests, named YOLO_MRC. This paper introduces three key improvements: (1) Constructing a new module called Multicat into the neck network increases the focus on the detection target by incorporating an attention mechanism; (2) Reducing the original three detection heads to two and then adjusting their sizes to decrease the number of parameters in the network model; (3) Devising a novel module, C2flite, to enhance the deep feature extraction capability of the backbone network. According to the above points, this paper conducts ablation experiments to compare the performances of different models. Experiments showed that the Multicat module significantly offsets the large increase in GFLOPs and processing time caused by reducing the detection head and can further reduce the number of parameters and improve the accuracy when combined with the C2flite module. On our Bactrocera cucurbitae pest dataset, the mAP@0.5 of the YOLO_MRC model reached 99.3%. Simultaneously, as the number of parameters decreases by 63.68%, GFLOPs is reduced by 19.75%, and the processing time is shortened by 5%. To ensure the validity of the model, YOLO_MRC is compared with four excellent detection models by using manual counting results as the benchmark. YOLO_MRC achieves an average pest counting accuracy of 94%, demonstrating superior performance in terms of model size and processing time. To further explore the performance of YOLO_MRC in multiclass insect detection tasks, we choose the public dataset Pest_24_640 for comparison with four state-of-the-art models. YOLO_MRC achieves a 3.6 ms processing time and 70.4% accuracy with only a 2.4 MB model size, which demonstrates the potential of YOLO_MRC in multiclass pest detection.

Incidence and Population Dynamics of Various Associated Insect-pests of Late Direct Sown Paddy, Oryza sativa L. at Gajapati, Odisha

Background: Rice is the most important staple food of the world. Rice production is now-a-days reduced due to insect pest attacking to the crop in various growing stages. There are more than 1400 pest species, which are cause great menace to the rice cultivation. Incidences and abundance of pests in rice is growing day by day due to climatic change and excess use of chemical pesticides. In late direct sown paddy is also facing the insect pest problems in different growing stages. The study aimed to layout the different pest’s incidence and population dynamics as well, on various stages of direct sown paddy. The knowledge of incidence timing for various pests can be further utilized for the suitable management. Methods: The present study has been conducted during the late Kharif seasons of 2021-22 for 11 most widely grown paddy cultivars of farmers field around the locality of MS Swaminathan School of Agriculture, Centurion University of Technology and Management, Paralakhemundi, Odisha. The surveyed cultivars were Anjali, Arize 8433, BAM-6, Bhuban, Chandra, CR Dhan 100, Varsha Dhan, CR Dhan 306, Sumit, Luna Sankhi and Vandana, respectively. These cultivars were surveyed for the abundance of various associated insect-pests at two different crop growth stages. Result: The results revealed that the incidence of various pests namely Scirpophaga incertulus, Orseolia oryzae, Cnaphalocrocis medinalis, Parapoynx stagnalis, Dicladispa armigera, Leptocorisa acuta, Grasshoppers, Nezara virdula, Nephotettix virescens, Melantis leda and Mythimna separate was found to be significant for both the growth stages. The maximum population on late direct sown rice was found to be of Scirpophaga incertulus (3.67) and Orseolia oryzae (2.67) at the vegetative stage of rice while pests such as Cnaphalocrocis medinalis (6.34), Leptocorisa acuta (7.34) and Mythimna separate (5.67) were recorded maximum during the milking stage of rice.

Landscape complexity effects on Brassicogethes aeneus abundance and larval parasitism rate: a two-year field study

Global biodiversity has suffered a decline primarily attributed to landscape simplification and intensified agricultural practices. Agricultural environments, characterized by homogeneity and frequent disturbances, are often suboptimal habitats for various insect species. While agricultural fields do favour pests, they generally fail to provide suitable habitats for natural enemies. The inclusion of diverse supporting habitats, such as semi-natural habitats, grassy and woody field margins etc. surrounding agricultural fields, play a crucial role in fostering effective biodiversity conservation. Moreover, determining the influence of different adjacent habitat types is essential in elucidating their influence on pest abundance and parasitism rates. Our two-year field study focused on assessing the abundance of Brassicogethes aeneus and its parasitism rate. The findings revealed that the adjacent habitat type did not significantly increase pest abundance and the parasitism rate of B. aeneus larvae consistently stayed over the threshold for effective biological control throughout the fields. This was attributed to the high proportion (35 and 38% in the 2 study years) of semi-natural habitats within most of the 1 km radius study areas. While our study did not identify any specific adjacent habitat type or habitat within a 1 km radius that directly impacted B. aeneus abundance, it emphasises the intricate interplay between the pests, parasitism and the surrounding environment because the interactive effect of distance from the crop edge and habitat type had a significant influence on B. aeneus infestation levels but not on parasitism. Decision tree analysis suggests that > 18% semi-natural habitat is needed to ensure sufficient levels of parasitism for effective biological control. A comprehensive understanding of habitats that influence not only B. aeneus but also other pests is critical for the successful implementation of IPM strategies and conservation initiatives within the agricultural sector.

A deep learning-based pipeline for whitefly pest abundance estimation on chromotropic sticky traps

Integrated Pest Management (IPM) is an essential approach used in smart agriculture to manage pest populations and sustainably optimize crop production. One of the cornerstones underlying IPM solutions is pest monitoring, a practice often performed by farm owners by using chromotropic sticky traps placed on insect hot spots to gauge pest population densities. In this paper, we propose a modular model-agnostic deep learning-based counting pipeline for estimating the number of insects present in pictures of chromotropic sticky traps, thus reducing the need for manual trap inspections and minimizing human effort. Additionally, our solution generates a set of raw positions of the counted insects and confidence scores expressing their reliability, allowing practitioners to filter out unreliable predictions. We train and assess our technique by exploiting PST - Pest Sticky Traps, a new collection of dot-annotated images we created on purpose and we publicly release, suitable for counting whiteflies. Experimental evaluation shows that our proposed counting strategy can be a valuable Artificial Intelligence-based tool to help farm owners to control pest outbreaks and prevent crop damages effectively. Specifically, our solution achieves an average counting error of approximately 9% compared to human capabilities requiring a matter of seconds, a large improvement respecting the time-intensive process of manual human inspections, which often take hours or even days.

Modeling the effect of multiple pests on ecosystem services provided by fruit crops: Application to apple

CONTEXTIn agroecosystems, crop pests have long been controlled by the intensive use of synthetic pesticides. To lower the dependency on pesticides, alternative crop protection strategies such as Integrated Pest Management (IPM) and Agroecological Crop Protection (ACP) have been proposed. In this context, it is crucial to consider multiple pests and their effects on host plant functioning and, ultimately, on system performance. OBJECTIVEWe aim to develop a pest-crop model to account for the effect of multiple pests on fruit tree functioning and the resulting ecosystem services provided by an orchard, using apple as a case study. METHODSFirst, we identified possible mechanisms of pest disturbance on apple tree for ten major pests: rosy and woolly apple aphid, codling, oriental and tortrix moths, red mite, powdery mildew, European canker, fire blight and apple scab. We classified them into seven functional groups: resource stealers, leaf area reducers, assimilation rate reducers, water transport reducers, assimilate sappers, fruit senescence accelerators and fruit marketability depreciators. Second, we defined coupling functions for each functional group. These describe the reduction of target variables in an existing fruit tree model (QualiTree), i.e. the variables to which the pest disturbances directly apply, as a function of pest abundances. Parameter values of the coupling functions were estimated based on the literature. Third, we used simulations in standard cultural conditions and a Monte Carlo Bayesian Sensitivity Analysis to test and hierarchize the effect of pests on the variation of nine indicators of four classes of ecosystem services (namely fruit production, climate regulation, soil nitrogen availability and water cycle maintenance and regulation).RESULTS AND CONCLUSIONSOnly four indicators were affected by the considered pests: refractometric index (measuring fruit sugar content), marketable yield, carbon sequestration and water drainage. The variations in refractometric index and in marketable yield were largely explained by the main effects of water transport reducers and fruit senescence accelerators, respectively. The latter also contributed the most to carbon sequestration variation. The variation in water drainage was largely explained by the main effect of mildew, an assimilation rate reducer. SIGNIFICANCEOur approach provides an operational tool to assess the impact of multiple pests on orchard ecosystem services. The model also opens up the possibility of studying the impact of pests in different ecological and technical contexts. For this, it must be coupled with models capable of predicting pest abundances as a function of cultivation practices and biotic and abiotic conditions.

Warmer temperatures trigger insecticide-associated pest outbreaks.

Rising global temperatures are associated with emerging insect pests, reflecting earlier and longer insect activity, faster development, more generations per year and changing species' ranges. Insecticides are often the first tools available to manage these new threats. In the southeastern US, sweet potato whitefly (Bemisia tabaci) has recently become the major threat to vegetable production. We used data from a multi-year, regional whitefly monitoring network to search for climate, land use, and management correlates of whitefly activity. Strikingly, whiteflies were detected earlier and grew more abundant in landscapes with greater insecticide use, but only when temperatures were also relatively warm. Whitefly outbreaks in hotter conditions were not associated with specific active ingredients used to suppress whiteflies, which would be consistent with a regional disruption of biocontrol following sprays for other pests. In addition, peak whitefly detections occurred earlier in areas with more vegetable production, but later with more cotton production, consistent with whiteflies moving among crops. Altogether, our findings suggest possible links between warmer temperatures, more abundant pests, and frequent insecticide applications disrupting biological control, though this remains to be explicitly demonstrated. Climate-initiated pesticide treadmills of this type may become an increasingly common driver of emerging pest outbreaks as global change accelerates. © 2023 Society of Chemical Industry.

Relative Abundance of Insect Pests on French Bean (Phaseolus vulgaris L.) in Relation to Abiotic Factors

The present investigation was carried out during Rabi 2021-22. The incidence of insect pests like aphid, whitefly, Jassid, leaf miner, pod borer was initiated 25 days after sowing till harvesting. The highest incidence of Jassid was observed on French bean crop at 9th SMW (7.20 per cage) and lowest 1st SMW (0.30 per cage), Aphid 8thSMW (45.20 aphids per 10cm terminal shoot) and 52thSMW (2.60 aphids per 10cm terminal shoot). The highest incidence of whitefly observed in 8th SMW (20.70 per cage) and lowest 2nd SMW (0.60 per cage). The highest incidence of Leaf miner was recorded in 11th SMW (40.50% leaf damage) and lowest in 51th SMW (1.50% leaf damage). The highest incidence of pod borer was noticed in 9th SMW (8.70 larvae per plant) and lowest in 1st SMW (0.30 larvae per plant). The Jassid population showed highly significant positive correlation with sunshine and positive significant correlation with maximum temperature and positive correlation with minimum temperature whereas, significant negative correlation with rainfall and negative non-significant correlation with relative humidity. The aphid population showed highly significant positive correlation with sunshine and positive non-significant correlation with minimum and maximum temperature. The whitefly population showed highly significant positive correlation with sunshine and positive non-significant correlation with minimum and maximum temperature. The leaf miner population showed positive highly significant correlation with minimum and maximum temperature and significant positive correlation with relative humidity. The pod borer population showed highly significant correlation with maximum temperature and sunshine. The information generated in the present research can be successfully utilized to formulated effective insect pest management strategies in French bean.

The Pest Risk Reduction Scenario Tool (PRReSTo) for quantifying trade-related plant pest risks and benefits of risk-reducing measures

Plant pest risks posed by trade in agricultural commodities are managed through pest risk analysis which involves assessing risk and selecting phytosanitary measures to manage unrestricted risk if it is unacceptably high. Diverse measures can be used to reduce risk. However, calibrating risk management protocols with the level of unrestricted risk is challenging. Agreed methods and user-friendly tools for comparatively evaluating risk-reducing measures in different pest-host systems are lacking. Here, we describe the Pest Risk Reduction Scenario Tool (PRReSTo), a generic Bayesian network model that estimates likely infestation rates of host items in consignments. PRReSTo considers host items’ vulnerability to pest infestation, the pest abundance to which host items are exposed during production, and the individual and cumulative effects of risk-reducing measures aimed at either minimising host vulnerability, pest exposure or infestation rates. We apply a PRReSTo implementation developed for assessing trappable insect pests in horticultural produce to test its versatility. First, we evaluate likely (unrestricted) host infestation rates under different levels of pest exposure and host vulnerability. Next, we evaluate the adequacy of risk-reducing measures under different host infestation scenarios and acceptability thresholds. We find that equivalent risk reduction may be achieved by highly effective individual measures or combinations of measures in a phytosanitary systems approach. The current implementation of PRReSTo is supported by an open access web application to facilitate adoption as a scenario analysis and decision-support tool by industry and regulators.

Climate‐Smart IPM: Key to U.S. Ag Resilience

AbstractFarmers, ranchers, and foresters are facing increasing challenges related to changing climate and weather, manifested in rising average temperatures, more frequent extreme rainfall events, extended drought, and heat waves. These changes are also impacting pest abundance and distribution, creating new pest problems and straining current pest management options and decision‐making. Key factors for U.S. agriculture and producer resilience in tackling new environmental and pest challenges lie in the ability of producers to apply effective, economical integrated pest management (IPM) approaches and in support for research and development of new and renewed IPM tactics and systems to meet 21st century needs. Earn 0.5 CEUs in Integrated Pest Management by reading this article and taking the quiz at https://web.sciencesocieties.org/Learning‐Center/Courses.

Urban Pest Abundance and Public Enquiries in Zurich 1991-2022.

Zurich's Urban Pest Advisory Service (UPAS) aims to survey, control and reduce hazards posed by pests. Records submitted to the UPAS may not exactly correlate with abundance but can reveal patterns of change. These reflect changes in species, public and media perceptions and the effects of climate and COVID-19, along with the effectiveness of new pest controls. Records for Blattodea and Plodia interpunctella declined in the period 1990-2022, while Cimex lectularius and Psocoptera increased. Summer has typically revealed the largest number of insects reported and Google searches show parallel seasonal variations. The Blattodea declined five-fold over time, likely due to better pest control methods (gel baits). Aedes albopictus, though rare, was the subject of media reports and awareness campaigns, which resulted in much public interest. Vespidae are abundant and have been reported in sufficient numbers to warrant an analysis of seasonal records, suggesting that July temperatures affect numbers. COVID-19 restrictions led to more frequent reports of rodents, pigeons, Zygentoma and Stegobium paniceum. The long-term reporting to the UPAS gives a useful indication of the changing concerns about pests in Zurich.

Insect excluding mesh enhances Spotted-wing Drosophila (Drosophila suzukii) control in tunneled raspberry with limited effects on natural enemy abundance

Spotted-wing Drosophila (Drosophila suzukii) oviposits in a wide range of soft and stone fruit, which can result in a reduction of fruit quality and yield. An invasive, polyphagous species, D. suzukii targets ripe fruit, such as raspberries, which are commonly grown in polytunnels. With increasing restriction on the use of agrochemicals, effective alternative approaches to D. suzukii are needed. We assessed the impacts of insect mesh on D. suzukii abundance and oviposition in tunnel-grown raspberries, as well as how it impacts the abundance of other pests and natural enemies, fruit quality and tunnel microclimate. Drosophila suzukii abundance in traps was lower in mesh tunnels compared to adjacent non-crop areas although no significant difference between mesh and control tunnels was observed. Although D. suzukii emergence from harvested fruit was significantly lower on fruit collected in mesh tunnels compared to control tunnels. Mesh impacted sooty shoulder coverage of fruit and had only limited impacts on the abundance of natural enemies such as ants, spiders and parasitic wasps while increasing instances of peak temperature and humidity were found. We highlight the varying impacts mesh netting has on soft fruit production and discuss how these findings can be used to help incorporate insect mesh into IPM strategies to effectively control D. suzukii.

Tree species richness around urban red maples reduces pest density but does not enhance biological control

Urban trees often host greater insect pest abundance than trees in rural forests. This may be due, in part, to differences in tree diversity and canopy cover between these settings. Urban trees are often planted in isolation or monoculture, which favors pest accumulation. Gloomy scale, Melanaspis tenebricosa Comstock, is a pest of urban red maples (Acer rubrum L.) that is abundant where impervious surfaces dominate the local landscape. Increasing tree diversity and canopy cover around urban red maples may reduce gloomy scale abundance by supporting natural enemy communities. We investigated the effect that surrounding tree species richness and tree canopy cover had on gloomy scale abundance, natural enemy abundance, and biological control in red maple trees in Raleigh, NC, USA. We collected scales and natural enemies from red maples that spanned a gradient of tree species richness, canopy cover, and impervious surface values. We also measured gloomy scale parasitism and predation of sentinel prey in red maple canopies. Greater tree species richness and canopy cover were associated with lower gloomy scale density. Red maples in diverse settings also hosted fewer scales per natural enemy. Parasitoids were less common in maples in diverse settings, but generalist predator abundance was unaffected by tree diversity. Finally, tree species richness and canopy cover did not increase biological control of scales or sentinel prey. Our findings suggest that higher tree diversity and greater canopy cover may reduce gloomy scale density, but this is not entirely explained by the effects of natural enemies and biological control.

Pesticide use, arthropod fauna and fruit damage in apple orchards in a Nordic climate Pesticides and arthropods in Nordic apple orchards.

Integrated pest management (IPM) has a long history in fruit production and has become even more important with the implementation of the EU directive 2009/128/EC making IPM mandatory. In this study, we surveyed 30 apple orchards in Norway for three years (2016-2018) monitoring pest- and beneficial arthropods as well as evaluating fruit damage. We obtained growers' diaries of pest management and used these data to study positive and negative correlations of pesticides with the different arthropod groups and damage due to pests. IPM level had no significant effects on damage of harvested apples by arthropod pests. Furthermore, damage by arthropods was mainly caused by lepidopteran larvae, tortricids being especially important. The number of insecticide applications varied between 0 and 3 per year (mean 0.8), while acaricide applications varied between 0 and 1 per year (mean 0.06). Applications were often based on forecasts of important pest species such as the apple fruit moth (Argyresthia conjugella). Narrow-spectrum insecticides were commonly used against aphids and lepidopteran larvae, although broad-spectrum neonicotinoid (thiacloprid) insecticides were also applied. Anthocorid bugs and phytoseiid mites were the most abundant natural enemies in the studied orchards. However, we found large differences in abundance of various "beneficials" (e.g. lacewings, anthocorids, parasitic wasps) between eastern and western Norway. A low level of IPM negatively affected the abundance of spiders. Lepidoptera was found to be the most important pest group in apple orchards. Insecticide use was overall low, but number of spray applications and use of broad-spectrum insecticides varied between growers and regions. IPM level did not predict the level of fruit damage by insects nor the abundance of important pests or most beneficial groups in an apple orchard. This article is protected by copyright. All rights reserved.

SOWING TIME OPTIMIZATION FOR INSECT PEST MANAGEMENT AND ENHANCED CROP YIELD IN COTTON

Sowing time has a significant role in minimizing insect pest damage by disrupting synchronization between host plant and insect life cycle. The effect of different times of sowing viz. April, May and June designated as early, intermediate and late was determined on the ability of four cotton genotypes (NIA-30, NIA-88, NIA-98 and Sadori) to resist sucking insect pests and bollworms. Cotton genotypes were sown on the 15th of each month. The results showed that the planting time had pronounced effect on the infestation of insect pests. April sown cotton had a higher infestation of jassid compared to May and June sown cotton. The occurrence of thrips was recorded highest in the May sowing followed by April. Infestation of whiteflies and spotted bollworm was negligible on all the genotypes and were below the economic threshold levels during the entire period of observation. Furthermore, April sown cotton showed the higher infestation of spotted and pink bollworms. Among the tested genotypes in different sowing times, they exhibited similarity in insect pest abundance, except for jassid population which significantly differed in May sown genotypes. Concerning yield, April sowing yielded the most at 2107.7 kg/ha, followed by May (1917.6 kg/ha) and June (801.7 kg/ha). Notably, NIA-88 followed by Sadori consistently yielded the highest across all sowing times compared to the other two genotypes. This study indicates that sowing of cotton varieties in April is recommended for achieving higher yields.

Macro-scale perspectives in conservation biological control: latitudinal differences in the effects of organic farming on insect pests and natural enemies in rice paddy ecosystems

The pest control services provided by natural enemies are important for maintaining crop productivity in environmentally friendly agriculture with reduced use of pesticides. Organic farming is generally considered to increase the abundance of natural enemies and to enhance ecosystem services, but species and guild compositions vary from region to region, and so the population levels of pests and their natural enemies can be expected to vary geographically. Here, we surveyed the abundance of rice insect pests and spiders as their natural enemies in 51 organic and 45 conventional paddy fields at 22 locations in Japan and examined latitudinal differences in the effects of farming practices on their abundance. Independently of latitudinal differences, organic farming had positive effects on the abundance and species diversity of spiders caught in nets and on Tetragnatha and lycosid spiders. It increased the abundances of the leafhopper Nephotettix cincticeps and the white-backed planthopper Sogatella furcifera, and decreased that of the small brown planthopper Laodelphax striatellus. Both spiders and insect pests showed diverse responses to the interaction between farming practice and latitude. In particular, insect pests distributed in warmer regions, such as So. furcifera and Ne. cincticeps, tended to be more abundant in the south. The ratios of spider to pest abundance, as indicators of pest suppression, were lowest in organic paddies at lower latitudes for So. furcifera and Ne. cincticeps; at higher latitudes they were higher in organic paddies than in conventional paddies for La. striatellus. These results suggest that the effectiveness of pest suppression by natural predators in organic paddy fields varies by region depending on the ecological characteristics of each organism. As such, it is necessary to devise field management strategies appropriate to each region to balance crop production and biodiversity.

Seasonal Dynamics of the Brown Marmorated Stink Bug, Halyomorpha halys (Hemiptera: Pentatomidae), in Apple Orchards of Western Slovenia Using Two Trap Types

The invasive Halyomorpha halys is a serious pest for several fruit trees, causing millions of dollars of crop damage every year across the world’s major fruit-growing regions. Once established in an orchard, H. halys quickly becomes the predominant stink bug species and is a major season-long pest. Annual increases in the population size of H. halys have resulted in increased pest pressure and a growing risk of severe crop damage. Reliable monitoring is indispensable for H. halys control and management, providing comprehensive information on the seasonality of pest population dynamics, abundance, and interaction with the environment, and is essential for the successful implementation of integrated pest management (IPM) strategies to prevent crop damage. Our study followed the seasonal population dynamics of H. halys in three apple orchards in the Goriška region of western Slovenia over the period 2019–2021. Pherocon® Dual Panel Adhesive Traps (Trece Inc.) and pyramidal Rescue® Stink Bug Traps, both baited with Trécé lures (two-component H. halys aggregation pheromone + pheromone synergist), were used to monitor H. halys adults and nymphs weekly from late March to the end of November. Captures taken with both types of trap clearly describe the seasonal dynamics of H. halys, with the first occurrence of overwintering adults in April and May, and with two peak occurrences in adults, in the middle of summer and in the beginning of autumn, corresponding to the appearance of two generations per year in the study area. The growing trap captures observed during the 3-year monitoring period suggest that H. halys was only recently introduced to the area and that natural enemies have not yet been fully recruited. Pyramid traps captured significantly more adults and nymphs than clear sticky traps and provided accurate monitoring of H. halys life stages throughout the season. Regardless of the lower trap catches of adults and juveniles, clear sticky traps clearly displayed H. halys seasonal dynamics pattern. Therefore, their use is recommended as an early detection tool in areas where pests are not yet present, or in areas with small H. halys populations. Halyomorpha halys adult trap captures were higher in Šempeter orchards, within areas of great landscape diversity and a large share of urban land. The seasonal dynamics of H. halys over the 3-year period were closely related to weather conditions, with temperature and relative humidity as the major factors affecting population growth.

Environmental factors affecting honey bees (Apis cerana) and cabbage white butterflies (Pieris rapae) at urban farmlands.

Rapid urbanization results in a significantly increased urban population, but also the loss of agricultural lands, thus raising a concern for food security. Urban agriculture has received increasing attention as a way of improving food access in urban areas and local farmers' livelihoods. Although vegetable-dominant small urban farmlands are relatively common in China, little is known about environmental factors associated with insects that could affect ecosystem services at these urban farmlands, which in turn influences agricultural productivity. Using Asian honey bee (Apis cerana) and cabbage white butterfly (Pieris rapae) as examples, I investigated how environmental features within and surrounding urban farmlands affected insect pollinator (bee) and pest (butterfly) abundance in a megacity of China during winters. I considered environmental features at three spatial scales: fine (5 m-radius area), local (50 m-radius area), and landscape (500 m-raidus and 1 km-radius areas). While the abundance of P. rapae increased with local crop diversity, it was strongly negatively associated with landscape-scale crop and weed covers. A. cerana responded positively to flower cover at the fine scale. Their abundance also increased with local-scale weed cover but decreased with increasing landscape-scale weed cover. The abundance of A. cerana tended to decrease with increasing patch density of farmlands within a landscape, i.e., farmland fragmentation. These results suggest that cultivating too diverse crops at urban farmlands can increase crop damage; however, the damage may be alleviated at farmlands embedded in a landscape with more crop cover. Retaining a small amount of un-harvested flowering crops and weedy vegetation within a farmland, especially less fragmented farmland can benefit A. cerana when natural resources are scarce.

Survey on the Occurrence of Insect Pests in Stored Grains in Thiruvananthapuram District, Kerala State

To identify the species composition and relative abundance of insect pest in stored grains, a preliminary investigation was conducted by collecting grain samples from 16 grain merchant stores in Thiruvananthapuram District, Kerala state. Insect pest collected during the study were pulse beetle, Callosobruchus chinensis, cow pea beetle, C. maculatus, grain weevil, Sitophilus granarius, long headed flour beetle, Latheticus oryzae, rice weevil, Sitophilus oryzae, red flour beetle, Tribolium castaneum, lesser grain borer, Rhyzopertha dominica, saw toothed grain beetle, Oryzaephilus surinamensis, Angoumois grain moth, Sitotroga cerealella. Tribolium castanaeum, Sitophilus oryzae, Rhizopertha dominica (32.25%, 24.51%, 21.91% respectively per 200 g sample) were the most abundant pest species in the grain samples.