Severe Infestation Research Articles

Biological Control and Habitat Management for the Control of Onion Thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), in Onion Production in Quebec, Canada.

Onion thrips (Thrips tabaci) can pose a significant threat to onion crops, causing leaf damage, reduced bulb size and quality, and yield loss during severe infestations. Conventional insecticide use has been the primary method for managing this pest species, but the efficacy of this approach is inconsistent. Furthermore, emerging pest resistance is a growing concern in some regions. This two-year field study aimed to assess the effectiveness of several pest management strategies in controlling onion thrips populations and limiting their impact on onion yields. The strategies tested consisted of habitat manipulations (including flower strips and straw mulch), biological control agents (Stratiolaelaps scimitus, Neoseiulus cucumeris, Amblyseius swirskii, and Beauveria bassiana), as well as physical barrier control methods (exclusion nets, kaolin, and mineral oil). Habitat manipulation techniques, particularly the use of flower strips, reduced thrips populations by up to 50% and increased onion yields by 25%. In contrast, exclusion nets had a detrimental effect on onion yields, and the other alternative control methods produced results comparable to those obtained for untreated controls. When used alone, biological control agents were not effective at maintaining thrips populations below economically damaging levels. This study offers valuable insights into effective and sustainable pest management practices for the onion industry.

Revealing a Novel Potential Pest of Plum Trees in the Caucasus: A Species Resembling the European Leaf-Mining Stigmella plagicolella, Nepticulidae.

In instances of severe infestations, Nepticulidae larvae can inflict damage on cultivated plants. Previously, it was assumed that the Prunus-feeding Nepticulidae have continuous distribution from Europe to the neighboring Caucasus. During recent fieldwork in the Caucasus, leaf mines were found on plum trees that initially resembled those of Stigmella plagicolella (Stainton) in Europe. However, upon rearing the adults, significant differences emerged, leading to the hypothesis that a different Prunus-feeding species exists in the Caucasus; this challenges previous records in Western Asia. This paper presents the outcomes of our morphological, molecular, and statistical investigations, unveiling S. colchica sp. nov., a previously unknown potential plum-tree pest. Distinguished by male genitalia characteristics, the new species differs from S. plagicolella. The inter- and intraspecific divergences between S. colchica sp. nov. and S. plagicolella range from 3.5% to 6.02%. Moreover, the utilized delimitation algorithms reliably clustered two species separately, as does our mitotype network. A statistical analysis also shows a discernible trend between the leaf mines of S. colchica sp. nov. and S. plagicolella. This unexpected discovery not only documents a new potential pest, enhancing our understanding of the Caucasian fauna, but also contributes to the broader biological inventory.

Perennial flower margins reduce orchard fruit damage by rosy apple aphid, Dysaphis plantaginea (Homoptera: Aphididae)

Abstract Sown or natural flower strips are a commonly used management practice in agroecosystems and have been demonstrated to increase the abundance of predators of orchard pests. There is less evidence of the extent to which such strips can reduce pest damage in orchards. Here we examined the effect of managed, perennial flower margins on fruit damage by an economically significant crop pest, Dysaphis plantaginea, rosy apple aphid, in conventional apple orchards over 2 years, compared to orchards without flower margins. We found orchard flower margins reduced the percentage of apple trees with fruit damage by D. plantaginea, from 80% to 48%. In 2021, a period of severe infestation (65% of trees had fruit damage), there was reduced spread of D. plantaginea on infested apple trees and the number of trees with fruit damage was significantly reduced up to 50 m into orchards. During 2022, a period of lower infestation (25% of trees damaged), fruit damage was significantly reduced up to 10 m from the flower margin. A significant reduction in predation of aphids from bait cards in flower margin compared with control orchards suggests specialists, rather than generalist predators, may be driving the positive effects of the margin on pest pressure. There was no significant effect of flower margins on abundance of important aphid predators, including Syrphidae (hoverflies) and Coccinellidae (ladybirds). Synthesis and applications: To our knowledge, this study is the first to detect a reduction in fruit damage by pests at harvest in orchards with a flower margin. We highlight the potential for established perennial flower margins to deliver measurable, sustainable, D. plantaginea control benefits and provide insights into the optimal spatial arrangement of flower strips in orchards.

Quantifying the impacts of management and herbicide resistance on regional plant population dynamics in the face of missing data

Abstract A key challenge in the management of populations is to quantify the impact of interventions in the face of environmental and phenotypic variability. However, accurate estimation of the effects of management and environment, in large‐scale ecological research is often limited by the expense of data collection, the inherent trade‐off between quality and quantity, and missing data. In this paper we develop a novel modelling framework, and demographically informed imputation scheme, to comprehensively account for the uncertainty generated by missing population, management, and herbicide resistance data. Using this framework and a large dataset (178 sites over 3 years) on the densities of a destructive arable weed (Alopecurus myosuroides) we investigate the effects of environment, management, and evolved herbicide resistance, on weed population dynamics. In this study we quantify the marginal effects of a suite of common management practices, including cropping, cultivation, and herbicide pressure, and evolved herbicide resistance, on weed population dynamics. Using this framework, we provide the first empirically backed demonstration that herbicide resistance is a key driver of population dynamics in arable weeds at regional scales. Whilst cultivation type had minimal impact on weed density, crop rotation, and earlier cultivation and drill dates consistently reduced infestation severity. Synthesis and applications: As we demonstrate that high herbicide resistance levels can produce extremely severe weed infestations, monitoring herbicide resistance is a priority for farmers across Western Europe. Furthermore, developing non‐chemical control methods is essential to control current weed populations, and prevent further resistance evolution. We recommend that planning interventions that centre on crop rotation and incorporate spring sewing and cultivation to provide the best reductions in weed densities. More generally, by directly accounting for missing data our framework permits the analysis of management practices with data that would otherwise be severely compromised.

Biology of the invasive species Eragrostis plana in Southern Brazil: What have we learned and how may this help us manage it?

AbstractSince its accidental introduction in 1951, the South African species Eragrostis plana has invaded a large part of the Pampa biome in South America, a highly diverse grassland ecosystem that has coexisted with livestock since its introduction at the beginning of the 17th century. E. plana, a perennial tussock grass with a deep and abundant root system, is resistant to frost and cattle grazing, and a successful competitor for environmental resources. The species is diploid, C4 dispersed endozoochorically, and flowers in late spring and early summer, with optimal germination occurring at 35°C and viability up to 39–40°C. It is allelopathic because it produces several phenols and alkaloids. Extreme soil disturbance or intense grazing favours initial invasion. Nonetheless, grazing exclusion enhances E. plana competition and affects the grassland community and diversity. E. plana is highly tolerant to interspecific competition, especially with grasses exhibiting a similar growth habit. Under water stress, it responds faster by increasing its root system by 66% more than native grass. Moreover, antioxidant system activity increases, and the species recovers quickly through osmolyte production. In non‐invaded fields, avoiding soil disturbance and intensive grazing are key strategies to preserving Biome Pampa. Nonetheless, in fields where the invasion has already occurred, grazing must be maintained, cattle quarantined practiced, along with strategies that reduce cover and prevent the spread of E. plana. Liming and fertilising native grasslands improve their potential to compete with E. plana. The wiper applicator, a device that allows glyphosate herbicide application selectively to E. plana, is an important component of the integrated weed management system, especially with very severe infestations. Establishing strategies to contain or manage E. plana should be a priority to preserve the biodiversity of the Pampa. In the future, innovative options could also help prevent new invasions.

Plant–herbivore–natural enemy trophic webs in date palm agro-ecosystems

Understanding the composition and dynamics of ecological communities is challenging because of the large number of organisms present and their numerous interactions. Among agricultural systems, intercropping considerably increases the complexity of communities compared to monocultures and alternative host plants can influence insect pest damage. Using literature records, we construct and analyse connectance trophic webs of date palm (Phoenix dactylifera) agro-ecosystems, including and excluding intercrops. Estimates of connectance (community complexity) are relatively low and little affected by consideration of intercrops. Plant–herbivore overlap is relatively high, suggesting that herbivores are typically not specialists. Herbivore–natural enemy overlap is greater when intercrops are considered, suggesting that diffuse apparent competition regulates pest populations. We pay particular attention to how trophic web structure might affect Batrachedra amydraula (Lesser date moth), an important economic pest. Records indicate it having 15 species of natural enemies and sharing 9 of these with other herbivores; these may maintain populations of natural enemies when the moth is seasonally rare, contributing to pest suppression. The estimated potential for apparent competition between the lesser date moth and other herbivores is higher when intercrops are considered. The consequent expectation of less severe infestations in plantations that are intercropped compared to monocultures matches empirically derived reports. Further, comparing results obtained from the literature on one country (Oman) and from 15 Middle Eastern countries, we find that community metric estimates are relatively little affected by the geographical scale considered. Overall, our results suggest that literature-based trophic web construction can provide an efficient and robust alternative, or in addition, to direct empirical methodologies and that the presence of intercrops will contribute to major pest suppression via indirect apparent competition.

Invasion of an Afrotemperate forest complex by the polyphagous shot hole borer beetle

AbstractThe polyphagous shot hole borer (PSHB), Euwallacea fornicatus Eichhoff (Coleoptera: Curculionidae, Scolytinae), is a significant tree‐killing pest recently introduced into South Africa. Many native trees in urban settings are susceptible to infestation, but the presence of PSHB in natural ecosystems is unstudied. The presence and drivers of PSHB colonization in 1682 trees of 68 species were evaluated in 51 plots across a native Afrotemperate forest complex in South Africa. Breeding colonies of PSHB were found in six native species (breeding hosts). An additional 11 species did not contain PSHB colonies but hosted its mutualistic fungus Fusarium euwallaceae Freeman et al. (Hypocreales: Nectriaceae). Invasibility increased when plots were closer to the urban infestation border, further away from surface water, and when containing a larger number of breeding hosts. Invasibility decreased with an increase in tree species richness. Polyphagous shot hole borers were found in climax forest distant to urban areas at sites frequented by tourists. The severity of infestation of trees increased with an increase in host diameter, breeding host abundance, and infested tree abundance. Probability of infestation increased with an increase in the number of infested trees. Infested trees were not spatially clumped. Instead, PSHB preferentially selected eight of the 17 native host species. And the data suggest that larger trees of these species may be more susceptible to PSHB. Eight species were infested at random and two were infested seemingly accidentally. Infestations increased more rapidly on larger trees and on those surrounded by a high abundance of breeding hosts. This study confirms that Afrotemperate forests are highly susceptible to invasion by PSHB. Direct anthropogenic impact had no discernible effect on infestations, but humans aided spread of PSHB to distant sites. Halting movement of contaminated wood is important. Management of PSHB should focus on highly infested areas and trees as these increase the likelihood of further and more severe infestations.

Immune response of the Almaco jack (Seriola rivoliana) against the infestation with Neobenedenia sp. in three cultivated temperatures.

The Almaco jack (Seriola rivoliana) is a marine fish maintained in mariculture systems and frequently infested by monogenean parasites like Neobenedenia sp. Severe infestations can lead to high mortalities and economic losses for farmers. This study evaluated the effects of temperature on the immune response on Almaco jack infested with Neobenedenia sp. We exposed infested fishes at temperatures of 20°C, 24°C, and 30°C for 20days and took samples of different tissues at the beginning of the experiment, and after 3 and 20days. The tissues considered were the skin, thymus, cephalic kidney, and spleen to evaluate the relative gene expression of different genes: Hsp70, IgM, IL-1β, IL-10, and MyD88. Our results showed an increase in IL-1β gene expression in the skin after 20days of infestation but no significant effect of temperature on gene expression, despite increases in infestation rates with temperature. Therefore, relative genetic expression was controlled by the number of parasites and the days post-infestation. These results show that the parasite infestation induced a local response in the skin, but that temperature has an indirect effect on the immune system of Almaco jack.

Efficacy and safety of geranium-oregano-thymol formulations to control of dog tick Rhipicephalus sanguineus sensu lato under laboratory and field conditions

The present study evaluated, in laboratory and field, the efficacy and safety of formulations of Pelargonium graveolens (geranium – G), Origanum majorana (oregano - O) commercial essential oils (EO) and thymol (T) to control of Rhipicephalus sanguineus sensu lato. In the laboratory, three formulas (A: 2% tween 80%, B: powder and C: nanoemulsion) by a mixture of these components (GOT) were prepared and evaluated, and the best one was used to assess its safety and field application against R. sanguineus s. l. on naturally infested dogs. Besides the major compounds of the EO used were identified. The results of the lab study showed that formula A (2.5 g of each G + O + T + 2% tween 80 to complete 100 mL) was significantly more effective than the other two formulas tested and exhibited highly effective adulticidal, larvicidal, and ovicidal activity against R. sanguineus s.l. Significant LC50 and LC90 values of GOT were evaluated (13.4 and 21.5 mg/mL, respectively) for the adulticidal activity, (2.81 and 4.46 mg/mL, respectively) for ovicidal activity and (2.44 and 4.45 mg/mL, respectively) for larvicidal activity. The safety of formula A has been proven by the absence of its cytotoxicity on a cell line of human epidermoid carcinoma. Citronella and carvacrol were the major compounds identified in the commercial essential oils of P. graveolens and O. majorana, respectively. Formula A was used in a field control trial for almost 8 months, during the tick infestation season (April to November, 2022). Fourteen naturally infested dogs were divided into two groups, each with seven dogs. One group received formula A spraying five times during an experiment that continued for 8 months, while the other group received treatment with commercially available malathion acaricide. The animals were sprayed on five occasions throughout the experiment (April, June, July, August, and September). The results showed a substantial percentage of effectiveness after the first application of formula A with a 99.3% reduction in tick count at day 28 post-application (PA). In the case of severe infestation 60 days after the first application of formula A (more than 180 ticks per dog), the second application was done, achieving an efficacy of 54.9% at day 3 PA, so an emergency spray was done at day 5 PA to combat the rest of the tick infestation, achieving efficacy of 99% after 3 days. Consequently, a regular spray (third, fourth, and fifth application) was done every 35 days. This regular spray revealed 100% effectiveness at 14 days PA. Biochemical parameters of treated dogs were evaluated to confirm the safety of formula A. Creatinine, ALT, and albumin of the dogs treated with formula A were within the normal range of dogs, while urea and AST were higher than the normal range. In conclusion, formula A can safely treat R. sanguineus s.l. infestations in dogs with regular application every 5 weeks.

Invasive behaviour of oak lace bug in forest ecosystems: a comparative analysis between thermophilous and mesophilous oak forests

Forest ecosystems provide invaluable ecological, economic, and social benefits, making them essential for global well-being. However, these ecosystems face various threats, including biological invasions by alien species. Among these, the oak lace bug (OLB), an invasive North American insect, has rapidly spread in Europe, impacting oak forests and raising concerns about its adaptation to new environments. OLB feeds on the undersides of oak leaves, extracting sap and causing chlorotic discoloration. Severe infestations lead to premature defoliation, increased susceptibility to diseases or pests and can also result in a substantial reduction in photosynthesis activity. This study aims to analyse OLB’s invasive behaviour in Romanian forest ecosystems, with a specific focus on the differences between thermophilous and mesophilous oak forests. The analysis covers 6 years of data and reveals critical insights. In the initial 4 years, OLB predominantly inhabited the extracarpathian regions of Romania, with concentrated presence in the southern, western, and northwestern areas. Forest ecosystems mainly affected between 2017 and 2020 were characterized by thermophilous oak forests in southern and western regions. However, in the last 2 years (2021–2022), OLB presence increased, particularly in lowland ecosystems, albeit with reduced damage intensity. The analysis also unveiled an adaptation and expansion of OLB in mesophilous forest ecosystems. Climatic factors, specifically temperature and precipitation, significantly influenced OLB’s behaviour, points with severe attacks exhibiting specific climatic conditions. In summary, this study provides crucial insights into OLB’s behaviour, emphasizing the role of climatic and environmental factors in its invasive tendencies.

Investigating the second whitefly population outbreak within a decade in the cotton growing zone of North India.

The whitefly, Bemisia tabaci (Gennadius), is a polyphagous and major pest of cotton worldwide. Both adults and nymphs of B. tabaci affect the crop by causing direct and indirect damage. A severe whitefly outbreak was experienced during 2015 on cotton in North India and this was followed by a profound infestation during 2022. The present research rigorously examined whether the proliferation in the whitefly population was an outbreak or the result of a multi factor resurgence. During 2015, whitefly counts remained above the economic threshold level (ETL) between 28th and 35th Standard Meteorological Week (SMW). However, during 2022 above ETL population was observed in 27th SMW and it persisted until 36th SMW. The peak incidence of the whitefly was noticed during 31st and 29th SMW in 2015 and 2022, respectively. The early pest build up in 2022 and longer persistence (≥10 weeks) over the cotton season resulted in more damage to cotton crop. Additionally, pest survillence across the zone on the farmers' fields during 2022 revealed 44.4 per cent spots (585 out of 1,317 locations) above ETL while the corresponding locations in 2015 was 57% (620 out of 1,089). Thus, in 2022 infestation was not uniform in the entire zone wherein only few blocks of Punjab, Haryana and Rajasthan states of India experienced severe infestations of the whitefly. This study reports the complex of factors including weather, delayed sowing, use of tank mixtures/ subleathal doses of insecticides, pest resurgence etc. that might have possibly contributed to these upsurges in whitefly on cotton in north India.

Toxicity evaluation of oxamyl against tomato russet mite, Aculops lycopersici (Massee) (Acari: Eriophyideae) and two spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) under greenhouse conditions.

Agriculture sector of Saudi Arabia is growing swiftly and tomato is an important crop cultivated mostly under green houses. Unfortunately, it is facing severe infestation due to divers mite species. Present study, relates to evaluation of toxicity of oxamyl against two phytophagous mites; Aculops lycopersici and Tetranychus urticae, isolated from tomato plants suffering from infestation. Simultaneous effect of oxamyl on two predatory mites; Neosiulus cucumeris and Euseius scutalis, was also evaluated. Three concentrations of oxamyl; half of the recommended dose (HRD), recommended dose (RD) and double recommended dose (DRD), were used against each mite specie to observe mortality within seven days as compared to the control. Significant mortality of 97.91% and 93.92% was observed in A. lycopersici and T. urticae, respectively at RD. In case of predatory mites; N. cucumeris and E. scutalis, mortality was 60.61% and 64.48%, respectively, under same conditions. Mortality of mites observed at HRD was insignificant and there was negligible increase in mortality at DRD. Oxamyl being less toxic to predatory mites and significantly mortal to phytophagous mites is recommended as a tool to as a tool to achieve biological control parallel to pesticidal effect.

Use of Chemicals and Biological Control Agents as Activators of Plant Defense Against Endoparasitic Sedentary Nematodes.

Full compatible interactions between crop plants and endoparasitic sedentary nematodes (ESNs) lead to severe infestation of the roots and plant growth impairing, as well as to the increase of nematode population in the soil that is a threat for the next planting crop. In the absence of activators, basic plant defense is overcome by nematode secretion of effectorsthat suppress defense gene expression,inhibit ROS generation andtheoxidative burstused byplants to hamper nematode feeding site settlementandlimit its development and reproduction. Activators can be exogenously added as a preventive measure to prime plants and strengthen their defense against ESNs. Activators can be an array of antioxidant compounds or biocontrol agents, such as mutualist microorganisms living in the rhizosphere (biocontrol fungi (BCF), arbuscular mycorrhizal fungi (AMF), plant growth-promoting bacteria (PGPB), etc.). In this chapter, methods are described for usage of both salicylic acid (SA) and its methylated form (Met-SA), and BCF/AMF as elicitors of resistance of vegetable crops against root-knot nematodes (RKNs). The rhizosphere-living BCF/AMF were recovered from commercial formulates pre-incubated in suitable growth media and provided exclusively as soil drench of potted plants. The plant hormones SA and Met-SA were provided to plants as soil drench, foliar spray, and root dip. It is indicated that activators' dosages and plant age are crucial factors in determining the success of a pre-treatment to reduce nematode infection. Therefore, dosages should be expressed as amounts of activators per g of plant weight at treatment. Thresholds exist above which dosages start to work; overdoses were found to be toxic to plants and useless as activators.

Potato agriculture research Station Batakundi, naran, a hot spot for cyst nematode (Globodera spp.) of potato in Pakistan

In Pakistan, potato summer crop in being cultivated in different agro-ecologies of Khyberpukhtun Khwa and in valleys of Gilgit Baltistan provinces. To understand the current biotic stresses scenario in the potato germplasm developed by National Institute of Genomics and Advanced Biotechnology (NIGAB) was cultivated in 2022-23. The valleys comprised on Sharan Forest Kaghan, Potato Agriculture Research Station, Batakundi Naran of KPK and Babusar valley as well as Mountain Agriculture Research Station, Chillas of Gilgit Baltistan were systematically surveyed. The soil samples were analyzed in for the cyst nematode (Globodera spp.) in potato fields as an invasive and quarantine regulated pest. Severe infestation of PCN was observed in PARS, Batakundi Naran. However, there were no any cyst was found in the rest of ecologies surveyed. The population dynamics of PCN was estimated ranges from 113-150 cysts in 100grams of soil samples. The center is being used as potato monoculture and crop breeding. The egg count estimates ranges from 270-320 eggs/cyst. There are some cysts showed the suppressive soil state as the eggs were infested with endophytes or rhizospheric microorganisms (bacteria or fungi). The cysts were morphologically characterized and identified in Crop Diseases Research Institute (CDRI) and National Nematological Research Center Pakistan.

Relative impact of vermiwash against phytophagous insects and growth properties of yardlong bean (<em>Vigna unguiculata</em>)

Due to severe insect infestation, yardlong (Vigna unguiculata) bean expansion and production have been declining in Sri Lanka. This experiment tested the effectiveness of several vermiwash against phytophagous insects in yardlong bean. Ten distinct types of vermiwash were generated by alternately and separately feeding exotic (Eudriluseuginea) and indigenous types earthworm with the specified botanicals, viz. onion and garlic peel, marigold and neem leaves, and the materials given for mass culturing. Eleven treatments including 10 vermiwash and untreated control and three blocks were laid on Randomized Complete Block Design. Since the third week of planting, vermiwashes have been administered to the corresponding plots at weekly intervals. Before each application of treatment, the total number of insects in each treated and untreated plot were carefully counted. ANOVA assessed treatment effects, and Duncan's Multiple Range Test compared mean separation values at 5% significance using SAS software. Plots treated with vermiwash made from indigenous earthworm varieties with garlic peel (1.33), exotic varieties with onion peel (2.33), and native varieties with onion peel (3.00) had the significantly similar fewest epilachna beetles. Further, vermiwash of an indigenous variety with neem leaves, where the maximum yield of yardlong beans was also discovered, had a considerably lower population of epilachna beetles. Furthermore, with the exception of the vermiwash of exotic species with onion peel, practically all treatments were less harmful to ladybird beetles. As demonstrated by this experiment, vermiwash has a beneficial effect on plant development in terms of both plant height and leaf area. Vermiwash made from combining an indigenous species of earthworm with neem leaves was potentially suggested for yardlong bean production since it was both environmentally and economically efficient.

Seed Bank Distribution of Kongwa Weed (Astripomoea Hyoscyamoides) for Different Land Use Types in Kongwa District, Tanzania

Weed invasion poses significant challenges to agriculture and ecosystems, leading to substantial economic losses globally. Astripomoea hyoscyamoides Vatke Verdc. commonly known as Kongwa weed, is a highly invasive species causing a severe infestation in the Kongwa district, Tanzania. This study investigated the seed bank distribution of Kongwa weed across different land use types, specifically arable land, fallow land, and range land in the Kongwa district. Soil samples were collected from chamae, chigwingwili, chimotolo, machenje, msunjulile, ndalibo, nyerere, and sejeli villages, representing range, arable, and fallow land, at different soil depths (0-5 cm, 5-10 cm, 10-15 cm, and 15-20 cm). The results showed significant variations in Kongwa weed seed density among villages, with Msunjulile exhibiting the highest density across all land use types (1.92 seeds/m2 in arable, 6.67 seeds/m2 in fallow, and 9.83 seeds/m2 in range land). In comparison, Chigwingwili displayed the lowest density (0.33 seeds/m2 in arable land) The study revealed a decline in seed density with increased soil depth, with the topsoil (0-5 cm) showing the highest seed density. Also, range land exhibited the highest seed density, while arable and fallow land were comparable. Generally, kongwa weed seeds are observed to be higher in range land with a depth of 0–5 cm, particularly in areas near ranch areas. Implementing control measures, especially before the flowering stage, is crucial to mitigating the kongwa weed invasion. Further research on seed germination patterns is recommended to enhance weed management strategies.

Longhorn beetles as new pests for exotic plantations in Vietnam

Longhorn beetles are important pests in commercial forests and exotic tree plantations worldwide, consequently leading to economic losses for timber producers and plantation owners. Acacia, Eucalyptus and Pinus plantations have been established widely in Vietnam for reforestation, wood products and paper industry. However, severe infestations of these three exotic trees have occurred due to longhorn beetles. The present study identified Coptops annulipes Gahan, 1894, Anagelasta apicalis Pic, 1925, Desisa subfasciata (Pascoe, 1862), and Cephalallus unicolor (Gahan, 1906) as four new longhorn beetles attacking Acacia crassicarpa in Quang Tri province, Eucalyptus hybrid (E. urophylla × E. grandis) in Bac Giang province, and Pinus caribaea in Quang Tri province, Vietnam. The infestation levels caused by C. annulipes, A. apicalis, D. subfasciata and C. unicolor were 16.8%, 29.5%, 39.2% and 24.3%, respectively. The damage indeces were 0.41, 0.85, 1.16 and 0.71, respectively. A. apicalis damaged at the base, C. annulipes and C. unicolor damaged at the lower trunk of host trees, D. subfasciata infested the top of trees. This information is expected to assist forest owners and government authorities across the country in pest surveillance and in developing suitable management plans for these four emerging pests.

Lethal and Sublethal Effects of Cyromazine on the Biology of Musca domestica Based on the Age-Stage, Two-Sex Life Table Theory.

Cyromazine is a triazine insect growth regulator insecticide that is recommended for control of Musca domestica worldwide. Cyromazine is highly effective in causing mortality of M. domestica; however, some aspects of its lethal and sublethal effects on the biology of M. domestica are still unknown. The present study explored lethal and sublethal effects on several biological traits and population parameters of M. domestica. Concentration-response bioassays of cyromazine against third-instar larvae of M. domestica exhibited sublethal and lethal effects from concentrations of 0.03 (LC10), 0.06 (LC25), and 0.14 (LC50) μg/g of a larval medium. Exposure of M. domestica larvae to these concentrations resulted in reduced fecundity, survival, longevity and oviposition period, and delayed development of immature stages (i.e., egg hatch time and larval and pupal durations) in the upcoming generation of M. domestica. The values of population parameters such as intrinsic rate of increase, finite rate of increase, net reproductive rate, age-specific survival rate and fecundity, and age-stage life expectancy and reproductive value, analyzed using the age-stage and two-sex life table theory, were significantly reduced in a concentration-dependent manner in comparison with the control group. In conclusion, the study highlights the significant effects of cyromazine on the biology of M. domestica that could help suppress its population in cases of severe infestations.

Grasshopper Species Composition and Severe Attack in the Semi-Arid Region of Rajasthan, India

Adequate knowledge is needed to know when grasshopper species abundance shifts and to follow severe outbreaks during microclimatic variations. Grasshoppers regularly cause enormous harm to a wide variety of crops and grazing lands; sometimes they show a potential attack on particular crops. A study was carried out in the southern region of Jaipur, Rajasthan, where 11 sites were weekly sampled to monitor grasshopper population dynamics, grasshopper densities, species composition, and vegetation loss from July 2021 to December 2022. A serious grasshopper attack was reported in 2021, with the highest grasshopper densities ranging from 5 to 17.5 per m2, whereas grasshopper densities dropped in 2022 from 4 to 14.5 per m2. In the survey area, the acridid grasshopper Hieroglyphus banian (Acrididae:Orthoptera) was reported as the most abundant species that was accountable for the majority of the crop damage in agricultural fields, followed by Spathosternum praciniferaum and Acrida turrita, respectively. The grasshopper population density was revealed to be significantly different in 2021 and 2022 (t = 1.568, df = 20, P = 2.086). Severe infestation was observed in all of the pearl millet fields and also in seasonal crops and vegetables, where H. banian caused 91% infestation, followed by S. praciniferaum with 7% and A. turrita with 2%, respectively. The study confirmed that climatic factors were significantly related to outbreaks and assessed their effect, which revealed a rare population in the summer season and peaked in the monsoon season. The finding provides important information for grasshopper risk forecasting, which is advantageous for preparing grasshopper risk maps, predicting the intensity of outbreaks, and developing an integrated pest management plan.

Fenoxaprop-P-ethyl, mesosulfuron-ethyl, and isoproturon resistance status in Beckmannia syzigachne from wheat fields across Anhui Province, China

Severe infestations of American sloughgrass (Beckmannia syzigachne (Steud.) Fernald) in wheat fields throughout Anhui Province, China, pose a significant threat to local agricultural production. This study aims to evaluate the susceptibility of 37 B. syzigachne populations collected from diverse wheat fields in Anhui Province to three commonly used herbicides: fenoxaprop-P-ethyl, mesosulfuron-ethyl, and isoproturon. Single-dose testing revealed that out of the 37 populations, 31, 26, and 11 populations had either evolved or were evolving resistance to fenoxaprop-P-ethyl, mesosulfuron-ethyl, and isoproturon, respectively. Among them, 25 populations displayed concurrent resistance to both fenoxaprop-P-ethyl and mesosulfuron-ethyl, while eight exhibited resistance to all three tested herbicides. Whole-plant bioassays confirmed that approximately 84% of the fenoxaprop-P-ethyl-resistant populations manifested high-level resistance (resistance index (RI) ≥10); 62% of the mesosulfuron-ethyl-resistant populations and 82% of the isoproturon-resistant populations exhibited low- to moderate-level resistance (2 ≤ RI <10). Three distinct target-site mutations were identified in 27% of fenoxaprop-P-ethyl-resistant populations, with no known resistance mutations detected in the remaining herbicide-resistant populations. The inhibition of cytochrome P450s (P450s) and/or glutathione S-transferases (GSTs) substantially increased susceptibility in the majority of resistant populations lacking mutations at the herbicide target site. In conclusion, resistance to fenoxaprop-P-ethyl and mesosulfuron-ethyl was widespread in B. syzigachne within Anhui Province's wheat fields, while resistance to isoproturon was rapidly evolving due to its escalating usage. Target-site mutations were present in approximately one-third of fenoxaprop-P-ethyl-resistant populations, and alternative mechanisms involving P450s and/or GSTs could explain the resistance observed in most of the remaining populations.