Search Results (90)

The invasive Delottococcus aberiae is one of the most harmful mealybugs on citrus in Spain, since it causes deformations and the premature falling of fruits in citrus orchards. To improve control strategies, this study evaluates its population above- and belowground, their distribution in the soil in addition to identifying natural enemies. The distribution in the soil of emerged males varies significantly with the distance to the tree trunks with an annual average number of 0.95 males/trap/day at 0.5 m, and ranging between 0.25 and 0.32 at 1 m, 1.5 m and 2 m. There is a consistent emergence of males throughout the year, both above- and belowground, with four distinct peaks, the first two occurring in February and April. This observation is essential to manage fruit damages that follows between March and June. Among the natural enemies detected belowground the following are highlighted: Bdellidae mites (52%), Hymenoptera parasitoids (16%) and spiders (11%). When implementing IPM strategies, emphasis should be placed on adequate soil management (crops, mulching, or the release of natural enemies) and to the appearance of first generation. We propose a belowground population sampling method as a simple and practical tool to quantify this pest’s the winter and spring populations, which remain undetectable using current methodologies. Full article

In mountainous citrus orchards, the application of conventional ground sprayers for the control of citrus red mite (Panonychus citri) is often constrained by complex terrain and low operational efficiency. The Unmanned Aerial Spraying System (UASS), due to its low-altitude, low-volume, and high-maneuverability characteristics, has emerged as a promising alternative for pest management in such challenging environments. To evaluate the spray performance and field efficacy of different UASS types in controlling P. citri, five representative UASS models (JX25, DP, T1000, E-A2021, and T20), four mainstream pesticide formulations, and four novel tank-mix adjuvants were systematically assessed in a field experiment conducted in a typical hilly citrus orchard. The results showed that T20 delivered the best overall spray deposition, with upper canopy coverage reaching 10.63%, a deposition of 3.01 μg/cm², and the highest pesticide utilization (43.2%). E-A2021, equipped with a centrifugal nozzle, produced the finest droplets and highest droplet density (120.3–151.4 deposits/cm²), but its deposition and coverage were lowest due to drift. Nonetheless, it exhibited superior penetration (dIPR 72.3%, dDPR 73.5%), facilitating internal canopy coverage. T1000, operating at higher flight parameters, had the weakest deposition. Formulation type had a limited impact, with microemulsions (MEs) outperforming emulsifiable concentrates (ECs) and suspension concentrates (SCs). All adjuvants improved spray metrics, especially Yimanchu and Silwet, which enhanced pesticide utilization to 46.8% and 46.4% for E-A2021 and DP, respectively. Adjuvant use increased utilization by 4.6–11.9%, but also raised ground losses by 1.5–4.2%, except for Yimanchu, which reduced ground loss by 2.3%. In terms of control effect, the rapid efficacy (1–7 days after application, DAA) of UASS spraying was slightly lower than that of ground sprayers—electric spray gun (ESG), while its residual efficacy (14–25 DAA) was slightly higher. The addition of adjuvants improved both rapid and residual efficacy, making it comparable to or even better than ESG. E-A2021 with 5% abamectin·etoxazole ME (5A·E) and Yimanchu achieved 97.4% efficacy at 25 DAA. Among UASSs, T20 showed the rapid control, while E-A2021 outperformed JX25 and T1000 due to finer droplets effectively targeting P. citri. In residual control (14–25 DAA), JX25 with 45% bifenazate·etoxazole SC (45B·E) was most effective, followed by T20. 5A·E and 45B·E showed better residual efficacy than abamectin-based formulations, which declined more rapidly. Adjuvants significantly extended control duration, with Yimanchu performing best. This study demonstrates that with optimized spraying parameters, nozzle types, and adjuvants, UASSs can match or surpass ground spraying in P. citri control in hilly citrus orchards, providing valuable guidance for precision pesticide application in complex terrain. Full article

Thaumatotibia leucotreta, an important citrus pest in southern Africa, is subject to phytosanitary regulations for certain export markets. A systems approach has been developed as an alternative to standalone postharvest disinfestation methods, integrating multiple risk mitigation steps, including preharvest infestation monitoring. This study aimed to validate an existing preharvest monitoring protocol based on fallen fruit collected under designated data trees and to develop a novel monitoring system based on sampling of sanitation fruit. Monitoring was conducted in seven Navel orange orchards (N = 7 each year) during the 2021 and 2022 seasons, representing high and low infestation levels, respectively. Infestation levels were assessed over 11–12 weeks by inspecting fruit beneath four sets of five trees and all sanitation fruit collected per orchard. The new system, which involves inspecting a 100-fruit sample per orchard, was compared with the previous method. While the five-tree protocol tended to overestimate infestation, it remained effective. The sanitation-fruit sampling approach accurately reflected orchard-level infestation, with a 100-fruit sample sufficient for orchards as large as 20 hectares. Although random sampling is recommended, it was not essential for effectiveness. These results support the use of the new monitoring procedure in the systems approach for citrus exports for T. leucotreta risk mitigation. Full article

Field mapping is one of the most important aspects of precision agriculture, and community drones will be able to empower young rural entrepreneurs who will be the generational replacement of a new agrosocial paradigm. This research presents an agroecological participatory innovation methodology that utilizes precision technology through geographic information systems and unmanned aerial vehicles to evaluate the integrated ecological management of weeds for glyphosate substitution in a transitional area of Citrus sinensis in San Luis Potosí, Mexico. Modeling methods and spatial analyses supported by intelligent georeference protocols were used to determine the number of weeds with tolerance and glyphosate resistance. Four control flights were conducted to monitor seven treatments. Glyphosate-resistant weeds were represented with the highest number of individuals and frequency in all experimental treatments. Although the treatment with maize stubble showed a slightly better result than the use of Mucuna pruriens mulch, which prevents the emergence of glyphosate resistant weeds before emergence, the second treatment is considered better in terms of the cost–benefit ratio, not only because of significantly lower cost but also because of the additional benefits it offers. Geospatial technologies will determine the nature of citrus and fruit tree agroecological treatments and highlight areas of the plot with binomial soil and plant nutrient deficiencies and pest and disease infestations, which will improve the timely application of bio-inputs through the development of accurate maps of agroecological transitions. Full article

Reported in Europe in the early 2000s, Delottococcus aberiae (De Lotto) (Hemiptera: Pseudococcidae) is an invasive mealybug pest that is causing severe damage to citrus production in eastern Spain. Once its main sex pheromone component was identified in a previous work as (4,5,5-trimethyl-3-methylenecyclopent-1-en-1-yl)methyl acetate 1, the revision of virgin female effluvia is here reported to improve knowledge about the biology of D. aberiae. A new minor component has been identified in the volatile samples collected from virgin females as ((1R, 4R)-3,4,5,5-tetramethylcyclopent-2-en-1-yl)methyl acetate (trans-α-necrodyl acetate, (1R, 4R)-2), a compound also found in the essential oil of Lavandula stoechas subsp. luisieri. Bioassay testing of the activity of this compound showed that a synthetic sample of the racemate (±)-(trans)-2 was attractive to D. aberiae males both in the laboratory and field but with a lower attractant power than enantiopure (1R, 4R)-2 and (±)-(1). The 1:1 mixture of (1R, 4R)-2 and (±)-1 provided a slight additive effect. Further trials are needed to know the pest control potential of this minor compound but the possibility of obtaining this substance from a natural source could pose an important advantage to implement new methods for the sustainable control of D. aberiae. Full article

Citrus greening disease (CGD), also known as Huanglongbing in China, is caused by the endophytic bacterium ‘Candidatus Liberibacter asiaticus’ and poses a severe threat to the global citrus industry. The disease affects microbial communities in leaves, stems, roots, and soil. Soil nematodes, which occupy multiple trophic levels, play crucial roles in nutrient cycling, pest regulation, and plant-soil interactions. However, the impact of CGD on soil nematode community structure and energy flow remains unclear. This study examined the effects of different levels of CGD infection on soil nematode communities and energy dynamics. Three infection levels were selected: control (healthy plants with no yellowing symptoms), mild infection (≤50% leaf yellowing), and severe infection (entire canopy affected). The results showed that increasing CGD severity significantly reduced the nematode abundance, community structure index, and total energy flux by 94.2%, 86.7%, and 93.5%, respectively, in the severely infected group. Both mild and severe infections resulted in a higher proportion of bacterivorous nematodes compared to the control. Moreover, herbivorous energy flux was significantly reduced by 99.2% in the severe infection group, suggesting that herbivorous endophytic nematodes are particularly sensitive to CGD. The total energy flux through nematode food web, the energy flux through fungal or herbivorous channels, and the energy flow uniformity were positively correlated with the nematode structure index but negatively correlated with the nematode richness and evenness indices. Furthermore, the reduction in soil resource input (especially total nitrogen and total carbon) caused by CGD was the primary driver of the changes in nematode communities and energy flows. These findings highlight the destructive effects of CGD on soil ecosystems through bottom-up control. The CGD-induced obstruction of photosynthate transport primarily impacts phytophagous organisms and could also influence other trophic levels. To mitigate these effects and ensure healthy citrus production, future research should focus on early detection and effective CGD management strategies. Full article

We developed a programmable LED array to evaluate different wavelength illumination (UV, blue, green, yellow, amber, and red) and modulation schemes to improve catch rates in insect traps. The device can communicate through Bluetooth^® with a simple Android app to update the operational settings to facilitate field experiments, including which LEDs to operate, when to operate (always, night only, or predefined intervals after sunset and/or before sunrise), and to change the LED intensities/modulation during operation. We used the devices to evaluate different wavelengths to improve catches in traps for coconut rhinoceros beetle (CRB; Oryctes rhinoceros Linnaeus) in the field, as well as to evaluate lighting preferences of Asian citrus psyllid (ACP; Diaphorina citri Kuwayama). In both cases, insects were most strongly attracted to constant UV illumination. However, CRB avoided traps with any “visible” wavelength LEDs placed in panels of traps, while ACP was moderately attracted to blue, yellow, and amber. For CRB, UV illumination of cups at the bottom of panel traps reduced catch rates compared to UV illumination higher in the panels of traps, consistent with observations of dorsal orientation towards light observed by other researchers in nocturnal beetles and moths. Finally, we provide some hardware design recommendations to improve the energy efficiency of similar devices for more widespread deployment in insect traps and for controlling the LEDs to evaluate the effects of intensity and modulation with minimal pulsing, which our observations suggest may result in insects avoiding traps. Full article

Citrus nematode (Tylenchulus semipenetrans) is one of the dominant plant-parasitic nematodes in citrus-growing regions, resulting in an average yield loss between 10 and 30%. Tylenchulus semipenetrans is a sedentary semi-endoparasitic nematode that infects the roots of citrus trees, causing stunted growth, reduced fruit yield, and poor fruit quality; collectively this pathology and thus the disease caused is referred to as the slow decline of citrus. Despite its huge importance, the citrus nematode is regarded as a neglected parasite, and most research focuses on biological control and integrated pest management. Advancements in understanding the molecular mechanisms of other plant-parasitic nematodes, such as sedentary endoparasites with biological similarities to citrus nematodes, can be leveraged to gain deeper insights into the molecular mechanisms of citrus nematodes. In this review, we examine the biology, and integrated pest management of citrus nematodes, and explore future research directions toward understanding the role of genomics, gene-editing tools, and the molecular mechanisms of host-seeking and effectors used by other plant-parasitic nematodes to cause infection, which can serve as a foundation for future work in citrus nematode management. Full article

The Asian citrus psyllid, Diaphorina citri, serves as the primary vector for Huanglongbing (HLB) by transmitting Candidatus Liberibacter asiaticus. Lambda-cyhalothrin and thiamethoxam are commonly employed for the control of D. citri. The multicolored Asian lady beetle, or harlequin ladybird, Harmonia axyridis, is an important predator of D. citri in both greenhouse and field settings. The effectiveness of integrated pest management (IPM) relies on the judicious use of selective insecticides that minimize harm to natural enemies. However, the effects of these insecticides on H. axyridis’ predation of D. citri remain thoroughly unexplored. In this study, we assessed the toxicity of lambda-cyhalothrin and thiamethoxam to H. axyridis and examined their impact on the functional response of this predator to D. citri using direct contact exposure methods. We also evaluated the indirect effects on predator voracity through ingestion exposure. Our results demonstrated that exposure to both insecticides at LC₅₀ concentrations significantly prolonged the developmental durations of H. axyridis larval stages. The type-II functional response model effectively described the prey consumption patterns of H. axyridis, revealing a significant reduction in predation capacity across all life stages, particularly among second instar larvae, which experienced reductions of 85.30% and 88.58% following lambda-cyhalothrin and thiamethoxam treatments, respectively. Furthermore, H. axyridis’ predation significantly declined when feeding on D. citri contaminated at LC₅₀ concentrations. These findings indicate that lambda-cyhalothrin and thiamethoxam adversely affect the predation of H. axyridis, both via direct contact and ingestion. Evaluating the potential impacts of these insecticides on H. axyridis is critical for the development of effective IPM strategies targeting D. citri. Full article

This study investigates the nematicidal efficacy of Purpureocillium lilacinum strain (AUMC 10620) combined with avermectin (B1a and B1b) against the citrus nematode Tylenchulus semipenetrans, both in vitro and in vivo. Laboratory experiments tested four concentrations of P. lilacinum (2.5, 5, 10, and 15 × 10⁷ spores/mL) mixed with 250 ppm avermectin, assessing their effects on nematode juveniles (J2) and eggs. Results showed significant increases in juvenile mortality and egg hatching inhibition with the combined treatments compared to individual applications. The highest concentration (15 × 10⁷ spores/mL + 250 ppm avermectin) achieved 100% juvenile mortality and 83.33% egg hatching inhibition after 72 h. Field trials confirmed the superior efficacy of the combined treatment, with P. lilacinum (15 × 10⁷ spores/mL) and avermectin (1000 ppm) reducing nematode populations by 70.85% in mandarin trees and 70.77% in sweet orange trees after three weeks, compared to the 83.59% and 81.76% reduction, respectively, achieved by oxamyl. These findings suggest that mixtures of P. lilacinum and avermectin can serve as effective, eco-friendly alternatives for controlling nematodes in citrus orchards. Full article

Sitophilus oryzae, Tribolium castaneum, Tribolium confusum, Oryzaephilus surinamensis, Rhyzopertha dominica, Tenebrio molitor, Trogoderma granarium, Acarus siro, and Alphitobius diaperinus represent significant arthropod stored-product pests worldwide. To combat these noxious arthropods, the current study examines the pesticidal effect of essential oils (EOs) derived from four aromatic plants, i.e., Illicium verum Hook. F., Citrus reticulata Blanco, Monodora myristica (Gaertn.) Dunal, and Xylopia aethiopica (Dunal) A. Rich. Considering the challenge of pesticide resistance, the current study focuses on assessing the efficacy of these EOs as an eco-friendly alternative to traditional synthetic insecticides. Two EO concentrations (500 and 1000 µL/kg wheat) were applied to different life stages of these pests in the bioassays. Mortality rates were monitored over several days under controlled environmental conditions. The findings demonstrated that C. reticulata and I. verum EOs had elevated insecticidal effects, especially against larval stages, resulting in 100% mortality in several species. On the contrary, M. myristica and X. aethiopica EOs showed less overall efficacy despite their potency against some pests. Both I. verum and C. reticulata EOs outperformed the positive control, pirimiphos-methyl, in several assays. The results of the current study highlight the potential of several EOs as effective alternatives in reducing synthetic pesticide use for integrated pest control management. Full article

Asian citrus psyllid (ACP), Diaphorina citri (Hemiptera: Liviidae), is one of the most devastating pests in citrus orchards due to its role in transmitting Huanglongbing (HLB). Currently, chemical control remains the most effective strategy for ACP management. Mineral oils are commonly used as insecticides or adjuvants in integrated pest management (IPM) practices. To extend the product life of synthetic pesticides, we evaluated the toxicity of chlorpyrifos (CPF), thiamethoxam (THX), or pyriproxyfen (PPF) mixed with mineral oil Lvying (LY) against ACP nymphs under different weather conditions. Individual application of CPF, THX, and PPF effectively controlled against ACP nymphs under no rain conditions, with mortality rates varying from 20 to 100% during 1–5 d after treatment. The addition of LY at 1.0% or 0.5% rates to CPF, THX, and PPF significantly enhanced their control efficacy, achieving sustained mortality rates from 60 to 100% during the same period. Light rain had less impact on the control efficacy of these insecticide mixtures compared to individual insecticides. However, cumulative rainfall above 20 mm significantly reduced the control efficacy of individual insecticides and their mixtures. The addition of LY decreased both surface tension and contact angle of THX solution on citrus leaves, thereby enhancing the solution’s wetting and increasing THX deposition. Moreover, the rainfastness of THX was improved after adding LY, leading to a greater retention on the leaves. LY at a rate of 1.0% exhibited excellent efficacy against ACP nymphs, and observations using scanning electron microscopy (SEM) showed that LY altered ACP mouthpart morphology and blocked spiracles, likely contributing to its insecticidal effects. This study revealed that mineral oils can serve as both insecticides to combine with synthetic pesticides for enhancing toxicity against ACP and as adjuvants to facilitate the deposition and rainfastness of synthetic pesticides on leaves, which could be recommended for sustainable ACP management in citrus orchards. Full article

The tightening of sanitary and phytosanitary (SPS) regulations, along with stringent private standards in international fresh produce trade, requires citrus producers, especially in developing regions, to adopt robust compliance mechanisms. This study examines the integration of a Risk Management System (RMS) into the existing Quality Management System (QMS) of citrus producers in the Western Cape (WC), South Africa, aimed at improving adherence to European Union (EU) market requirements. Through a comprehensive survey of citrus producers, the research identifies the primary barriers to effective risk management integration, such as financial constraints, limited human resources, and the prevalent non-compliance in the export chain, including pest infestations and exceeding Maximum Residue Limits (MRLs). The results highlight the fact that producers of varying scales face substantial challenges in resource allocation for RMS implementation. The study advocates for a strategic, top-down integration approach, which includes targeted financial support, the establishment of dedicated teams, and well-structured implementation plans. Additionally, the role of both governmental and private sector support is emphasised, particularly in providing training, technical assistance, and infrastructure investments to strengthen compliance efforts. These actions are crucial for ensuring sustained market access, enhancing the competitiveness of citrus producers, and promoting sustainable agricultural practices in the global market. Full article

Citrus rust mites (Phyllocoptruta oleivora Ashmead) are a major pest in citrus orchards, significantly affecting fruit quality and yield. Effective management of these mites is crucial for maintaining the economic viability of citrus production. This study investigated the ecological distribution of citrus rust mites and their natural predator, A. largoensis, in a mandarin orchard in Zengcheng District, Guangzhou City, of China. This research focused on population densities across different orchard sections and assessed the impact of mite infestations on the biochemical composition of mandarins, including vitamin C, soluble solids, acidity, and mineral content. Results showed that citrus rust mite populations were highest in the southern and western sections of the orchard. Infested fruits had reduced vitamin C and soluble solids but increased acidity and calcium levels. A. largoensis exhibited a strong functional (Type II) and numerical response, with higher predation rates and reproductive output for moderate prey densities. The findings emphasize the importance of targeted pest management strategies in citrus rust mite hotspots and highlight A. largoensis as a promising biological control agent. Future research should optimize its use in integrated pest management programs by focusing on areas of the orchard with high mite densities. Full article

Integrated pest management based on the use of biopesticides is largely applied. Experimental bioassays are critical to assess biopesticide biosafety at the ecotoxicological level. In this study, we investigated the effects of the new Bacillus thuringiensis subsp. kurstaki (Btk)-formulated-based biopesticides BLB1 and Lip, efficiently tested in field assays (IPM-4-CITRUS EC project no. 734921) on two aquatic non-target organisms, precisely the water flea Daphnia magna and the bioluminescent bacteria Aliivibrio fischeri. Acute toxicity studies, carried out in a comparative manner with Delfin^® as the reference bioproduct and the lactose-based Blank formulation, show that no significant toxicity was observed up to 1 g/L. Our results indicated that BLB1- and Lip-formulated new bioproducts are far less toxic than the Delfin^® reference bioproduct. Full article