Endosymbiotic bacteria play fundamental roles in arthropod biology, by influencing development, reproduction, and ecological interactions. Among them, Wolbachia is the most widespread and impactful symbiont, capable of manipulating host reproduction through mechanisms such as cytoplasmic incompatibility (CI), parthenogenesis induction, and other reproductive alterations. This study investigated the effects of tetracycline-mediated reduction of Wolbachia infection on key biological traits and reproductive compatibility in Encarsia lutea, a parasitoid of Bemisia tabaci. Given the importance of E. lutea in biological control programmes, the study further evaluated whether changes in Wolbachia infection status affect parasitoid survival, longevity, parasitisation capacity, and reproductive compatibility tetracycline-treated and untreated individuals. Wolbachia infection was confirmed using diagnostic PCR. A tetracycline-treated line was maintained for two generations, and newly emerged third-generation adults were used for longevity and parasitism assays. The results indicate that tetracycline treatment significantly reduced the survival rates and longevity of both male and female E. lutea with females showing a significant decline in fitness compared to untreated controls. Mating experiments demonstrated that crosses between uninfected females and infected males resulted in no progeny. Given the heteronomous biology of E. lutea, in which males develop on alternative hosts and only females emerged under the experimental conditions, the absence of offspring indicates CI-induced embryonic mortality of fertilised eggs. These findings provide insights into the reproductive biology of Wolbachia-infected E. lutea populations and have important implications for the optimising mass-rearing strategies and the efficacy of biological control programmes involving this and related parasitoid species.
Strongylids are among the most prevalent helminths affecting equines and are responsible for significant health and economic losses. This study evaluated the efficacy of aqueous suspensions and oil-based formulations of the entomopathogenic fungus Beauveria bassiana against equine gastrointestinal nematodes under laboratory and semi-natural conditions during the rainy and dry seasons in the Rec & ocirc;ncavo region of Bahia, Brazil. Faecal samples were collected from naturally infected equines. Four treatment groups were established: water control, oil control, aqueous suspension of B. bassiana, and oil-based formulation of B. bassiana. Semi-natural assays were conducted using pots containing Urochloa brizantha MG-5, while in vitro assays consisted of quantitative stool cultures. The fungal product used was Boveril (R) WP (B. bassiana), and nematode larvae were recovered and quantified using the Baermann technique. Under laboratory conditions, efficacy reached 80.4% for the aqueous suspension and 92% for the oil-based formulation. In semi-natural assays, the aqueous suspension showed low efficacy during both the rainy 10.51% and dry 14.28% seasons. In contrast, the oil-based formulation achieved high efficacy during the rainy season 92.59% and moderate efficacy during the dry season 46.9%. Soil analysis confirmed fungal persistence under both climatic conditions, with B. bassiana remaining detectable up to 52 days after application. The most frequently identified larvae were Strongyloides westeri, cyathostomins, Strongylus equinus, and Strongylus vulgaris. These results demonstrate that oil-based formulations of B. bassiana are effective against immature stages of equine gastrointestinal nematodes, particularly under favourable environmental conditions.
The present study aimed to evaluate the virulence and reproductive potential of four new and native strains of entomopathogenic nematodes (EPNs), Heterorhabditis casmirica SKUAST-K 101, H. casmirica SKUAST-K 103, H. casmirica SKUAST-K 104 and Steinernema anantnagense SKUAST-K 101 against cabbage butterfly, Pieris brassicae (L.) (Lepidoptera: Pieridae), a serious pest of cauliflower in Kashmir valley. Laboratory bioassays were conducted against different larval instars to determine median lethal concentration (LC50), median lethal time (LT50), and reproductive potential within the host, followed by field evaluation of the most promising strains. LC(50)values were directly proportional to the larval size of the insect but inversely proportional to the time interval. Similarly, LT50 values were directly proportional to the size of the insect larva but inversely proportional to the nematode concentration, irrespective of the nematode strain. Multiplication rate of nematode within the host was also directly related to the size of the insect host. Under laboratory conditions, the best performance was shown by H. casmirica SKUAST-K 103 followed by H. casmirica SKUAST-K 101, H. casmirica SKUAST-K 104 and S. anantnagense SKUAST-K 101 in killing the host and producing progenies. Under field conditions, H. casmirica SKUAST-K 103 at the rate of 3.0 & times; 10(5) IJs m(-)& sup2; caused highest larval mortality (77.9%) that ultimately resulted in 48.5% increase in crop yield as compared to control. The higher pathogenicity and faster killing speed highlight the potential of H. casmirica SKUAST-K 103 as a promising candidate for biological control applications.
Australian Acacia species are invasive in South Africa and traditionally controlled through felling followed by herbicide application to the stumps. In some instances, a cleared area is burnt or felled, and biomass is removed where affordable. Seed-attacking biological control agents have been released against these Acacia species to reduce spread. Here, we studied the changes in the abundance of Acacia saligna (Labill.) H. L. Wendl. (Fabaceae) and Acacia cyclops A. Cunn. ex G. Don (Fabaceae), in the presence of biological control, to assess whether investments made in the development of the biological control agents contributed to conventional control. Biological control had no meaningful impact in the short-term (up to six years) and resulted in no material cost reductions in other control interventions over this period. However, for the medium-term (up to 12 years), substantial cost reductions in alternative control methods were recorded. Considering the 12-year assessment period, the most realistic estimated savings per hectare of land treated amounted to USD304. Savings were higher (USD322) where both burn scars and areas with evidence of biomass removal were included. For the long-term (22 years), the impact of biological control was substantial, with the cost of control being reduced by between USD831 and USD827/ha for two scenarios using the Le Maitre (1998. An analysis of invasion processes and risks and a strategy for modelling invasions by alien plant species at a national and regional scale. Appendix 7. In D. B. Versfeld, D. C. Le Maitre, & R. A. Chapman (Eds.), Alien invading plants and water resources in South Africa: A preliminary assessment. Report TT99/98. Water Research Commission) and Higgins et al. (2000. Using a dynamic landscape model for planning the management of alien plant invasions. Ecological Applications, 10(6), 1833-1848) models as benchmarks. Biological control of these two Acacia species contributed materially to reducing the cost of conventional control methods, but this saving was realised in the medium to long-term.
To identify the natural enemy species closely associated with Brevipalpus obovatus Donnadieu in Wuniuzao and Huangshan large-leaf tea plantations, clustered sample variance analysis combined with grey correlation analysis was employed to study the spatial relationships between B. obovatus and natural enemies. Concurrently, the spatial distribution patterns, aggregation causes and ranges of B. obovatus within tea plantations were analyzed using diffusion coefficient, mean population aggregation and rho-index respectively. The correlation analysis between the number of clustered plots for B. obovatus and natural enemies revealed that the four natural enemies most closely associated spatially with the mite were the spiders Plexippus setipes Karsch, Clubiona reichlini Fabricius, the ladybug Harmonia axyridis Pallas and Plexippus paykulli Andouin. The population diffusion coefficients of B. obovatus were greater than F-0.05 when the number of basic quadrats K in a cluster was 1 or 2 in Wuniuzao tea plantation on two survey days and Huangshan large-leaf tea plantation on one survey day, indicating a clustered distribution pattern. The mean population aggregation lambda of the pest exceeded 2 in most instances, indicating self-driven clustering. The minimum range of individual aggregation was determined by rho-indices of B. obovatus in different cluster sizes. The optimal sampling quadrat size in Wuniuzao tea plantations was 1 basic quadrat (2 m & sup2;), while in Huangshan large-leaf tea plantations, it was 8 basic quadrats (16 m & sup2;). These findings provided a scientific foundation for determining quadrat size when sampling B. obovatus, as well as for protecting and utilising the dominant natural enemy species during biological control.
Maize sheath blight caused by Rhizoctonia solani is a destructive disease threatening global maize production. Chemical control leads to environmental pollution and residues, so eco-friendly biocontrol strategies are urgently needed. However, single Bacillus strains often show unstable efficacy, and the synergistic system combining Bacillus co-culture with vetch fertiliser remains poorly studied. We hypothesized that co-culture of biocontrol bacteria could enhance disease control and plant growth via direct antagonism and host defense induction. Two antagonistic strains, 24-2 (Bacillus subtilis) and 26-2 (B. amyloliquefaciens), were screened and identified. In dual culture, the percent inhibition of radial growth (PIRG) reached 79.05% and 79.63%, respectively. Co-culture at a 2:8 ratio produced fermentation broth with 64.44% inhibition, significantly higher than single strains (p < 0.05). Pot experiments showed that microbial vetch fertiliser (MVF, decomposed vetch straw: co-culture broth = 6:1) significantly promoted maize growth. Compared with the control, plant height increased by 14.84%, stem diameter by 23.47%, and chlorophyll SPAD by 11.25% (p < 0.05). SOD and POD activities were 1.71-and 2.17-fold higher (p < 0.05), indicating activated plant defense. This study provides a novel synergistic biocontrol system for maize sheath blight, supporting sustainable agricultural disease management.
This study aimed to isolate and select endophytic bacterial strains from banana plants with antagonistic activity against Fusarium oxysporum f. sp. cubense TR4 (Foc TR4), the pathogen responsible for Fusarium wilt, and with potential to enhance the growth of banana plants. Twelve endophytic bacterial strains were isolated from different parts of Cavendish bananas collected from several provinces in southern Vietnam. Among them, three isolates exhibited the highest inhibitory effects on Foc TR4 mycelial growth, with inhibition of 78.1% (R-BHDN2.2), 66.71% (R-DPBP1.3), and 61.11% (R-TCTV2.3), respectively. All three isolates demonstrated bioactivities, with maximum values recorded for indole-3-acetic acid (IAA) production (85.49 +/- 8.98 & micro;g/mL), siderophore production (94.40 +/- 3.98 & micro;g/mL), and phosphate solubilisation (314.45 +/- 10.91 & micro;g/mL). Biochemical assays and 16S rDNA sequencing identified the three isolates as Pseudomonas putida R-TCTV2.3, Bacillus amyloliquefaciens R-DPBP1.3, and Bacillus siamensis R-BHDN2.2. In greenhouse experiments, these endophytic strains significantly suppressed Fusarium wilt in the tissue of Cavendish bananas, with the lowest disease incidence (26.7%) and disease index (26%) observed in the treatments compared to 98% and 100%, respectively, in the untreated and Foc TR4 inoculated controls. The highest biocontrol efficacy was achieved at 73.3% (B. siamensis R-BHDN2.2). In addition, these bacterial strains were able to affect the growth of banana plants, such as increasing plant height, stem diameter, and root dry matter. This study demonstrates that endophytic bacteria isolated from Cavendish bananas possess strong biocontrol potential against Fusarium wilt caused by Foc TR4 and promote plant growth.
The development of microbial herbicides in the alpine ecological zone of the Qinghai-Tibet Plateau remains largely unexplored. This study isolated strain HL-12 from naturally infected Setaria viridis leaves and evaluated its herbicidal potential. The taxonomic status of HL-12 was determined through morphological characteristics and multi-locus (ITS, 28S rDNA-LSU, and TEF1-alpha) phylogenetic analysis. Its herbicidal potential was assessed against four dominant broadleaf weeds in the Qinghai-Tibet Plateau (Chenopodium album, Elsholtzia densa, Malva verticillata, and Senecio vulgaris) using detached leaf and pot experiments. Safety evaluations were conducted on six major crops and three cold-tolerant vegetables in Qinghai Province. Scanning Electron Microscopy (SEM) was employed to observe the infection mechanisms, and nutritional optimisation experiments identified the optimal carbon and nitrogen sources. HL-12 was identified as Bipolaris sivanesaniana. Seven days post-inoculation, disease incidence rates in potted plants of the four species listed above reached 90.48%, 90%, 100%, and 100%, respectively. Regarding crop safety, HL-12 was safe for Triticum aestivum and Solanum melongena but unsafe for Hordeum vulgare, Zea mays, Brassica napus, Cucumis sativus, Solanum lycopersicum, Vicia faba, and Pisum sativum. The hyphae of HL-12 invaded S. vulgaris leaves through stomata and wounds. Corn meal and soybean meal were identified as the optimal carbon and nitrogen sources, respectively, as they yielded superior mycelial growth and spore production. Strain HL-12 demonstrates good potential as a bioherbicide agent in alpine regions. Further optimisation of culture parameters, formulation development, and field efficacy evaluation are warranted.
Haemonchus contortus limits sheep production through severe clinical symptoms and, sometimes, death in young animals. Overuse of anthelmintics has led to drug-resistant parasites, threatening animal health. The oral administration of suspensions of the fungi Arthrobotrys musiformis (Am) and Duddingtonia flagrans (Df) to reduce infective larvae in sheep faeces was assessed. Twenty-four infected sheep were divided into three groups: Am, Df, and a control. Both fungi significantly reduced larval counts compared to the control. Maximum reductions were 90.7% (Am, day 3) and 96.4% (Df, day 11). This study shows that nematophagous fungi can help to reduce the contamination by H. contortus larvae in sheep faeces.
To enhance the stress resistance of agricultural biocontrol fungi, this study developed a starch-based microcapsule delivery system using food extrusion technology. Food-grade flour was used as the wall material, and a one-step low-temperature extrusion process simultaneously encapsulated the model biocontrol agent Purpureocilliumlilacinum spores and tomato extract. The microcapsules exhibited sustained-release behaviour in water, with spore release peaking at 24 h and solubility increasing from similar to 20% to similar to 80% within 3 d. Particle size gradually decreased from similar to 550 mu m to similar to 35 mu m during immersion. Microencapsulation improved spore survival after short-term heat treatment (60 degrees C, 2 h), although prolonged exposure still caused marked viability loss. SEM, XRD, and FT-IR analyses showed that extrusion induced starch gelatinisation and V-type crystal formation, generating a dense protective matrix stabilised by hydrogen bonding. Tomato extract provided flavour and nutritional support while demonstrating the feasibility of co-encapsulation through extrusion. Overall, this work presents a preliminary biodegradable formulation strategy for fungal biocontrol agents and a potential platform for developing controlled-release agricultural biocontrol products.
Considering the global challenge of artificial multiplication of biocontrol agents in managing agricultural pests, our study attempted to develop an amenable, cost-effective multiplication technique for two indigenously identified parasitoids, Trichogramma chilonis and Trichogramma evanescens, on locally available host wax moth (Galleria mellonella) eggs in varied temperatures (15, 20, 25, 30, and 35 degrees C) and humidity regimes (55, 65, and 75%), following a completely randomised design with three repetitions. According to the three-way ANOVA, the individual and combined effects of two factors, temperature and humidity, differed significantly for most of the studied variables, except for the factor of parasitoids. Maximum adult emergence was achieved at 25 degrees C with 65% relative humidity for both species, T. chilonis and T. evanescens. A combination of 25 degrees C with 65% RH turned out to be the optimal abiotic conditions for most of the variables, such as parasitoid longevity, fecundity, egg mortality, and male-female ratio. Notably, no statistical variation was recorded between 25 degrees C and 30 degrees C alongside 65% and 75% RH. Correlation analysis demonstrated that temperature had a significant positive relation with all variables, while cubic regression indicated that increased temperature up to a certain point accelerated the adult emergence rate and egg parasitising rate, explaining 76.3% and 71.6% variability, respectively. Principal component analysis identified fecundity and oviposition period as key variables accounting for the maximum variance. Additionally, a three-variable contour depicted a significant positive relation between egg emergence rate and egg parasitising rate (0.84**). Thus, the research findings paved the way for parasitoid mass rearing at low investment, facilitating sustainable, eco-efficient management of lepidopteran agricultural pests.
This study evaluated the antimicrobial activity of three Bacillus strains (dhm1-dhm3: B. amyloliquefaciens, B. velezensis, and B. subtilis) and two Trichoderma strains (dhm4-dhm5: T. harzianum, T. asperellum) against maize stalk rot (F. graminearum) and watermelon wilt (F. oxysporum f. sp. niveum) via dual culture. The strains were co-fermented with vetch straw to develop microbial vetch fertiliser (MVF-1 for maize, MVF-2 for watermelon), of which the disease-suppressive, growth-promoting, and chemical fertiliser-reducing effects were verified through pot and field trials. T. asperellum dhm5 exhibited the highest inhibition rates (89.0-91.8%). Pot experiments showed MVF-1 increased maize dry weight by 42.8% and MVF-2 reduced watermelon wilt incidence by 28.6%. Combined with reduced chemical fertiliser, MVF performed superiorly to full chemical fertilisation. Field trials confirmed MVF-1 increased maize yield by 77.0% and reduced disease incidence by 62.5%, while MVF-2 elevated watermelon yield by 72.7% and lowered disease incidence by 64.2%. This novel MVF integrates yield enhancement, disease control, and chemical fertiliser reduction, providing a viable strategy for sustainable agriculture.
Aedes aegypti and Aedes albopictus are major vectors of medically important arboviruses established in Misiones Province, Argentina, where projected expansion highlights the need for sustainable control. We evaluated sixteen Argentine oomycete isolates (eleven Leptolegnia chapmanii, one Leptolegnia caudata, three Leptolegnia spp., one Geolegnia helicoides) against larvae of both species. Mortality at 24 and 48 h was analysed using Firth's penalised logistic regression with & Scaron;id & aacute;k-adjusted pairwise comparisons. All isolates caused significantly higher mortality than controls at 48 h (P < 0.001). Four L. chapmanii isolates produced >80% mortality, providing the first quantitative evidence that Argentine oomycetes are pathogenic to Ae. albopictus.
In 2021, Lilioceris egena (Weise) was introduced in Florida as a biocontrol agent of the air potato vine, Dioscorea bulbifera L. This beetle feeds primarily on the vine's aerial reproductive structures known as bulbils. Due to Florida's latitudinal gradient, the state experiences a wide range of temperatures that can affect the reproduction of L. egena. To understand the impact of temperature on L. egena's reproduction, we evaluated oviposition, development, and fecundity life table parameters at five constant temperatures (10, 15, 20, 25, and 30 degrees C). Adult beetles held at 25 and 30 degrees C laid significantly more eggs than those held at 15 and 20 degrees C, whereas no eggs were laid at 10 degrees C. The optimal temperature for oviposition ranged from 26.2 - 27.1 degrees C. Only eggs held at 20 and 25 degrees C reached adulthood, with those at 25 degrees C developing twice as fast as those kept at 20 degrees C. Beetles maintained at 25 degrees C exhibited the longest oviposition period and the highest intrinsic rate of increase. Additionally, we monitored the longevity and survival of L. egena adults feeding solely on air potato leaves, bulbils, and a combination of both. These structures correspond to different phenological stages of air potato. Beetles that fed exclusively on leaves had the longest lifespan and survival. Our results provide a better understanding of L. egena biology under different temperatures, its response to air potato phenology, and a foundation for future research towards increasing its population growth and establishment in Florida.
Haemonchus contortus is a parasite of ruminants that causes significant economic losses on farms worldwide. Purpureocillium lilacinum (Pl), a member of the Hypocreales group, is a natural enemy of nematodes. Pl invades nematodes and produces bioactive nematocidal compounds. This study aims to investigate the major compounds produced by Pl using bio-fermentation and to identify the ovicidal activity (Oa) of its fungal extract against H. contortus. The extract was fractionated using chromatography techniques. The highest Oa (90%) was observed at a concentration of 40 mg/mL (Reunions 13-16). Meanwhile, at 10 mg/ml in reunions 21 and 24, an 83.7% ovicidal activity (Oa) was achieved. From these reunions, two fractions - F8 and F28 - were collected and subsequently analysed by HPLC. Gallate group derivatives were identified and may be linked to Oa.
Laboratory experiments were conducted to determine the efficacy of entomopathogenic nematodes (EPN), Steinernema kushidai and Heterorhabditis bacteriophora, against the adults of banana leaf and fruit scarring beetle, Basilepta subcostatum (Jacoby). Both EPN species were pathogenic against B. subcostatum, exhibiting time and dose-dependent mortality. The infective juveniles (IJs) of S. kushidai achieved 95% mortality, while those of H. bacteriophora caused 90% mortality at 300 IJs/adult after 120 h compared to 30% mortality in the control. S. kushidai was found to be more pathogenic than H. bacteriophora based on LD50 and LT50 values. The lowest LD50 and LT50 values obtained for S. kushidai were 97.3 IJs/adult and 53.9 h, respectively, while those of H. bacteriophora were 153.2 IJs/adult and 62.2 h, respectively. Considering the pathogenic potential at 72 h, the lethal dose, 265.0 IJs/adult for S. kushidai and 284.9 IJs/adult for H. bacteriophora were further evaluated in formulations with chitosan or Aloe vera gel and compared with imidacloprid 17.8 SL 0.3%, castor oil 3% and water (control). S. kushidai with chitosan 5 g/L H20 achieved 100% mortality after 168 h, which was significantly at par with imidacloprid 17.8 SL (100%) and castor oil (100%). H. bacteriophora with chitosan 5 g/L H20 resulted in 93.3% mortality after 168 h.
