Biological Control Options Research Articles

Influence of Prey Consumption on the Predatory Potential and Biological Parameters of Exochomus nigripennis (Erichson) Against Phenacoccus solenopsis Tinsley and Icerya seychellarum (Westwood)

Phenacoccus solenopsis Tinsley and Icerya seychellarum (Westwood) are recent invasive sap-sucking insects in Egypt. Exochomus nigripennis (Erichson) being a viable option for conventional biological control. In the laboratory of the Plant Protection Research Institute, Agricultural Research Centre, Egypt, the biological parameters and predatory potential of E. nigripennis were assessed using P. solenopsis and I. seychellarum as preys. Fourth instar E. nigripennis larvae was recorded the highest average total consumption of 455 individuals, with a feeding capacity of 43.10 when reared on P. solenopsis. While the third larval instar of E. nigripennis consumed the maximum number of I. Seychellarum 43.11 with a feeding capacity of 45.18 compared to other instars. E. nigripennis females had a lifespan of 30.9 ± 1.21 days, and consuming 3255 preys on P. solenopsis, while males had a feeding capacity of 2198.64. The immature stages of E. nigripennis varied significantly based on the prey species. Larvae developed faster on I. Seychellarum, while pupal periods were shortest on I. Seychellarum and longest on P. solenopsis. The shortest development time was on I. Seychellarum (22.8 days), while the longest was on P. solenopsis (30.37 days). The longevity and reproduction of E. nigripennis were significantly influenced by the preys they were reared on. Males and females fed on P. solenopsis exhibited longer survival and females had an extended oviposition period. The fecundity was highest when females were fed P. solenopsis supplemented with sugar solution. The study suggests that an integrated pest management program can effectively manage P. solenopsis and I. seychellarum, by utilizing E. nigripennis as a biological control agent, making it suitable for mass rearing in agricultural ecosystems.

Hemp regulates the fitness of corn earworm (Lepidoptera, Noctuidae) and its tachinid (Diptera) parasitoids.

Pest management on hemp is still in its infancy, and biological control options are limited. Helicoverpa zea (corn earworm) is one of the key pests of hemp cultivated outdoors, especially on cultivars grown for cannabinoids and grain. In a three-year study, we assessed the effect of diet on the performance of H. zea and its tachinid parasitoids. Parasitized (bearing fly eggs) and unparasitized (without eggs) H. zea larvae were fed on hemp flowers or an artificial diet. Five tachinid species parasitized H. zea larvae, but the most abundant species were Winthemia rufopicta (68.8%) and Lespesia aletiae (28.3%). Overall, 55.2% of H. zea larvae bearing tachinid eggs died, while the mortality of unparasitized larvae reached 24.7%. The success of tachinids increased by 2-fold when the host larvae were fed on an artificial diet. Our results demonstrated that high protein food (artificial diet), intensity of parasitism, and caterpillar size play a role in the fitness of both the herbivores (H. zea) and its tachinid parasitoids. These findings have important implications for understanding biological control mechanisms and open new insights into the impact of landscape variation on plant-herbivore-parasitoid interactions. This study contains supporting evidence that makes both Winthemia rufopicta and Lespesia aletiae excellent candidates for biological control programs against H. zea, a key pest of hemp in the United States.

Metarhizium-Inoculated Coffee Seeds Promote Plant Growth and Biocontrol of Coffee Leaf Miner.

Metarhizium (Hypocreales: Clavicipitaceae) has a multifunctional life cycle, establishing as a plant endophyte and acting as entomopathogenic fungi. Metarhizium robertsii and Metarhizium brunneum can be associated with coffee plants and provide enhanced protection against a major pest of coffee, the coffee leaf miner (CLM) (Leucoptera coffeella). This association would be an easily deployable biological control option. Here we tested the potential of inoculating coffee seeds with M. robertsii and M. brunneum collected from the soil of coffee crops in the Cerrado (Brazil) for control of the CLM and the enhancement of plant growth with a commonly used fungicide. We conducted the experiment in a greenhouse and after the seedlings grew, we placed them in a cage with two couples of CLMs. We evaluated the CLM development time, reproduction, and plant growth traits. We observed a longer development time of CLMs when fed on plants inoculated with both isolates. In addition, the CLMs laid fewer eggs compared to those fed on plants without fungal inoculation. Plant growth was promoted when seeds were inoculated with fungi, and the fungicide did not affect any evaluated parameter. Coffee seed inoculation with M. robertsii and M. brunneum appears to provide protection against CLMs and promote growth improvement.

Comparative susceptibility of adult house fly (Diptera: Muscidae) and an important predator, Carcinops pumilio (Coleoptera: Histeridae), to Beauveria bassiana (Hypocreales: Cordycipitaceae).

House flies (Musca domestica L.) (Diptera: Muscidae) are challenging pests to control. Biological control using Carcinops pumilio beetles may help to reduce house fly populations. However, it is unknown if C. pumilio beetles are compatible with Beauveria bassiana, another house fly biological control option. Five strains of commercially available (GHA, HF23, and L90) and newly discovered (NFH10 and PSU1) strains of B. bassiana were used to test the comparative susceptibility of adult house flies and adult C. pumilio using different laboratory exposure methods. Adult house flies were susceptible to B. bassiana in contact filter paper assays (89%-98% mortality) and immersion assays (100% mortality) at the same 108 conidia suspension using 0.1% CapSil as an aqueous surfactant. Carcinops pumilio were less susceptible than flies to B. bassiana infection using the contact and immersion assays at the same 108 conidial concentration, with 4.4%-12.2% and 8.3%-24.6% mortality, respectively. Immersion in an aqueous conidial suspension resulted in higher mortality compared to contact with treated filter papers at the same 108 concentration with house flies and beetles. We conclude that C. pumilio can safely be used as a biological control agent for house flies with B. bassiana in animal production systems.

Screening of Endophytic Antagonistic Bacteria in Wheat and Evaluation of Biocontrol Potential against Wheat Stripe Rust.

Wheat stripe rust is globally one of the most important diseases affecting wheat. There is an urgent need to develop environmentally safe and durable biological control options to supplement the control that is achieved with breeding and fungicides. In this study, endophytic bacteria were isolated from healthy wheat through the tissue separation method. Antagonistic endophytic bacteria were screened based on the control effect of urediniospore germination and wheat stripe rust (WSR). The taxonomic status of antagonistic strains was determined based on morphological, physiological, and biochemical characteristics and molecular biological identification (16S rDNA and gyrB gene sequence analysis). Finally, the potential growth-promoting effect of different concentrations of antagonists on wheat seedlings and the biological control effect of WSR were studied. A total of 136 strains of endophytic bacteria belonging to 38 genera were isolated. Pseudomonas was the most common bacterial genus, with 29 isolates (21%). The biological control effect of different isolates was assessed using an urediniospore germination assay. The isolate XD29-G1 of Paenibacillus polymyxa had the best performance, with 85% inhibition of spore germination during primary screening. In the deep screening, the control effect of XD29-G1 on wheat stripe rust was 60%. The antagonist XD29-G1 promoted the germination of wheat seeds and the growth of wheat seedlings at a solution dilution of 10-7 cfu/mL. The pot experiment results showed that different dilution concentrations of the strain had different levels of antibacterial activity against WSR, with the concentration of 10-1 cfu/mL having the best control effect and a control efficiency of 61.19%. XD29-G1 has better biological control potential against wheat stripe rust.

Evaluation of the green lacewing, Mallada signatus as a biological control agent for the invasive tomato potato psyllid, Bactericera cockerelli

Evaluation of the green lacewing, <i>Mallada signatus</i> as a biological control agent for the invasive tomato potato psyllid, <i>Bactericera cockerelli</i>

Biology, impact, management and potential distribution of Aromia bungii, a major threat to fruit crops around the world

AbstractAromia bungii Faldermann (Coleoptera: Cerambycidae) is an emerging invasive pest of economically important Prunus species that is native to China, Mongolia, the Russian Far East, Korea, and Vietnam. It was recently introduced to Japan, Germany, and Italy, where it is spreading and damaging crops and ornamental trees. It exhibits an adaptable lifecycle, a high reproductive output, and the larvae live concealed under the bark of infested trees, which are traits that promote its invasiveness. Detection and monitoring of A. bungii currently rely upon visual identification of infested trees that are usually already damaged, which is inefficient and not target-specific. Current control methods rely primarily upon the labour-intensive physical removal of infested trees. Although native parasitoid natural enemies of A. bungii provide control in Chinese orchards, none are appropriate for classical biological control in invaded areas due to biosafety concerns surrounding their broad host ranges. However, entomopathogenic fungi and nematodes may provide viable options for biological control in invaded ranges. Recent advancements in semiochemical baited traps may provide sustainable, target-specific, and efficacious methods to monitor and control A. bungii. There remains much to learn about the biology and control of A. bungii, and continued advancements in the study of sustainable control tools are needed for the management of this emerging pest.

Nut bush pesticide limits: urgent need for a comprehensive strategy to address current and emerging insect pests and insecticide options in the Australian macadamia industry.

In Australia, macadamia orchards are attacked by four main insect pest groups. Management and control of three of these key pests currently relies on broad-spectrum insecticides whose long-term future is questionable. Of the 23 insecticides registered for use in macadamia in Australia, 19 face issues affecting their availability and 12 are presently not approved in the EU, the USA or Canada. These international markets may refuse produce that does not adhere to their own insecticide use standards, hence Australian produce may be excluded from market access. Many of the potential replacement integrated pest management methods of pest control are generally considered less effective by the industry and have not been adopted. There are 17 insect pest groups identified by the industry, any of which have potential to become major problems if broad-spectrum insecticide options become unavailable. Thirteen pest groups need urgent attention as they are at risk of losing current effective control methods, and no replacement solutions have yet been developed. The lag period for research and development to identify new chemical and biological control solutions means there is now an urgent need for the macadamia industry to craft a strategy for sustainable pest management for each pest. Critically, this industry strategy needs to address the vulnerabilities identified in this paper, identify potential solutions for any cases of market failure and consider funding mechanisms to address these gaps. On economic and sustainability grounds, potential biological control options should be explored, especially in cases where insecticide control options are vulnerable. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Evaluation of augmentative biological control options against fruit and shoot borer, Conogethes punctiferalis (Guenée) (Lepidoptera: Crambidae) in guava in India

BackgroundConogethes punctiferalis (Guenée) (Lepidoptera: Crambidae) has emerged as one of the important pests of guava in Punjab, India. Chemical insecticides have been used for its management, which could have serious implications on environmental and human health. As an alternative to chemical insecticides, biocontrol is the most appropriate alternative for its eco-friendly management. Two field experiments were therefore, conducted to evaluate efficacy of two biocontrol agents, Trichogramma chilonis Ishii (Hymenoptera: Trichogrammatidae) (egg parasitoid) and Chelonus blackburni Cameroon (Hymenoptera: Braconidae) (egg-larval parasitoid) against the borer during rainy season, 2020 and winter season, 2020–21.ResultsFour releases of both parasitoids at various dosages were carried out at weekly intervals starting from first week of July in rainy season and first week of October in winter season. Trichogramma chilonis @ 2000 parasitized eggs per tree was the best in reducing the fruit damage and increasing yield and net income over check in both rainy as well as winter season crops. There was 73.6% reduction in damage over control, 1.70 Metric tons (MT) increase in yield over control and 258.36 US $ per acre increase in net income over control in rainy season crop. During winter season, there was 62.5% reduction in damage, 1.98 MT increase in yield and 488.23 US $ per acre increase in net income over control.ConclusionFour augmentative releases of T. chilonis @ 2000 parasitized eggs per tree successfully controlled the fruit and shoot borer incidence in guava during rainy and winter season.

Analysis of Endophytic Bacterial Communities and Investigation of Core Taxa in Apple Trees.

ire blight disease, caused by Erwinia amylovora, is a devastating affliction in apple cultivation worldwide. Chemical pesticides have exhibited limited effectiveness in controlling the disease, and biological control options for treating fruit trees are limited. Therefore, a relatively large-scale survey is necessary to develop microbial agents for apple trees. Here we collected healthy apple trees from across the country to identify common and core bacterial taxa. We analyzed the endophytic bacterial communities in leaves and twigs and discovered that the twig bacterial communities were more conserved than those in the leaves, regardless of the origin of the sample. This finding indicates that specific endophytic taxa are consistently present in healthy apple trees and may be involved in vital functions such as disease prevention and growth. Furthermore, we compared the community metabolite pathway expression rates of these endophyte communities with those of E. amylovora infected apple trees and discovered that the endophyte communities in healthy apple trees not only had similar community structures but also similar metabolite pathway expression rates. Additionally, Pseudomonas and Methylobacterium-Methylorobrum were the dominant taxa in all healthy apple trees. Our findings provide valuable insights into the potential roles of endophytes in healthy apple trees and inform the development of strategies for enhancing apple growth and resilience. Moreover, the similarity in cluster structure and pathway analysis between healthy orchards was mutually reinforcing, demonstrating the power of microbiome analysis as a tool for identifying factors that contribute to plant health.

Parthenium Rust (Puccinia abrupta var. Partheniicola) As a Potential Biological Control against Parthenium weed (Parthenium hysterophorus L.)

Parthenium (Parthenium hysterophorus L.), the invasive weed of global significance, have a direct and indirect impact on human and animal health as well as the overall ecosystem health. Since its introduction to Ethiopia and the Tigray region, it rapidly covers millions of hectares of crop fields. Different biological control options were tested in many countries including Ethiopia, that ranging from fungus inoculation to the introduction of insect pests (bioagents) and two bioagents, the leaf-feeding beetle (Zygogramma bicolorata) and stem-boring weevil (Listronotus setosipennis) were reported to have better performance. Nevertheless, susceptibility of the bioagents to weather variability and predators were among the important factors that halts the effectiveness of the bioagent based biological control. In the Tigray region, the native pathogen, parthenium rust(Puccinia abrupta var. partheniicola) showed very promising effect against the noxious weed, parthenium, and proved to be reliable. In field condition, disease incidence that ranges between 20-100% was observed. As a result of the pathogenicity effect of the parthenium rust, symptoms like leaf and flower defoliation, chlorosis, necrosis, and stunted vegetative growth, and failure of seed production have been portrayed. The future use of uredospore suspensions of the parthenium rust as foliage application and as a mycoherbicide, and development of tolerant crop varieties via breeding are discussed.

Two strains Neocosmosporastercicola (Sordariomycetes, Nectriaceae) with high nematicidal activity, isolated from the cysts of Globodera sp. (Heteroderidae) in China.

Plant-parasitic nematodes (PPNs) are significant pests that result in considerable economic losses in global crop production. Due to the high toxicity of chemical nematicides, there is a need to develop new strategies for nematode control. In this context, nematophagous fungi may offer a viable option for biological control. Two fungal strains (GUCC2212 and GUCC2232) were isolated from cysts of Globodera sp., identified as Neocosmosporastercicola. The fungal filtrates of the strains were evaluated for their nematicidal activity against three species of PPNs: Aphelenchoidesbesseyi, Bursaphelenchusxylophilus and Ditylenchusdestructor. The fermentation filtrates of two strains exhibited substantial toxicity towards the evaluated nematodes, with mortality rates reaching up to 100% within 72 h. Concurrently, N.stercicola also demonstrated predatory and parasitic behavior. The eggs of Globodera sp. were parasitized by the two strains. N.stercicola represents a newly recorded species in China and a novel nematophagous species. In conclusion, the two strains of N.stercicola show promise as biocontrol agents for PPNs management.

Estimating the Cost of Production of Two Pentatomids and One Braconid for the Biocontrol of Spodoptera frugiperda (Lepidoptera: Noctuidae) in Maize Fields in Florida

The fall armyworm is a polyphagous lepidopteran pest that primarily feeds on valuable global crops like maize. Insecticides and transgenic crops have long been a primary option for fall armyworm control, despite growing concerns about transgenic crop resistance inheritance and the rate of insecticide resistance development. Global dissemination of the pest species has highlighted the need for more sustainable approaches to managing overwhelming populations both in their native range and newly introduced regions. As such, integrated pest management programs require more information on natural enemies of the species to make informed planning choices. In this study, we present a cost analysis of the production of three biocontrol agents of the fall armyworm over a year. This model is malleable and aimed towards small-scale growers who might benefit more from an augmentative release of natural enemies than a repetitive use of insecticides, especially since, though the benefits of using either are similar, the biological control option has a lower development cost and is more environmentally sustainable.

Alien vs. herbivore: ant-mediated plant defense as an option for biological control of leafcutter ants

Leafcutter ants are a major pest in vineyards in Argentina, but their damage to vine plants has not been sufficiently quantified. Biological control against leafcutter ants has not been successful so far. Sugary rewards can trigger ants to act as plant bodyguards against a wide range of herbivores. The Argentine ant Linepithema humile (Mayr) is a common invader of vineyards worldwide and has a strong preference for carbohydrates. In a first 10-week field experiment, we attracted L. humile ants to a group of plants using sugar feeders, while no feeders were used for a second group. Ant-excluded control plants were also deployed. We quantified the damage inflicted by the leafcutter ant Amoimyrmex bruchi (Forel) on potted vines with and without L. humile ants. In a second short field experiment, we evaluated the impact of L. humile on A. bruchi foraging through the quantification of foraging activity and the amount of transported material as a function of L. humile presence. We found that A. bruchi caused >90% leaf area reductions in plants without L. humile, while plants where the species was present were rarely attacked and leaves developed similar to those of ant-excluded controls. Active interaction with L. humile decreased A. bruchi’s foraging activity and the amount of material transported by it. This is the first report of A. bruchi as a vineyard pest and the first quantification of the damage inflicted by a leafcutter ant on organic grapevines. We demonstrate that L. humile defends vine plants against herbivore pests and artificial sugar sources boost can this defense service. The development of biological control strategies that include the ecological services of ants as natural enemies of herbivorous pests could become a useful tool in sustainable viticulture and horticulture.

Preliminary inventory of native natural enemies of the new pest; Fall armyworm (Spodoptera frugiperda)

Fall Armyworm (Spodoptera frugiperda), which began to spread in Bhutan in recent years, is a highly destructive pest of maize that is native to the Americas. Due to the limited information available for developing sustainable management options for the new pest, current management practices are largely chemical-dependent. For use as a biological control option, we present a preliminary list of native natural enemies associated with Fall Armyworm that is collected from infested maize fields in west-central Bhutan. Visual observation, sweep net collection, and rearing of different Fall Armyworm stages were used for detection of the natural enemies. We identified 48 natural enemy species associ- ated with the Fall Armyworm infested maize fields. Parasitism was noted for Chelonus formosanus, Trichogramma sp., Winthemia trinitatis, Linnaemya sp. and Campoletis sonorensis while predation was observed by Polistes olivaceus, Stenodynerus smilibaronii, Tetraponera allaborans, Crematogaster rogennhoferi and Dolichoderus thoracicus on the Fall Armyworm.

Lethality of Three Phasmarhabditis spp. (P. hermaphrodita, P. californica, and P. papillosa) to Succinea Snails

Succinea snails are considered to be invasive and pestiferous gastropods to those in the floricultural industry. Their small size makes them difficult to locate within large plant shipments, and their presence on decorative plants can constitute for an entire shipment to be rejected for sale and distribution. Research performed on Succinea snails is limited, especially in terms of effective mitigation strategies. The nematode Phasmarhabditis hermaphrodita is a biological control agent used on pestiferous gastropods throughout some European nations. Here, three strains of Phasmarhabditis from the United States (P. hermaphrodita, P. californica, and P. papillosa) were assessed as biological control agents against Succinea snails in controlled laboratory conditions, along with the molluscicide Sluggo Plus® as a control. All species of Phasmarhabditis applied at 30 IJs/cm2 caused significant mortality compared to the non-treated control and treatment with Sluggo Plus®. P. californica caused 100% mortality 6 days after exposure, while P. hermaphrodita and P. papillosa caused the same mortality rate 7 days after exposure. The molluscicide was unable to cause significant mortality compared to the non-treated control. Additional research with US Phasmarhabditis strains, including their non-target effects and distribution may lead to their being a viable option for biological control against Succinea snails.

Release of the lady beetle (Oenopia conglobata L.) to control the common pistachio psylla

Common pistachio psylla, Agonoscena pistaciae Burckhardt & Lauterer (Hemiptera: Psyllidae), is a major pest of pistachio trees in Turkey, which can be difficult to control due to insecticide resistance. This study evaluated augmentative releases of larvae and adults of lady beetle, Oenopia conglobata L. (Coleoptera: Coccinellidae) for biological control of the psylla at densities of 25, 50, or 100 adults or larvae per tree in two pistachio orchards located in Turkey during 2016 and 2017. The pest population never reached the economic threshold in trees where 50 or 100 larvae or adults were released, whereas it exceeded the economic threshold in all other treatments (control and 25 larvae or adults release), locations-years except for Gaziantep in 2017. Higher release rates (100 larvae or adults per tree) reduced pest density by >50% on average, with efficacy ranging from 20% to 88%. The results indicate that augmentative releases of O. conglobata can result in additional generations of the predator in pistachio orchards. Although no differences were noted between releases of larval and adult stages of O. conglobata, release of large numbers of larvae in similar stages of development poses logistical challenges, rendering mass release of adults a more feasible approach. In conclusion, release of 100 adults per tree could be an effective biological control option for managing A. pistaciae in pistachio orchards.

Integrating the Strength of Multi-Date Sentinel-1 and -2 Datasets for Detecting Mango (Mangifera indica L.) Orchards in a Semi-Arid Environment in Zimbabwe

Generating tree-specific crop maps within heterogeneous landscapes requires imagery of fine spatial and temporal resolutions to discriminate among the rapid transitions in tree phenological and spectral features. The availability of freely accessible satellite data of relatively high spatial and temporal resolutions offers an unprecedented opportunity for wide-area land use and land cover (LULC) mapping, including tree crop (e.g., mango; Mangifera indica L.) detection. We evaluated the utility of combining Sentinel-1 (S1) and Sentinel-2 (S2) derived variables (n = 81) for mapping mango orchard occurrence in Zimbabwe using machine learning classifiers, i.e., support vector machine and random forest. Field data were collected on mango orchards and other LULC classes. Fewer variables were selected from ‘All’ combined S1 and S2 variables using three commonly utilized variable selection methods, i.e., relief filter, guided regularized random forest, and variance inflation factor. Several classification experiments (n = 8) were conducted using 60% of field datasets and combinations of ‘All’ and fewer selected variables and were compared using the remaining 40% of the field dataset and the area underclass approach. The results showed that a combination of random forest and relief filter selected variables outperformed (F1 score &gt; 70%) all other variable combination experiments. Notwithstanding, the differences among the mapping results were not significant (p ≤ 0.05). Specifically, the mapping accuracy of the mango orchards was more than 80% for each of the eight classification experiments. Results revealed that mango orchards occupied approximately 18% of the spatial extent of the study area. The S1 variables were constantly selected compared with the S2-derived variables across the three variable selection approaches used in this study. It is concluded that the use of multi-modal satellite imagery and robust machine learning classifiers can accurately detect mango orchards and other LULC classes in semi-arid environments. The results can be used for guiding and upscaling biological control options for managing mango insect pests such as the devastating invasive fruit fly Bactrocera dorsalis (Hendel) (Diptera: Tephritidae).

Comparison of Chemical and Biological Wireworm Control Options in Serbian Sunflower Fields and a Proposition for a Refined Wireworm Damage Assessment

Recent European Union regulations aim at reducing the use of chemical pesticides in agriculture. In sunflower production in Serbia, the use of synthetic insecticides for soil and seed treatments has become a prevailing practice for wireworm (Coleoptera: Elateridae) control. However, a number of compounds efficiently used as seed treatments have been phased out. This work aimed at assessing the potential of an environmentally friendly “Attract and Kill” strategy (A&amp;K) for controlling wireworms in sunflower in comparison to conventional insecticides. The experiments were carried out in 2018, 2019 and 2021 involving (a) soil treatments with ATTRACAP® and a Force 1.5 G; (b) seed treatments with Sonido, Force 20 CS, Lumiposa and Buteo Start 480 FS; (c) controls (i.e., untreated seeds). The efficacy of the treatments was assessed based on the plant density and emerging plant damage (%). A damage rating scale (levels 0–5) was created, aiming for a more reliable and concrete interpretation of the results. Data were processed using binomial and multinomial regressions, followed by modelling of the damage and calculating the odds of damage occurrence, depending on the applied insecticide. In all experimental years and at all localities, the Force 20 CS and/or Force 1.5 G treatments resulted in the highest plant density and the lowest percentage of plant damage. ATTRACAP® showed good effectiveness, since plant density and percentage of damaged plants were at the same level of significance as the commonly used conventional insecticides in sunflower production (Sonido for seed treatment and Force 1.5 G for soil treatment). Thus, the A&amp;K strategy was efficient in controlling wireworms at conditions of low abundance, based on three-year experimental results. Although the damage rating scale enabled a clear differentiation of plant damage caused by wireworms responsible for reduced plant density, more reliable models were obtained by binomial regressions, classifying plants as damaged or undamaged.

Biological Control of Diamondback Moth-Increased Efficacy with Mixtures of Beauveria Fungi.

Diamondback moth (DBM) is an important horticultural pest worldwide as the larvae of these moths feed on the leaves of cruciferous vegetables. As DBM has developed resistance to more than 100 classes of synthetic insecticides, new biological control options are urgently required. Beauveria species are entomopathogenic fungi recognized as the most important fungal genus for controlling a wide range of agricultural, forestry, and veterinary arthropod pests. Previous research, aimed at developing new Beauveria-based biopesticides for DBM, has focused on screening single isolates of Beauveria bassiana. However, these fungal isolates have individual requirements, which may limit their effectiveness in some environments. This current study separately assessed 14 Beauveria isolates, from a range of habitats and aligned to four different species (Beauveria bassiana, B. caledonica, B. malawiensis, and B. pseudobassiana), to determine the most effective isolate for the control of DBM. Further assays then assessed whether selected combinations of these fungal isolates could increase the overall efficacy against DBM. Six Beauveria isolates (three B. bassiana and three B. pseudobassiana) achieved high DBM mortality at a low application rate with the first documented report of B. pseudobassiana able to kill 100% of DBM larvae. Further research determined that applications of low-virulent Beauveria isolates improved the control of DBM compared to mixtures containing high-virulent isolates. This novel approach increased the DBM pest mortality and shortened the time to kill.