Efficacy Of Biological Control Agents Research Articles

Adaptation of an arthropod predator to a challenging environment is associated with a loss of a genome-wide plastic transcriptional response.

Structural and chemical plant defence traits may reduce the efficacy of biological control agents in integrated pest management. Breeding programmes have shown arthropod predators' potential to acclimate to challenging host plants. However, whether and how these predators adapt to novel plant environments remain unclear. Using the predatory mite Phytoseiulus persimilis - herbivorous mite Tetranychus urticae system in an experimental evolution setup, we studied the adaptation mechanisms to tomato and cucumber, plants that possess a distinct repertoire of defensive traits. Experimental evolution experiments on whole plants revealed that allowing P. persimilis to adapt to tomatoes led to an ~100% larger population size. Independent feeding assays showed that tomato- and cucumber-adapted prey reduced predator fecundity. The deleterious effect of ingesting low-quality prey persisted after adaptation of the predator to both cucumber and tomato. We demonstrated that jasmonic acid (JA)-dependent defences reduce prey quality by evaluating predator performance on prey fed on JA defence-deficient tomato plants. Transcriptomic profiling of the replicated P. persimilis lines showed that long-term propagation on tomato and cucumber plants produces distinctive gene-expression levels. Predator adaptation to tomatoes results in the loss of a large transcriptional response, in which predicted cuticle-building rather than detoxification pathways are affected. We showed that the adaptation of predatory arthropods to a novel, challenging plant does not necessarily occur via the prey, but rather through the physical environment of the plant. We provided first insights into the underlying molecular mechanisms. © 2023 Society of Chemical Industry.

Pest Elaterids of North America: New Insights and Opportunities for Management.

The larval stages of click beetle (Coleoptera: Elateridae) species, several of which are serious agricultural pests, are called wireworms. Their cryptic subterranean habitat, resilience, among-species differences in ecology and biology, and broad host range, as well as the lack of objective economic injury thresholds, have rendered wireworms a challenging pest complex to control. Significant progress has been made in recent years, introducing a new effective class of insecticides and improving species identification and our understanding of species-specific phenology, chemical ecology (i.e., adult sex pheromones and larval olfactory cues), and abiotic and biotic factors influencing the efficacy of biological control agents. These new developments have created opportunities for further research into improving our risk assessment, monitoring, and integrated pest management capabilities.

Probing efficacy of biological control agents, plant extracts and resistance inducing chemicals against damping-off of tomato

Probing efficacy of biological control agents, plant extracts and resistance inducing chemicals against damping-off of tomato

Efficacy of Biological Control Agents and Resistance Inducer for Control of Mal Secco Disease.

Mal secco, caused by Plenodomus tracheiphilus, is an economically important fungal vascular disease in citrus-growing countries of the Mediterranean basin. Preventing fungal infections usually requires a high number of copper treatments but European legislation imposes the minimization of their accumulation in soil. In our study, biological control agents (BCAs) and a plant resistance inducer (PRI), tested in four different experiments on citrus seedlings under controlled conditions, have resulted in promising strategies to control mal secco disease. Foliar (Experiment I) and soil (Experiment II) applications of two formulations of Bacillus amyloliquefaciens strain D747 (Amylo-X® LC and Amylo-X® WG) provided similar performances in reducing the disease amount (incidence and symptoms severity) over time compared to the untreated control, whereas copper hydroxide (Kocide Opti®) used as standard was the most effective treatment over time. In the third experiment, Pythium oligandrum strain M1 (Polyversum®) and Trichoderma asperellum strain ICC012 + Trichoderma gamsii strain ICC080 (Remedier®) were able to reduce disease incidence and symptoms severity compared to the untreated control. Remedier® provided the best performances in reducing the disease amount, whereas the Polyversum® application was the least effective treatment over time. The effectiveness of the Trichoderma spp. formulation in reducing P. tracheiphilus infections did not significantly differ from the standard copper compound (Kocide Opti®). Comprehensively, in the last experiment (IV), acibenzolar-S-methyl (ASM) alone and in mixture with metalaxyl-M proved as effective as B. amyloliquefaciens strain FZB24, with no dose-response relationships observed. These findings provide important insight for the integrated management of mal secco disease.

Sequestration of cucurbitacins from cucumber plants by Diabrotica balteata larvae provides little protection against biological control agents

Cucurbitaceae plants produce cucurbitacins, bitter triterpenoids, to protect themselves against various insects and pathogens. Adult banded cucumber beetles (Diabrotica balteata), a common pest of maize and cucurbits, sequester cucurbitacins, presumably as a defensive mechanism against their natural enemies, which might reduce the efficacy of biological control agents. Whether the larvae also sequester and are protected by cucurbitacins is unclear. We profiled cucurbitacin levels in four varieties of cucumber, Cucumis sativus, and in larvae fed on these varieties. Then, we evaluated larval growth and resistance against common biocontrol organisms including insect predators, entomopathogenic nematodes, fungi and bacteria. We found considerable qualitative and quantitative differences in the cucurbitacin levels of the four cucumber varieties. While two varieties were fully impaired in their production, the other two accumulated high levels of cucurbitacins. We also observed that D. balteata larvae sequester and metabolize cucurbitacins, and although the larvae fed extensively on both belowground and aboveground tissues, the sequestered cucurbitacins were mainly derived from belowground tissues. Cucurbitacins had no detrimental effects on larval performance and, surprisingly, did not provide protection against any of the natural enemies evaluated. Our results show that D. balteata larvae can indeed sequester and transform cucurbitacins, but sequestered cucurbitacins do not impact the biocontrol potential of common natural enemies used in biocontrol. Hence, this plant trait should be conserved in plant breeding programs, as it has been demonstrated in previous studies that it can provide protection against plant pathogens and generalist insects.

Factors Influencing the Efficacy of Biological Control Agents Used to Manage Insect Pests in Indoor Cannabis (Cannabis sativa) Cultivation

Current biological control strategies in cannabis (Cannabis sativa) cultivation have resulted in poor efficacy for managing certain insect pests. The cannabis industry has grown at a rapid pace, surpassing our ability to develop knowledge on the production systems for this crop. Currently, the research focus is on optimizing agronomic and environmental factors to maximize the yield and quality of cannabis. However, cannabis growers are increasingly challenged by severe insect pest pressure, with few effective options. Decades of research have optimized biological control strategies in other crops. The implementation of effective biological control strategies in cannabis is hindered by a variety of morphological, biochemical, and agronomic factors unique to this crop. Here, we review the rather limited literature relevant to insect pest management in indoor cannabis production. Further, we have identified three factors that we believe are primarily responsible for the ineffectiveness of biological control in cannabis: Plant morphology including trichome density and floral resources, effects of plant biochemistry on prey suitability, and finally the effects of supplemental lighting including photoperiod, intensity, and spectrum. We highlight the importance of prioritizing the evaluation of these factors to improve our understanding of the tritrophic interactions governing the success of biological control in cannabis cultivation. As intensive research efforts are underway to optimize agronomic practices for cannabis, it is also important to consider their relevance to biological control.

High temperature exposure reduces the susceptibility of Helicoverpa armigera to its nucleopolyhedrovirus (HearNPV) by enhancing expression of heat shock proteins.

High temperatures will occur more frequently with global warming, with potential impacts on the efficacy of biological control agents. Heat shock proteins (HSPs) are induced by high temperature, but their possible roles in pest resistance to entomopathogens remain unexplored. We investigated the effects of high temperature (35 °C) on Helicoverpa armigera resistance to H. armigera nucleopolyhedrovirus (HearNPV) and the putative roles of HSPs in this process. Even short periods (24 h) of high temperature (35 °C) reduced mortality in HearNPV-infected H. armigera larvae. Sustained 35 °C exposure significantly shortened developmental time, and increased fresh weight and locomotor activity in infected larvae. Moreover, high temperature inhibited virus replication and thickened the epidermis of H. armigera, resulting in reduced spread of infection from cadavers. Real-time polymerase chain reaction (PCR) analysis showed that expression of 11 HSP genes was altered by the 35 °C treatment, and that mostly small heat shock protein (sHSP) genes were up-regulated, the same sHSPs were induced when larvae were infected with HearNPV. Finally, RNA interference (RNAi) suppression of these sHSPs showed that only Hsp24.91 and Hsp21.8 diminished H. armigera defensive responses to HearNPV infection. Even short periods of exposure to high temperature can significantly reduce susceptibility of H. armigera larvae to HearNPV by stimulating the production of sHSPs which enhance immune responses, with important implications for the use of entomopathogens as biological control agents under global warming scenarios. © 2022 Society of Chemical Industry.

How long-term mass rearing affects the quality of the Trichogramma embryophagum (Hartig) (Hymenoptera: Trichogrammatidae) reared on Sitotroga cerealella (Olivier) eggs

BackgroundMaintaining the quality and efficacy of biological control agents during long-term mass rearing plays a crucial role in the success of a biological control program. In this study, the biological traits of a local population colony of Trichogramma embryophagum (Hartig) with rearing on Sitotroga cerealella (Olivier) eggs for over 40 generations (G) were assessed.ResultsFemale adult longevity was significantly different among generations, ranging from 7.98 d in G5 to 5.19 d in G40. The reared wasps showed highest fecundity (60.50 eggs/female) in G5 compared to the other generations. The female sex ratio varied from 63.16% in G5 to 49.31% in G40. Significant differences were observed in population growth parameters and the highest gross reproductive rate (GRR) (40.96 eggs/individual) and net reproductive rate (R0) (38.21 eggs/individual) were found in G5. However, a non-significant difference was found in the intrinsic rate of natural increase (r) until the 10th generation, but its values significantly declined with increasing the generation numbers. The finite parasitism rate (ω) ranged from 0.468 host/parasitoid/day in G5 to 0.274 host/parasitoid/day in G40.ConclusionsThe results showed that the quality of T. embryophagum reared under continuous laboratory conditions declined after 10 generations, and for use of them in biological control programs under field conditions, the reared population should be refreshed by adding wild individuals from time to time.

Long-term captive-rearing affects oviposition behavior and nymphal survival of a weed biological control agent

Adaptation to artificial rearing conditions is a well-documented phenomenon in insects and has been shown to reduce the efficacy of biological control agents. The knotweed psyllid, Aphalara itadori Shinji (Hemiptera: Psyllidae), is a biological control agent for Fallopia japonica (Houtt.) Ronse Decr. (Caryophyllales: Polygonaceae) that has been released in North America and Europe, however, to date successful establishment of the insect over multiple field seasons has not been observed. We conducted a series of experiments to explore the possibility that long-term rearing in laboratory conditions has impaired the psyllid’s ability to survive in the field. We used light intensity to manipulate leaf toughness in F. japonica, and used the resulting plants in laboratory bioassays to assess the effects of foliage toughness on the survival of the psyllids. We conducted laboratory-choice tests to compare the effects of leaf age on oviposition behavior by A. itadori. Finally, we conducted a field experiment, comparing the effects of foliage age on adult oviposition and nymphal survival. All experiments were conducted using a line of psyllids that have been reared in captivity since their collection from Japan, in 2004 (K1 psyllids). The final two experiments also utilized a line of psyllids collected from the same location more recently in 2019 (K2 psyllids). We observed a reduction in K1 A. itadori nymphal survival on tough F. japonica plants compared to soft plants. Aphalara itadori from the K1 line laid significantly more eggs on young versus old leaves, and survived best on young F. japonica regrowth in the field. Conversely, K2 A. itadori showed no oviposition preference between young and old leaves, and no preference between cut and uncut F. japonica foliage in the field. Our results indicate that recently collected psyllids (K2) may be better able to establish on field-conditioned knotweed in North America than older colonies and highlights the possible effects of long-term rearing on biological control agent performance.

Does natural vegetation from olive groves benefit the olive moth, Prays oleae?

AbstractConservation biological control aims to enhance the efficacy of biological control agents, such as predators and parasitoids, by providing them access to key requisites, for example floral or other alternative food resources. However, the occurrence of floral resources in agricultural systems may have positive effects not only on natural enemies but also on the pests themselves. For this reason, we have studied in laboratory common Mediterranean plants as potential food resources for an important lepidopteran olive pest, the olive moth, Prays oleae. The effects of 15 wild flowering plants from olive grove ecosystems, and four sugars present in floral nectars, on key biological parameters of P. oleae (i.e. longevity, pre‐oviposition and oviposition periods, fertility and fecundity) were evaluated. The three pest generations were analysed. Only few of the plants tested increased some reproductive parameters of the insect individuals compared to the water‐fed controls, while sugars generally improved them. This could be due to a higher concentration of sugars provided by individual sugars than by flower nectar. These results indicate that, in general, P. oleae will not benefit from the availability of the floral resources tested.

Lethal and Sublethal Effects of Two Commercial Insecticides on Egg Parasitoids (Hymenoptera: Scelionidae) of Green Stink Bugs (Hem: Pentatomidae).

Pistacia vera L. is one of the most important horticultural crops in Iran. The stink bugs Acrosternum arabicum and Brachynema germari are two of the key pests that cause significant direct and indirect damage on Pistacia vera. Egg parasitoids have been considered as potential biological control agents of pistachio green stink bugs. Among them, Trissolcus semistriatus and Psix saccharicola are the most abundant and efficient parasitoid for A. arabicum in pistachio orchards. In this study, we assessed lethal and sublethal effects of two commonly used insecticide products (fenitrothion and a binary mixture of lambda-cyhalothrin + thiamethoxam) on these two parasitoid wasps under laboratory conditions. The median lethal concentration (LC50) values for fenitrothion and thiamethoxam + lambda-cyhalothrin in P. saccharicola and T. semistriatus were estimated as 1.03, 0.48 and 0.87, 0.98 mg a.i./liter, respectively. In terms of sublethal effects, insecticide treatments altered the type of functional response from type III to type II in T. semistriatus. However, P. saccharicola exhibited a type II functional to density of A. arabicum for all treatments, although attack rates were lower for insecticide-exposed wasps while handling times increased. Our results show that sublethal effects of insecticides further reduce the efficacy of biological control agents. Effective integrated pest management programs should avoid antagonistic interactions between chemical and biological control methods. The results of this study provide useful information to develop comprehensive integrated pest management programs for stink bugs in pistachio orchards.

Exploring Rain as Source of Biological Control Agents for Fire Blight on Apple.

Poor survival on plants can limit the efficacy of Biological Control Agents (BCAs) in the field. Yet bacteria survive in the atmosphere, despite their exposure to high solar radiation and extreme temperatures. If conditions in the atmosphere are similar to, or more extreme than, the environmental conditions on the plant surface, then precipitation may serve as a reservoir of robust BCAs. To test this hypothesis, two hundred and fifty-four rain-borne isolates were screened for in vitro inhibition of Erwinia amylovora, the causal agent of fire blight, as well as of other plant pathogenic bacteria, fungi and oomycetes. Two isolates showed strong activity against E. amylovora and other plant pathogenic bacteria, while other isolates showed activity against fungal and oomycete pathogens. Survival assays suggested that the two isolates that inhibited E. amylovora were able to survive on apple blossoms and branches similarly to E. amylovora. Pathogen population size and associated fire blight symptoms were significantly reduced when detached apple blossoms were treated with the two isolates before pathogen inoculation, however, disease reduction on attached blossoms within an orchard was inconsistent. Using whole genome sequencing, the isolates were identified as Pantoea agglomerans and P. ananatis, respectively. A UV-mutagenesis screen pointed to a phenazine antibiotic D-alanylgriseoluteic acid synthesis gene cluster as being at the base of the antimicrobial activity of the P. agglomerans isolate. Our work reveals the potential of precipitation as an under-explored source of BCAs, whole genome sequencing as an effective approach to precisely identify BCAs, and UV-mutagenesis as a technically simple screen to investigate the genetic basis of BCAs. More field trials are needed to determine the efficacy of the identified BCAs in fire blight control.

The influence of the carbohydrate levels on viability of Stagonospora cirsii drying mycelium

The Stagonospora cirsii mycelium is considered as the infectious basis of a potential mycoherbicide for the control of Canadian thistle and perennial sow thistle. Successful commercialization of mycoherbicides is often constrained by poor drying survival. In this study was shown that the highest viability of mycelium S. cirsii during drying is achieved in the stationary phase of growth. The mycelium in the stationary phase is characterized by maximum level of carbohydrates. We suggest the level of arabitol as a criterion evaluation of the mycelium resistance to drying. Culturing conditions, and especially the fermentation time, allow prediction of polyols and trehalose levels, which are very critical in enhancing the storage life and efficacy of biological control agent.

Selection of an Endophytic Streptomyces sp. Strain DEF09 From Wheat Roots as a Biocontrol Agent Against Fusarium graminearum.

Selection of biological control agents (BCA) profits from an integrated study of the tripartite interactions occurring among the BCA, the plant and the pathogen. The environment plays a crucial role in the efficacy of BCA, therefore, the selection process shall utmost mimic naturally occurring conditions. To identify effective biocontrol strains against Fusarium graminearum, the major cause of Fusarium head blight (FHB) in wheat and deoxynivalenol (DON) accumulation in grains, a workflow consisting of in vitro and in vivo assays was set up. Twenty-one Streptomyces strains, 16 of which were endophytes of different plants, were analyzed. In vitro and in vivo tests characterized their plant growth promoting (PGP) traits. Biocontrol activity against F. graminearum was firstly assessed with a dual culture assay. An in vivo germination blotter assay measured Fusarium foot rot and root rot symptoms (FFR-FRR) reduction as well as growth parameters of the plant treated with the Streptomyces strains. A selected subset of Streptomyces spp. strains was then assessed in a growth chamber measuring FFR symptoms and growth parameters of the wheat plant. The approach led to the identification of an effective Streptomyces sp. strain, DEF09, able to inhibit FHB on wheat in controlled conditions by blocking the spread of the pathogen at the infection site. The results were further confirmed in field conditions on both bread and durum wheat, where DEF09 decreased disease severity up to 60%. This work confirms that FRR and FFR pathosystems can be used to identify BCA effective against FHB.

Efficacy of biological control agents, synthetic insecticides, and their combinations to control tobacco budworm [Heliothis virescens (Lepidoptera: Noctuidae)] in pigeon pea

Tobacco budworm, Heliothis virescens (F.) (Lepidoptera: Noctuidae), is an important pest in pigeon pea [Cajanus cajan (L.) Mill.] in Puerto Rico and the tropics. The use of chemicals is the most effective strategy to control this pest. Our objective was to assess the efficacy of two biological control agents, five synthetic insecticides, and four combinations to control tobacco budworm larvae. Pigeon pea plots were sprayed with 11 insecticide treatments and water as control in 2017 and 2018. Tobacco budworm incidence and severity, and data of dry-pod/seed yield were evaluated at harvest. Plots sprayed with water, the biological control agents [Steinernema carpocapsae (Weiser) (SC), and nucleopolyhedrovirus (NP)], and chlorpyrifos had significantly higher incidences (>24%) compared with plots applied with spinetoram alone and combined with SC and NP (12–18%) in both planting years. However, there were no significant differences (P ≥ 0.05) between treatments for tobacco budworm severity (mean scores of 4.00 to 4.83 in 2017 and 2.90 to 3.60 in 2018). In contrast, significantly lower incidence (<2.00) and severity (≤2.50) were recorded with applications of chlorantraniliprole and its combination with NP and SC. However, the use of low dosages of chlorantraniliprole + NP (0.20 + 0.10 l/ha), and chlorantraniliprole + SC + oil (0.20 l + 550 g + 1.25 l/ha) increased significantly dry-pod (2.18 and 2.20 t/ha) and seed-yield (1.27 and 1.23 t/ha) only in 2017; while high dosages of β-cyfluthrin (0.20 l/ha) and chlorantraniliprole (0.30 l/ha) increased yield significantly (2.04 and 2.44; 1.72 and 1.69 t/ha) compared to the control (1.25 and 0.76 for dry-pod; and 0.78 and 0.26 t/ha for seed in 2017 and 2018, respectively). We concluded that timely applications of β-cyfluthrin and chlorantraniliprole may increase net incomes over $4000/ha and should be incorporated in insecticide rotations to control tobacco budworm in pigeon pea.

Effects of floral resources on the efficacy of a primary parasitoid and a facultative hyperparasitoid

AbstractResources added to agroecosystems to enhance biological control are potentially available to multiple members of the resident insect community—not only the biological control agents for which the resources are intended. Many studies have examined the effects of sugar feeding on the efficacy of biological control agents. However, such information is lacking for other, interacting species such as facultative hyperparasitoids, which may contribute to pest suppression but can also interfere with introduced biological control agents. Under greenhouse conditions, we tested the direct effects of sugar and nectar provisioning on the longevity, host‐killing impact and offspring production of two pupal parasitoids associated with leek moth, Acrolepiopsis assectella: the introduced biological control agent, Diadromus pulchellus, and the native facultative hyperparasitoid, Conura albifrons. Adding sucrose, buckwheat or a combination of buckwheat and common vetch to a sugar‐deprived system (potted leek plants in cages) increased parasitoid longevity and resulted in higher leek moth parasitism and mortality compared to water or common vetch treatments. However, the two parasitoid species exhibited a distinct temporal response to the treatments, likely influenced by differences in their life histories. This study provides insight into how integrating conservation biological control techniques could affect the success of a classical biological control programme.

Impact of delivery method on the efficacy of biological control agents and the virulence of Fusarium root rot pathogens in the greenhouse

ABSTRACTBiological control methods are now more valuable as a plant disease management strategy and are a particularly promising method for managing fusarium root rot, an economically important soilborne disease of row crops. Currently, the management of the disease relies on fungicide seed treatment, but a better understanding of disease development by fusarium root rot pathogens is crucial to enable the better utilisation of biological control agents (BCAs) or biological products. The BCA application method is a very important factor that affects efficacy. This study aimed to (i) identify the inoculation method that leads to appropriate inoculum level and reliable disease development in the greenhouse for fusarium root rot pathogens in corn, soybean, and wheat and (ii) evaluate different application methods for biocontrol agents to determine the most consistent method for enhancing the efficacy of biocontrol agents and products. Greenhouse studies were conducted in a randomised complete block design and the experiments were repeated. Disease severity was significantly high and consistent in the greenhouse when pathogens were inoculated through millet inoculation or agar plug inoculation methods. The pathogen dose rate did not affect disease development. The performance and efficacy of BCAs against fusarium root rot in soybean, corn, and wheat were highest when a combination of coating by seed spray and drenching was the method of application.

Selective effects of floral food sources and honey on life‐history traits of a pest–parasitoid system

AbstractMany parasitoids and their herbivorous hosts forage on the same floral resources in agroecosystems. Floral resources that benefit natural enemies without supporting pests can improve the efficacy of biological control agents. Here, we report the results of a study on selective effects of floral and non‐floral food sources on the life‐history traits of the parasitoid Diadegma insulare (Cresson) (Hymenoptera: Ichneumonidae) and its host Plutella xylostella (L.) (Lepidoptera: Plutellidae). Under standard laboratory conditions, insects were exposed to four flowering plant species, 10% honey solution, and water. All food sources increased the longevity of the herbivore and its parasitoid by as much as four‐ to nine‐fold, respectively, compared to the water control diet. Diadegma insulare survived the longest on Thlaspi arvense L. (Brassicaceae) and P. xylostella on Sinapis arvensis L. (Brassicaceae). However, none of the food sources tested was beneficial to the parasitoid alone, though Lobularia maritima L. (Brassicaceae) was found to selectively favor the longevity of D. insulare. Diadegma insulare adults were heavier when fed on S. arvensis, whereas feeding on the honey solution led to higher body weights of P. xylostella. In conclusion, we demonstrated that floral and non‐floral food sources varied in their suitability and acted differently on life‐history traits of a host–parasitoid system. The selective characteristics of nectar‐producing plants and their influence on the herbivore‐natural enemy combination can, therefore, be employed to increase their impact in integrated P. xylostella management.

C-di-GMP turnover influences motility and biofilm formation in Bacillus amyloliquefaciens PG12

Bis-(3′→5′) cyclic dimeric guanosine monophosphate (c-di-GMP) is defined as a highly versatile secondary messenger in bacteria, coordinating diverse aspects of bacterial growth and behavior, including motility and biofilm formation. Bacillus amyloliquefaciens PG12 is an effective biocontrol agent against apple ring rot caused by Botryosphaeria dothidea. In this study, we characterized the core regulators of c-di-GMP turnover in B. amyloliquefaciens PG12. Using bioinformatic analysis, heterologous expression and biochemical characterization of knockout and overexpression derivatives, we identified and characterized two active diguanylate cyclases (which catalyze c-di-GMP biosynthesis), YhcK and YtrP and one active c-di-GMP phosphodiesterase (which degrades c-di-GMP), YuxH. Furthermore, we showed that elevating c-di-GMP levels up to a certain threshold inhibited the swimming motility of B. amyloliquefaciens PG12. Although yhcK, ytrP and yuxH knockout mutants did not display defects in biofilm formation, significant increases in c-di-GMP levels induced by YtrP or YuxH overexpression stimulated biofilm formation in B. amyloliquefaciens PG12. Our results indicate that B. amyloliquefaciens possesses a functional c-di-GMP signaling system that influences the bacterium's motility and ability to form biofilms. Since motility and biofilm formation influence the efficacy of biological control agent, our work provides a basis for engineering a more effective strain of B. amyloliquefaciens PG12.

The socioeconomic benefits of biological control of western corn rootworm Diabrotica virgifera virgifera and wireworms Agriotes spp. in maize and potatoes for selected European countries

Innovative biological pest control of the western corn rootworm (WCR) Diabrotica virgifera virgifera and wireworms Agriotes spp. in maize and potato cultivation in Europe is driven by (1) the economic damages caused and (2) the restrictions on chemical pesticides. We analyze the efficacy of biological control agents for WCR and wireworms based on European field trails. A partial equilibrium displacement model is used to estimate the changes in producer and consumer surplus for France, Italy, Spain, Germany, Austria and Romania given different adoption ceiling and adoption speed. Furthermore, the benefit of a potential reduction in pesticide use due to biological control application is evaluated. The results suggest a total annual welfare gain of ca. €190 million from biocontrol of WCR in maize production for the countries under consideration at an adoption ceiling and adoption speed of 30% and 2.41, respectively. In potato production, an annual welfare gain of over €2 million may be recorded in ecological and/or organic cultivation. Overall, the biological control methods provide an economical alternative in maize and can contribute to increase the competitiveness of European Union (EU) agriculture, while they look promising for certified organic potato production at the current level of control efficiency.