Biocontrol Programs Research Articles

Sex, life history and morphology drive individual variation in flight performance of an insect parasitoid

1. The movement of organisms can be driven by multiple factors and has implications for fitness and the spatial distribution of populations. Insects spend a large proportion of their adult lives foraging by flying for resources; however, their capability and motivation to move can vary across individuals.2. The aims of this study were to examine interindividual and sex differences in flight performance and flight characteristics, using a flight mill bioassay, in Megarhyssa nortoni (Hymenoptera; Ichneumonidae), a parasitoid of the invasive woodwasp Sirex noctilio (Hymenoptera: Siricidae), one of the most important pests of pine afforestation worldwide. We also assessed the influence of morphological traits in combination with sex on flight and explored the cost of flight on longevity and mass loss.3. The results show a difference between sexes in flight characteristics and performance. Females show greater total distance flown than males, and have a better capacity to undergo sustained flight. Sexual size dimorphism was also found and it was noted that size positively affects distances travelled. Females have a longer life span than males, yet no differences were noted in longevity within sex between individuals that did not fly and those that flew. Age did not influence flight performance of females or impacted on post‐flight longevity. Females lost less body mass than males even after flying longer distances.4. These results suggest that sex‐specific behaviours probably govern flight abilities together with (and not only because of) morphological traits. The paper discusses sex‐specific life‐history strategies in parasitoids and their implications for biocontrol programmes.

The nature of the immune response in novel Wolbachia-host associations

Wolbachia is an obligate, intracellular symbiont that is commonly found in insects and causes a diverse array of reproductive manipulations. Normally transmitted vertically, the occasional horizontal host species jump can be seen in the lack of concordance between Wolbachia and host phylogenies. In the laboratory, the symbiont can be artificially introduced into novel hosts and selected to produce persistent infections. In the case of the vector of dengue virus, Aedes aegypti, the symbiont was successfully introduced with the aim of developing the bacterium for biocontrol. In this insect and others, Wolbachia limits co-infection with pathogens including viruses, bacteria and parasites. Here we have novelly infected cell lines derived from diverse insect species with Wolbachia in an attempt to determine if there are commonalities in the early host response to the symbiont. We then monitored the expression of genes in the antibacterial Toll and Imd pathways in the first several passages. We focused on immunity gene expression as it underpins the bulk of the transcriptional response to Wolbachia and because it may play a role in the pathogen blocking effect. We found that successful cell infections of Wolbachia were difficult to achieve and often required repeated rounds of reinfection. We saw significant variation in the nature of the transcriptional changes across cell lines and no attenuation of gene expression changes in the first several passages. These results suggest that insect species are likely to exhibit distinct responses to Wolbachia infection. They also reveal that any evolution of an attenuated transcriptional response, as predicted by long-standing Wolbachia x host associations, is not likely to occur rapidly. The findings will have implications for biocontrol programs that rely on the novel infection of naive hosts.

A new haplotype of the coconut rhinoceros beetle, Oryctes rhinoceros, has escaped biological control by Oryctes rhinoceros nudivirus and is invading Pacific Islands

The coconut rhinoceros beetle (CRB; Oryctes rhinoceros) is a major pest of coconut and oil palm, but the discovery and release of Oryctes rhinoceros nudivirus (OrNV) in the 1960s and 70s suppressed the pest such that no new invasions of uninfested islands by CRB were reported for over 30years after implementation of the biocontrol programme. Surprisingly, a highly damaging outbreak was reported from Guam (2007), which could not be controlled by OrNV. Subsequently, new invasions have been reported from Port Moresby, Papua New Guinea (2009); O'ahu, Hawai'i (2013); and Honiara, Solomon Islands (2015). We have found that all of these outbreaks have been caused by a previously unrecognized haplotype, CRB-G, which appears to be tolerant to OrNV. PCR analysis shows that OrNV is generally present at high incidence in established populations of CRB, but is generally absent from the invasive CRB-G populations. CRB-G from Guam was not susceptible to OrNV infection by oral delivery, but injection of the virus did cause mortality. Further genetic analysis shows that CRB populations can be divided into a number of clades that coincide with the endemic and invasive history of the beetle. Analysis suggests that CRB-G originated in Asia, though the precise location remains to be discovered.

Crystal structures of the isochorismatase domains from Vibrio anguillarum

Antibiotic resistance is becoming a global threat and overuse of antibiotics in aquaculture disease control worsens the situation. To reduce the risk of drug resistance developed in aquaculture, safer biocontrol programs are needed. Antivirulence therapy, with less chance for developing drug resistance, is a promising approach. To facilitate antivirulence inhibitor design against Vibrio anguillarum, a serious aquaculture pathogen, we present crystal structures for isochorismatase domains of AngB and VabB, which are required to synthesize siderophore, a critical virulence factor. Both structures are highly similar to known isochorismatases in fold and active site, therefore we conclude inhibitors for isochorismatases can be developed in a common framework. The structural information will improve design of virulence inhibitors against Vibrio anguillarum. We also firstly report that isochorismatase family could bind endogenous metabolite during the hetero-expression process, which is likely nicotinic acid, nicotinamide or pyrazinic acid, based on structural analysis and affinity prediction. Taken together, our results provide precise structural information of isochorismatase domains for antivirulence inhibitor design against Vibrio anguillarum.

Burkholderia isolates from a sand dune leaf litter display biocontrol activity against the bole rot disease of Agave sisalana

Sisal (Agave sisalana) is an important source of biodegradable hard fiber for diverse industrial uses. The disease known as sisal bole rot leads to plant death and is caused by black aspergilli, including Aspergillus niger, A. brasiliensis and A. tubingensis. Bole rot is among the factors responsible for the decline of sisal production in Brazil. The potential of 16 Burkholderia sp. isolates obtained from sand dune leaf litter to control the disease was evaluated as part of a biocontrol program. The isolates of Burkholderia clustered in a new phylogenetic clade related to, but different from B. gladioli, B. plantari and B. glumae, its closest known relatives. All isolates secreted several enzymes, diffusible compounds, siderophores, volatile organic compounds (VOCs) and were able to solubilize phosphate, and inhibit mycelial growth and spore germination of Aspergillus niger in vitro. The Burkholderia isolates varied in their activity in vitro and in a greenhouse experiment, but consistently reduced disease severity by 54–77% in two independent field experiments. Because species of Burkholderia are opportunistic and might be pathogenic to plants and animals, the development of biocontrol products containing living cells of these bacteria has been viewed with care by regulatory agencies and scientists around the world. Future studies will focus on the development of products containing metabolites and heat-killed cells of these isolates to control sisal bole rot disease.

Infections of Wolbachia may destabilize mosquito population dynamics

Recent efforts in controlling mosquito-borne diseases focus on biocontrol strategies that incapacitate pathogens inside mosquitoes by altering the mosquito's microbiome. A case in point is the introduction of Wolbachia into natural mosquito populations in order to eliminate Dengue virus. However, whether this strategy can successfully control vector-borne diseases is debated; particularly, how artificial infection affects population dynamics of hosts remains unclear. Here, we show that natural Wolbachia infections are associated with unstable mosquito population dynamics by contrasting Wolbachia-infected versus uninfected cage populations of the Asian tiger mosquito (Aedes albopictus). By analyzing weekly data of adult mosquito abundances, we found that the variability of the infected populations is significantly higher than that of the uninfected. The elevated population variability is explained by increased instability in dynamics, as quantified by system nonlinearity (i.e., state-dependence). In addition, predictability of infected populations is substantially lower. A mathematical model analysis suggests that Wolbachia may alter mosquito population dynamics by modifying larval competition of hosts. These results encourage examination for effects of artificial Wolbachia establishment on mosquito populations, because an enhancement of population variability with reduced predictability could pose challenges in management. Our findings have implications for application of microbiome alterations in biocontrol programs.

Response of Bactrocera oleae to different photoperiods and temperatures using a novel method for continuous laboratory rearing

BackgroundThe development of a continuous rearing protocol for the olive fly Bactrocera oleae (Rossi) (Diptera: Tephritidae) remains a fundamental goal of biocontrol programs. We report a new method for continuous small-scale laboratory rearing on olive fruits. The effect of different photoperiod (long and short-day), in combination with two levels of temperature (16°C and 27°C), was verified. ResultsLaboratory colonies were successfully maintained on olive fruits for more than 24months, until project termination. Data showed a short-day photo-phase response: all tested parameters (pupation, emergence, life span, sex ratio) substantially increased on the short-day, except for the emergency rate. Also, changes in the population size were observed in response to photoperiodic condition. There was a significant interaction effect between temperature and photoperiod for pupal stage duration, adult emergence and population size. ConclusionIn earlier and recent literature, most of the rearing procedures adopted long-day photophase and high temperature, but scarce investigation was performed on the effects of the photoperiod on the olive fly. In the present work, we developed a novel method for continuous laboratory rearing of the olive fly on its natural host, which allowed to demonstrate a clear effect of the photoperiod on the effectiveness of the rearing procedures. Laboratory colonies with access to olive fruits showed a short-day photoperiodic response: the optimal combination of climatic parameters was photoperiod 8:16 LD and temperature 16°C.

Evidence for rapid evolutionary change in an invasive plant in response to biological control.

We present evidence that populations of an invasive plant species that have become re-associated with a specialist herbivore in the exotic range through biological control have rapidly evolved increased antiherbivore defences compared to populations not exposed to biocontrol. We grew half-sib families of the invasive plant Lythrum salicaria sourced from 17 populations near Ottawa, Canada, that differed in their history of exposure to a biocontrol agent, the specialist beetle Neogalerucella calmariensis. In a glasshouse experiment, we manipulated larval and adult herbivory to examine whether a population's history of biocontrol influenced plant defence and growth. Plants sourced from populations with a history of biocontrol suffered lower defoliation than naïve, previously unexposed populations, strongly suggesting they had evolved higher resistance. Plants from biocontrol-exposed populations were also larger and produced more branches in response to herbivory, regrew faster even in the absence of herbivory and were better at compensating for the impacts of herbivory on growth (i.e. they exhibited increased tolerance). Furthermore, resistance and tolerance were positively correlated among genotypes with a history of biocontrol but not among naïve genotypes. Our findings suggest that biocontrol can rapidly select for increased defences in an invasive plant and may favour a mixed defence strategy of resistance and tolerance without an obvious cost to plant vigour. Although rarely studied, such evolutionary responses in the target species have important implications for the long-term efficacy of biocontrol programmes.

Climatic suitability ranking of biological control candidates: a biogeographic approach for ragweed management in Europe

AbstractBiological control using natural antagonists has been a most successful management tool against alien invasive plants that threaten biodiversity. The selection of candidate agents remains a critical step in a biocontrol program before more elaborate and time‐consuming experiments are conducted. Here, we propose a biogeographic approach to identify candidates and combinations of candidates to potentially cover a large range of the invader. We studiedAmbrosia artemisiifolia(common ragweed), native to North America (NA) and invasive worldwide, and sixNAbiocontrol candidates for the introduced Europe (EU) range of ragweed, both under current and future bioclimatic conditions. For the first time, we constructed species distribution models based on worldwide occurrences and important bioclimatic variables simultaneously for a plant invader and its biocontrol candidates in view of selecting candidates that potentially cover a large range of the target invader. Ordination techniques were used to explore climatic constraints of each species and to perform niche overlap tests with ragweed. We show a large overlap in climatic space between candidates and ragweed, but a considerable discrepancy in geographic range overlap betweenEU(31.4%) andNA(83.3%). This might be due to niche unfilling and expansion of ragweed inEUand the fact that habitats with high ragweed occurrences inEUare rare inNAand predicted to be unsuitable for the candidates. Total geographic range of all candidates combined is expected to decrease under climate change in both ranges, but they will respond differently. The relative geographic coverage of a plant invader by biocontrol candidates at home is largely transferable to the introduced range, even when the invader shifts its niche. Our analyses also identified which combination of candidates is expected to cover the most area and for which abiotic conditions to select in order to develop climatically adapted strains for particular regions, where ragweed is currently unlikely to be controlled.

Effects of sub-culturing on genetic and physiological parameters in different Beauveria bassiana isolates

Beauveria bassiana is a fungus which is widely used as a biological insecticide to control a number of economically important insect pests. Knowledge of the genetic diversity of the isolates, understanding the underlying nature of these evolutionary phenomena and finding appropriate and simple screening tools play an important role in developing effective biocontrol agents. Here, we monitored changes of electrophoretic karyotype of small molecules of extrachromosomal DNAs, presumably mitochondrial DNA or plasmids in several individual isolates of B. bassiana during the forced in vitro evolution by continual subculture on artificial media and then we evaluated these changes on the virulence of the isolates. Through agarose gel electrophoresis of the small extrachromosomal DNAs molecules, we found that mutations accumulate quickly and obvious changes take place in extrachromosomal DNAs of some isolates, although this did not always occur. This plasticity in response to culturing pressure suggests that buffering capacity of fungal genome against mutations is isolate dependent. Following the forced evolution by sub-culturing, five discriminable electrophoretic karyotype of extrachromosomal DNAs was observed among isolates. The results showed that some isolates are prone to deep mutations, but during enforced sub-culturing some others have efficiently conserved genome. These differences are influensive in screening appropriate isolates for mass production as a keystone in biocontrol program. To determine the effects of these changes on isolate traits, virulence, germination rate and spore-bound Pr1 activity were assessed parallel to sub-culturing. The results clearly revealed that parallel to sub-culturing and in correlation with karyotypic changes, isolates significantly suffered from virulence, germination rate and spore-bound Pr1 activity deficiencies.

Four-trophic level food webs reveal the cascading impacts of an invasive plant targeted for biocontrol.

Biological invasions are a major threat to biodiversity and as such understanding their impacts is a research priority. Ecological networks provide a valuable tool to explore such impacts at the community level, and can be particularly insightful for planning and monitoring biocontrol programmes, including the potential for their seldom evaluated indirect non-target effects. Acacia longifolia is among the worst invasive species in Portugal, and has been recently targeted for biocontrol by a highly specific gall-wasp. Here we use an ambitious replicated network approach to: (1) identify the mechanisms by which direct and indirect impacts of A.longifolia can cascade from plants to higher trophic levels, including gallers, their parasitoids and inquilines; (2) reveal the structure of the interaction networks between plants, gallers, parasitoids and inquilines before the biocontrol; and (3) explore the potential for indirect interactions among gallers, including those established with the biocontrol agent, via apparent competition. Over a 15-month period, we collected 31,737 galls from native plants and identified all emerging insects, quantifying the interactions between 219 plant-, 49 galler-, 65 parasitoid- and 87 inquiline-species-one of the largest ecological networks to date. No galls were found on any of the 16 alien plant species. Invasion by A.longifolia caused an alarming simplification of plant communities, with cascading effects to higher trophic levels, namely: a decline of overall gall biomass, and on the richness, abundance and biomass of galler insects, their parasitoids, and inquilines. Correspondingly, we detected a significant decline in the richness of interactions between plants and galls. The invasion tended to increase overall interaction evenness by promoting the local extinction of the native plants that sustained more gall species. However, highly idiosyncratic responses hindered the detection of further consistent changes in network topology. Predictions of indirect effects of the biocontrol on native gallers via apparent competition ranged from negligible to highly significant. Such scenarios are incredibly hard to predict, but even if there are risks of indirect effects it is critical to weigh them carefully against the consequences of inaction and invasive species spread.

Inoculative release strategies of Macrolophus pygmaeus Rambur (Hemiptera: Miridae) in tomato crops: population dynamics and dispersal

Macrolophus pygmaeus Rambur (Hemiptera: Miridae) is a key biological control agent in greenhouse tomato crops. In the present study, we describe the population dynamics of M. pygmaeus after release during two generations in semi-commercial greenhouses in order to optimize biocontrol programs. We tested the effect of the number of weekly supplementary food applications consisting of a mixture of Ephestia kuehniella Zeller and Artemia franciscana Kellogg in a tomato crop on population numbers of M. pygmaeus at low and high initial release densities of the predator. Also, the effect of supplementary feeding on the predator’s dispersal was studied. Larger population densities of M. pygmaeus were obtained when food was supplied for a longer period. However, we observed fruit damage by M. pygmaeus at high densities resulting from too frequent food applications. Also, dispersal was slowed down as the number of supplementary food applications increased. Distributing M. pygmaeus over more plants at release results in higher total population densities. The optimal inoculative release strategy of M. pygmaeus is a trade-off between high population densities and fruit damage, fast or slow dispersal throughout the greenhouse and the number of release plants and work/costs related to the supplementation of food. The optimal strategy to overcome negative effects like fruit damage, slow dispersal and potential cannibalism proved to be a weekly provision of supplementary food during 6–8 weeks, with an initial release density strategy of 20 M. pygmaeus adults per plant. These results contribute to a more sustainable tomato production. A reliable and efficient inoculative release strategy for the key predator M. pygmaeus enhances the biocontrol potential and is of great value for tomato growers.

Biocontrol of common carp in Australia poses risks to biosecurity.

The Australian government is considering employing the koi herpesvirus (KHV) for biocontrol of invasive common carp (Cyprinus carpio) in the Murray–Darling river system of southeast Australia in 20181,2. KHV is on the World Organisation of Animal Health (OIE) list of notifiable diseases3, yet the biocontrol programme has been framed as a safe and manageable proposition1,2. Previous reports highlight that viruses have been successfully employed in the biocontrol of terrestrial vertebrates1, including cats on Marion Island, and feral rabbits in Australia and New Zealand. However, compared with the biocontrol of terrestrial vertebrates, the biocontrol of large, highly fecund aquatic animals such as carp adds novel risks.

Isolation, identification and characterisation of the nematophagous fungus Arthrobotrys thaumasia (Monacrosporium thaumasium) from China

ABSTRACTThe objective of this study is to select a native isolate of Arthrobotrys thaumasia (Monacrosporium thaumasium), a nematophagous fungus that shows potential for use in biocontrol programmes for ruminants. First, we looked for native isolates of A. thaumasia and characterised them using light microscopy and molecular markers. Then, we determined the effect of temperature, pH and nutrition on the growth rate and trap formation of a representative isolate. Of the 1532 samples of different types related to sheep and cattle, 11 isolates of A. thaumasia were isolated, and their occurrence frequency in the samples was 0.71% (11/1532). We sequenced the rDNA internal transcribed spacer of isolate NBS005, submitted it to GenBank (ID: KX640093) and then sequenced it using BLAST. The NBS005 could not grow at 37.5°C but could grow from 11°C to 35°C, and it exhibited its optimum growth at 30°C on 1% corn meal agar (CMA). Over 4 days, the fungus did not grow in the pH interval from 1 to 3 or from 13 to 14 but did grow in the pH interval from 4 to 12 and exhibited its optimum growth between pH 9 and 10 on 2% CMA. The factors responsible for the trap formation of NBS005 in liquid culture were identified. Trap formation was induced only by contact with L3 lysate. The concentrations of sucrose, ammonium chloride and tryptone of 0.4, 0.2 and 0.2%, respectively, promoted trap formation, and there were higher numbers of trapping nets in 2% wheat bran liquid medium containing L3 lysate.

Clarifying the source of Conicofrontia sesamoides Hampson (Lepidoptera: Noctuidae) population in South African sugarcane using morphological identification and mitochondrial DNA analysis

Valid identification of a novel pest species and clarifying its origin are the primary steps in understanding population structure and development of biocontrol programs. In this study geographical populations of Conicofrontia sesamoides Hampson (Lepidoptera: Noctuidae) collected during surveys conducted in the years 2009, 2014 and 2015 were morphologically identified and their genetic diversity was analysed by using sequences of the mitochondrial cytochrome-c oxidase I (COI) gene in an attempt to examine host plant, or/and altitude associated differences among populations and determine the source of the newly recorded population of this species in the South African sugarcane. The C. sesamoides specimens in this study were collected from Miscanthus capensis (Nees) (Poaceae) and sugarcane (Saccharum officinarum L.) (Poaceae) in Eastern Cape and KwaZulu-Natal Provinces of South Africa. Analysis of Molecular Variance showed a moderate to highly significant genetic differentiation between C. sesamoides populations from different host plants (FST = 0.115, p = 0.14) and altitudinal range (FST = 0.159, p = 0.18). This result was however, contradictory to outcomes of phylogenetic analyses, haplotype networking and uncorrected sequence divergence (0.0–1.54%) which revealed no detectable genetic differentiation between populations from different host plants and altitudes. As it is difficult to measure FST accurately without a large data set, the very small sample used in the analysis might have resulted in inflation of the FST value in this study. After evaluation of the results, it was concluded that the sugarcane population of C. sesamoideshas originated from the population residing in wild host plants in the Eastern Cape and/or KwaZulu-Natal provinces of South Africa. Possible reasons for the host plant expansion and its implications to commercial sugarcane production in the country are discussed.

Comparative biology and life table of Habrobracon hebetor (Hymenoptera: Braconidae) on Anagasta kuehniella (Lepidoptera: Pyralidae) at five constant temperatures

ABSTRACTHabrobracon hebetor Say is an ectoparasitoid that has been used as a control agent of various lepidopteran pests. Temperature-dependent life table and thermal characteristics of H. hebetor are important in understanding the dynamics of host–parasitoid relationships and for optimizing biocontrol programmes. The influence of five constant temperatures (15, 20, 25, 30 and 35 °C) on the biology of H. hebetor when parasitizing Anagasta kuehniella Zeller was studied. The survival rate of immature stages increased from 16.67% to 83.81% as temperature increased from 15 to 30 °C and then decreased at 35 °C. Total development time ranged from 45.70 days at 15 °C to 7.10 days at 35 °C. The lower temperature threshold for immature stages varied slightly around a value of 11–12 °C. The net reproductive rate (R0) values were significantly different among temperatures and the highest value was found at 30 °C (85.10). The high survival rate and net reproductive rate combined with a relatively short generation time at 30 °C resulted in the intrinsic rate of increase (rm) being highest (0.312 d−1) at this temperature. Considering the acquired results, the temperature range between 25 and 30 °C was optimal for H. hebetor.

Low labor “in vivo” mass rearing method for entomopathogenic nematodes

The wide spread use of biological control agents in commercial agriculture is frequently limited by the high cost of the biological control agents. We describe in this paper an entomopathogenic nematode (EPN) “in vivo” mass rearing method, not based on the White trap concept, which is both “low technology” and “low labor”, reducing the cost of producing large quantities of EPN IJ to the level conducive for use in an area-wide biocontrol program. Rearing temperature has a significant impact on the number of EPN IJ produced per host larvae and the IJ viability at any point in time. Emerged IJs remain within a non-aqueous, high humidity environment with improved oxygen access without extra steps or equipment. Depending on storage conditions, IJs remain viable for 7–14d without extra labor. Our laboratory has used this rearing method to rear more than 100 billion IJ in the past 8years to support an area wide biological control program.

Two for one: inadvertent introduction of Euglandina species during failed bio-control efforts in Hawaii

The introduction of the predatory land snail, Euglandina rosea (Ferrusac, 1821) from Florida to Hawaii to control the giant African snail, Lissachatina fulica (Bowdich, 1822) is among the most publicized biological control cases gone awry. Following preliminary genetic analyses that revealed a second, possibly undescribed Euglandina species was probably introduced to Hawaii, we used an integrative systematic approach combining both genetic and morphological assessments to examine the taxonomic status of the snail referred to as E. rosea in Hawaii. Genetic and morphological analyses support the interpretation that two Euglandina species were introduced to and have become established in Hawaii and can be readily distinguished based on morphological differences. This finding has significant ramifications for understanding both historical and contemporary biocontrol as it suggests that: (1) other species may have been inadvertently introduced through bio-control programs, (2) inadequate understanding of the taxonomy of bio-control agents has obscured our ability to effectively study their ecological impacts, and (3) while the US has no comprehensive regulatory framework for importing biological control agents, one is urgently needed. This also has wide-ranging implications for conservation efforts throughout the tropics because Euglandina from Oahu, Hawaii were released on other Hawaiian Islands, New Guinea, Okinawa, Palau Islands, Philippines, India, Bonin Islands and Bermuda for use in biological control programs that led to catastrophic loss of endemic land snail diversity.

The production and uses of Beauveria bassiana as a microbial insecticide.

Among invertebrate fungal pathogens, Beauveria bassiana has assumed a key role in management of numerous arthropod agricultural, veterinary and forestry pests. Beauveria is typically deployed in one or more inundative applications of large numbers of aerial conidia in dry or liquid formulations, in a chemical paradigm. Mass production is mainly practiced by solid-state fermentation to yield hydrophobic aerial conidia, which remain the principal active ingredient of mycoinsecticides. More robust and cost-effective fermentation and formulation downstream platforms are imperative for its overall commercialization by industry. Hence, where economics allow, submerged liquid fermentation provides alternative method to produce effective and stable propagules that can be easily formulated as dry stable preparations. Formulation also continues to be a bottleneck in the development of stable and effective commercial Beauveria-mycoinsecticides in many countries, although good commercial formulations do exist. Future research on improving fermentation and formulation technologies coupled with the selection of multi-stress tolerant and virulent strains is needed to catalyze the widespread acceptance and usefulness of this fungus as a cost-effective mycoinsecticide. The role of Beauveria as one tool among many in integrated pest management, rather than a stand-alone management approach, needs to be better developed across the range of crop systems. Here, we provide an overview of mass-production and formulation strategies, updated list of registered commercial products, major biocontrol programs and ecological aspects affecting the use of Beauveria as a mycoinsecticide.

Acute toxicity and repellent activity of the Origanum scabrum Boiss. & Heldr. (Lamiaceae) essential oil against four mosquito vectors of public health importance and its biosafety on non-target aquatic organisms.

The recent outbreaks of dengue, chikungunya, and Zika virus highlighted the pivotal importance of mosquito vector control in tropical and subtropical areas worldwide. However, mosquito control is facing hot challenges, mainly due to the rapid development of pesticide resistance in Culicidae and the limited success of biocontrol programs on Aedes mosquitoes. In this framework, screening botanicals for their mosquitocidal potential may offer effective and eco-friendly tools in the fight against mosquitoes. In the present study, the essential oil (EO) obtained from the medicinal plant Origanum scabrum was analyzed by GC-MS and evaluated for its mosquitocidal and repellent activities towards Anopheles stephensi, Aedes aegypti, Culex quinquefasciatus, and Culex tritaeniorhynchus. GC-MS analysis showed a total of 28 compounds, representing 97.1% of the EO. The major constituents were carvacrol (48.2%) and thymol (16.6%). The EO was toxic effect to the A. stephensi, A. aegypti, C. quinquefasciatus, and C. tritaeniorhynchus larvae, with LC50 of 61.65, 67.13, 72.45, and 78.87μg/ml, respectively. Complete ovicidal activity was observed at 160, 200, 240, and 280μg/ml, respectively. Against adult mosquitoes, LD50 were 122.38, 134.39, 144.53, and 158.87μg/ml, respectively. In repellency assays, the EOs tested at 1.0, 2.5, and 5.0mg/cm2 concentration of O. scabrum gave 100% protection from mosquito bites up to 210, 180, 150, and 120min, respectively. From an eco-toxicological point of view, the EO was tested on three non-target mosquito predators, Gambusia affinis, Diplonychus indicus, and Anisops bouvieri, with LC50 ranging from 4162 to 12,425μg/ml. Overall, the EO from O. scabrum may be considered as a low-cost and eco-friendly source of phytochemicals to develop novel repellents against Culicidae.