Biological Pest Control Research Articles

Herbivore-induced plant volatiles emitted by citrus in response to spider mite infestation can attract predatory mites.

Understanding the nutritional interplay among plants, pests, and natural enemies is essential for sustainable pest management. Enhancing the efficiency of natural enemies, such as Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) is critical, and exploiting herbivore-induced plant volatiles (HIPVs) offers a promising approach. However, N. californicus has rarely been reported to utilize HIPVs to improve their biological control capabilities. Our research revealed a significant difference in the diversity of volatile compounds detected in clean Citrus reticulata Blanco leaves compared to those in C. reticulata leaves infested with Panonychus citri (McGregor) (Acari: Tetranychidae), regardless of mite presence. This suggests that P. citri infestation induces a wide array of HIPVs in C. reticulata leaves. We conducted olfactory behavioral assays to evaluate the response of N. californicus to synthetic HIPVs. Results revealed that linalool (1.00 mg/mL), 2,2,4-trimethylpentane (10.0 mg/mL), undecylcyclohexane (1.00 mg/mL), and (+)-dibenzoyl-L-tartaric anhydride (10.0 mg/mL) significantly attracted N. californicus while pentadecanal (1.00 mg/mL) significantly deterred it. A 3-component blend of linalool, undecylcyclohexane, and (+)-dibenzoyl-L-tartaric anhydride was better than other combinations in attracting N. californicus. This combination provided the basis for developing an attractant for N. californicus, facilitating the rate of its dispersal to enhance its biological control of pests. Consequently, this research offers vital insights into improving the sustainable pest control potential of predatory mites.

Application of a Mechanistic Model to Explore Management Strategies for Biological Control of an Agricultural Pest

Despite the known benefits of integrated pest management, adoption in Australian broadacre crops has been slow, in part due to the lack of understanding about how pests and natural enemies interact. We use a previously developed process-based model to predict seasonal patterns in the population dynamics of a canola pest, the green peach aphid (Myzus persicae), and an associated common primary parasitic wasp (Diaeretiella rapae), found in this cropping landscape. The model predicted aphid population outbreaks in autumn and spring. Diaeretiella rapae was able to suppress these outbreaks, but only in scenarios with a sufficiently high number of female wasps in the field (a simulated aphid:wasp density ratio of at least 5:1 was required). Model simulations of aphid-specific foliar pesticide applications facilitated biological control. However, a broad-spectrum pesticide negated the control provided by D. rapae, in one case leading to a predicted 15% increase in aphid densities compared to simulations in which no pesticide was applied. Biological and chemical control could therefore be used in combination for the successful management of the aphid while conserving the wasp. This modelling framework provides a versatile tool for further exploring how chemical applications can impact pests and candidate species for biological control.

Movers and shakers: Do nematodes that move more invade more?

Entomopathogenic nematodes (EPNs) are roundworms that parasitize insects with the aid of symbiotic bacteria. These nematodes have been used both as model organisms and for biological control of pests. The specialized third stage of an EPN, known as an infective juvenile (IJ) must forage to find a host with strategies varying from species to species (cruising, ambushing, and intermediate). Some IJs move more than others to find a host, despite an increased risk of predation and desiccation. This hints at potential underlying benefits (e.g., increased invasion) for EPNs that move more. We assessed whether EPNs that moved farther down a soil column also exhibit higher levels of invasion when compared to nematodes that remained at or near their point of origin. We found that movers in the cruisier and intermediate species: Steinernema riobrave, Heterorhabditis bacteriophora, and H. indica had higher invasion rates compared to their counterparts that did not move. S. carpocapsae, an ambusher, did not exhibit invasion differences between EPNs that moved versus those that did not. For the three cruiser/intermediate EPNs we tested, our results support our hypothesis that EPNs that tend to move more enjoy related benefits such as increased invasion potential. Further studies are required to explore other parameters that may interact with movement. The results of this study can potentially be used to develop EPN strains that move more and invade more, and thus can potentially be more effective biological control agents.

Entomopathogenic pseudomonads can share an insect host with entomopathogenic nematodes and their mutualistic bacteria.

A promising strategy to overcome limitations in biological control of insect pests is the combined application of entomopathogenic pseudomonads (EPPs) and nematodes (EPNs) associated with mutualistic bacteria (NABs). Yet, little is known about interspecies interactions such as competition, coexistence, or even cooperation between these entomopathogens when they infect the same insect host. We investigated the dynamics of bacteria-bacteria interactions between the EPP Pseudomonas protegens CHA0 and the NAB Xenorhabdus bovienii SM5 isolated from the EPN Steinernema feltiae RS5. Bacterial populations were assessed over time in experimental systems of increasing complexity. In vitro, SM5 was outcompeted when CHA0 reached a certain cell density, resulting in the collapse of the SM5 population. In contrast, both bacteria were able to coexist upon haemolymph-injection into Galleria mellonella larvae, as found for three further EPP-NAB combinations. Finally, both bacteria were administered by natural infection routes i.e. orally for CHA0 and nematode-vectored for SM5 resulting in the addition of RS5 to the system. This did not alter bacterial coexistence nor did the presence of the EPP affect nematode reproductive success or progeny virulence. CHA0 benefited from RS5, probably by exploiting access routes formed by the nematodes penetrating the larval gut epithelium. Our results indicate that EPPs are able to share an insect host with EPNs and their mutualistic bacteria without major negative effects on the reproduction of any of the three entomopathogens or the fitness of the nematodes. This suggests that their combination is a promising strategy for biological insect pest control.

Can Capsicum spp. genotypes resist simultaneous damage by both Phytophthora capsici and Bemisia tabaci? Can natural enemies of Bemisia complement plant resistance?

Capsicum (Solanaceae) includes peppers and chilies. Phytophthora capsici (Peronosporaceae) and Bemisia tabaci (Hemiptera: Aleyrodidae) are two relevant problems in the production of this genus. Among the sustainable alternatives for disease and pest control, plant resistance and biological control stand out. The main objective of this research was to evaluate the resistance of Capsicum genotypes to damage by P. capsici and infestation by B. tabaci, as well as to diagnose whether the action of predators and parasitoids against B. tabaci could complement the resistance of the plants. The progression of disease caused by P. capsici and infestation by B. tabaci was estimated in 23 Capsicum genotypes, corresponding to the species: Capsicum annuum, Capsicum baccatum, Capsicum chinense, Capsicum frutescens and Capsicum. pubescens, from the GenBank of the National Institute of Agricultural Research (INIAP-Ecuador). Three genotypes: ECU-11993 (C. baccatum), ECU-11991 and ECU-2244 (C. pubescens) showed high susceptibility to both P. capsici damage and B. tabaci infestation. C. baccatum, C. chinense and C. frutescens genotypes showed the highest resistance to both pests, suggesting multiple resistance. Six taxa of predators and parasitoids reduced B. tabaci populations that developed in the most infested genotypes. Plant resistance is a control alternative that could allow the use of biological control, making it environmentally friendly. These results provide the basis for breeding programs in Capsicum.

Local Habitat Complexity and Its Effects on Herbivores and Predators in Urban Agroecosystems.

In urban community gardens, cultivated vegetation provides variable levels of habitat complexity, which can suppress pests by promoting predator diversity and improving pest control. In this study, we examine three components of the structural complexity of garden vegetation (cover, diversity, and connectivity) to investigate whether higher garden vegetation complexity leads to fewer herbivores, more predators, and higher predation. We worked in eight community gardens where we quantified vegetation complexity, sampled the arthropod community, and measured predation on corn earworm eggs. We found that plots with high vegetation cover supported higher species richness and greater abundance of predatory insects. High vegetation cover also supported a greater abundance and species richness of spiders. In contrast, high vegetation diversity was negatively associated with predator abundance. While high predator abundance was positively associated with egg predation, greater predator species richness had a negative impact on egg predation, suggesting that antagonism between predators may limit biological control. Community gardeners may thus manipulate vegetation cover and diversity to promote higher predator abundance and diversity in their plots. However, the species composition of predators and the prevalence of interspecific antagonism may ultimately determine subsequent impacts on biological pest control.

A parasitoid regulates 20E synthesis and antibacterial activity of the host for development by inducing host nitric oxide production.

Parasitoids are important components of the natural enemy guild in the biological control of insect pests. They depend on host resources to complete the development of a specific stage or whole life cycle and thus have evolved towards optimal host exploitation strategies. In the present study, we report a specific survival strategy of a fly parasitoid Exorista sorbillans (Diptera: Tachinidae), which is a potential biological control agent for agricultural pests and a pest in sericulture. We found that the expression levels of nitric oxide synthase (NOS) and nitric oxide (NO) production in host Bombyx mori (Lepidoptera: Bombycidae) were increased after E. sorbillans infection. Reducing NOS expression and NO production with an NOS inhibitor (NG-nitro-L-arginine methyl ester hydrochloride) in infected B. mori significantly impeded the growth of E. sorbillans larvae. Moreover, the biosynthesis of 20-hydroxyecdysone (20E) in infected hosts was elevated with increasing NO production, and inhibiting NOS expression lowered 20E biosynthesis. More importantly, induced NO synthesis was required to eliminate intracellular bacterial pathogens that presumably competed for shared host resources. Inhibiting NOS expression down-regulated the transcription of antimicrobial peptide genes and increased the number of bacteria in parasitized hosts. Collectively, this study revealed a new perspective on the role of NO in host-parasitoid interactions and a novel mechanism for parasitoid regulation of host physiology to support its development.

Monitoring the feeding and parental care behavior of a pair of free-living owls (Tyto furcata) in the nest during the reproductive period in Rio de Janeiro, Brazil.

The American Barn Owl (Tyto furcata) lives in urban, periurban and wild environments and feeds mainly on small rodents, meaning it has great importance in the biological control of pests. The aim of this work was to describe the reproductive, parental and eating habits of a pair of American barn owls naturally living outside a residence in the urban area of the municipality of Campos dos Goytacazes, Rio de Janeiro state, Brazil. A wood box was installed on an outside wall of the home, monitored by a video camera. A spreadsheet was created to keep track of the observations recorded. The female laid four eggs, and after an incubation period of 30-32 days all the eggs hatched, but only two chicks survived after cannibalism among the chicks. Initially, the male provided the food to the chicks and the female remained in the nest caring for the brood. After approximately a month, the female also began to leave the nest and return with prey, which was offered to the chicks, with the male also continuing this behavior. The chicks left the nest in September, 2017. The data obtained show the existence of cooperation and division of tasks between male and female owls during the reproductive period.

Além dos campos: as prospecções tecnológicas sustentáveis da EMBRAPA para o agronegócio brasileiro

Abstract This research aimed to understand the future of sustainable agricultural innovations, analyzing the technologies developed by EMBRAPA, in the conceptual light of innovation, sustainable economic development, and the entrepreneurial state. An exploratory and qualitative methodology was used to chronologically organize 1188 technological solutions, 363 patents and, 2043 cultivars. The method guided the application of a prospective scenario questionnaire adapted to the Likert-type SERVQUAL Scale. Based on the obtained results, a tendency to invest in improved water catchment systems, intelligent irrigation, heat and drought tolerant varieties, soil management technologies, biological pest control, use of renewable raw materials, and genetic improvement was observed. Finally, investments in methodologies, processes, and expansion of EMBRAPA services were also prioritized, as well as the celebration of partnerships with agricultural groups, companies, and institutes. Based on all the information presented in this study, it is evident that EMBRAPA has already established technologies. However, it is more urgent and imperative than ever to invest and drive sustainable innovation, making it accessible to all Brazilian producers, and providing a prosperous future for production and conservation in the sector.

Constraints in Adopting Biological Based Pest Management Strategies

Biological control of insect pests is a “viable alternative” to insecticides with an aim to suppress the pest populations below economic injury levels and is the need of the hour. The key biological based management strategies include erection of pheromone traps for mass trapping/monitoring the incidence of moths (adults) of insect pests; conservation of natural enemies like predators/parasitoids in crop ecosystem; augmentation and inundative release of bio-agents like parasitoids and predators against the targeted pests; and application of bio-rational or “reduced risk” insecticides that effectively controls the insect pests and non toxic to other organisms with meager environment risk. Many research findings had strongly witnessed the biological pest management as superior method in suppressing the pest infestation levels in almost all crops, but the success rate is not substantial at farmer’s level. In order to assess the constraints in adopting biological methods and restraints in low success rate of these methods in suppressing the insect pests an explorative research study was conducted for a period of two successive years i.e., 2020-2021 and 2021-22. A total of ten mandals in Krishna district of Andhra Pradesh was selected for the study wherein biological based management strategies are being practiced by the farmers. From each mandal three villages were randomly selected and from each mandal ten farmers were chosen for personal interview to document the constrains in adopting bio-control methods. The methodologies being practiced by farmers were also recorded. The results inferred that among the various restraints, non availability of bio-control agents/materials at market level (63%), adopting the methods at improper time (59%) and lack of knowledge on pest behavior/ecology (55%) are the major influencing factors for low success rate of biological control at farmer’s level. It can be accomplished from the present study that adoption levels of biological pest management strategies at farmers are to be strengthened by conducting regular training programmes, result demonstrations, front line demonstrations and also by encouraging farmers through some incentives and certifications of the harvested organic produce.

Pathogenicity of bacteria and viruses to Spodoptera frugiperda (Lepidoptera: Noctuidae)

Combining integrated pest management and biological control has been an effective, economical, and sustainable strategy for controlling agricultural pests. The larvae of Spodoptera frugiperda, a pest of several crops, cause financial losses to the agribusiness sector, and entomopathogens have been widely used for the biological control of this species. Therefore, the objective of this study was to evaluate the pathogenicity of bacteria and viruses for the control of S. frugiperda under laboratory conditions. Two bioassays were conducted in a completely randomized design, one using second-instar and other using third-instar larvae, with six treatments and five replications. The entomopathogens used were S. frugiperda Multiple nucleopolyhedrovirus (SfMNPV), Autographa californica multiple nucleopolyhedrovirus (AcMNPV), Bacillus subtilis, B. thuringiensis subsp. thoworthy, and B. thuringiensis subsp. kurstaki. Mortality was assessed daily until the end of the larval cycle. Analysis of variance (F-test) was applied, followed by mean comparison through the Scott-Knott test at a 5% significance level. The efficacy of the entomopathogens as bioinsecticides was evaluated using Abbott's formula. Overall, the most effective entomopathogens for controlling second-instar S. frugiperda larvae were SfMNPV and B. subtilis, resulting in 100% control, whereas AcMNPV was the most effective against third-instar larvae, showing maximum lethality in 76.67% of samples.

Predator-prey interactions: How thrips avoid predation

Biological pest control is successful in many agricultural systems, yet various pests can still not be controlled with natural enemies. Examples are invasive thrips species such as Echinothrips americanus Morgan and Thrips parvispinus (Karny) in Europe. The lack of biological control of these pests in several crops has been subscribed to their complex life cycle and cryptic behaviours, but their antipredator behaviours may prevent successful control and have not been studied extensively. One of these behaviours is the potential of thrips to kill the eggs of predatory mites, which we quantified. Furthermore, we observed the behaviour of first- and second-instar thrips larvae when attacked by starved predatory mites Amblyseius swirskii Athias-Henriot. For comparison, we included Frankliniella occidentalis (Pergande), which shows an array of defensive behaviours, but can be controlled successfully by several species of predatory mites. Second-instar larvae and adults of F. occidentalis and T. parvispinus killed predator eggs, but E. americanus did not. First- and second-instar larvae of all three species swung their abdomen to defend themselves, and F. occidentalis and T. parvispinus produced anal droplets, which are also involved in defence. Predators were not successful in attacking any second-instar larvae during 15-minute observations, which is sufficiently long for an attack. First-instar larvae of F. occidentalis and T. parvispinus were sometimes successfully attacked by the predatory mite before they could mount a defence, but first-instar E. americanus always defended themselves and were almost never preyed upon. Cooling thrips larvae to suppress antipredator behaviour increased predation for all species and stages, except for first instars of F. occidentalis. In conclusion, the lack of successful control of E. americanus is not caused by killing predator eggs, but by the efficient defensive behaviour of both larval instars. Our study furthermore suggests that T. parvispinus can potentially be controlled by A. swirskii.

Entomopathogenic Fungi: Nature's Secret Weapon Against Agricultural Pests

Insect pests pose significant challenges to agricultural productivity and crop yield worldwide. Conventional pest control methods, such as chemical pesticides, have limitations and adverse environmental effects. Therefore, there is a growing need for sustainable and eco-friendly alternatives in pest management. This review explores the potential of entomopathogenic fungi as a promising biological control agent for insect pests in agriculture. The review begins by providing an overview of entomopathogenic fungi and their significancce. These fungi possess unique mechanisms to infect and kill insect pests. The mode of action involves attachment of fungal spores to the insect's cuticle, followed by penetration, colonization, and release of toxic metabolites within the host. Various factors influence the efficacy of entomopathogenic fungi, including environmental conditions, insect host susceptibility, and formulation/application methods. The benefits of entomopathogenic fungi as biological control agents are discussed, including their compatibility with integrated pest management (IPM) strategies and minimal impact on non-target organisms. However, challenges exist in scaling up their commercial application. The review presents case studies showcasing successful field applications of entomopathogenic fungi in pest management. Future prospects and research directions are identified, emphasizing the importance of continued advancements in understanding the interactions between entomopathogenic fungi and insect pests. Regulatory frameworks and public acceptance are crucial for the widespread adoption of these fungi in agriculture. In conclusion, entomopathogenic fungi offer immense potential as sustainable and effective tools for biological control of insect pests in agriculture. Their ability to target specific pests, compatibility with IPM, and minimal environmental impact make them a viable alternative to chemical pesticides. Further research, collaboration, and implementation are necessary to fully harness the potential of entomopathogenic fungi in integrated pest management strategies.

DNA Barcoding Unveils New Species of the Sexually Dimorphic Genus Anteon Jurine (Hymenoptera, Dryinidae) from China.

Species of Anteon Jurine, 1807 are a large group of parasitoids attacking leafhoppers, which are important insect pests. Despite their great potential in pest biological control, the taxonomy and biology of these parasitoids are far from clear. Sexual dimorphism is extreme in Anteon species and has hampered the taxonomy of these parasitoids, resulting in many species described based on a single sex. In this paper, we employed an integrated taxonomic approach for delimitating species, combining morphological examinations with DNA barcoding, to investigate Anteon species from China. In total, 53 COI sequences representing 29 species of Anteon were obtained and analyzed. On the basis of both morphology and DNA barcoding, five new species of Anteon were discovered and described: A. clariclypeum sp. nov., A. maguanense sp. nov., A. parafidum sp. nov., A. shaanxianum sp. nov., and A. shandonganum sp. nov. The neotype of A. claricolle Kieffer is designated. The sexual association of six species was confirmed by DNA barcoding, which led to the synonymy of Anteon liui Xu, Olmi & He 2010, new syn., under Anteon meifenganum Olmi, 1991. Keys to species of Anteon from the Oriental and Eastern Palaearctic are updated to contain the five new species. Our study demonstrates that DNA barcoding is a potent tool for tackling the taxonomic challenges in parasitoids with extreme sexual dimorphism.

Parasitism success of Microplitis manilae (Hymenoptera: Braconidae) on different diet‐fed Spodoptera frugiperda (Lepidoptera: Noctuidae) larvae

AbstractEfficient rearing is necessary for the successful biological control of pests. The braconid wasp, Microplitis manilae, is a natural solitary parasitoid of larval Spodoptera frugiperda. However, the effect of the host diet on the parasitism success of M. manilae on S. frugiperda larvae remains unclear. Here, we determined the parasitism rate, oviposition, eclosion rate, developmental period and offspring sex ratio of M. manilae parasitizing S. frugiperda fed with fresh corn leaves or an artificial diet. M. manilae parasitizing the corn leaf‐fed S. frugiperda larvae exhibited a significantly higher parasitism rate (40%), oviposition (62.50 eggs/female) and eclosion rate (81.38%) than the wasp parasitizing the artificial diet‐fed S. frugiperda larvae (22%, 38.33 eggs/female, and 58.73%, respectively). Furthermore, M. manilae parasitizing the corn leaf‐fed S. frugiperda larvae exhibited a significantly shorter developmental period (16.35 days) and lower sex ratio (1.17) than the wasp parasitizing the artificial diet‐fed S. frugiperda larvae (18.00 and 2.15 days, respectively). Overall, M. manilae exhibited better parasitic success on corn leaf‐fed S. frugiperda larvae than on artificial diet‐fed S. frugiperda larvae. Therefore, using fresh corn leaf‐fed S. frugiperda is the most suitable strategy for mass‐rearing M. manilae for pest biocontrol. Our findings suggest M. manilae as an effective biocontrol candidate for controlling S. frugiperda in corn fields.

Leveraging insect viruses and genetic manipulation for sustainable agricultural pest control.

The potential of insect viruses in the biological control of agricultural pests is well-recognized, yet their practical application faces obstacles such as host specificity, variable virulence, and resource scarcity. High-throughput sequencing (HTS) technologies have significantly advanced our capabilities in discovering and identifying new insect viruses, thereby enriching the arsenal for pest management. Concurrently, progress in reverse genetics has facilitated the development of versatile viral expression vectors. These vectors have enhanced the specificity and effectiveness of insect viruses in targeting specific pests, offering a more precise approach to pest control. This review provides a comprehensive examination of the methodologies employed in the identification of insect viruses using HTS. Additionally, it explores the domain of genetically modified insect viruses and their associated challenges in pest management. The adoption of these cutting-edge approaches holds great promise for developing environmentally sustainable and effective pest control solutions. © 2023 Society of Chemical Industry.

Environmental complexity and predator density mediate a stable earwig-woolly apple aphid interaction

Regulation of insect pests by predators is an integral component of biological pest control. However, predator-prey interactions often reach a stable state leading to coexistence, which can be problematic for plant protection if the persisting herbivores exceed a damage threshold. Consequently, understanding the factors mediating this stability is crucial for successful biocontrol. Here, we investigated the predator-prey interaction of an important apple pest, the woolly apple aphid (WAA) (Eriosoma lanigerum Hausm.) (Hemiptera: Aphididae), and its predator, the omnivorous common earwig (Forficula auricularia L.) (Dermaptera: Forficulidae). To this end, we introduced increasing densities of earwigs in gauze-bagged branches harbouring defined amounts of WAA and recorded predation on individual WAA colonies for almost one month. We showed that the spatial complexity of the predation environment and the earwig density determined the predation efficiency on WAAs. Earwigs could eradicate WAAs regardless of density on short apple branches without lateral twigs (first trial). However, on longer, more complex branches (second trial), stable states of WAAs and earwigs were observed. Only the highest earwig density could completely consume WAA regardless of branch complexity. We introduce a conceptual model to describe the searching capability of earwigs, which determines their efficiency in locating prey. Our model predicts that searching capability is reduced by environmental complexity; this effect is alleviated by increased earwig density, as more predators possess a higher searching capability. Conclusively, our model explains why only the highest earwig density could completely consume WAA irrespective of complexity and illustrates how predator density and environmental complexity jointly influence predation. Thus environmental characteristics not inherent to our predator-prey interaction were a decisive factor for effective predation on gauze-bagged branches. Based on these results, reducing tree complexity by pruning or augmenting earwig populations in orchards can increase biocontrol of the WAA.

The Viromes of Six Ecosystem Service Provider Parasitoid Wasps.

Parasitoid wasps are fundamental insects for the biological control of agricultural pests. Despite the importance of wasps as natural enemies for more sustainable and healthy agriculture, the factors that could impact their species richness, abundance, and fitness, such as viral diseases, remain almost unexplored. Parasitoid wasps have been studied with regard to the endogenization of viral elements and the transmission of endogenous viral proteins that facilitate parasitism. However, circulating viruses are poorly characterized. Here, RNA viromes of six parasitoid wasp species are studied using public libraries of next-generation sequencing through an integrative bioinformatics pipeline. Our analyses led to the identification of 18 viruses classified into 10 families (Iflaviridae, Endornaviridae, Mitoviridae, Partitiviridae, Virgaviridae, Rhabdoviridae, Chuviridae, Orthomyxoviridae, Xinmoviridae, and Narnaviridae) and into the Bunyavirales order. Of these, 16 elements were described for the first time. We also found a known virus previously identified on a wasp prey which suggests viral transmission between the insects. Altogether, our results highlight the importance of virus surveillance in wasps as its service disruption can affect ecology, agriculture and pest management, impacting the economy and threatening human food security.

Infestation with chewing (Spodoptera frugiperda) and piercing-sucking (Tetranychus urticae) arthropod lead to differential emission and biosynthesis of HIPVs underscoring MeSA and terpenoids in chrysanthemum foliage

Many volatiles that are induced in plant foliage as a result of herbivorous insect infestation can act as cues for natural enemy attraction or for priming defense mechanisms. However, the qualitative and quantitative differences in volatile emissions in chrysanthemum plants that are fed upon by pests with different mouthparts have not been explored. In this study, Tetranychus urticats (TEU) with piercing-sucking mouthparts and Spodoptera frugiperda larvae (FAW) with chewing mouthparts were selected to infest the Chrysanthemum morifolium leaves to determine the response of volatile emission and production induced by herbivore feeding with different mouthparts. Our results showed that FAW-infestation significantly increased the emission rate of monoterpenes and specifically induced the emission of β-pinene. In contrast, TEU-infested plants significantly enhanced the emission rate of sesquiterpenes and phenylpropanoids compared to the control group. In particular, β-funebrene and methyl salicylate (MeSA) were exclusively induced in TEU-infested plants. CmSAMTs responsible for the elicited emission of MeSA, were functionally characterized. Additionally, multiple CmTPSs with strikingly elevated expression induced by TEU and FAW-infestation were subjected to enzymatic assay for the identification of their biochemical function. The products (β-pinene, α-copaene, germacrene D, β-caryophyllene, β-funebrene and β-ylangene) of two pivotal CmTPSs covered the major terpene profiles elicited by TEU and FAW feeding. Overall, these results could deepen our understanding of the corresponding defensive strategies against herbivores feeding with different mouthparts in chrysanthemum plants and provide theoretical basis for the biological control of pests in the cultivation and production of chrysanthemum.

Distribution and accumulation of Cadmium in different trophic levels affecting Serangium japonicum, the predatory beetle of whitefly Bemisia tabaci, biologically, physiologically and genetically: An experimental study

Cadmium (Cd) is a heavy metal that is of great concern in agroecosystems due to its toxicity to plants, herbivores, carnivores, and human beings. The current study evaluated the allocation and bioaccumulation of Cd from soil to cotton plants, cotton plants to herbivore pests, and herbivorous pests to a natural enemy predator. When soil was spiked with 100 mg/kg Cd, results demonstrated that cotton roots accumulated more Cd than the stems and leaves. The bioaccumulation of Cd was less in 4th instar larvae, pupa, and adults of Serangium japonicum than in Bemisia tabaci adults. The bioaccumulation in S. japonicum elongated the immature development period and reduced adult longevity, oviposition days, fertility, and total pre-oviposition duration. The net reproduction of S. japonicum was also reduced, as was female mature weight and feeding potential; as a result, Cd exposure could reduce the future population size compared to uncontaminated populations. There was decreased activity of the antioxidant enzymes (SOD, CAT, and POD) and energy-conserving lipids (glycogen, triglyceride, and total cholesterol) in Cd-contaminated S. japonicum compared to controls. The detoxifying enzyme activity of GST and P450 increased while AChE activity did not change. The qRT-PCR research showed that SOD1, CAT, POD, glycogen, and triglyceride gene expression was higher than in controls, whereas detoxification gene expression did not change. Our results indicate that Cd exposure has a physiological trade-off between its adverse effects on life history traits and elevated detoxification and antioxidation of S. japonicum, which could result from gene expression alteration. Further studies are needed to assess whether Cd exposure causes irreversible DNA damage in S. japonicum.