Pest Control Agents Research Articles

Biosynthesis of silver nanoparticles using Ocimum tenuiflorum extract and its efficacy assessment against Helicoverpa armigera

Traditional methods of pest control are not able to prevent crop damage due to devastating pests. Therefore, through nanobiotechnology nano-bio pesticides and conjugated nanoparticles are produced as a pest control agent. The present work focused on the synthesis, characterization of silver nanoparticles (AgNPs) using Ocimum tenuiflorum leave extract and its larvicidal activity against Helicoverpa armigera. AgNPs were characterized by UV–Vis spectral analysis, indicated an absorbance of 4.695 at 560 nm. Moreover, Scanning Electron Microscope and X-ray Powder Diffraction showed that particles were spherical, ranging from 10 nm to 65 nm. The larvae of H. armigera were provided with an artificial diet with AgNPs coating of 0.25%, 0.5%, 0.75%, and 100% pure concentration. After 24 h, a dose response relationship in mortality was found maximum in pure AgNPs treated group, 83.33% and 75% in 0.75% treated group and 0.5% treated group, respectively. While the least mortality of 50% was observed in the 0.25%, AgNPs treated group. The LC50 calculated was 20.33 µL for AgNPs. It can be concluded that silver-nanoparticles possess a larvicidal effect. Furthermore, the biosynthesis of these particles is an efficient and profitable approach.

Patterns of invertebrate functional diversity highlight the vulnerability of ecosystem services over a 45-year period

Declines in invertebrate biodiversity1,2 pose a significant threat to key ecosystem services.3-5 Current analyses of biodiversity often focus on taxonomic diversity (e.g., species richness),6,7 which does not account for the functional role of a species. Functional diversity of species' morphological or behavioral traits is likely more relevant to ecosystem service delivery than taxonomic diversity, as functional diversity has been found to be a key driver of a number of ecosystem services including decomposition and pollination.8-12 At present, we lack a good understanding of long-term and large-scale changes in functional diversity, which limits our capacity to determine the vulnerability of key ecosystem services with ongoing biodiversity change. Here we derive trends in functional diversity and taxonomic diversity over a 45-year period across Great Britain for species supporting freshwater aquatic functions, pollination, natural pest control, and agricultural pests (adisservice). Species supporting aquatic functions showed a synchronous collapse and recovery in functional and taxonomic diversity. In contrast, pollinators showed an increase in taxonomic diversity, but a decline and recovery in functional diversity. Pest control agents and pests showed greater stability in functional diversity over the assessment period. We also found that functional diversity could appear stable or show patterns of recovery, despite ongoing changes in the composition of traits among species. Our results suggest that invertebrate assemblages can show considerable variability in their functional structure over time at a national scale, which provides an important step in determining the long-term vulnerability of key ecosystem services with ongoing biodiversity change.

In-silico ADMET Pharmacoinformatics of Geraniol (3,7-dimethylocta-trans-2,6-dien-1-ol) - acyclic monoterpene alcohol drug from Leaf Essential Oil of Cymbopogon martinii from Sirumalai Hills (Eastern Ghats), INDIA

Cymbopogon martinii is a grass from genus Cymbopogon (lemongrasses) native to India, but widely cultivated in other places for its aromatic essential oil. C. martinii known as Palmarosa smells sweet with rose-like odor. Geraniol, a terpene alcohol present in Cymbopogon martinii essential oil (CMEO) is much valued for its typical aroma and medicinal uses. In addition to the pleasant odor, Geraniol is known for fungicidal, nematicidal, acaricidal, insecticidal, repellent properties hence, used as Natural Pest Control Agent (NPCA) exhibiting low toxicity. Furthermore, geraniol has been suggested to exemplify a new class of chemoprevention agents in the treatment of cancer. Biological activities such as antimicrobial, anti-oxidant, anti-inflammatory and vascular effects have been investigated. In the present study, GCMS based in-silico ADMET pharmacoinformatics aspects (Physicochemical, Lipophilicity, Medicinal Chemistry, Druglikeness, Absorption, Water Solubility, Distribution, Metabolism, Pharmacokinetics, Excretion, Environmental Toxicity, Tox21 Pathway and Toxicophore Rules) with PASS prediction of geraniol from CMEO has been bioprospected from human health perspective point of view.
 Keywords: GCMS; ADMET; Pharmacoinformatics; Geraniol; Essential Oil; Cymbopogon martinii; Palmarosa; CMEO; PBNPs; Sirumalai Hills; Eastern Ghats

Insectivorous birds are not effective pest control agents in olive groves

Although avian-mediated pest control is a significant ecosystem service with important economic implications, few experimental studies have ever documented its role in Mediterranean agroforests. Specifically, information on pest control by birds is lacking in certain permanent agroecosystems of worldwide importance such as olive groves.Here, we assess experimentally for the first time the effectiveness of insectivorous birds in controlling the two main olive-tree pests. We also explore the effects of distance to semi-natural habitat patches on avian insectivore abundance and pest control. We combined bird and pest surveys with pest damage monitoring and two field experiments (branch exclusion and plasticine models) at a regional scale.The experiments showed that birds played a negligible role as pest controllers (measured in terms of attack rates on plasticine models and controlled pest damage) in the studied olive groves; overall, pests were abundant and pest damage was high on most farms. In addition, surveys showed that insectivorous birds were more abundant and diverse in patches of semi-natural habitat, compared to the matrix of olive groves, and that proximity to semi-natural patches was not a driver of bird-driven pest control.This study experimentally demonstrates that insectivorous birds are not effective pest controllers in olive groves. The absence of patterns linking insectivorous birds’ availability and observed pest control suggests that birds are unable to exert effective control over the main olive-tree pests. This lack of biocontrol by birds is probably due to low accessibility and/or appetence for the current insectivorous groups. Habitat improvement aimed at encouraging some under-represented forager species could improve the likelihood that birds will provide this ecosystem service.

Plant-Derived Pesticides as an Alternative to Pest Management and Sustainable Agricultural Production: Prospects, Applications and Challenges.

Pests and diseases are responsible for most of the losses related to agricultural crops, either in the field or in storage. Moreover, due to indiscriminate use of synthetic pesticides over the years, several issues have come along, such as pest resistance and contamination of important planet sources, such as water, air and soil. Therefore, in order to improve efficiency of crop production and reduce food crisis in a sustainable manner, while preserving consumer’s health, plant-derived pesticides may be a green alternative to synthetic ones. They are cheap, biodegradable, ecofriendly and act by several mechanisms of action in a more specific way, suggesting that they are less of a hazard to humans and the environment. Natural plant products with bioactivity toward insects include several classes of molecules, for example: terpenes, flavonoids, alkaloids, polyphenols, cyanogenic glucosides, quinones, amides, aldehydes, thiophenes, amino acids, saccharides and polyketides (which is not an exhaustive list of insecticidal substances). In general, those compounds have important ecological activities in nature, such as: antifeedant, attractant, nematicide, fungicide, repellent, insecticide, insect growth regulator and allelopathic agents, acting as a promising source for novel pest control agents or biopesticides. However, several factors appear to limit their commercialization. In this critical review, a compilation of plant-derived metabolites, along with their corresponding toxicology and mechanisms of action, will be approached, as well as the different strategies developed in order to meet the required commercial standards through more efficient methods.

Dodecanol, metabolite of entomopathogenic fungus Conidiobolus coronatus, affects fatty acid composition and cellular immunity of Galleria mellonella and Calliphora vicina

One group of promising pest control agents are the entomopathogenic fungi; one such example is Conidiobolus coronatus, which produces a range of metabolites. Our present findings reveal for the first time that C. coronatus also produces dodecanol, a compound widely used to make surfactants and pharmaceuticals, and enhance flavors in food. The main aim of the study was to determine the influence of dodecanol on insect defense systems, i.e. cuticular lipid composition and the condition of insect immunocompetent cells; hence, its effect was examined in detail on two species differing in susceptibility to fungal infection: Galleria mellonella and Calliphora vicina. Dodecanol treatment elicited significant quantitative and qualitative differences in cuticular free fatty acid (FFA) profiles between the species, based on gas chromatography analysis with mass spectrometry (GC/MS), and had a negative effect on G. mellonella and C. vicina hemocytes and a Sf9 cell line in vitro: after 48 h, almost all the cells were completely disintegrated. The metabolite had a negative effect on the insect defense system, suggesting that it could play an important role during C. coronatus infection. Its high insecticidal activity and lack of toxicity towards vertebrates suggest it could be an effective insecticide.

The Density and Viability of Metarhizium anisopliae Conidia on Several Growth Media

Metarhizium anisopliae is a parasitic fungus on insects, and thus called entomopathogenic fungus. This fungus is used as a biological control agent for insect pests. Fungal propagation can be done using a variety of media. The purpose of this study was to analyze the growth of M. anisopliae on four types of media, with conidial density and viability as the growth parameters. This research was conducted at the Laboratory of Microbiology, Universitas Negeri Semarang. This study was an experimental research used a Completely Randomized Design (CRD) with one factor and four treatments: Control (PDA/Potato Dextrose Agar medium), Treatment I (ELSA/Extract Larvae Sucrose Agar medium), Treatment II (CWSA/Coconut Water Sucrose Agar medium), Treatment III (CWELSA/Coconut Water and Extract Larvae Sucrose Agar medium). The and results showed that there was an effect of growth media on the density and viability of M. anisopliae conidia. CWELSA media had the highest conidial density (2.91 x 108 cfu/mL) and viability (97.17%). CWSA media had 2.82 x 108 cfu/mL and 95.33%. PDA media had 2.25 x 108 cfu/mL and 92.83%. ELSA media had 1.64 x 108 cfu/mL and 90.83%. The high conidial density and viability of M. anisopliae is CWELSA medium. This study is as an alternative growth medium to improve the quality of M. anisopliae propagation.

Seasonal prey availability and diet composition of Lesser Asiatic Yellow House Bat Scotophilus kuhlii Leach, 1821

Diet is an important factor in understanding bat ecology and conservation. This study assessed seasonal prey availability and diet composition of the Asiatic Lesser Yellow House Bat Scotophilus kuhlii in various districts of Uttar Pradesh between January 2016 to December 2018. Fecal and insect samples were collected seasonally using sweep nets between 1800 and 1900 h. From each location 20 fecal pellets were selected for analysis and searched for taxonomically recognizable remnants. The analysis revealed that S. kuhlii fed on Coleoptera, Diptera, Hymenoptera, Isoptera, Orthoptera, Odonata, Blattodae, Lepidoptera, and Hemiptera, identified from legs, antennae and wings/elytra in fecal pellets. Seasonal variation in the presence of isolated insect remnants and insect abundance at foraging grounds was observed. Thus S. kuhlii is a voracious feeder and plays an important role as a pest control agent.

Identification and Expression Profile of Chemosensory Genes in the Small Hive Beetle Aethina tumida.

Simple SummaryThe small hive beetle is a destructive pest of honeybees, causing severe economic damage to the apiculture industry. Chemosensory genes play key roles in insect behavior, such as foraging and mating partners. However, the chemosensory genes are lacking in the small hive beetle. In order to better understand its chemosensory process at the molecular level, a total of 130 chemosensory genes, including 38 odorant receptors, 24 ionotropic receptors, 14 gustatory receptors, 3 sensory neuron membrane proteins, 29 odorant binding proteins, and 22 chemosensory proteins were identified from the transcriptomic data of antennae and forelegs. Reverse-transcription PCR showed that 3 OBPs (AtumOBP3, 26 and 28) and 3 CSPs (AtumCSP7, 8 and 21) were highly expressed in antennae. Overall, this study could provide a basis for elucidating functions of these chemosensory genes at the molecular level.Aethina tumida is a parasite and predator of honeybee causing severe loss to the bee industry. No effective and environmentally friendly methods are available to control this pest at present. Chemosensory genes play key roles in insect behavior which can potentially be used as targets for developing environmentally friendly pest control agents. In this study, the putative chemosensory genes in antennae and forelegs of A. tumida involved in olfaction or contact chemical communication of adults were investigated using RNA transcriptome sequencing and PCR methods. Based on transcriptomic data, unigenes encoding 38 odorant receptors (ORs), 24 ionotropic receptors (IRs), 14 gustatory receptors (GRs), 3 sensory neuron membrane proteins (SNMPs), 29 odorant binding proteins (OBPs), and 22 chemosensory proteins (CSPs) were identified. The analyses of tissue expression profiles revealed that genes encoding 38 ORs, 13 antennal IRs, 11 GRs, 1 SNMP, 24 OBPs, and 12 CSPs were predominately expressed in antennae. No significant differences in expression levels of these genes were found between males and females. Genes encoding 5 non-NMDA iGluRs, 3 GRs, 2 SNMPs, 5 OBPs, and 12 CSPs were predominately expressed in forelegs. RT-PCR assays for SNMPs, OBPs and CSPs further revealed that 3 OBPs (AtumOBP3, 26 and 28) and 3 CSPs (AtumCSP7, 8 and 21) were highly expressed in antennae. Our results enrich the gene inventory of A. tumida and facilitate the discovery of potential novel targets for developing new pest control measures.

Host Deprivation Effects on the Functional Response and Parasitism Rate of Habrobracon hebetor (Hymenoptera: Braconidae) on Ephestia elutella (Lepidoptera: Pyralidae) in the Laboratory.

Habrobracon hebetor (Say) is an important biological control agent for lepidopteran pests of stored products. In this study, the age-specific functional response, paralysis rate, and parasitism rate of H. hebetor under different host deprivation treatments (PC: without host deprivation, used as the control, P1d: host deprivation, but the host was removed after 1 d contact, and PW: host deprivation from beginning) were evaluated at different larval densities (5, 10, 20, 40, and 80) of the Ephestia elutella (Hübner) at 28 ± 1°C, 75 ± 5% RH and 16:8 h L:D. Ages of parasitoid females used were 2, 5, 10, and 20 d old. The logistic regression results indicated that the functional response of H. hebetor females under different host deprivation treatments was type II. The longest handling time was observed in 20-d old females, while the shortest handling time and highest maximum attack rate (T/Th) were estimated at the age of 2 d in all treatments. The paralysis and parasitism rates of H. hebetor were the highest at 2, 5, and 10-d old in all treatments. The results of this study suggest that H. hebetor females up to 10-d old can be used as an efficient biological control agent against E. elutella. The data of this study can also be used to predict the efficacy of different aged H. hebetor females in controlling E. elutella populations.

Coordinated transcriptomics and peptidomics of central nervous system identify neuropeptides and their G protein-coupled receptors in the oriental fruit moth Grapholita molesta

The oriental fruit moth Grapholita molesta is a cosmopolitan pest of orchard, which causes serious economic losses to the fruit production. Neuropeptides and their specific receptors (primarily G protein-coupled receptors, GPCRs) regulate multiple biological functions in insects and represent promising next-generation pest management strategy. Here, we generated a transcriptome of the central nervous system (CNS) of G. molesta. Overall, 57 neuropeptide precursor genes were identified and 128 various mature peptides were predicted from these precursors. Using peptidomic analysis of CNS of G. molesta, we identified total of 28 mature peptides and precursor-related peptides from 16 precursors. A total of 41 neuropeptide GPCR genes belonging to three classes were also identified. These GPCRs and their probable ligands were predicted. Additionally, expression patterns of these 98 genes in various larval tissues were evaluated using quantitative real-time PCR. Taken together, these results will benefit further investigations to determine physiological functions and pharmacological characterization of neuropeptides and their GPCRs in G. molesta; and to develop specific neuropeptide-based agents for this tortricid fruit pest control.

Predation of mosquitos by odonates in a tropical urban environment: insights from functional response and field mesocosm experiments

Mosquito borne diseases (e.g., dengue fever, Zika fever, chikungunya fever) are a recurring problem worldwide. Using the natural predators of mosquitoes, such as odonates (dragonflies and damselflies), provides an alternative, more sustainable approach towards vector control. We assessed the biological control potential of the larvae of three common urban odonates (Crocothemis servilia, Ischnura senegalensis, Orthetrum sabina) using laboratory-based functional response and field-based mesocosm experiments. Functional response experiments using fourth instar Aedes albopictus mosquito larvae as prey revealed Type II functional responses in all three odonate species, highlighting their predatory efficiencies at low prey densities and demonstrating that urban odonates can consume substantial numbers of mosquito larvae (up to 44 per day) under experimental conditions. Complementary field-based experiments, however, showed little impact of odonate larvae predation on the overall composition of naturally colonizing aquatic macroinvertebrate communities, but revealed substantial size-selective predation by odonate larvae on mosquito larvae. Our results provide the first assessment of the predation efficiencies of urban odonate larvae, and highlight their potential as biological control agents of mosquitoes and other aquatic insect pests in highly modified urban landscapes.

Ecology and biology of the parasitoid Trechnites insidiosus and its potential for biological control of pear psyllids.

Pear cultivation accounts for a large proportion of worldwide orchards, but its sustainability is controversial because it relies on intensive use of pesticides. It is therefore crucial and timely to find alternative methods to chemical control in pear orchards. The psyllids Cacopsylla pyri and Cacopsylla pyricola are the most important pests of pear trees in Europe and North America, respectively, because they infest all commercial varieties, causing damage directly through sap consumption or indirectly through the spread of diseases. A set of natural enemies exists, ranging from generalist predators to specialist parasitoids. Trechnites insidiosus (Crawford) is undoubtedly the most abundant specialist parasitoid of psyllids. In our literature review, we highlight the potential of this encyrtid species as a biological control agent of psyllid pests by first reviewing its biology and ecology, and then considering its potential at regulating psyllids. We show that the parasitoid can express fairly high parasitism rates in orchards, and almost perfectly matches the phenology of its host and is present early in the host infestation season, which is an advantage for controlling immature stages of psyllids. We propose new research directions and innovative approaches that would improve the use of T. insidiosus in integrated pest management strategies in the future, regarding both augmentative and conservation biocontrol. We conclude that T. insidiosus has many advantages and should be included as part of integrated biological control strategies of pear psyllids, along with predators, in-field habitat conservation, and the rational use of compatible chemicals. © 2021 Society of Chemical Industry.

Identification and tissue distribution of odorant binding protein genes in Harmonia axyridis (Coleoptera: Coccinellidae)

The olfactory system of insects is crucial in modulating behaviors such as host seeking, mating, and oviposition. Odorant-binding proteins (OBPs) are involved in semiochemical recognition. OBPs recognize and bind odorants and transport them to odorant receptors located in olfactory neurons. Harmonia axyridis (Coleoptera: Coccinellidae) is a widely used predacious biological control agent for many agricultural and forestry pests. This study identified 19 OBPs in H. axyridis based on the antennal and whole-body transcriptomes of adults and obtained all the full-length open reading frames, including 11 ‘Classic’ OBPs, 7 ‘Minus-C’ OBPs and 1 ‘Plus-C’ OBP. They encoded 125 to 241 amino acid proteins with molecular weights ranging from 13.75 to 27.75 kDa and isoelectric points ranging from 4.15 to 8.80. Phylogenetic analyses were used to study the relationships between H. axyridis OBPs and OBPs from other species of Coleoptera. Quantitative real-time PCR (qPCR) analysis showed that HaxyOBP2, 3, 5, 8, 10, 12, 13, 14, and 15 were highly expressed in antennae of both adult females and males. Moreover, HaxyOBP2, 3, 5, 12, and 15 were more abundantly expressed in antennae than other body parts, while HaxyOBP13 and HaxyOBP14 were expressed predominantly, and at similar levels, in the head and antennae. The other OBP genes were highly expressed in non-olfactory tissues including the thorax, abdomen, legs, and wings. These results provide valuable information for further study of H. axyridis olfaction, which may ultimately enhance its use as a biocontrol agent.

Characterisation of the complete mitochondrial genome of the insect-parasitic nematode Heterorhabditis bacteriophora: an idiosyncratic gene order and the presence of multiple long non-coding regions

Summary We present here the complete mtDNA genome (mitogenome) of Heterorhabditis bacteriophora, an important biological control agent of soil-dwelling insect pests in agriculture and horticulture. This is the first description of a mitogenome for a member of the family Heterorhabditidae. The genome contains the typical chromadorean complement of 12 protein-coding genes, 22 tRNA genes and two rRNA genes. All genes are transcribed in the same direction and have a nucleotide composition high in A and T. For the entire genome, the nucleotide contents are 47.02% (T), 28.81% (A), 16.10% (G), 8.08% (C) and 75.83% (AT). Heterorhabditis bacteriophora has a unique, idiosyncratic gene arrangement. It differs from that of Caenorhabditis elegans in having a block of seven genes: trnQ-trnF-cytb-trnL1-cox3-trnT-nad4 translocated to a position between nad3 and nad5, as well as having a change in the position of the four tRNA block gene cluster, trnC-trnM-trnD-trnG, where trnC and trnM have switched places and trnD and trnG have translocated between nad4 and nad5 genes. The H. bacteriophora mitogenome is 18 128 bp long, and thus is ca 4 kb larger than the mitogenomes of most chromadoreans. This relatively large genome is due to the presence of five non-coding regions (NCR): NCR1 (114 bp), NCR2 (159 bp), NCR3 (498 bp), NCR4 (1917 bp) and NCR5 (2154 bp), which make up 26.7% of the genome. The NCR5 had the highest A + T content of 83.47% indicating that this region is the likely AT-rich control region. The complete 498 bp NCR3 sequence is duplicated in NCR4 and in NCR5 (the putative AT-rich control region). Such an organisation has not been reported previously in nematode mtDNA.

Exploring the potential of engineering polygalacturonase-inhibiting protein as an ecological, friendly, and nontoxic pest control agent.

In plants, polygalacturonase-inhibiting proteins (PGIPs) play critical roles for resistance to fungal disease by inhibiting the pectin-depolymerizing activity of endopolygalacturonases (PGs), one type of enzyme secreted by pathogens that compromises plant cell walls and leaves the plant susceptible to disease. Here, the interactions between PGIPs from Phaseolus vulgaris (PvPGIP1 and PvPGIP2) and PGs from Aspergillus niger (AnPG2), Botrytis cinerea (BcPG1 and BcPG2), and Fusarium moniliforme (FmPG3) were reconstituted through a yeast two hybrid (Y2H) system to investigate the inhibition efficiency of various PvPGIP1 and 2 truncations and mutants. We found that tPvPGIP2_5-8, which contains LRR5 to LRR8 and is only one-third the size of the full length peptide, exhibits the same level of interactions with AnPG and BcPGs as the full length PvPGIP2 via Y2H. The inhibitory activities of tPvPGIP2_5-8 on the growth of A. niger and B. cinerea were then examined and confirmed on pectin agar. On pectin assays, application of both full length PvPGIP2 and tPvPGIP2_5-8 clearly slows down the growth of A. niger and B. cinerea. Investigation on the sequence-function relationships of PGIP utilizing a combination of site directed mutagenesis and a variety of peptide truncations suggests that LRR5 could have the most essential structural feature for the inhibitory activities, and may be a possible target for the future engineering of PGIP with enhanced activity. This study highlights the potential of plant-derived PGIPs as a candidate for future in planta evaluation as a pest control agent.

Toxicity of Suaeda maritima (L) against the Scirpophaga incertulas (W) and Xanthomonas oryzae pv. oryzae (Xoo) disease and its non-target effect on earthworm, Eisenia fetida Savigny

In this study, the botanical pesticide Suaeda maritima (L) leaf extract was evaluated against the yellow stem borer (YSB), Scirpophaga incertulas Walker (Lepidoptera: Pyralidae), and bacterial leaf blight disease Xanthomonas oryzae pv. oryzae (Xoo), of rice. S. maritima leaves were powdered and subjected to various organic solvents, like petroleum ether, ethyl acetate, and methanol based on the polarity, in which ethyl acetate extract of S. maritima produced significant mortality rate against the YSB larvae in a dose dependent manner and also affected the development and feeding activity of the larvae. The extracts also displayed an effective disease control against bacterial blight of Xoo. The gas chromatography–mass spectrometry (GC–MS) analysis of the ethyl acetate extract revealed the presence of nine vital compounds. We have observed the extract is safe to non-target organisms, as they did not cause any toxicity to the earthworm Eisenia foetida. Therefore, these findings suggest that S. maritima can be used as effective pest control agent against disease and pest of rice.

Predicting direct and indirect non-target impacts of biocontrol agents using machine-learning approaches.

Biological pest control (i.e. 'biocontrol') agents can have direct and indirect non-target impacts, and predicting these effects (especially indirect impacts) remains a central challenge in biocontrol risk assessment. The analysis of ecological networks offers a promising approach to understanding the community-wide impacts of biocontrol agents (via direct and indirect interactions). Independently, species traits and phylogenies have been shown to successfully predict species interactions and network structure (alleviating the need to collect quantitative interaction data), but whether these approaches can be combined to predict indirect impacts of natural enemies remains untested. Whether predictions of interactions (i.e. direct effects) can be made equally well for generalists vs. specialists, abundant vs. less abundant species, and across different habitat types is also untested for consumer-prey interactions. Here, we used two machine-learning techniques (random forest and k-nearest neighbour; KNN) to test whether we could accurately predict empirically-observed quantitative host-parasitoid networks using trait and phylogenetic information. Then, we tested whether the accuracy of machine-learning-predicted interactions depended on the generality or abundance of the interacting partners, or on the source (habitat type) of the training data. Finally, we used these predicted networks to generate predictions of indirect effects via shared natural enemies (i.e. apparent competition), and tested these predictions against empirically observed indirect effects between hosts. We found that random-forest models predicted host-parasitoid pairwise interactions (which could be used to predict attack of non-target host species) more successfully than KNN. This predictive ability depended on the generality of the interacting partners for KNN models, and depended on species' abundances for both random-forest and KNN models, but did not depend on the source (habitat type) of data used to train the models. Further, although our machine-learning informed methods could significantly predict indirect effects, the explanatory power of our machine-learning models for indirect interactions was reasonably low. Combining machine-learning and network approaches provides a starting point for reducing risk in biocontrol introductions, and could be applied more generally to predicting species interactions such as impacts of invasive species.

Detection of cryII gene from Bacillus thuringiensis using Polymerase Chain Reaction (PCR)

Bacillus thuringiensis is one species of bacteria that has been applied as a microbiological control agent for pests and a vector of plant disease. The availability of Cry proteins in B. thuringiensis can be acted as a specific insect exterminator that only toxic to certain insects. The cryII gene is an example of a type of cry gene that encodes a CryII Protein. The CryII protein is toxic to Lepidoptera insects which can attack Helicoverpa armigera species which is a corn borer. Polymerase Chain Reaction (PCR) is a general method that can be used to amplify the gene. This research purposed to design a good primer candidate for cryII gene amplification from B. thuringiensis. In silico analysis for designing cryII primer was carried out using some software, such as BLAST for searching cryII gene sequence, Bioedit for sequences alignment, and DINAmelt for analyzing dimer structure of primers. Ten primer candidates were successfully obtained based on the result of the primer 3 software. A pair of primer was selected to amplify the cryII gene, with forward primer 5’-GGTAGTGGACCACAGCAGAC-3’and reverse primer 5’-TCTTCTGGCGCCAAATGGAT-3’. This primer has fulfilled good primer characteristics because it does not cause dimer structure and the resulting amplicons do not form secondary structures. Amplification of the cryI gene by PCR method using selected primer resulting in a PCR product with a length of approximately 800 bp.

In vitro studies on Bacillus sp. and Pseudomonas sp. compatibility with botanical pesticide

The effect of botanical pesticides as an insect pest control agent has been proven in several studies. Despite capable of controlling pests, botanical pesticides have not been reported to promote plant growth. One technique for making botanical pesticides served in dual function is to combine them with beneficial microbes. This study was aimed to determine the compatibility of 3 isolates of Bacillus sp. and 3 isolates of Pseudomonas sp. against botanical pesticides. The botanical pesticides were made from a mixture of Ageratum conyzoides, Aglaia odorata, and Azadirachta indica leaves. The solvent used 96% ethanol, and the process of making botanical pesticides was performed using a rotary evaporator at 45˚C. The compatibility test was performed in vitro by dropping 10 µl of botanical pesticides on the bacterial culture. Tests were carried out using various concentrations, namely 0%, 25%, 50%, 75%, and 100%. The test results showed that Bacillus sp. A and Pseudomonas sp. E strain were compatible on all assay concentrations. Bacillus sp. A and Pseudomonas sp. D and Pseudomonas sp. E were compatible with the concentrations of 0 to 75%. Furthermore, Bacillus sp. B, Bacillus sp. C, and Pseudomonas sp. F were compatible with the assay concentrations of 0 to 50%.