Biopesticides Research Articles

Biological strategies to control caterpillars in soybean, cotton and maize in the main producing regions of Brazil

Soybean, cotton and maize crops represent some of the main agricultural commodities grown during the hot season in Brazil. In order to provide more effective control options to producers, it is essential to deepen studies on management strategies using biological insecticides. This study aims to evaluate the effectiveness of the application of the bioinsecticide Ocimum basilicum, in controlling the caterpillar complex, notably the looper (Chrysodeixis includens) in soybeans, the fall armyworm (Spodoptera frugiperda) in maize and the cotton leafworm caterpillar (Alabama argillacea) in cotton, as a control alternative aimed at mitigating damage and contributing to more sustainable agricultural practices. Experiments were carried out in each culture in various environments in the states of MT, MS, SP and PR in Brazil. A randomized block design with four replications was used in all the experiments. Agronomic traits, insect pest incidence and insecticide efficiency were evaluated for each of the crops. The data were subjected to after being subjected to stratified analysis of variance for each experimental phase. The interaction significant interactions were broken down to simple effects using Tukey's multiple comparison test of means at 5% probability. Subsequently, Scott-Knott mean grouping was used at 5% probability. Management using 1L per hectare of basil extract (Ocimum basilicum L) demonstrated satisfactory efficacy in controlling the caterpillar complex, approaching the results obtained with traditional chemical control.

Efficacy of some botanical insecticides against <em>Aphis gossypii</em> Glover (Hemiptera: Aphididae) on chrysanthemum

An evaluation of various botanical insecticides to control Aphis gossypii and its impact on aphid population dynamics on chrysanthemum plants was investigated. In order to control A. gossypii on chrysanthemum, the effectiveness of several botanical insecticides extracted from Melia azedarach, Toona sinensis, and Chrysanthemum cinerariaefolium was investigated in the current study. The research was carried out in the experimental field of the Indonesian Ornamental Crops Research Institute under plastic house conditions. Five concentrations, i.e., 1.5, 2.0, 2.5, 3.0, and 3.5 g/L of three plant extracts, M. azedarach, T. sinensis, and C. cinerariaefolium, were sprayed on chrysanthemum cultivar White Fiji after 28 to 84 days after planting. A. gossypii had a dynamic population that changed according to the plant’s developmental stages. In vegetative growth, the alate adult and nymphal stages were dominant, and the population of nymphs increased along the plant ages. The insect colonized young leaf surfaces in the terminal apices. During the reproductive stages, the population of alate adults diminished, and the distribution of the insect extended to mature, old leaves, flower buds, and bloomed flowers. The application of several botanical insecticides revealed various responses of aphid populations. Among the tested insecticides, C. cinerariaefolium extract at 3.0 and 3.5 g/L demonstrated the highest average percentage efficacy (76 and 72%) and was the most consistent in suppressing the population. The results of this study indicate the potential efficacy of botanical insecticides against A. gossypii suggesting a different approach to efficient and environment-friendly chrysanthemum pest management.

Biorationals and Synthetic Insecticides for Controlling Fall Armyworm and Their Influence on the Abundance and Diversity of Parasitoids

Spodoptera frugiperda (fall armyworm, FAW) is a significant economic pest of maize in Uganda. Many Ugandan maize farmers employ synthetic insecticides as their main form of control despite the negative impacts of these chemicals. We tested the effectiveness of Beauveria bassiana; General Biopesticide Cocktail (mixture of B. bassiana, M. anisopliae, Isaria fumosoroseus, Lecanicillium lecani and Purporeocillium lilacanus three strains of Metarhizium anisopliae, Nimbecidine® (azadirachtin 0.03%EC), and Roket® (cypermethrin 4% and profenofos 40%); and Amdocs® (emamectin benzoate 2% and abamectin 1%) on fall armyworm and parasitoids, respectively, in 2020 and 2021. The treatments with the greatest decrease in leaf damage and infestation were Amdocs® and Roket®, followed by Nimbecidine®. The biopesticides were not always more effective than the untreated control, though; their efficacy was often lower than that of the synthetic and botanical pesticides. We recovered one egg parasitoid, Telenomus remus, and seven egg and egg-larval parasitoids (Coccygidium luteum, Coccygidium sp., Cotesia icipe, Chelonus sp., Micranisa sp., Charops cf. diversipes, and an unidentified Tachinidae). Among these, C. cf diversipes, Chelonus sp., C. luteum, C. icipe and the Tachinidae were the most abundant. Parasitism was low, averaging 10% for egg masses and 5.3% for larvae. Application of synthetic pesticides and Nimbecidine® often resulted in higher yield when compared with the untreated control. In general, a low population of parasitoids was observed. Although the parasitoid population reduced in plots treated with Amdocs® and Roket®, the percentage of parasitism of FAW was not affected. In some instances, higher yields were realized in untreated control when compared with the treated plots. Pest management practices more compatible with biological control need to be considered for the management of fall armyworm.

Biosynthesis of Copper Nanoparticles from Acacia cornigera and Annona purpurea and Their Insecticidal Effect against Tribolium castaneum

Diverse studies have showed that the pesticides can cause important damages in ecosystem. Therefore, the development of bio pesticides through nanotechnology can increase efficacy and limit the negative impacts in the environmental that traditionally seen through the use of chemical pesticides. Nanoparticles obtained from plants’ extracts can be used for effective pest management as a combined formulation of metal and some other organic material present in the plants. In the present study, our evaluated biosynthesis of nanoparticles of copper used two plant extracts (Acacia cornigera and Annona purpurea), and the Taguchi method was adopted for the synthesis optimization of the following variables of biosynthesis: temperature, pH, extract concentration, and reaction times to maximize the insecticidal activity on Tribolium castaneum. Our results showed that the nanoparticles were successfully synthesized using Acacia cornigera and Anona purpurea extract under optimum conditions under Taguchi L 9 orthogonal design, where copper nanoparticles were obtained with a size of 63–153 nm for using A. cornigera extract, 87–193 nm for A. purpurea extract, and a zeta potential of 9.6 mV and −32.7 mV, respectively. The nanoparticles of copper from A. cornigera showed effective insecticidal activity against Tribolium castaneum, and 90% mortality compared to the 76.6% obtained from nanoparticles of copper from A. purpurea. The results suggest that Cu-nanoparticles derived from both plants could be used as a biocontrol agent of Tribolium castaneum, a pest of stored grain with great economic importance.

Virulence Bioassay of Entomopathogenic Fungi against Adults of Atta mexicana under Controlled Conditions

Leafcutter ants (Atta spp.) are one of the mos t economically harmful pests in agriculture, considered dominant in the Neotropics and South America. Mature colonies of A. mexicana have a great economic impact on Mexico’s agriculture. Microbial agents in the form of biopesticides are an effective component of integrated pest management (IPM) strategies and may present a better alternative to synthetic insecticides. Among the fungi most used as biological insecticides there are Beauveria bassiana and Metarhizium anisopliae. The objective of this research was to evaluate the effect of the entomopathogenic fungi B. bassiana and M. anisopliae of commercial origin and a native strain of B. bassiana from México (MA-Bb1) on adults of Atta mexicana under controlled conditions. In the bioassay, five formulations and a control group were tested (B. bassiana MA-Bb1, B. bassiana MA-Bb1+ Diatomin®, B. bassiana®, M. anisopliae®, Diatomin®, and Tween 80 (0.01%). The MA-Bb1+ Diatomin® biopreparation induced the highest mortality (100%) in four-week-old A. mexicana, followed by the MA-Bb1, M. anisopliae®, and B. bassiana® biopreparations, which caused mortality of 83.33%, 73.98%, and 68.70%, respectively. Treatments containing B. bassiana and M. anisopliae were efficient in controlling A. mexicana under controlled conditions. The most efficient biological control was achieved with the B. bassiana fungus and Diatomin®, which presented the highest total death rate in A. mexicana 96 h post infection, in contrast to the control group (Tween 80), which attained the lowest speed of death in the present investigation.

Comparative Efficacy of Different Biopesticides against the Tobacco Caterpillar [Spodoptera litura (Fabricius)]

Tobacco caterpillar, Spodoptera litura (Fabricius) is an economically important polyphagous pestinflicting significant economic damage to numerous field and horticultural crops. Overreliance of chemical insecticides to manage the pest has led to the development of resistance, resurgence and residue problem in the crop ecosystems, in addition to high operating costs. Biopesticides have been reported to be effective for managing this pest in ecofriendly manner. Hence, the present study was conducted to assess the efficacy of different bio pesticides against S. litura under laboratory conditions at Bihar Agricultural College, Sabour, Bhagalpur during the rabi of 2022-23. It was conducted in completely randomized design (CRD) with eight treatments and three replications.  Among the various biopesticides evaluated, Steinernema carpocapsae- 500 IJs/Petri Plate and Metarhizium anisopliae 1×108 spores/ml -5g/l were most effective treatments and at par each other with 93.00 and 82.50 per cent larval mortality, respectively. They had performed equally with chemical check, Emmamectin benzoate 5 SG- 0.4 g/l which recorded with 95.63 % larval mortality. Neem oil 1500 ppm- 5 ml/litre and Beauveria bassiana 1×108 @5ml/l were the next best treatments with 78.31 and 59.38 % larval mortality respectively. The order of efficiency was Emamectin benzoate 5 SG (0.4g/l) > EPNs (500 IJs) >Metarhizium anisopliae 1% WP (5g/l) >Neem oil 1500 ppm (5 ml/litre) >Beauveria bassiana1 % WP (5 g/l) >Metarhizium anisopliae 1 % WP (2.5 g/l) >Beauveria bassiana 1 % WP (2.5 g/l).

Transgenerational effect of a tea saponin–matrine mixture promotes fecundity and alters associated bacteria in the fall armyworm Spodoptera frugiperda

The fall armyworm Spodoptera frugiperda is a one of the most invasive and damaging pests that causes serious economic losses in several crops. Botanical insecticides such as tea saponin and matrine, as environmentally acceptable biopesticides, are widely used for controlling pests. Insecticide stress affects both individuals and the associated bacteria in insects. However, it remains unclear that if sublethal effects and bacteria are the drivers for the adaptive mechanisms of insecticides in fall armyworm. We examined the effectiveness of a 10:1 v/v mixture of biological insecticides against the fall armyworm and the impacts of several biological parameters and demographic variables of the armyworm targeting two generations at primary exposure. Moreover, the influence of the insecticide mixture on the associated bacteria of the fall armyworm was assessed via 16 S rRNA sequencing. The results showed that the mixture was highly toxic to fall armyworms, and the fecundity of the initially exposed generation (F0) significantly decreased; however, there was no significant effect on longevity. The larval duration, the total pre-reproductive period, longevity, fecundity, and mean generation time of the fall armyworm in the F1 significantly increased; yet the intrinsic and finite rates of the increase and the net reproductive rate remained fairly constant. Additionally, the population of associated bacteria was affected in both generations, with an increase in the microbial diversity within the fall armyworm compared to that of the F0 generation. Also, an increase in abundance of several genera of bacteria, including Acinetobacter, Serratia, Enterococcus, and Pseudomonas, was noted following treatment with the insecticide mixture. These results broaden our understanding of the impact of sublethal insecticide concentrations on the fall armyworm and its associated bacterial community.

Kekayaan Flora di Kecamatan Mangkubumi Yang Potensial Dapat Dimanfaatkan Sebagai Pestisida Nabati Ramah Lingkungan

This research aims to know the types of floras and their distribution in Mangkubumi District area it has potential to be enviromentally friendly botanical pesticides. This reserch carried out in Mangkubumi District, Tasikmalaya City for three months from Agustus to Oktober 2023. The methode used in this research is literature study. Two data collected in this research namely primary data and secondary data. Primary data collected by field observation to find the types of plant in Mangkubumi District its potential as botanical pesticides, while secondary data was obtained by conducting literature studies. Based on tne results of field observations and literature studies, 8 types of plant were found has potential as botanical pesticides to treat various plant diseases such as aphids, whitefly, fruit flies, planthopper pets, caterpillars, etc

Development and Application of Attenuated Plant Viruses as Biological Control Agents in Japan

In 1929, it was reported that yellowing symptoms caused by a tobacco mosaic virus (TMV) yellow mosaic isolate were suppressed in tobacco plants that were systemically infected with a TMV light green isolate. Similar to vaccination, the phenomenon of cross-protection involves a whole plant being infected with an attenuated virus and involves the same or a closely related virus species. Therefore, attenuated viruses function as biological control agents. In Japan, many studies have been performed on cross-protection. For example, the tomato mosaic virus (ToMV)-L11A strain is an attenuated isolate developed by researchers and shows high control efficiency against wild-type ToMV in commercial tomato crops. Recently, an attenuated isolate of zucchini yellow mosaic virus (ZYMV)-2002 was developed and registered as a biological pesticide to control cucumber mosaic disease. In addition, attenuated isolates of pepper mild mottle virus (PMMoV), cucumber mosaic virus (CMV), tobacco mild green mosaic virus (TMGMV), melon yellow spot virus (MYSV), and watermelon mosaic virus (WMV) have been developed in Japan. These attenuated viruses, sometimes called plant vaccines, can be used not only as single vaccines but also as multiple vaccines. In this review, we provide an overview of studies on attenuated plant viruses developed in Japan. We also discuss the application of the attenuated strains, including the production of vaccinated seedlings.

Nanoencapsulation of natural products and their role in the preservation and control of contaminations in the food industry

Microbial resistance is a problem of high notoriety and importance, being investigated in several scientific areas. Directly correlated to the abuse of macrolides in the pandemic context, the difficulty in eliminating resistant microorganisms and the control of bacterial contamination in an industrial food environment have been increasingly worrying nowadays. The present study demonstrates hypotheses of microbial control using the encapsulation of essential oils and products of natural origin through the technology used in nanocomposites. The aid in the prevention and control of microorganisms with high antimicrobial resistance factors in food industry environments can be seen. Furthermore, new approaches and themes applied in the denaturation of pathogenic biofilms and nanoencapsulation and the use of common metals and transition metals are highlighted.

Integrated Management of the Cotton Charcoal Rot Disease Using Biological Agents and Chemical Pesticides

Charcoal rot disease (CRD), caused by the phytopathogenic fungus Macrophomina phaseolina, is a significant threat to cotton production in Israel and worldwide. The pathogen secretes toxins and degrading enzymes that disrupt the water and nutrient uptake, leading to death at the late stages of growth. While many control strategies were tested over the years to reduce CRD impact, reaching that goal remains a significant challenge. The current study aimed to establish, improve, and deepen our understanding of a new approach combining biological agents and chemical pesticides. Such intervention relies on reducing fungicides while providing stability and a head start to eco-friendly bio-protective Trichoderma species. The research design included sprouts in a growth room and commercial field plants receiving the same treatments. Under a controlled environment, comparing the bio-based coating treatments with their corresponding chemical coating partners resulted in similar outcomes in most measures. At 52 days, these practices gained up to 38% and 45% higher root and shoot weight and up to 78% decreased pathogen root infection (tracked by Real-Time PCR), compared to non-infected control plants. Yet, in the shoot weight assessment (day 29 post-sowing), the treatment with only biological seed coating outperformed (p < 0.05) all other biological-based treatments and all Azoxystrobin-based irrigation treatments. In contrast, adverse effects are observed in the chemical seed coating group, particularly in above ground plant parts, which are attributable to the addition of Azoxystrobin irrigation. In the field, the biological treatments had the same impact as the chemical intervention, increasing the cotton plants’ yield (up to 17%), improving the health (up to 27%) and reducing M. phaseolina DNA in the roots (up to 37%). When considering all treatments within each approach, a significant benefit to plant health was observed with the bio-chemo integrated management compared to using only chemical interventions. Specific integrated treatments have shown potential in reducing CRD symptoms, such as applying bio-coating and sprinkling Azoxystrobin during sowing. Aerial remote sensing based on high-resolution visible-channel (RGB), green–red vegetation index (GRVI), and thermal imaging supported the above findings and proved its value for studying CRD control management. This research validates the combined biological and chemical intervention potential to shield cotton crops from CRD.

Assessment of the nutritional content of cowpea seed exposed to plant-derived (azadirachtin, myristicin and α-humulene) insecticides against Callosobruchusmaculatus

The utilization of synthetic insecticides for safeguarding cowpea seed against C. maculatus infestation, while effective, faces substantial opposition due to safety apprehensions. The detrimental impact of Callosobruchus maculatus infiltration on cowpea seed quality serves as an indicator that could be utilized to assess the effectiveness and reliability of newly developed eco-friendly botanical insecticides. This study aimed to analyse the nutritional composition of cowpea seed treated with specific botanical insecticides namely, azadirachtin, myristicin, and α-humulene-based insecticides against C. maculatus. Concentrations (0.0061 μg/mL, 0.0122 μg/mL, and 0.0244 μg/mL) of azadirachtin, myristicin, and α-humulene-based insecticides respectively exhibited sustained effectiveness against C. maculatus. Notably, the protein, ash, lipid, and fibre content of the infested untreated cowpea seed were significantly (P < 0.06) lower than those of the treated infested cowpea seed. Conversely, the carbohydrate and moisture content of the untreated infested cowpea seed were significantly (P < 0.05) higher than those found in the treated infested cowpea seed. When examining the mineral content, cowpea seed treated with botanical insecticides displayed significantly (P < 0.05) higher mineral levels compared to the untreated uninfested cowpea seed, yet significantly (P < 0.05) lower mineral levels in comparison to the untreated infested cowpea seed. The outcomes of this investigation suggest that the aforementioned botanical insecticides hold promise as viable alternatives to the synthetic options in post-harvest cowpea bruchid management.

Simultaneous use of Beauveria bassiana and Bacillus subtilis-based biopesticides contributed to dual control of Trialeurodes vaporariorum (Hemiptera: Aleyrodidae) and tomato powdery mildew without antagonistic interactions

BackgroundImplementing pest and disease control techniques that have low environmental impact is important for sustainable agriculture. Microbial biopesticides are an effective approach due to their low environmental impact and low risk of resistance development. Because it is not usually possible to control multiple pests and diseases with a single microbial biopesticide, it is essential to investigate the potential for combining microbial biopesticides with varying control spectrums effectively. Many biopesticides have antimicrobial activity and may therefore interact negatively in combination.ResultsThis study demonstrated that a mixture of Beauveria bassiana and Bacillus subtilis formulations proved potential for simultaneous control of greenhouse whitefly (Trialeurodes vaporariorum Westwood) and tomato powdery mildew (Oidium neolycopersici). Three greenhouse experiments were conducted to assess the efficacy of mixed and single-use treatments. A laboratory experiment comparing the insecticidal effect of each treatment was also conducted. In all greenhouse experiments, the combined treatment controlled the greenhouse whitefly (78.9–88.3%) and tomato powdery mildew (47.2–81.0%) compared to untreated controls, which was as well as each treatment alone. In some greenhouse and laboratory experiments, the mixed treatment showed an approximately 1.32 to 1.78 times higher insecticidal effect compared to single-use treatments. Regarding the control efficacy against the pest and disease, negative effects of microbial agents on each other were not observed.ConclusionsThese results demonstrated the effectiveness of concurrent use of two microbial pesticides examined on dual control of pest and disease and showed potential for improved control of certain pests. The knowledge of this work could suggest the possibility of more environmentally friendly pest control systems with the use of microbial pesticides.

Impact of Chemical Insecticide Application on Beneficial Insects in Maize

The European corn borer (ECB) (Ostrinia nubilalis Hübner) and to a lesser extent the western corn rootworm (Diabrotica virgifera virgifera LeConte) are a threat to maize in the Po Valley (Northern Italy), and their control can require insecticide applications. The results of a study to evaluate the effects of insecticide sprays on the beneficial insect Trichogramma brassicae (Hymenoptera: Trichogrammatidae) and aphid predators are reported. A three-year research project was carried out in two Study Areas, in Lombardy. In area 1, crop rotation was a common practice, while in area 2 repeated maize crop was practiced. The natural trend of ECB egg masses attacked by T. brassicae was affected and parasitism rates were reduced as a result of insecticide exposure (chlorpyriphos methyl, cypermethrin, alphacypermethrine). Repeated maize crop and insecticides spraying increased the abundance of the aphid population and negatively affected the aphid predator community, which mainly included ladybirds, hoverflies, true bugs and lacewings. The predator community was dominated by hoverflies in sprayed fields managed according to repeated maize crop protocols, whereas ladybirds and Orius spp. dominated in maize fields managed according to crop rotation protocols. Crop rotation protocols help to prevent ECB outbreaks; when the risk of exceeding the economic threshold limit is high, and this may be the case when maize is cultivated for seeds or for horticultural crops such as sweet corn, inundative release of T. brassicae and/or microbial control (i.e., use of Bacillus thuringiensis preparations) can integrate natural biocontrol, and provide a valuable alternative to chemical insecticides.

Manipulating multi-level selection in a fungal entomopathogen reveals social conflicts and a method for improving biocontrol traits.

Changes in parasite virulence are commonly expected to lead to trade-offs in other life history traits that can affect fitness. Understanding these trade-offs is particularly important if we want to manipulate the virulence of microbial biological control agents. Theoretically, selection across different spatial scales, i.e. between- and within-hosts, shapes these trade-offs. However, trade-offs are also dependent on parasite biology. Despite their applied importance the evolution of virulence in fungal parasites is poorly understood: virulence can be unstable in culture and commonly fails to increase in simple passage experiments. We hypothesized that manipulating selection intensity at different scales would reveal virulence trade-offs in a fungal pathogen of aphids, Akanthomyces muscarius. Starting with a genetically diverse stock we selected for speed of kill, parasite yield or infectivity by manipulating competition within and between hosts and between-populations of hosts over 7 rounds of infection. We characterized ancestral and evolved lineages by whole genome sequencing and by measuring virulence, growth rate, sporulation and fitness. While several lineages showed increases in virulence, we saw none of the trade-offs commonly found in obligately-killing parasites. Phenotypically similar lineages within treatments often shared multiple single-nucleotide variants, indicating strong convergent evolution. The most dramatic phenotypic changes were in timing of sporulation and spore production in vitro. We found that early sporulation led to reduced competitive fitness but could increase yield of spores on media, a trade-off characteristic of social conflict. Notably, the selection regime with strongest between-population competition and lowest genetic diversity produced the most consistent shift to early sporulation, as predicted by social evolution theory. Multi-level selection therefore revealed social interactions novel to fungi and showed that these biocontrol agents have the genomic flexibility to improve multiple traits-virulence and spore production-that are often in conflict in other parasites.

Afforestation enhances glomalin-related soil protein content but decreases its contribution to soil organic carbon in a subtropical karst area

Afforestation on degraded croplands has been proposed as an effective measure to promote ecosystem functions including soil organic carbon (SOC) sequestration. Glomalin-related soil protein (GRSP) plays a crucial role in promoting the accumulation and stability of SOC. Nevertheless, mechanisms underlying the effects of afforestation on GRSP accumulation have not been well elucidated. In the present study, 14 pairs of maize fields and plantation forests were selected using a paired-site approach in a karst region of southwest China. By measuring soil GRSP and a variety of soil biotic and abiotic variables, the pattern of and controls on GRSP accumulation in response to afforestation were explored. The average content of total GRSP (T-GRSP) and its contribution to SOC in the maize field were 5.22 ± 0.29 mg g−1 and 42.33 ± 2.25%, and those in the plantation forest were 6.59 ± 0.32 mg g−1 and 25.77 ± 1.17%, respectively. T-GRSP content was increased by 26.4% on average, but its contribution to SOC was decreased by 39.1% following afforestation. T-GRSP content decreased as soil depth increased regardless of afforestation or not. Afforestation increased T-GRSP indirectly via its positive effects on arbuscular mycorrhizal fungi biomass, which was stimulated by afforestation through elevating fine root biomass or increasing the availability of labile C and N. The suppressed contribution of T-GRSP to SOC following afforestation was due to the relatively higher increase in other SOC components than T-GRSP and the significant increase of soil C:N ratio. Our study reveals the mechanisms underlying the effects of afforestation on T-GRSP accumulation, and is conducive to improving the mechanistic understanding of microbial control on SOC sequestration following afforestation.

Urea Cycle of Bacillus thuringiensis Affects Its Survival under UV Stress.

Bacillus thuringiensis (Bt) is widely used to produce biological pesticides. However, its persistence is limited because of ultraviolet (UV) rays. In our previous study, we found that exogenous intermediates of the urea cycle were beneficial to Bt for survival under UV stress. To further explore the effect of the urea cycle on the resistance mechanism of Bt, the rocF/argG gene, encoding arginase and argininosuccinate synthase, respectively, were knocked out and recovered in this study. After the target genes were removed, respectively, the urea cycle in the tested Bt was inhibited to varying degrees. The UV stress test showed that the urea cycle disorder could reduce the resistance of Bt under UV stress. Meanwhile, the antioxidant enzyme activities of Bt were also decreased to varying degrees due to the knockout of the target genes. All of these results revealed that the urea cycle can metabolically regulate the stress resistance of Bt.

Microbial control of soil DOM transformation during the vegetation restoration in the Loess Plateau

Microbial control of soil DOM transformation during the vegetation restoration in the Loess Plateau

Laboratory evaluation of a bio-insecticide candidate from tangerine peel extracts against Trialeurodes vaporariorum (Homoptera: Aleyrodidae).

The excessive use of synthetic insecticides in modern agriculture has led to environmental contamination and the development of insect resistance. Also, the prolonged use of chemical insecticides in producing flowers and tomatoes in greenhouses has caused health problems for workers and their offspring. In this study, we analyzed the efficacy of mandarin peel (Citrus reticulata L.) essential oil (EO) as a natural insecticide against greenhouse whitefly (Trieurodes vaporariorum W., Homoptera: Aleyrodidae), a common pest in greenhouse production of different crops. Petroleum ether (PET) and n-hexane (HEX) were used as solvents to extract essential oil (EO) from tangerine peels. The yield of EO was 1.59% and 2.00% (m/m) for PET and HEX, respectively. Additionally, the insect-killing power of EO was tested by checking how many greenhouse whiteflies died at different times. The results showed that PET and HEX extracts of tangerine EO effectively controlled greenhouse whiteflies. Furthermore, with both solvents, a 12.5% (v/v) application was as practical as the commercial insecticide imidacloprid. Further characterization tests with the polarimeter, FTIR, HPLC-RP, and GC-MS showed that the essential oil (EO) contained about 41% (v/v) of d-limonene and that this compound may be responsible for the observed insecticidal properties. Therefore, tangerine peel essential oil is an excellent botanical insecticide candidate for controlling greenhouse whiteflies.

Field Evaluation of Biological and Conventional Insecticides for Managing Multiple Insect Pests in Cotton

Abstract Cotton, Gossypium hirsutum (L.), is an economically important crop in the United States that is plagued by a complex of insect pests. Two key pests of cotton in the midsouthern United States are the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois) (Hemiptera: Miridae), and bollworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae). A suite of highly effective synthetic insecticides is typically used for control of these pests. However, it is unclear how the combined management of these two insect pests with biological insecticides impacts the economics of cotton production. To address this shortcoming, we conducted a field experiment in the Mississippi Delta over 2 yr to study the effects of synthetic and biological insecticides for control of the tarnished plant bug and bollworm on cotton yield. The results indicated the control of tarnished plant bug with synthetic insecticides had the most significant impact on cotton yield and net returns. The conventional tarnished plant bug treatment also significantly increased bollworm density and damage, but these increases did not significantly alter yield or net return in non–Bacillus thuringiensis (Bt) or Bt cottons. The economic benefit of a conventional approach to tarnished plant bug control with synthetic insecticides was US$438.07/ha in non-Bt and $700.88/ha in Bt cotton relative to those treated with a biological insecticide. The biological insecticides used for this study were ineffective at significantly altering yield or net return. However, for insect management in cotton to be sustainable, alternatives must be found to complement conventional synthetic insecticides.