Control Of Insect Pests Research Articles

A biobased superabsorbent formulation for above-ground application of a new entomophthoralean fungus for biological psyllid pest control

Entomophthoralean fungi have long been recognized as promising candidates for biological insect pest control. However, due to technical challenges, no preparation based on these fungi has been established for practical use so far. Low water availability is a key limiting factor of conidial discharge and germination. In the present study, sporulation of psyllid-pathogenic entomophthoralean fungus Pandora cacopsyllae Eilenberg, Keller and Humber (Entomophthorales Entomophthoraceae) was not observable under reduced water activity (aW ≤ 0.97). To support sporulation of encapsulated P. cacopsyllae hyphae from submerged culture under low humidity conditions in above-ground applications in field, we developed a novel paste-type formulation containing biobased superabsorbents, which retained water for a prolonged time period. In co-application with the superabsorbent formulation, the otherwise fast-drying capsules were kept sufficiently moist for sporulation for at least six days in laboratory trials at low humidity below 40%. Using the new formulation, we measured conidial discharge by P. cacopsyllae from the capsules under dry semi-field conditions in summertime by trapping conidia at a vertical distance of up to 40 cm from the sporulation source. By considering the cardinal directions, fewer conidia were discharged on the sun-facing side in the east than on the sun-averted side in the west. The developed formulation improved the sporulation efficacy significantly. Since water availability is a limiting factor for many fungal biocontrol agents, the developed formulation has the potential to also improve their efficacy.

The Prospect of Hydrolytic Enzymes from Bacillus Species in the Biological Control of Pests and Diseases in Forest and Fruit Tree Production.

Plant diseases and insect pest damage cause tremendous losses in forestry and fruit tree production. Even though chemical pesticides have been effective in the control of plant diseases and insect pests for several decades, they are increasingly becoming undesirable due to their toxic residues that affect human life, animals, and the environment, as well as the growing challenge of pesticide resistance. In this study, we review the potential of hydrolytic enzymes from Bacillus species such as chitinases, β-1,3-glucanases, proteases, lipases, amylases, and cellulases in the biological control of phytopathogens and insect pests, which could be a more sustainable alternative to chemical pesticides. This study highlights the application potential of the hydrolytic enzymes from different Bacillus sp. as effective biocontrol alternatives against phytopathogens/insect pests through the degradation of cell wall/insect cuticles, which are mainly composed of structural polysaccharides like chitins, β-glucans, glycoproteins, and lipids. This study demonstrates the prospects for applying hydrolytic enzymes from Bacillus sp. as effective biopesticides in forest and fruit tree production, their mode of biocidal activity and dual antimicrobial/insecticidal potential, which indicates a great prospect for the simultaneous biocontrol of pests/diseases. Further research should focus on optimizing the production of hydrolytic enzymes, and the antimicrobial/insecticidal synergism of different Bacillus sp. which could facilitate the simultaneous biocontrol of pests and diseases in forest and fruit tree production.

Efficacy of Targeted Insecticides against Major Insect Pests of Phalsa (Grewia asiatica Linn.)

A two-year field experiment were conducted in a phalsa orchard situated at the Regional Horticulture Research Station (RHRS), Raya, District-Samba to study the efficacy of selected insecticides against major insect pests of phalsa. During the experiment, seven treatments were taken which were replicated thrice in the randomized block design. The insecticides were sprayed at the peak or ETL level of the insect problem population, insect population was noted one day before the spraying and three and ten days after the spraying. Five randomly chosen plants were subjected to pre- and post-treatment of herbicides, and insect counts was taken. Further, ten days after a second spray, 100 randomly selected fruits from each plant were examined to figure out the amount of fruits that were injured overall. Fruit damage (%) was then computed. The yield was calculated by employing the net plot area method, and the yield and cost of plant protection were utilized to calculate the monetary benefits and incremental cost-benefit ratios of the treatments. The application of imidacloprid 17.8 SL @ 0.3 ml/L was found to be the most effective method for suppressing aphids, with Fipronil 5 SC @ 1.0 ml/L, Chlorpyriphos 20 EC, and control following suit. Additionally, plots treated with imidacloprid had the highest cost-benefit ratio, followed by treatments with Fipronil and dichlorvos Therefore, in Jammu's subtropical climate, applying imidacloprid 17.8 SL @ 0.3 ml/L is the most efficient way to control insect pests and increase phalsa yield.

Both long-term grasslands and crop diversity are needed to limit pest and weed infestations in agricultural landscapes.

Increasing landscape heterogeneity has been suggested to be an important strategy to strengthen natural pest control in crops, especially through enhancing the amount of seminatural habitats. Increasing crop diversity is also a promising strategy to complement or replace seminatural habitat when seminatural habitat is scarce. However, their relative or possibly interactive effects on pest and weed infestation remain poorly investigated, and the role of different types of seminatural habitats has been understudied. Using an extensive sampling effort in 974 arable fields across 7 y, we evaluated the separate and interactive effects of crop diversity (seven arable crop types) and the amount of four types of seminatural habitats (meadows, hay, forests, and hedgerows) in the landscape on pest and weed control. Meadows and crop diversity, respectively, supported insect pest and weed control services in agricultural landscapes through a complementarity effect. Crop diversity increased weed seed predation rate (by 16%) and reduced weed infestation (by 6%), whereas long-term grasslands (to a much higher degree than hay or woody habitats) increased insect pest predation rates (by 23%) and reduced pest infestation (by 19%) in most arable crops. Our results demonstrate that diversification of the agricultural landscape requires long-term grasslands as well as improved crop diversity to ensure the delivery of efficient pest and weed control services.

Albendazole-induced genotoxicity in the larvae of fall armyworm as a safe environmental tool

Anthelmintic drugs are considered a new alternative strategy to control insect pests. Spodoptera frugiperda, fall armyworm (FAW), is one of the most serious pests of maize and cultivated plants. Albendazole (ABZ) is one of the safest anthelmintic drugs and is used worldwide in human and veterinary medicine. ABZ has not previously been used for controlling FAW, so the present study aimed to investigate the insecticidal and genotoxic effects of ABZ on FAW. ABZ produced a significant effect on the mortality of FAW. Also, drug treatment significantly disrupted the larval, pupal, and adult durations associated with malformations. Because ABZ interferes with microtubule formation, it could induce mortality and affect all physiological processes in FAW. Additionally, it can disrupt the chromosomes' alignment and result in the formation of micronuclei (MN), DNA damage, and cell death, thus causing ABZ-induced genotoxic effects on FAW larval hemocytes. The present study shows that the ABZ drug has a strong insecticidal potency and is a promising environmental safety tool to control the fall armyworm pest.Graphical abstract

Sublethal concentrations of thiamethoxam induce transgenerational hormesis in cotton aphid, Aphis gossypii Glover

In agroecosystems, insects have to compete with chemical insecticides, which are frequently present at sublethal concentrations. The exposure of insects to these modest stresses is now well-established to generate hormesis effects, which has implications for controlling insect pests. In this study, we assessed the sublethal effects of thiamethoxam on the biological parameters of Aphis gossypii Glover (Hemiptera: Aphididae), adults (F0) and subsequent transgenerational impacts, i.e., on the progeny (F1 generation), using an age stage, two-sex life table analysis. Results showed that thiamethoxam exhibited high toxicity against adult A. gossypii with the LC50 of 0.313 mg L−1 after 48 h exposure. The LC5 and LC10 of thiamethoxam considerably reduced the adult cotton aphids (F0) longevity and fecundity, while the reproductive days were reduced only at LC10. The pre-adult stage was decreased, while the adult longevity, total longevity, and fecundity were significantly extended in F1 aphids after exposure of F0 aphids to the sublethal concentrations of thiamethoxam. Moreover, the key demographic parameters such as intrinsic rate of increase, finite rate of increase and reproductive days were significantly increased, while mean generation time and total prereproductive were significantly reduced in the progeny. No significant effects were observed on the net reproductive rate. Taken together, these results showed that the sublethal concentrations of thiamethoxam affect the directly exposed aphids (F0) while causing transgenerational hormetic effects on the F1 generation of A. gossypii. In conclusion, our research showed that thiamethoxam has both sublethal and transgenerational effects on cotton aphids; it could be effective in IPM programs targeting this key pest.

Biological insecticides efficient alternatives for the control of insect pests in agricultural and horticultural crops

This work aimed to evaluate the agronomic effectiveness and practicality of microbiological insecticides in cotton, sugar cane, citrus, beans, tomatoes, coffee, wheat, soybeans and maize crops based on bacteria of the genus Pseudomonas fluorescens Pseudomonas chlororaphis and Bacillus thuringiensis, in the control of insect pests. Experiments were carried out to evaluate biological insecticides in each crop individually. Experiments were carried out in each culture in various environments in the states of MT, MS, SP, MG 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. A heat map was made to understand the efficiency of insecticides in controlling insect pests in each crop. The linear correlation coefficients between the pairs of characters evaluated were calculated. The use of bacteria of the genus Pseudomonas fluorescens, Pseudomonas chlororaphis and Bacillus thuringiensis to control insect pests is a promising alternative for use alone or in combination with pesticides. The use of azadirachtin is effective for controlling mites in cotton, Diaphorina citri in citrus and moth in tomato.

Rugose spiralling whitefly, Aleurodicus rugioperculatus Martin infested host plant volatiles elicit a host locating behavior of aphelinid parasitoid, Encarsia guadeloupae Viggiani (Hymenoptera: Aphelinidae)

Parasitoids find their hosts by using cues released by herbivores and their host plants. In crop fields, these semiochemicals could be used for insect pest control by attracting and retaining natural enemies. The hymenopteran aphelinidae endoparasitoid, Encarsia guadeloupae (E. guadeloupae), selectively parasitizes rugose spiralling whitefly (RSW), Aleurodicus rugioperculatus Martin, an invasive pest of coconut in India, thus offering an effective way to improve RSW control under natural field conditions. However, the chemical interactions that occur in between the RSW infected host plants and E. guadeloupae were unknown. Hence, using olfactometer assays and chemical analyses, we investigated the volatile organic compounds (VOCs) mediating attraction of the parasitoid to RSW infested host plants. To investigate the attraction of the E. guadeloupae towards the healthy and RSW infected leaves of coconut (Cocos nucifera L), banana (Musa paradisiaca L) and custard apple (Annona squmosa L), we employed a six-arm olfactometer. The E. guadeloupae preferred the volatile compounds from RSW-infested host plants rather than healthy plants. A higher percent response rate of E. guadeloupae was observed in RSW-infected banana (35.83 %), followed by healthy banana (24.33 %), RSW-infested custard apple (16.33 %), and RSW-infested coconut (9.00 %) leaf volatiles, respectively. The volatile compounds emitted from RSW-infested and healthy plants have been studied using GC–MS with thermal desorption (TD). The results revealed more than 20 volatile compounds belonging to seven chemical classes were identified and characterized from infested plants by RSW. Of these, α-Ocimene, α-Pinene, 3-Carene, trans-α-Ocimene, and (E)-hex-3-ene-2, 5-diol were emitted at higher levels than other compounds its proven through PCA and Heat map analysis. These five compounds elicited the greatest attraction of E. guadeloupae towards RSW damaged plants. The synthetic blend of the above volatiles could be used as attractants to enhance the population of E. guadeloupae to manage RSW under field conditions.

Efficiency of temperature and storage duration on some morphological measurements and reproductive capacity of the entomopathogenic nematode Heterorhabditis bacteriophora Poinar, 1976 (Rhabditida: Heterorhabditidae)’s Turkish HBH hybrid strain

Entomopathogenic nematodes (EPNs) are successfully used in the biological control of agricultural insect pests. This study aims to determine the body length of hermaphrodite individuals, egg diameter and reproductive capacity obtained from Infective Juveniles (IJs) stored at different temperatures and durations. Heterorhabditis bacteriophora Poinar, 1976 (Rhabditida: Heterorhabditidae)’s Hybrid Strain HBH was used in the study. IJs stored at 15, 25 and 35°C for 7, 14 and 21 days were inoculated onto Galleria mellonella L., 1758 (Lepidoptera: Pyralidae) last instar larvae at a dose of 100 IJs. On the 2nd day of infection, hermaphrodite individuals and eggs were obtained by dissecting the larvae. The reproductive capacity was determined 10-12 days after infection. The study was conducted in Bursa Uludağ University, Faculty of Agriculture, Plant Protection Department, Nematology Laboratory in 2023. In conclusion, the longest hermaphrodite individuals and egg diameter were obtained as 6207.22 µm and 55.65 µm, respectively from the IJs stored for 7 days at 15°C. The highest reproductive capacity was also observed as 167.500 IJs per G. mellonella larva in IJs stored under the same conditions with respect to temperature and time. This study is important for assessing the morphological effects of different temperature values and storage durations on EPNs.

Hypovirulence-associated mycovirus epidemics cause pathogenicity degeneration of Beauveria bassiana in the field

BackgroundThe entomogenous fungus Beauveria bassiana is used as a biological insecticide worldwide, wild B. bassiana strains with high pathogenicity in the field play an important role in controlling insect pests via not only screening of highly virulent strains but also natural infection, but the pathogenicity degeneration of wild strains severely affected aforementioned effects. Previous studies have showed that multiple factors contributed to this phenomenon. It has been extensively proved that the mycovirus infection caused hypovirulence of phytopathogenic fungi, which has been used for plant disease biocontrol. However, it remains unknown whether the mycovirus epidemics is a key factor causing hypovirulence of B. bassiana naturally in the field.MethodsWild strains of B. bassiana were collected from different geographic locations in Jilin Province, China, to clarify the epidemic and diversity of the mycoviruses. A mycovirus Beauveria bassiana chrysovirus 2 (BbCV2) we have previously identified was employed to clarify its impact on the pathogenicity of host fungi B. bassiana against the larvae of insect pest Ostrinia furnacalis. The serological analysis was conducted by preparing polyclonal antibody against a BbCV2 coat protein, to determine whether it can dissociate outside the host fungal cells and subsequently infect new hosts. Transcriptome analysis was used to reveal the interactions between viruses and hosts.ResultsWe surprisingly found that the mycovirus BbCV2 was prevalent in the field as a core virus in wild B. bassiana strains, without obvious genetic differentiation, this virus possessed efficient and stable horizontal and vertical transmission capabilities. The serological results showed that the virus could not only replicate within but also dissociate outside the host cells, and the purified virions could infect B. bassiana by co-incubation. The virus infection causes B. bassiana hypovirulence. Transcriptome analysis revealed decreased expression of genes related to insect epidermis penetration, hypha growth and toxin metabolism in B. bassiana caused by mycovirus infection.ConclusionBeauveria bassiana infected by hypovirulence-associated mycovirus can spread the virus to new host strains after infecting insects, and cause the virus epidemics in the field. The findings confirmed that mycovirus infection may be an important factor affecting the pathogenicity degradation of B. bassiana in the field.

Efficacy of topical administration of prallethrin-permethrin-piperonyl butoxide (Bronco® Equine Fly Spray) for the treatment and control of flies and other nuisance insects of horses

Numerous biting and nuisance insects are a noted cause of discomfort and stress to horses. Pyrethrins and pyrethroids have been used for many years in numerous formulations for the control of insect pests in animals, humans and environment. There are, however, few studies reporting their field efficacy in horses. The aim of the present study was to evaluate the repellent activity of a spray formulation based on prallethrin and permethrin synergized with piperonyl butoxide (BRONCO® Equine Fly Spray, Farnam Companies, Inc., USA) against annoying and harmful insects for horses in field conditions. Nine horses of mixed breed were divided into 2 groups (treatment and control). Pre-treatment insect counts were compared to daily counts for 4 days post-treatment (pt). One minute after the administration of the product (day 0), all the horses were negative for the presence of insects. All counts up to the 6-h pt check remained negative for Hippobosca equina, tabanid flies and Simulium spp., showing 100% efficacy. This remained above 90% throughout the study. For the H. equina, the repellent efficacy remained > 99.7% for all 4 days pt, for tabanid flies > 93.3% and for Simulium spp. > 97.4%. The efficacy against Musca spp. decreased from 82.2% at day 0 to 62.2% at day 3. Treatment was well-tolerated. In conclusion, despite the low number of tested horses, Bronco® has demonstrated high insecticide and repellent efficacy and a good persistence, maintained for up to 4 days post-treatment, against the most common species of insects harmful for horses.

Use of Botanicals Plant for Stored Grain Pest Management: A Critical Review

The current paper has been studied to understand the significance of various plant products (botanicals) against storage insect pests of seeds and grains. Grain storage is critical in agriculture for the next generation and food security. Insect pests are economically relevant among the several biotic and abiotic elements that impact the fate of grains during storage because they cause significant loss. The expanding demands of the world's growing population can be met by lowering or eradicating the insect pest population while storing. The most damaging storage insect pests are Sitotroga cerealella, Sitophilus sp., Rhyzopertha Dominica, Trogoderma granarium, Tribolium sp., Callosobruchus sp., and others. Insect damage includes the ingestion of seed, exuviae debris, webbing, and cadavers, rendering the grain unfit for human consumption and reducing both quality and quantity. They manipulated the storage environment, resulting in the formation of hotspots that are conducive to the spread of storage fungi and other dangerous microflora. Conventionally, we use synthetic pesticides to manage various insect pests that are hazardous to the environment and ecosystem in a variety of ways, including the elimination of natural enemies, insect resistance and resurgence, making soil, water, and air sick, and having residual effects that cause various disorders or diseases in animals and humans. Botanicals such as neem (Azadirachta indica), Bach (Acorus calamus), phoolakri (Lantana camara), draik (Melia azadarach), kali mirch (Piper nigrum), and basuti (Adhatoda zeylanica) are biodegradable, non-residual, equally effective, and widely available etc. may show to be a superior solution for controlling insect pests, particularly storage pests, without impacting grain or seed quality or harming our ecology or environment. Thus, botanicals can be used alone or in conjunction with IPM to manage insect pests.

Use of double-stranded RNA targeting β2 divergent nicotinic acetylcholine receptor subunit to control pea aphid Acyrthosiphon pisum at larval and adult stages.

In recent years, the use of the RNA interference technology (RNAi) has emerged as one of the new strategies for species-specific control of insect pests. Its specificity depends on the distinctiveness of the target gene sequence for a given species. In this work, we assessed in the pea aphid Acyrthosiphon pisum (A. pisum) the use of a double-stranded RNA (dsRNA) that targets the β2 divergent nicotinic acetylcholine receptor (nAChR) subunit (dsRNA-β2), which shares low sequence identity with other subunits, to control populations of this pest at different developmental stages. Because nAChRs are targeted by neonicotinoid insecticides such as imidacloprid, we also assessed the effect of dsRNA-β2 coupled to this insecticide on aphid survival. Finally, because the effect of a control agent on beneficial insect must be considered before any use of new pest management strategies, the acute toxicity of dsRNA-β2 combined with imidacloprid was evaluated on honeybee Apis mellifera. In this work, we demonstrated that dsRNA-β2 alone has an insecticidal effect on aphid larvae and adults. Moreover, dsRNA-β2 and imidacloprid effects on aphid larvae and adults were additive, meaning that dsRNA-β2 did not alter the efficacy of imidacloprid on these two developmental stages. Also, no obvious acute toxicity on Apis mellifera was reported. Using RNAi that targets β2 divergent nAChR subunit is effective alone or combined with imidacloprid to control A. pisum at larval and adult stages. Because no obvious Apis mellifera mortality has been reported, this RNAi-based pest management strategy should be considered to control insect pest. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

In Vitro Antagonistic Activity of Entomopathogenic Fungi Against Phytophthora infestans

Potato downy mildew is a disease caused by a fungus called Phytophthora infestans (Mont.) de Bary, which is mainly seen in potatoes and tomatoes, but also in other culture and wild plants belonging to the Solanaceae family. This fungus is quite important both from an economic and historical point of view. In case of an epidemic, it can cause full crop deterioration or serious losses in potatoes. Although cultural and chemical control methods are generally used in the control of the disease, there is no specific biological control method in this regard. Entomopathogenic fungi (EPFs) are generally used as biological control agents in the control of insect pests. Recently, there are many studies showed that these fungi can live endophytically on various cultivated plants and provide beneficial properties to the plants they live with. In this study, it was aimed to determine the in vitro antagonistic activities of different entomopathogenic fungi previously isolated from potato fields and identified by molecular methods against P. infestans. Earlier work determined that these fungi had a lethal effect on Leptinotarsa decemlineata (Say, 1824). Antagonistic activity tests were performed according to the "direct opposition method" and percentage (%) activity values were calculated. As a result of the tests, the most effective isolates were found to be Beauveria sp. SK-14 (75.23%) and Metarhizium sp. SK-24 (76.23%). It is thought that the results obtained will contribute to the biocontrol of diseases and pests in potatoes.

Efficacy and toxicity of different plant extracts over the period of time in Bracon hebetor (Say) (Hymenoptera: Braconidae)

Bracon hebetor (Say) is an important parasitoid and played a suitable model role for bio control programs. Pest management through biocontrol approaches such as plant extracts is an ecologically responsive and enthusiastic means of reducing insect pests. The main objective of the present research was to discover the efficiency and susceptibility periods of plant extracts for the assessment of parasitoids. The toxicity of five plants (Cymbopogon nardus, Azadirachta indica, Syzygium aromaticum, Datura stramonium and Parthenium hysterophorus) extracts were evaluated against B. hebetor to detect the possible way forward to controlling insect pests along with the adverse effects on beneficial insects. The data was recorded regarding mortality of B. hebetor, after calculated time periods with different intervals of up to 2 days. Datasets were followed by a statistical probe which exhibited significant results. The extracts of C. nardus, A. indica, S. aromaticum and D. stramonium exhibited non-toxic effects, whereas P. hysterophorus indicated low toxicity annotations against investigated parasitoid. These investigations suggested that four plants examined are not hazardous to the parasitoids whereas P. hysterophorus somehow has detrimental effects at low toxicity levels. Further development of insecticide resistance mechanisms in the parasitoid favors the enhancement of parasitoid efficacy with plant extracts. The possible selective use of these plant extracts and their effects on the safety period of parasitoids for integration with other approaches in sustainable pest management programs is discussed.

Fitness costs of resistance to insecticides in insects

The chemical application is considered one of the most crucial methods for controlling insect pests, especially in intensive farming practices. Owing to the chemical application, insect pests are exposed to toxic chemical insecticides along with other stress factors in the environment. Insects require energy and resources for survival and adaptation to cope with these conditions. Also, insects use behavioral, physiological, and genetic mechanisms to combat stressors, like new environments, which may include chemicals insecticides. Sometimes, the continuous selection pressure of insecticides is metabolically costly, which leads to resistance development through constitutive upregulation of detoxification genes and/or target-site mutations. These actions are costly and can potentially affect the biological traits, including development and reproduction parameters and other key variables that ultimately affect the overall fitness of insects. This review synthesizes published in-depth information on fitness costs induced by insecticide resistance in insect pests in the past decade. It thereby highlights the insecticides resistant to insect populations that might help design integrated pest management (IPM) programs for controlling the spread of resistant populations.

Single-atoms (B, P, S, Si) doping of Pt-coordinated graphitic carbon nitride (Pt@g-C3N4) nanostructured as sensors for Buprofezin (BPF) insecticide: Outlook from computational study

As global agriculture seeks to reduce the reliance on conventional insecticides with potentially harmful effects for modern agriculture and insect-pest control practices, we improve the appeal of buprofezin as a safe and sustainable pest control option. Herein, we conducted theoretical investigations to explore the adsorption efficacy, sensibility, and reactivity of heteroatoms (B, N, P, S and Si) doped on a custom-engineered platinum-encapsulated graphitic carbon nitride (Pt@C3N4) as enhanced sensor materials for the adsorption of buprofezin (BPF) insecticide within the framework of density functional theory (DFT) computation at the B3LYP-GD3BJ/def2svp level of theory. Consequently, the notable variations observed in the energy gap of the studied surfaces when interacted with buprofezin accounted for the reactivity, stability, conductivity, work function, and overall adsorption potentials of the sensor material which projects the doped surfaces as a suitable sensor material for sensing buprofezin (BPF). More so, the negative adsorption energies observed for interacting surfaces doped with B, N, P, S and Si suggest the strong propensity to trap buprofezin molecule better as a considerably strong chemisorption was observed especially in the BPF_S_Pt@C3N4 which had highest adsorption of -51.355 kcal/mol. With firm conviction, this research study will be helpful and provide useful knowledge as background research for future study and experimental researchers to uncover the potentials in heteroatom doping of Pt@C3N4 materials for maintaining ecological balance and environmental sensing applications.

Effects of Annona squamosa leaf extract on the insects Aedes aegypti, Nasutitermes corniger, and Sitophilus zeamais and the microcrustacean Hyalella sp.

The high environmental toxicity of currently used insecticides and the emergence of resistant insect populations have prompted the search for new agents to control insect pests. In this study, we characterized a saline extract from Annona squamosa L. leaf to determine its chemical constituents and effects on third instar Aedes aegypti L. larvae, Nasutitermes corniger Motsch. workers and soldiers, Sitophilus zeamais Motsch. adults, and Hyalella sp. juveniles. The extract showed a protein concentration of 22.9 mg/mL and included lectins (specific hemagglutinating activity of 21,333.33) and trypsin inhibitors (specific activity of 15.6 U/mg), as well as the secondary metabolites cinnamic acid derivatives, rutin, and chlorogenic acid. The extract killed third instar Ae. aegypti larvae (50 % lethal concentration of 1.9 %, w/v) and increased the permeability of the peritrophic membrane of Ae. aegypti larvae. The extract did not affect the survival of N. corniger workers or soldiers but killed S. zeamais adults with mortality rates of 51.2–63.8 %. A strong deterrent feeding effect was detected, making S. zeamais adults reject an artificial diet containing the extract. Juveniles of the microcrustacean Hyalella sp. were highly sensitive to treatment with the extract at the 50 % lethal concentration for Ae. aegypti. In conclusion, A. squamosa leaf extract kills Ae. aegypti larvae and S. zeamais adults by increasing the peritrophic membrane permeability and exhibiting a strong food deterrent effect, respectively. However, as an insecticide, the extract should be used with caution because of its high non-target toxicity. The effects of A. squamosa leaf extract may be linked to the actions of lectins, trypsin inhibitors, rutin, and chlorogenic acid.

Outlook on RNAi-Based Strategies for Controlling Culicoides Biting Midges.

Culicoides are small biting midges with the capacity to transmit important livestock pathogens around much of the world, and their impacts on animal welfare are likely to expand. Hemorrhagic diseases resulting from Culicoides-vectored viruses, for example, can lead to millions of dollars in economic damages for producers. Chemical insecticides can reduce Culicoides abundance but may not suppress population numbers enough to prevent pathogen transmission. These insecticides can also cause negative effects on non-target organisms and ecosystems. RNA interference (RNAi) is a cellular regulatory mechanism that degrades mRNA and suppresses gene expression. Studies have examined the utility of this mechanism for insect pest control, and with it, have described the hurdles towards producing, optimizing, and applying these RNAi-based products. These methods hold promise for being highly specific and environmentally benign when compared to chemical insecticides and are more transient than engineering transgenic insects. Given the lack of available control options for Culicoides, RNAi-based products could be an option to treat large areas with minimal environmental impact. In this study, we describe the state of current Culicoides control methods, successes and hurdles towards using RNAi for pest control, and the necessary research required to bring an RNAi-based control method to fruition for Culicoides midges.

In Vivo Production, Development and Storage of Oscheius myriophila (Nematoda: Rhabditida) in Galleria mellonella (Lepidoptera: Pyralidae).

Entomopathogenic nematodes have been used in biological control for some time and are an alternative for the control of insect pests, but during their implementation, situations have arisen that can be improved. These vary with each species and include their production and storage. Oscheius myriophila, an entomopathogenic nematode (EPN), was monitored for its performance when produced in vivo, as well as its development using Galleria mellonella larvae, using the MC5-2014 strain isolated from soil samples in the municipality of Tepalcingo, Morelos, México. For a study with native strains of EPNs, a wide range of tests must be conducted because the required conditions can be very specific. In vivo production was quantified at initial infective juvenile (IJ) inocula of 50, 100 and 500, and we obtained the same production for the three inocula. The life cycle of the EPNs lasted 12 days, and two generations were observed in which adults were found at days 5 and 9. Both evaluations were performed at a temperature of 27 °C in G. mellonella larvae. In addition, the temperatures of 8, 12, 20 and 24 °C were evaluated for their storage, and we observed that the EPNs can be kept for at least 6 months, maintaining a survival rate of 58.67% and a good infective capacity at a temperature of 12 °C, remaining above 60%.