Diet Incorporation Research Articles

Assessing the toxicity of six insecticides on larvae of red palm weevil under laboratory condition

ObjectiveThe red palm weevil (RPW), is one of the most threatening pests of date palm trees worldwide, causing significant economic losses annually for date palm growers, both globally and in the Middle East, including Saudi Arabia. The primary objective of this research was to assess the insecticide market in Saudi Arabia, test various insecticides claimed to be effective against RPW, and evaluate their efficacy in laboratory settings. This evaluation aims to inform further trials under field conditions. MethodsSix insecticides, including imidacloprid, thiamethoxam, fipronil, emamectin benzoate, deltamethrin, and fenitrothion, were tested to assess their toxicity against red palm weevil 8th instar larvae by diet incorporation under laboratory conditions. The insecticides were applied according to the manufacturer’s recommendations with dosages of 1000 µl, 0.20 µl, 7.5 µl, 0.25 µl, 0.25 µl, and 0.5 µl for imidacloprid, thiamethoxam, fipronil, emamectin benzoate, deltamethrin, and fenitrothion, respectively. ResultsThe results revealed that all tested insecticides exhibited 100 % mortality against 8th instar RPW larvae, with the exception of deltamethrin. However, the time required to achieve this mortality varied. Fenitrothion caused 100 % mortality after 72 h, while thiamethoxam, imidacloprid, and fipronil caused 100 % mortality after 96 h. Emamectin benzoate and deltamethrin resulted in 100 % and 93 % mortality, respectively, after 10 days. The variability in mortality rates may be attributed to differences in their active ingredients, which show varying levels of lethality. In conclusion, all tested insecticides showed effectiveness against RPW larvae and represent viable options for controlling this pest in date palm orchards in Saudi Arabia.

Evaluation and Identification of Novel Insecticidal Toxin Genes From <i>Bacillus Thuringiensis</i> (Berliner) Isolates

The present study evaluated fifteen Bacillus thuringiensis (Berliner) isolates against second instar larvae of tobacco leaf eating caterpiller Spodoptera litura (F) and Vip genes were identified in the effective isolates. Four NCIM isolates (5111, 5112, 5116 and 5117) were found promising, and their LC50 ranged from 2.5x105 to 3.33x105 ppm and 2.20x105 to 2.85x105 ppm in diet incorporation and surface contamination methods, respectively. The NCIM-5111 isolate exhibited the lowest LC50 of 2.5x105 ppm in diet incorporation and 2.2x105 ppm in the surface contamination method. Surface contamination method revealed more mortality of 6.66 to 10.00% across the NCIM isolates. All the isolates were further used for identification of insecticidal toxin (Vip, Cyt) genes, and it was observed that four NCIM isolates harbour the Vip3Aa1 gene and one viz., NCIM-5112 isolate carries the Vip1/ Vip2 gene, which has distinct motifs from the Vip toxins that are currently in use.

Bio-efficacy of Xanthium strumarium L. Essential Oil against Castor Semilooper, Achaea janata L. (Lepidoptera: Noctuidae)

Background: Although use of synthetic insecticides causes excellent control of insect pests, it leads to adverse effects on non-target organisms as well as the environment. The present study determining the chemical composition and insecticidal activities of essential oil extracted from the leaves of rough cocklebur, Xanthium strumarium and its bioefficacy against the castor semilooper, Achaea janata shall show a new dimension in formulating an ecofriendly management strategy towards castor crop. Methods: Xanthium strumarium leaf essential oil was isolated through hydro-distillation method using Clevenger apparatus and the chemical composition was analysed using GC-MS. The ovicidal and insecticidal activity of the essential oil was determined by dipping and topical application methods, respectively. Larval feeding deterrence and growth inhibitory properties of the essential oil was evaluated through the diet incorporation method. Result: GC-MS analysis of the X. strumarium essential oil revealed the presence of 14 chemical compounds, of which the majority are the terpenes (94.48%). The LC50 values in terms of ovicidal and insecticidal activities were recorded to be 69.70 µL/mL and 0.30 µL/larvae, respectively. The fifty per cent larval feeding deterrence (DC50) and growth inhibitory properties (EC50) were recorded to be 1.88 µl/cm² and 213.94 µL/mL, respectively.

Bioassay Techniques in Entomological Research

BIOASSAY (Bio - life, Assay - determination) is the measurement of the potency of any stimulus (physical, chemical, biological, and psychological) and the reactions that it produces in living matter. In Entomology, to know about the potency, Specificity of any compounds, standardization of doses, and identify modes of action bioassay is needed. In addition to the basic bioassay methods such as poison food, dry film techniques, etc., depending upon the researcher’s necessity, they are modified or newly developed. Diet covering and diet incorporation for lepidopterans and homopterans have been developed as advancements over the poison food assay method, by using insecticide-incorporated artificial diet. WHO cone, Wire ball test, Susceptibility test, CDC bottle assay and MCD assay developed for mosquito resistance monitoring and Larval Packet Technique (LPT) for cattle ticks, Sandwich method, TIBS, and Adult vial test are advancements over dry film technique. In Thrips Insecticide Bioassay System (TIBS), treated vials can be stored for up to 3 weeks at 4˚C for future efficacy assays at the field level. Adult Vial Tests have been developed for pentatomid and mirid adult bug bioassays. Larval Immersion Technique (LIT), Adult Immersion Technique (AIT) for cattle ticks, and MEBS have been developed as advancements over topical bioassay. In Mite Egg Bioassay System (MEBS), entomopathogenic fungi have been tested against Tetranychus cinnabarinus. MTT colorimetric assay and Trypan Blue Dye Exclusion assay helps to identify cell viability in insect cell line cultures. Spodoptera frugiperda cell line, Sf – 21 was tested against a scorpion, Leiurus quinquestriatus toxin β– BUTX – LQQ1a and the toxicity was determined through the viability of cell lines. Various basic and advanced bioassay techniques are discussed elaborately in this review.

Characterization of Resistance to the Mexican Rice Borer (Lepidoptera: Crambidae) among Sugarcane Cultivars.

Simple SummaryThe Mexican rice borer, Eoreuma loftini, is one of the most important insect pests of sugarcane in the US. Management strategies that are environmentally friendly and economically profitable are needed to mitigate the pest’s impact. Cultivar resistance can become a key management strategy for Mexican rice borer control in sugarcane because it is inexpensive and easy for sugarcane growers to implement. Resistance is compatible with almost all other management strategies and minimizes further input costs incurred by the grower. However, the mechanisms of resistance are not completely understood. Elucidating which mechanisms and traits confer resistance can help sugarcane breeding programs increase the resistance level of future cultivar releases. We found that the currently grown commercial cultivars L 01-299 and HoCP 85-845 had the least amount of borer-related injury, while L 12-201 and HoCP 00-950 had the greatest level of injury. These differences appear to be related to the ability of recently hatched larvae to establish feeding rather than female preference to lay eggs on specific cultivars. Further work is needed to determine the influence of environmental factors on resistance expression and identify plant characteristics that are responsible for Mexican rice borer resistance.Cultivar resistance is an essential management strategy for the Mexican rice borer, Eoreuma loftini (Dyar), in sugarcane in the USA, but resistance mechanisms are poorly understood. Resistance was evaluated among Louisiana’s (USA) commercial sugarcane cultivars and experimental clones through field screenings, greenhouse trials, and a diet incorporation assay. Cultivars L 01-299 and HoCP 85-845 had the lowest borer injury levels, while HoCP 00-950 and L 12-201 were among the most heavily injured in field and greenhouse trials. The variability of results between the two field trials suggests that a genotype × environment interaction might affect the expression of resistance. Oviposition did not differ among evaluated cultivars in the greenhouse choice study. Results from the no-choice experiment showed that neonatal establishment differed among cultivars by up to 3-fold. In a diet incorporation assay, all cultivars reduced larval weight up to 86.5% and increased days to pupation by 1.8-fold relative to the diet-only control. Collectively, these results suggest that Louisiana’s sugarcane breeding germplasm contains various resistance levels to E. loftini, emphasizing the importance of screening cultivars before they are released to growers. Future studies should try to determine the influence of environmental factors on resistance expression.

Evaluation of the susceptibility to emamectin benzoate and lambda cyhalothrin in European populations of Cydia pomonella (L.) (Lepidoptera: Tortricidae)

The codling moth Cydia pomonella (L.) (Lepidoptera: Tortricidae) is one of the key pests of pome fruit and walnut in almost all growing regions of the world and has developed resistance to several insecticides. In this study, the susceptibilities of 15 codling moth populations to emamectin benzoate and 9 populations to lambda cyhalothrin collected in five European countries were measured by standard diet incorporation bioassays. Variation in susceptibility was observed among populations, with LC50 values ranging from 0.0017 to 0.0119 mg a.i./kg diet for emamectin benzoate and from 0.033 to 0.292 mg a.i./kg diet for lambda cyhalothrin. Our results revealed only small variations in emamectin benzoate susceptibility between populations, indicating no selection of resistance to this active ingredient. Even though a wider range of responses was detected for lambda cyhalothrin, our results also suggest that populations remain susceptible to this insecticide. Based on pooled LC95 evaluations, we propose the use of concentrations 0.02 mg a.i./kg of diet for emamectin benzoate and 0.60 mg a.i./kg of diet for lambda cyhalothrin in order to discriminate between resistant and susceptible individuals.

A comparative study on the virulence of entomopathogenic fungi against Trogoderma granarium (Everts) (Coleoptera: Dermestidae) in stored grains rice.

Entomopathogenic fungi (EPF) now a possible safer microbial control measure that could be considered as a substitute for chemical control of insect pests. Three EPF viz., Metarihizium anisopliae, Isaria furnosoroseus and Beauveria bassiana were evaluated for their virulence against the grubs of Khapra beetle, Trogoderma granarium (Everts) under laboratory conditions. The isolates were applied by two methods viz., diet incorporation and an immersion method with 3rd instar 20 grubs of T. granarium for each. The virulence of EPF was determined using percent mortality. Significantly higher mortality was observed in M. anisopliae applied through immersion (98.33%) and diet incorporation (93.33%) methods followed by B. bassiana (90.83 and 85.83%, respectively). The mortality caused by I. furnosoroseus was statistically lower in immersion and diet incorporation methods i.e. 81.67 and 73.33%, respectively. Based on the immersion method, all EPF were studied for multiple conidial concentration i.e., 1×104, 1×105, 1×106, 1×107 and 1×108 under the same in-vitro conditions. All the isolates were pathogenic to grub of T. granarium at the highest conidial concentration. M. anisopliae was proved the most effective virulent resulting in 98.33% mortality of the pest with LT50 4.61 days at 1 × 108 conidial concentration followed by 90.83 and 81.67 percent mortality with 5.07 and 8.01 days LT50, in the application of B. bassiana and I. furnosoroseus, respectively. M. anisopliae showed higher efficacy and could be considered as promising EPF for the development of myco-insecticides against effective biocontrol of T. granarium.

Management of Stemborers (Lepidoptera: Crambidae) Using Foliar-Applied Chlorantraniliprole in Rice

Rice is one of the most important crops in Louisiana and Texas, USA. It is subjected to various insect pests throughout the growing season. Lepidopteran stem-boring pests including the Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), are increasing in economic importance as insect pests in rice production, particularly in southwest Louisiana, USA. Field trials were conducted in Louisiana and Texas to examine the efficacy of foliar-applied insecticides (chlorantraniliprole and the pyrethroids ζ-cypermethrin and λ-cyhalothrin) and chlorantraniliprole seed treatment for control of rice stemborers during 2018 and 2019. Furthermore, a diet incorporation assay assessed the toxicity of chlorantraniliprole to laboratory-reared E. loftini. Results of field experiments in Louisiana showed foliar applications of chlorantraniliprole, at 22 to 35 d after permanent flood was established, reduced stemborer injury to rice by 57.9 to 96.5% in 2018 and 73.9 to 87.5% in 2019 compared to nontreated or pyrethroid-treated field plots. However, rice yields in 2019 did not vary among insecticide-treated and nontreated plots. In the Texas field experiments, chlorantraniliprole applied as seed treatment reduced stemborer injury, but was not effective in reducing injury when sprayed directly to soil after planting or when applied at permanent flood. The LC50 and LC90 (lethal concentration that produced 50% and 90% mortality, respectively) of chlorantraniliprole on third-instar E. loftini were 0.09 ± 0.03 and 0.53 ± 0.17 µg a.i. mL-1, respectively, at 6 d after exposure. At 10 d after exposure, LC50 and LC90 were 0.04 ± 0.02 and 0.16 ± 0.04 µg a.i. mL-1, respectively. In addition to chlorantraniliprole seed treatment, foliar application of chlorantraniliprole in rice could provide a new tool for management of damaging stemborer infestations.

Toxicity of different insecticides against the dwarf honey bee, Apis florea Fabricius (Hymenoptera: Apidae)

Honey bees are considered as critical beneficial insects in the term of honey production and pollination of crops. One of the essential honey bee species in Pakistan is Apis florea Fabricius (Hymenoptera: Apidae). These make nests on trees near human dwellings and agriculture crops. During foraging in the field for nectar and pollen collection from agriculture flowering plants, honey bees may be exposed to pesticide sprays which may cause a change in their foraging behavior and the death of their workers. The current study evaluates the toxicity of six insecticides (emamectin benzoate, spinetoram, chlorantraniliprole, fipronil, flonicamid, and imidacloprid) against workers of A. florea. There were six concentrations of each insecticide (causing > 0% to < 100 % mortality) prepared in water, and each concentration was replicated four times. The experiment was conducted using the diet incorporation method in a plastic container. Emamectin benzoate was found the most toxic insecticide with lower LC50 values (1.02 µg/mL) followed by spinetoram (1.10 µg/mL), chlorantraniliprole (2.74 µg/mL), imidacloprid (3.09 µg/mL), flonicamid (3.94 µg/mL), fipronil (6.00 µg/mL) after 48 h of exposure. The results showed that insecticides are very toxic to A. florea and should be used on agriculture crops with great care and during less activity.

Resistance to the Sugarcane Borer (Lepidoptera: Crambidae) in Louisiana Sugarcane Cultivars.

Cultivar resistance is a key management strategy for the sugarcane borer, Diatraea saccharalis (F.), the primary pest in Louisiana sugarcane, but mechanisms of resistance are not well understood. This research evaluated the potential mechanisms of cultivar resistance to D. saccharalis among commercially produced sugarcane cultivars and experimental lines through three field screenings, two greenhouse experiments, and one diet incorporation assay. The resistant standards HoCP 85-845, HoCP 04-838, and L 01-299 were among the cultivars with the lowest D. saccharalis injury levels in both field and greenhouse trials. Cultivars HoCP 00-950 and L 12-201 were among the most heavily injured in both trials. Differences in oviposition among cultivars in the greenhouse choice study were not detected, suggesting adult preference is not a key factor in resistance. This was also supported by the no-choice greenhouse experiment in which up to 9-fold differences in neonate establishment among cultivars were detected. Larval injury among cultivars in greenhouse experiments was consistent with field studies suggesting traits that affect neonate establishment (e.g., rind hardness) help to confer resistance in the field. In the diet incorporation assay, lower larval weights and longer time to pupation were observed on resistant cultivar Ho 08-9003, but no differences were found among current commercial cultivars. Continuous evaluation of cultivar resistance to D. saccharalis is important in developing effective integrated pest management strategies for this pest. More research into plant characteristics (e.g., leaf sheath tightness and pubescence) associated with resistance is needed.

Sublethal Effects of Abamectin on the Development, Reproduction, Detoxification Enzyme Activity, and Related Gene Expression of the Oriental Fruit Moth (Lepidoptera: Tortricidae).

Grapholita molesta is one of the most important fruit pests worldwide. Abamectin is a biological pesticide frequently used to control fruit borers like G. molesta in part owing to its translaminar properties. In this study, we characterized the toxicity of abamectin to G. molesta larvae using the diet incorporation method. The sublethal effects of abamectin on the development, reproduction, detoxification enzyme activity, and related gene expression of G. molesta were assessed. The results showed that the LC20 and LC50 values of the insecticide against G. molesta 72 h post-treatment were 1.17 mg L-1 and 5.85 mg L-1, whereas the LC20 and LC50 values 96 h post-treatment were 0.34 mg L-1 and 3.63 mg L-1. When compared to the control, sublethal concentrations of abamectin 1) significantly increased the mortality of the larvae, prepupae, and pupae of G. molesta, 2) prolonged the duration of 3rd to 5th instar larva, prepupal and pupal periods, 3) shortened the longevity of adults, and 4) reduced female fecundity. The enzymatic activity of glutathione S-transferase (GST) varied significantly after exposure to sublethal concentrations of abamectin, but the cytochrome P450 monooxygenases and carboxylesterase activity were not significantly affected. Thirteen of the 25 GST genes were significantly upregulated under different sublethal concentrations of abamectin. The combined findings increase our understanding of the effects of abamectin on G. molesta and the potential role of GSTs in the metabolic interactions of abamectin in this pest, and have applications for more rational and effective use of abamectin to control G. molesta.

Susceptibility of the Egyptian Cotton Leafworm, Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) to Entomocidal Crystal Proteins Cry1Ac and Cry 2Ab Baseline Responses

The present study maybe is the first attempt in Egypt to evaluate the effect of Entomocidal proteins (Cry toxins) from Bacillus thuringiensis (Bt)Cry 1Ac and Cry 2Ab againstthe Egyptian cotton leafworm Spodoptera littoralis. The cotton leafworm one of the important Lepidopteran species is the most important pests in cotton fields. It can be controlled using Genetically Modified (GM) crops expressing insecticidal Bt proteins like Bt cotton and Bt corn. The long-term success of this technology demands pest resistance management. Important information for the successful management of resistance is the baseline susceptibility of the different target pests to the different Bt proteins. The data on baseline susceptibility should enable risk assessors and managers to assess whether GM cotton produces a Bt protein in a high-dose to specific target organisms and resistance has evolved during the commercial cultivation of this GM cotton event. During this study, the toxicity of Cry 1Ac and Cry 2Ab from the bacterium Bacillus thuringiensis to larvae of S. littoralis was assessed using first instar larvae with diet incorporation bioassays. Larvae reared (4 generations) from 2 populations of S. littoralis collected from major cotton-growing regions of Sohag and Assuit Governorates were tested. The LC50 for the Assuit strain was 140.11 and 88.54 µg/ml forCry 1Ac and Cry 2Ab, respectively. While, the LC50 for the Sohag strain was 410.75 and 37.62 µg/ml for Cry 1Ac and Cry 2Ab, respectively. On the other hand, the laboratory strain was more sensitive for the same Cry’s (Cry 1Ac and Cry 2Ab) the LC50 was13.40 and 0.23 µg/ml, respectively. The lethal concentration (LC50) against S. littoralis for 2nd and 4th instars larvae when using the B. thuringiensis as spores (commercial product) was 1.16 and 2.49 for 2nd and 4th instars, respectively. This study is very important as a preliminary step and baseline ahead of the commercial cultivation and production of Genetically Modified cotton (Bt cotton).

English

Invasions of the red palm weevil (RPW) Rhynchophorus ferrugineus (Olivier) has become a well-known problem for several palm species in date palm-growing states, including Saudi Arabia. Although several control measures have been implemented in efforts against RPW, yet, no approach has proven consistently effective against this invasive pest. Therefore, further efforts are still needed to develop an effective and efficient control method for RPW management and mitigation. The objectives of the present study were to determine emamectin benzoate (ARETOR) efficacy against RPW larval stages, in the laboratory using a diet incorporation bioassay, along with field tests of the Syngenta Tree Micro-Injection Technique. Our laboratory bioassay showed that the median lethal concentration of emamectin benzoate (ARETOR) was 0.30 μg/mL−1 against wild populations of RPW larvae. In the field studies, emamectin benzoate (ARETOR) showed promising effects on RPW mortality for all stages. We found 100% mortality for both larval and pupal stages for all exposure times, except after 2 months, where 86% mortality was observed for larvae. Thus, we conclude that emamectin benzoate (ARETOR) is an effective biopesticide against RPW. Our results show that it killed RPW all stages, also prevented further damage to the healthy tissues of date palms, in addition, provided protection against RPW spread to other neighboring healthy date palms. © 2021 Friends Science Publishers

Susceptibility of North Carolina Chloridea (Heliothis) virescens (Lepidoptera: Noctuidae) Populations From Flue Cured Tobacco to Chlorantraniliprole.

The tobacco budworm, Chloridea (Heliothis) virescens (F.), has evolved resistance to numerous insecticides in the field. In tobacco, chlorantraniliprole can be applied as either a preventative systemic soil application at or near transplant, or a foliar application timed to current treatment thresholds. With a novel mode of action chlorantraniliprole provides an option for rotation with other insecticides to reduce the probability of insecticide resistance development. However, specific usage patterns in tobacco have the potential to increase the risk of resistance development to this insecticide. In particular, soil applied treatments may expose C. virescens to sublethal concentrations of the insecticide. We studied chlorantraniliprole susceptibility in nine field populations and one laboratory strain of C. virescens using a diet incorporation bioassay. Mortality was measured at 7, 10, and 14 d after exposure. Our results demonstrated that bioassays should be evaluated at 14 d after exposure to optimize interpretation of the dose-response due to the antifeeding properties of chlorantraniliprole. We observed low variation within field-collected populations. Field populations were as susceptible as the laboratory strain; the resistance ratio at the 14-d evaluation for field-collected populations ranged from 1.01 to 1.05. A discriminating dose of 0.117, 0.080, and 0.070 μg a.i./g diet could be used at 7, 10, and 14 d, respectively. Larval growth varied between field populations. Two field populations continued growing on diet containing chlorantraniliprole and differed in size from the laboratory and other populations. Further evaluation of growth inhibition will be necessary.

Innovative on-plant bioassay method for selection of superior genotype/cultivar/event against pink bollworm, Pectinophora gossypiella (Saunders) in cotton in protected screen house condition

Several methods have been advocated for screening of potential transgenic events that use either diet incorporation of toxins or excised plant parts expressing the pure protein (toxin) against insect pests of crops. However, considering the field level variations in transgenic plant expression due to abiotic environmental factors; mainly the temperature and moisture stress, it was a long felt need for development of a bioassay method that can be readily employed under field conditions. Here, we present a simple, rapid, relatively stable and reliable method of on-plant bioassay for screening of genotypes or transgenic events against pink bollworm, the major insect pest of global significance to cotton. The proposed method involved releasing neonate larvae of pink bollworm on approximately 12–15 days old undetached bolls of non-Bt and Bt (Bollgard I and Bollgard II) cotton plants and covering them with a kite paper bag to prevent larval escape. The tagged bolls were kept undisturbed for next 21 days. After completion of this period the observations on larval entry holes, locular damage, exit holes and per cent damaged bolls were recorded in each case. The experiments were repeated for two consecutive cotton cropping seasons of 2018–19 and 2019–20 on early (100 DAS) and late (150 DAS) formed bolls on cotton plants. Successful larval establishment and boll damage across the stages observed in non-Bt cotton plants compared to Bt cotton plants indicated the adequacy of proposed on-plant bioassay method. The late formed bolls exhibited relatively higher damage compared to early formed bolls in the plants that carrying Bt genes, indicating temporal decrease in toxin expression due to plant aging. This method being relatively easier and reliable, will be highly useful to the breeders, entomologists and seed producers in screening of superior transgenic material against pink bollworm in cotton.

Entomopathogenic fungi and plant essential oils are not compatible in controlling Tribolium castaneum (Herbst)

Entomopathogenic fungi (EPF) and essential oils (EOs) can show either positive or negative interactions when used for controlling insect pests. First, the insecticidal efficacy of EPF including Beauveria bassiana isolates Z1 and IRAN1395C, Lecanicillium lecanii, and Paecilomyces lilacinus was tested against adults of Tribolium castaneum using two methods (standard insect dip and wheat diet incorporation). Additionally, the toxicity of EOs from Trachyspermum ammi, Foeniculum vulgare, Eucalyptus globulus, Salvia mirzayanii, Majorana hortensis, and Thymus vulgaris was evaluated against adult T. castaneum. Thereafter, the effect of an LC25 concentration of F. vulgare (86.13 µl L−1), T. ammi (235.2 µl L−1), and E. globulus (111.33 µl L−1) EOs on mycelial growth, spore germination, and sporulation of the EPF was determined. In standard dip bioassay, the lowest LT50 of 10.4 days was induced by L. lecanii, while the wheat diet incorporation method resulted in LT50 values ranging between 13.1 and 15.2 days. The LC50 values for E. globulus, F. vulgare, and T. ammi were 162.3, 140.3, and 310 μl L−1 air against adults, respectively. The EOs examined showed strong inhibition of mycelial growth, conidial germination, and sporulation at sublethal concentrations. EOs of F. vulgare and T. ammi completely inhibited mycelial growth and sporulation of the tested EPF. Germination inhibition ranged from 100% in L. lecanii exposed to EO from F. vulgare to 52.3% in B. bassiana Z1 exposed to EO from T. ammi. Based on the results, although EOs and EPF are successful agents to control adults T. castaneum when used separately, it cannot be applied in combination because of the conflicting effect.

Efficacy of Providing the PI3K p110α Inhibitor BYL719 (Alpelisib) to Middle-Aged Mice in Their Diet.

BYL719 (alpelisib) is a small molecule inhibitor of PI3K p110α developed for cancer therapy. Targeted suppression of PI3K has led to lifespan extension in rodents and model organisms. If PI3K inhibitors are to be considered as an aging therapeutic, it is important to understand the potential consequences of long-term exposure, and the most practical way to achieve this is through diet administration. Here, we investigated the pharmacokinetics of BYL719 delivered in diet and the efficacy of BYL719 to suppress insulin signaling when administered in the diet of 8-month-old male and female mice. Compared to oral gavage, diet incorporation resulted in a lower peak plasma BYL719 (3.6 vs. 9.2 μM) concentration but similar half-life (~1.5 h). Consuming BYL719 resulted in decreased insulin signaling in liver and muscle within 72 h, and mice still showed impaired glucose tolerance and insulin sensitivity following 6 weeks of access to a diet containing 0.3 g/kg BYL719. However, consuming BYL719 did not affect food intake, body mass, muscle function (rotarod and hang time performance) or cognitive behaviors. This provides evidence that BYL719 has long-term efficacy without major toxicity or side effects, and suggests that administering BYL719 in diet is suitable for studying the effect of pharmacological suppression of PI3K p110α on aging and metabolic function.

Effects of Olive Cake and Cactus Cladodes as Alternative Feed Resources on Goat Milk Production and Quality

In the Mediterranean area, the olive cake (OC) and cactus cladodes (CC) are two alternative resources widely available that could be used for ruminants’ feeding. The objective of this study was to evaluate the effects of OC and/or CC diet incorporation on the production performance and quality of goat milk. Forty-four lactating goats were randomly allocated to four groups. The control one (Co) received a conventional feed. Test groups (TOC; TCC and TOC+CC) received 20% OC, 30% CC, or 15% OC and 20% CC, respectively, on concentrate dry matter basis. Over three months, milk production was evaluated, and samples were collected to analyze the milk quality. No significant differences were observed between control and test groups for daily milk production, yield, composition and acidity. In milk fat, OC incorporation increased C18:1n-9, mono-unsaturated (MUFA) and n-9 fatty acid (FA), and decreased 9t-C18:1 and poly-unsaturated FA (PUFA) (p &lt; 0.05). Significantly highest contents of C15:0, C18:1n-9, and C21:0, and lowest levels of C4:0, 9t-C18:1, 6t-C18:2, C20:0, and PUFA were obtained with cactus cladodes administration (p &lt; 0.05). The TOC + CC diet reduced C4:0, 9t-C18:1, 6t-C18:2, C22:6n-3, and PUFA proportions, and increased C18:1n-9, MUFA/PUFA, and thrombogenic indexes. The incorporation rates of OC and CC that could reach 20% and 30%, respectively, had no major negative effects on milk production performance, composition, and quality. Thus, they could be introduced in the diets of lactating goats.

Entomopathogenic screening of native Bacillus thuringiensis (Berliner) isolates against Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) under laboratory condition

Fall Armyworm, Spodoptera frugiperda (J E Smith) (Lepidoptera, Noctuidae) is native to the tropical and subtropical region of America. Being a polyphagous pest known to cause major damage to economically important cultivated grasses. This insect is one of the most important pests of maize, being firstly registered in the India in 2018 and it causes a 33% yield loss in the plant production. The use of chemical pesticides as a prophylactic method causes some problems such as ecological instability, pollution, high costs and death of natural enemies. In the current study, screening of native B. thuringiensis isolates and their insecticidal activities were tested against the 2nd instar larvae of maize fall armyworm, Spodoptera frugiperda under laboratory condition. Preliminary bioassay was conducted using diet incorporation method and treated with spore crystal lysates prepared from the native Bacillus thuringiensis isolates. Upon screening 50.0 per cent (of the B. thuringiensis isolates exhibited mortality in the range of 26-50 per cent while 10.0 per cent of the B. thuringiensis isolates showed more than 75 per cent mortality after 7 days of exposure. Among the seventy isolates, Bt-Oa1 and Bt-257 recorded maximum of 86.84% mortality after 7 days after treatment.

Metabolic mechanisms of indoxacarb resistance in field populations of Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae)

Synergism and metabolic studies were conducted to identify the resistance mechanism against indoxacarb in two Choristoneura rosaceana (Harris) field populations compared to a susceptible population. The synergism study was carried out using diet incorporation bioassay for indoxacarb and the three synergists PBO, DEM, and DEF. The metabolic study consists of indoxacarb in vitro reaction with fifth instar larvae 12,000 g midgut supernatant or with pre-inhibited (in vivo by the esterases inhibitor DEF) fifth instar larvae 12,000 g midgut supernatant at different incubation times. In both susceptible and cherry populations, only DEF significantly synergized indoxacarb with a synergism ratio (SR) of 6.5 and 22.6-fold respectively indicating an involvement of esterases in the both populations. In the apple population, all synergists PBO, DEM, and DEF significantly synergized indoxacarb with SR of 9.6, 7.7, and 285.6-fold respectively indicating a complex resistance case with the possible involvement of all three metabolic resistance mechanisms with the central role of esterase enzymes. In vitro, the indoxacarb (DPX-JW062) was very rapidly metabolized within 5 min into small molecules in the lower portion of the metabolic pathway when it reacted with the midgut supernatant of each population. None of the metabolites in the upper portion of the metabolic pathway were detected at any incubation time including the potent sodium channel blocker DCJW metabolite. The two field populations showed significantly higher rates of metabolism of DPX-JW062 compared to the susceptible population at five min of incubation and that may explain the presence of indoxacarb resistance. In the second part of the in vitro study, the bio-transformation of DPX-JW062 was remarkably decreased when it reacted with the pre-inhibited (by DEF) midgut supernatant of each population. Additionally, the degradation of metabolites in the upper portion of the metabolic pathway remarkably decreased, which resulted in accumulation of DCJW and MP819 metabolites. The accumulation of DCJW metabolite under the pre-inhibited midgut supernatants treatment provided a persuasive explanation of the synergistic impact of esterase inhibitor DEF on indoxacarb in C. rosaceana.