Effects Of Spinosad Research Articles

The effects of Spinosad on zebrafish larvae and THP-1 cells: Associated with immune cell damage and NF-kappa B signaling pathway activation

Spinosad is a highly effective macrolide insecticide with a wide range of applications. However, few studies have been reported on the effects of Spinosad on immune cells. The immune system is an important line of defense in the human body and plays an important role in maintaining the normal functioning of the organism. Meanwhile, macrophages, neutrophils and Thymic T cells are an important component of the immune system. We studied the immunotoxicity of Spinosad using zebrafish and THP-1 cells. In vivo, Spinosad (0–20 μM) did not cause developmental toxicity in zebrafish, but induced damage to immune cells. In vitro, Spinosad (0–20 μM) inhibited THP-1 cells viability and induced mitochondrial damage and oxidative stress production. In further studies, it impaired phagocytosis of THP-1 cells and interfered with lipid metabolism. In addition, we found that Spinosad can promote the formation of the inflammatory body NLRP3 (NLR family, pyrin domain-containing 3) and activate the NF-kappa B (NF-κB) signaling pathway. These results suggest that Spinosad has a potential risk for inducing immunotoxicity. This study has drawn attention to Spinosad-induced immunotoxicity.

Toxic and repellent potentials of spinosad against Cryptolestes pusillus (Schon.) (Coleoptera: Cucujidae)

The contact and gustatory effects of spinosad on the mortality and repellency of Cryptolestes pusillus (Schon.) were conducted under laboratory conditions. Spinosad at 0.32 l/g caused lowest mortality (16.67±1.67% of 2nd instar larva of C. pusillus in wheat after 24h and highest mortality (59.14±1.65%) was observed at 1.25 l/g in wheat after 72 h exposure. The LC50 value was 0.11 l/g in wheat after 72 h, which indicated that spinosad is highly toxic against the 2nd instar larvae of C. pusillus. In case of 4th instar larvae highest mortality (58.12±3.45%) were observed at 1.25 l/g concentration but lowest 10.00± 2.10 after 24 h exposure. The highest mortality was observed (40.00±2.88%) in adults. The different doses (1.25, 0.63, 0.32, 016 and 0.08 l/ml) of spinosad showed repellent activities against adults of C. pusillus. All the doses of spinosad offered 0.1% level of significance (P<0.01). Spinosad used in this experiment have great potential in the control of C. pusillus which is important from the Integrated Pest Management and the Global Environmental Protection point of views.

Spinosad combined with entomopathogenic nematode for biocontrol of the Mediterranean fruit fly (Ceratitis capitata [Wiedemann]) on citrus

BackgroundCultivation of citrus (Sapindales: Rutaceae) crops is continuously expanding in Egypt given the favorable ingredients of citriculture. Notwithstanding the Egyptian rank as the world's largest orange exporter, the Mediterranean fruit fly (Medfly), Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), is one of the major pests that considerably reduces the quality of citrus crops. Contrary to hazardous organophosphate insecticides that are commonly used to control the Medfly, biologically-based C. capitata control tactics were tried herein. The effect of spinosad as a bacterial fermentation product and the nematode Steinernema riobrave as biological insecticides applied singly or in combination on laboratory and field strains of Medfly were investigated.ResultsA significant difference in LC50 values was observed between laboratory strain (4.78 PPM) and field strain (8.12 PPM) of C. capitata larvae exposed to spinosad. A 1.7 fold decrease in susceptibility of field strain was recorded after treatment with spinosad. In a field experiment, a reduction in Medfly population by 80, 37, and 92% for spinosad, S. riobrave, and spinosad + nematode treatments was recorded, respectively.ConclusionsUtilization of spinosad-S. riobrave combination in citrus fields, as a novel alternative for unhealthy chemical insecticides to control C. capitata in Egypt can be suggested. Use of this combination should be incorporated into a holistic management package that can be economically feasible and environmentally sustainable for Egyptian agriculture.

New insights on the effects of spinosad on the development of Helicoverpa armigera

Helicoverpa armigera (cotton bollworm) is one of the most destructive pests worldwide. Due to resistance to Bacillus thuringiensis and conventional insecticides, an effective management strategy to control this pest is urgently needed. Spinosad, a natural pesticide, is considered an alternative; however, the mechanism underlying the developmental effects of sublethal spinosad exposure remains elusive. In this study, the mechanism was examined using an insect model of H. armigera. Results confirmed that exposure to sublethal spinosad led to reduced larval wet weight, delayed larval developmental period, caused difficulty in molting, and deformed pupae. Further investigation demonstrated that exposure to sublethal spinosad caused a significant decrease in 20E titer and increase in JH titer, thereby leading to the discordance between 20E and JH titers, and consequently alteration in the expression levels of HR3 and Kr-h1. These results suggested that sublethal spinosad caused hormonal disorders in larvae, which directly affect insect development. Our study serves as a reference and basis for the toxicity evaluation of spinosad on molting and pupation in insect metamorphosis, which may contribute to identifying targets for effective control of cotton bollworm.

Sublethal concentrations of spinosad synergize the pathogenicity of fungi to larvae of Ephestia kuehniella (Lepidoptera: Pyralidae)

We evaluated the efficacy of four entomopathogenic fungi (EPF) and their compatibility with the bioinsecticide spinosad for control of Ephestia kuehniella (Zeller) under laboratory conditions. Three EPF, including Beauveria bassiana (Balsamo-Criveili) Vuillemin isolates Z1 and Iran 1395C, Lecanicillium (= Verticillium) lecanii (Zimmerman) Zare & Gams, isolate Iran 229, and Purpureocillium (Paecilomyces) lilacinum (Thom) Luangs-ard, Hywel-Jones & Samson, isolate Iran 1026 were tested against third and fifth larval instars of Ephestia kuehniella using a filter paper bioassay. Mortality caused by the EPF ranged from 63.3-72.5% for third instars and 50-65.5% for fifth instars, with LT50 ranging from 8.4-10.5 d and 10.1-12.9 d, respectively. The effect of spinosad at LC10 (= 26.2 ppm) on EPF spore germination was evaluated and found to be negligible, ranging from 0% for B. bassiana Z1 to 5.7% for P. lilacinum. The LC50 values for spinosad against third and fifth instar E. kuehniella larvae were 452.5 and 1446 ppm, respectively. Subsequently, spinosad at LC10 was applied to third instar E. kuehniella larvae 24 h before application of the EPFs at LC50. The addition of spinosad to applications of L. lecanii and B. bassiana Z1 and Iran1395C isolates synergized their pathogenicity to E. kuehniella larvae, whereas the effect was merely additive for P. lilacinum. Our results suggest that these EPF isolates can be used effectively in combination with spinosad for management of E. kuehniella in stored products.

Toxicological and histological studies on the effect of spinosad or vinegar on Culex pipiens larvae (Diptera: Culicidae)

Efficacy of Spintor® 24% SC (spinosad) and vinegar were studied to control Culex pipiens larvae by testing different concentrations of spinosad (10, 50, 100, 500 and 1000 µl/10 ml) or vinegar (125, 250, 500 and 750 µl/10 ml). The percentage mortality of larvae was increased by increasing concentrations and time. While 100 % mortality was obtained at the concentration 1000 µl/10 ml of spinosad after 48 h, in the case of vinegar treatment 100 % mortality was obtained at the concentration of 750 µl/10 ml after 72 h. Both spinosad and vinegar exhibited a histological effect on the midgut by degeneration of the epithelial cells, the disintegration of the plasma and basement membranes and extensive disruption of the cellular microvillar. Generally, spinosad manifested a higher level of activity against Cu. pipiens larvae than vinegar.

Influence of spinosad on the reproductive potential of Tribolium castaneum (Herbst), (Coleoptera: Tenebrionidae) infesting wheat

Spinodad of different concentrations were screened against Tribolium castaneum (Herbst) reared on four local wheat varieties to observed the effects on reproductive potentials for two successive generations.The lowest number of eggs laid was 119 (23.80±0.97) observed in Shatabdi- 21 (S-21) in 45 d in F1 and 15 (3.00±0.71) in 15 d in F2 generation when treated at 0.12ìl/g of spinosad. Spinosad at all concentration totally inhibited egg laying oroviposition rate on day 45 in all wheat varieties except P-24 variety in F1 generation.The lowest fertility was found in Shatabdi-21 variety as 12.61percent in F1 and 6.67 percent in F2 generation at 0.12ìl/g.The latent effect of spinosad on number of eggs, larva, pupa and adult obtained in Shatabdi-21 as 2.00±0.32,0.80±0.37, 0.40±0.40 and 0.20±0.20 at 0.12ìl/g of spinosad in F2 generation.There was no significant difference between the number of males and females in F2 generation wheat varieties. Spinosad ultimately reduced the fecundity, fertility and decreased the egg to adult survivability in four wheat varieties compared to control and F1 and F2 generations. Results of the research revealed that comparatively higher concentrations of spinosad that used in this study would potentially control development and reproductive potentiality of T. castaneum in wheat varieties.

Response of different population sizes to traps and effect of spinosad on the trap catch and progeny adult emergence in Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae)

Tribolium castaneum is a major pest in stored products throughout the world. Male T. castaneum adults produce aggregation pheromone 4,8-dimethyldecanal (4,8 DMD) which is synthetically developed and available for monitoring T. castaneum populations but low trapping by 4,8 DMD is reported. Effects of biorational insecticides on orienting to pheromone and progeny production is shown but such tests using spinosad has areas for further discovery. Therefore the objective of this research was to determine the effect of population size and spinosad exposure on the trap catch and progeny production in T. castaneum adults. In the first experiment, T. castaneum adults were released at different population sizes and the attraction to the pheromone traps was determined. The second experiment tested attraction of T. castaneum adults pre-exposed to spinosad to the pheromone traps. In the third experiment, progeny production of T. castaneum adults exposed to spinosad was assessed. The trapping of T. castaneum is increased at high population sizes and pre-exposure to spinosad while progeny was reduced on exposure to spinosad showing sex-based effects. This study concludes with management opportunities for different population levels of T. castaneum through effects of spinosad on pheromone perception and progeny production.

The effects of spinosad on antioxidant system and cognitive performance of mice

Introduction There are few studies examining the effect of spinosad on cognitive functions in the literature. Methods In this study, we applied spinosad 3 weeks in different doses to mice and examined their effects on antioxidant system and cognitive performance. Results In the open field test, we observed a significant decrease (p < .05) in the total distance travelled and the time spent in the central area in all subjects who underwent spinosad. In the novel object recognition test, we observed decreases in the time spent with new and old objects. From the biochemical point of view, while BDNF and NGF levels were significantly lower in the spinosad applied group (p < .05), there was no difference in GPx and SOD levels (p > .05). Conclusions These results show that spinosad disrupts cognitive functions at the doses we used in our study and this negative effect may be related to the decrease in neurotrophic factors.

Larvicidal activity of spinosad and its impact on oviposition preferences of the West Nile vector Culex pipiens biotype molestus – A comparison with a chitin synthesis inhibitor

In the present study, the larvicidal activity of ageing aqueous suspensions of spinosad against larvae of Culex pipiens biotype molestus, as well as their effect on the oviposition preferences of adult gravid females were evaluated in laboratory bioassays. Spinosad was applied at its label dose and the aqueous stock suspensions were stored for various ageing intervals up to 38 days. Untreated distilled water and diflubenzuron served as negative and positive control, respectively. Stock suspensions were taken after 0, 2, 6, 8, 16, 30 and 38 days of storage for diflubenzuron and after 0, 2, 6, 8, 20 and 27 days for spinosad, and were used for the bioassays. Furthermore, the effect of spinosad on the oviposition response of Cx. p. biotype molestus gravid females was investigated in two-choice oviposition preference bioassays. Spinosad was evaluated at half of its label dose and at its label dose, whereas diflubenzuron and distilled water served as positive and negative control, respectively. Results showed that both insecticides were found highly effective for the control of Cx. p. biotype molestus larvae, for ageing intervals up to 27 and 38 days for spinosad and diflubenzuron, respectively. Spinosad acted immediately after the preparation of the insecticidal solution (LT50 = 1.5 h), whereas for aged samples, LT50 values increased with the increase of the ageing interval (LT50 = 5 days for the 27 days old sample). For diflubenzuron, ageing time increased its insecticidal activity, as for aged diflubenzuron-treated solutions, lower LT50 values were achieved. In the oviposition preference bioassays, significantly fewer egg rafts were laid in water treated with spinosad at its label dose compared to control. However, this was not the case for water treated with spinosad at half of its label dose. Oviposition Activity Index (OAI) values were always comprised between −0.3 and 0.3, showing no relevant oviposition deterrence or attraction. The results of the present study contribute to our understanding of the effect of ageing on insecticidal solutions widely used in urban areas to control Cx. p. biotype molestus. Although an important vector of high public health importance, Cx. p. biotype molestus has been scarcely studied as target of environmentally and toxicologically reduced risk insecticides, such as spinosad.

Spinosad-mediated effects on survival, overall group activity and the midgut of workers of Partamona helleri (Hymenoptera: Apidae)

Populations of stingless bees have declined around the world and pesticides have been indicated as one of the possible causes of this decrease. Spinosad, which is synthesized from the fermentation process produced by the soil actinomycete Saccharopolyspora spinosa, is one of the most used bioinsecticides today. This study aimed to evaluate the possible effects of spinosad (formulation) on survival, general group activity and the processes of autophagy, apoptosis and oxidative stress in two organs (midgut and brain) of workers of Partamona helleri, after 24 h of oral exposure. Workers were orally exposed to different concentrations of spinosad. The concentration (8.16 × 10−3 mg a.i./mL) that led to the mortality of approximately half the number of treated bees was considered LC50 and was used in behavior, histology and immunofluorescence bioassays. The results revealed that bee survival was substantially reduced with increasing spinosad concentrations. The LC50 of the bioinsecticide compromised general group activity, caused morphological alterations in the midgut and intensified the processes of autophagy, apoptosis and oxidative stress in this organ. The brain, on the other hand, did not present significant alterations under the tested conditions. The data obtained demonstrate, therefore, that spinosad negatively affects individual survival, general group activity and the midgut epithelium of P. helleri.

Spinosad-induced stress on the maize weevil Sitophilus zeamais:

Although seldom considered, sublethal insecticide exposure may lead to harmful, neutral, or even beneficial responses that may affect (or not) the behavior and fitness of the exposed insects. Intriguingly, little is known about such effects on stored product insect pests and even less is available regarding the bioinsecticide, spinosad. Thus, we assessed the sublethal effects of spinosad on walking, feeding, drinking and mating behaviors of maize weevils (Sitophilus zeamais), also assessing their survival, reproductive output, and grain loss compared with maize weevils exposed to the pyrethroid deltamethrin (as positive control), and water only (negative control). Both spinosad and deltamethrin were able to effectively control the insects, although the latter caused a faster mortality than the former. Behavioral pattern changes were caused by both insecticides, especially deltamethrin, triggering irritability (i.e., avoidance after contact). Different feeding and drinking responses were also detected with significant avoidance to deltamethrin, but not to spinosad. Maize weevil couples sublethally exposed to deltamethrin and spinosad exhibited altered reproductive behavior, a likely consequence of their altered activity, but deltamethrin caused greater behavioral changes. Curiously, higher progeny emergence and grain loss were observed in deltamethrin-exposed insects, suggesting that this pyrethroid insecticide elicits hormesis in maize weevils that may compromise control efficacy by this compound. In contrast, such effect was not detected with spinosad, which did not elicit avoidance allowing the intended weevil exposure and control.

Spinosad- and Deltamethrin-Induced Impact on Mating and Reproductive Output of the Maize Weevil Sitophilus zeamais.

Assessments of acute insecticide toxicity frequently focus on the lethal effects on individual arthropod pest species and populations neglecting the impacts and consequences of sublethal exposure. However, the sublethal effects of insecticides may lead to harmful, neutral, or even beneficial responses that may affect (or not) the behavior and sexual fitness of the exposed insects. Intriguingly, little is known about such effects on stored product insect pests in general and the maize weevil in particular. Thus, we assessed the sublethal effects of spinosad and deltamethrin on female mate-searching, mating behavior, progeny emergence, and grain consumption by maize weevils. Insecticide exposure did not affect the resting time, number of stops, and duration of mate-searching by female weevils, but their walking velocity was compromised. Maize weevil couples sublethally exposed to deltamethrin and spinosad exhibited altered reproductive behavior (walking, interacting, mounting, and copulating), but deltamethrin caused greater impairment. Curiously, higher grain consumption and increased progeny emergence were observed in deltamethrin-exposed insects, suggesting that this pyrethroid insecticide elicits hormesis in maize weevils that may compromise control efficacy by this compound. Although spinosad has less of an impact on weevil reproductive behavior than deltamethrin, this bioinsecticide also benefited weevil progeny emergence, but did not affect grain consumption. Therefore, our findings suggest caution using either compound, and particularly deltamethrin, for controlling the maize weevil, as they may actually favor this species population growth when in sublethal exposure requiring further assessments. The same concern may be valid for other insecticides as well, what deserves future attention.

Acaricidal activity and sublethal effects of the microbial pesticide spinosad on Tetranychus urticae (Acari: Tetranychidae)

Laboratory bioassays were conducted to evaluate the toxicity of the microbial pesticide spinosad to different life stages of the two-spotted spider mite, Tetranychus urticae Koch, as well as its sublethal effects on reproduction and population growth of this important mite pest. The biopesticide was applied to bean primary leaves or leaf discs carrying spider mites using a Potter spray tower (2.7 mg/cm2 aqueous deposit). The following LC50 and LC90 (mg/L) estimates for motile stages were obtained in acute toxicity bioassays: 27.52 and 116.72 (larvae), 36.55 and 136.20 (protonymphs), 82.76 and 721.28 (female deutonymphs), and 61.47 and 457.21 (adult females). Spinosad showed no significant ovicidal action: toxic effect observed after spraying eggs (LC50 = 105.78 mg/L, LC90 = 596.95 mg/L) was the result of its residual action on larvae that hatched from the treated eggs. The effects of spinosad on life history traits and population growth of adult female survivors from treatments with 240, 120 and 60 mg/L were evaluated in two successive 7-day bioassays on untreated leaf discs. In the first bioassay, females that survived treatments as 24 h old eggs and completed their juvenile development on treated leaves had significantly lower gross fecundity, net fecundity and instantaneous rate of increase (ri) but the reduction was merely 4–6%, 9–11%, and 2–3%, respectively. Female longevity was significantly reduced (approximately by half a day) only after treatment with 240 mg/L. In the second bioassay, in which females were treated during their pre-ovipositional period, the treatments with 240 and 120 mg/L significantly reduced their gross fecundity (16–17%), net fecundity (28–31%), ri values (8–9%) and female longevity (approximately by one day). Spinosad effects on the intrinsic rate of increase (rm) and other demographic parameters were evaluated in two successive bioassays in which life tables were constructed for females that survived treatment with 120 mg/L at the egg stage (first demographic bioassay) or pre-ovipositional period (second demographic bioassay). In the first bioassay, the intrinsic rate of increase was significantly higher in treated (rm = 0.278) than control mites (rm = 0.267) as a result of higher net fertility at the beginning of reproduction of treated females. In the second bioassay, treated females had significantly lower rm than control females (0.254 and 0.283, respectively). The results obtained in this study indicate that spinosad, applied against insect pests (at field relevant rates of 60–240 mg/L), could eliminate a part of T. urticae population as well, but survivors would retain a significant potential for population recovery.

Oxidative stress and DNA damage induced by spinosad exposure in Spodoptera frugiperda Sf9 cells

ABSTRACT Spinosad, a neurotoxic insecticide, is widely used for crop protection. In order to elucidate the effects of spinosad on oxidative stress and genotoxicity in Sf9 cells, the levels of lipid peroxidation, the activity of antioxidative enzymes, and DNA damage were measured. The results showed that spinosad caused a time-dependent increase in the formation of malondialdehyde and decrease in the activity of superoxide dismutase and catalase. Further studies confirmed that spinosad induced 8-oxoguanine accumulation in Sf9 cells, which is accompanied by increased expression of DNA repair enzymes (OGG1 and MTH1). The neutral comet assay revealed that spinosad induced significant time-related increases of DNA double-strand breaks in Sf9 cells. Our results indicate that spinosad effectively induced oxidative stress and DNA damage in Sf9 cells.

Spinosad and spinetoram disrupt the structure and the abundance of ground-dwelling arthropod communities in herbaceous fields

ABSTRACTIn the present study, the effects of spinosad, spinetoram and chlorpyrifos on ground-dwelling arthropod diversity and abundance were compared in a herbaceous field in order to evaluate their relative compatibility with conservation of arthropod densities. Ten different treatments of spinosad, spinetoram, and chlorpyrifos, which was used as a toxic reference, were allocated at random to experimental plots. A total of 101,119 individuals of epigeal arthropods belonging to 18 orders and suborders were captured in pitfall traps, with the most abundant taxa Hymenoptera, Collembola, Araneae, Acari, Coleoptera, Isopoda, Julida and Opiliones. The orders Araneae, Coleoptera, Collembola, Hymenoptera and Opiliones were identified to the family or species level. Gnaphosidae, Carabidae, Entomobryidae, Formicidae and Metaplatybunus grandissimus CL Koch (Phalangiidae) were the most abundant taxa of Araneae, Coleoptera, Collembola, Hymenoptera and Opiliones, respectively. Significant density reduction was observed for Gnaphosidae, Linyphiidae (Araneae), Carabidae, Entomobryidae, Formicidae and M. grandissimus after chlorpyrifos treatment. Formicidae individuals were significantly reduced after spinosad application, while the Entomobryidae and M. grandissimus individuals were reduced after the application of both spinosad and spinetoram. Our results showed no significant differences in diversity level of orders and suborders as well as of Araneae families between the spinetoram-treated plots at both concentrations tested and the control. In contrast, a significant difference in the diversity of Coleoptera was detected between the spinetoram treatments and the control. Our findings showed that spinosad and spinetoram may disrupt the structure and the abundance of surface-active arthropod fauna causing considerable changes in the ground-dwelling biodiversity of this ecosystem.

Lethal and sub‐lethal effects of spinosad on the life‐history traits of army worm, Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae), and its fitness cost of resistance

AbstractSpodoptera litura is one of the most destructive polyphagous insect pests, with more than 120 host‐plant species. In our present study, a field‐collected population of S. litura when selected with spinosad for 11 consecutive generations resulted in the development of 3921‐fold resistance to spinosad as compared to the susceptible strain. The spinosad‐resistant strain of S. litura had a relatively high fitness cost (0.17) as compared to the susceptible strain. Furthermore, the lethal and sub‐lethal effects of different concentrations of spinosad were checked on the susceptible strain at different levels; i.e., LC40, LC30, LC20 and LC10, which revealed that the impact of spinosad on the life‐history traits of S. litura increased with the increase in concentration of spinosad. A significant impact of spinosad was recorded on the larval duration, pre‐pupal weight, pupal duration, pupal weight, reproductive potential and adult emergence. The outcomes of the current research clearly indicate that fitness cost of spinosad and its sub‐lethal effects have a significant impact on population dynamics of S. litura, for which it can be incorporated in integrated pest management.

EVALUATION OF PROTEIN BAIT LACED WITH VARIOUS INSECTICIDES ON THE QUEENSLAND FRUIT FLY (DIPTERA: TEPHRITIDAE): ATTRACTION, FEEDING, MORTALITY AND BAIT PERSISTENCE

The use of malathion in fruit fly protein bait sprays has raised serious concerns due to its adverse effects on non-target organisms. This has necessitated the evaluation of novel reduced-risk compounds. This study evaluated the effects of spinosad, fipronil, malathion and chlorpyrifos mixed with fruit fly protein bait (Mauri Pinnacle protein®) on attraction, feeding and mortality of the Queensland fruit fly, Bactrocera tryoni (Froggatt). The effects of outdoor weathering of these mixtures on fly mortality were also determined. In field-cage experiment, protein-starved flies showed the same level of attraction to baits containing spinosad, fipronil, malathion, chlorpyrifos and protein alone used as control. Female protein-starved flies were deterred from feeding on baits containing malathion and chlorpyrifos compared to baits containing spinosad, fipronil and protein alone. Baits containing malathion and chlorpyrifos caused higher fly mortality and rapid fly knock down than spinosad and fipronil. However, spinosad acted slowly and caused an increase in fly mortality over time, causing up to 90% fly mortality after 72-h. Baits containing malathion and chlorpyrifos, applied on citrus leaves and weathered outdoors, had longer residual effectiveness in killing flies than spinosad and fipronil. Residual effectiveness of the spinosad bait mixture waned significantly after 3 days of outdoor weathering. Results suggest that spinosad and fipronil can be potential alternatives for malathion in protein bait sprays.

Effects of Spinosad as a Bioinsecticide on the Corn Stem Borer, Sesamia cretica Led. (Lepidoptera: Noctuidae)

The corn stem borer, Sesamia cretica Led. (Lepidoptera: Noctuidae) is one of the most economically important pests of maize crop in Egypt. The pest is generally controlled by repetitive application of chemicals, resulting in environmental pollution and resistance in pest population. In this study, efficacy of spinosad against different larval instars of S. cretica was evaluated under laboratory and field conditions. The impact of spinosad on larval protein content and glycogen level were also assessed. Data indicated that spinosad had exerted some toxic effect against the tested larval instars and the mortality was in the order of first instar > second instar > third instar > fourth instar > fifth instar, with respect to the LC50 values estimated as 0.008, 0.016, 0.028, 0.044 and 0.159 ml/l for the prementioned instars respectively, 7 days after treatment. The field experiment showed high efficiency of spinosad against S. cretica at the highest three concentrations down to 25% field rate (FR); inducing significant reduction in the number of plants containing either perforated stems or dead hearted cases, number of larvae, tunnels and excavated areas inside infested plants. Regarding the biochemical parameters, results proved that the protein content and glycogen level in the treated larvae were significantly lower those that of the control at all concentrations. The highest reduction in protein content, -54.5% was recorded in 2nd instar larvae exposed to 50% FR (0.25ml/l). Similarly, the highest reduction in glycogen level, -55.8%, was recorded in 2nd instar larvae exposed to 50% FR (0.25 ml/l), meanwhile, it was also noted that impact was concentration dependent.

Sublethal effects of spinosad on some biochemical parameters of Xanthogaleruca luteola (Müller) (Coleoptera: Chrysomelidae)

The effect of spinosad on some biochemical characteristics of Xanthogaleruca luteola was investigated. LC&lt;sub&gt;30&lt;/sub&gt; and LC&lt;sub&gt;50 &lt;/sub&gt;of spinosad for the third instar larvae were determined as 1.6 and 2.9 ppm, respectively. Biochemical tests were carried out on the 3&lt;sup&gt;rd&lt;/sup&gt; instar larvae treated with LC&lt;sub&gt;30&lt;/sub&gt; and LC&lt;sub&gt;50&lt;/sub&gt; of spinosad. The LC&lt;sub&gt;30&lt;/sub&gt; concentration decreased carbohydrate and glycogen content and increased lipid content significantly. There was a significant decrease in carbohydrate, glycogen, and protein contents following the exposure to LC&lt;sub&gt;50&lt;/sub&gt; concentration. Available energy of the larvae exposed to LC&lt;sub&gt;30&lt;/sub&gt; of spinosad increased significantly, whereas it decreased significantly at LC&lt;sub&gt;50&lt;/sub&gt;. However, the energy consumed was increased at both concentrations significantly. Cellular energy allocation of larvae treated with LC&lt;sub&gt;50&lt;/sub&gt; concentrations of spinosad decreased significantly. Glutathione-S-transferase and esterase activities were increased significantly at LC&lt;sub&gt;50&lt;/sub&gt;. However, lipase activity was decreased at both concentrations. &amp;nbsp;