Litura Eggs Research Articles

The phyto-compounds Fumaric acid, di(1-adamantylmethyl) ester and 2-Pentamethyldisilanyloxypentane Borne from Physalis longifolia Against Various Medical and Agronomic Pests

Objectives: To identify the major phytocompounds of Physalis longifolia leaf methanol extract and assess the ovicidal and larvicidal toxicity of target medical and agronomic pests of Aedes aegypti, Culex quinquefasciatus, Spodoptera litura and Helicoverpa armigera eggs and larvae. Methods: In this study, the phyto-compounds identification was made by GC-MS analysis. The selected phyto-compounds were applied towards eggs were tested various concentrations 4-16mg/ml and larvae were tested various concentrations 2- 200mg/ml of medical and agronomic pests. Overall mortality was examined using probit analysis to calculate LC50/LC90. Findings: The most common an Indian medicinal flora, Physalis longifolia leaf methanol extract and its derived major phyto-bioactive constituents Fumaric acid, di(1-adamantylmethyl) ester and 2-Pentamethyldisilanyloxypentane were authentically isolated by GCMS analysis. By phyto-chemical screening, more numbers of bio-active phytochemicals were occupied in high polar leaf extract. P. longifolia leaf methanol extract and its derived major phyto-bioactive constituents Fumaric acid, di(1-adamantylmethyl) ester and 2-Pentamethyldisilanyloxypentane were showed topper eggs toxicity above 90% which reached nearly 100% and the larval toxicity of LC50/ LC90 values were 11.01/18.73, 10.56/ 17.90, 14.19/ 26.59, 14.88/ 27.80 mg/ml and 10.91/ 18.75, 10.70/ 18.26, 15.77/ 29.29 and 14.86/26.55 mg/ml against the medical and agronomic pests of Ae. aegypti, Cx. quinquefasciatus, S. litura and H. armigera, respectively. Novelty: The biotoxicity of selected P. longifolia leaf methanol extract and its derived major phyto-bioactive constituents were well effective, environmental friendlier and produced least toxicity on non-target organisms. The medicinal flora, P. longifolia originated phyto-products could be a valuable farmer and ecofriendly bio-toxic weapon on medical and agronomic pests which promotelesser susceptible on non-target organisms. Keywords: Phytoproducts; Ecotoxicity; Physalis longifolia; Medical pest; Agronomic pest

Quality assessment of Telenomus remus successively reared on Spodoptera litura eggs for 30 generations.

Telenomus remus (Nixon) is a dominant natural enemy controlling the invasive pest Spodoptera frugiperda (J. E. Smith). Continuous rearing of egg parasitoids on alternative hosts is crucial for mass production and cost reduction. However, to ensure the effectiveness of natural enemy products against target pests in the field, it is necessary to evaluate the parasitoid quality during the mass-rearing process. Despite the successful rearing of this parasitoid on the alternative host Spodoptera litura (Fabricius) eggs, less attention has been paid to the quality of parasitoids continuously reared for multiple generations. Therefore, we evaluated the performance of T. remus reared on S. litura eggs for 30 generations via morphological characteristics, flight ability, and life table analysis. Wing length, wing width, body length, and right hind tibia length of T. remus did not differ among the different generations. However, the body length of female parasitoids was significantly longer than that of males for any generation. Although the proportion of 'flyers' and 'deformed' T. remus varied among generations, the flight ability did not decline significantly after rearing on S. litura eggs. Moreover, T. remus continuously reared on S. litura eggs maintained stable parasitism performance and life table parameters on the target host S. frugiperda eggs. S. litura eggs are suitable hosts for the mass-rearing of T. remus. This study can be subsequently used to guide the production and facilitate the application of T. remus in the control of S. frugiperda. © 2023 Society of Chemical Industry.

Effects of Nutritional Composition of Different Prey Eggs on Development and Reproduction of the Predatory Bug, Orius sauteri (Hemiptera: Anthocoridae).

Orius sauteri (Poppius) is an important predator of many economically important insect pests. The mass rearing of O. sauteri is difficult, limiting its application in pest control. Here we assessed the nutritional quality of eggs of Sitotroga cerealella (Olivier), Agrotis ypsilon (Rottemberg), or Spodoptera litura (Fabricius), and their potential for rearing O. sauteri in the laboratory for two generations. Of species tested, S. cerealella eggs resulted in the highest survival and reproduction of O. sauteri compared to the other two lepidopteran species. Eggs of A. ypsilon were a suitable diet for the nymphal stage, which developed faster on A. ysilon eggs than those of S. cerealella eggs. Conversely, eggs of S. litura were not a suitable diet for O. sauteri, and they disrupted the development and reproduction of O. sauteri. Sitotroga cerealella eggs showed advantages in all the nutritional components evaluated. Orius sauteri fed S. litura eggs contained significantly lower protein levels than those fed on the other eggs tested. Spodoptera litura eggs significantly enhanced the CAT activity in O. sauteri, which suggests that some components from S. litura eggs harmed the development and reproduction of O. sauteri. Based on these results, we suggest using a combined diet for mass rearing of the pirate bug, feeding the nymphs and adults with A. ypsilon eggs and S. cerealella eggs, respectively. This study contributes to the discovery of artificial diets for mass rearing O. sauteri and other Orius species in the future.

Effect of temperature on the life cycle of Harmonia axyridis (Pallas), and its predation rate on the Spodoptera litura (Fabricius) eggs

Biological control is one of the strategies of pest control which is determined by the biological fitness and metabolic rates of the predator species used. Temperature and resource are important factors which influence the role of insects as biocontrol agents. Harmonia axyridis is a cosmopolitan and non-specific polyphagous predator. It can survive ecologically diverse environments and exploit multiple preys. This study investigated the effects of temperature on the population parameters of H. axyridis and its predation on the eggs of prey Spodoptera litura. For this purpose, an age–stage, two-sex life table of the predator was constructed at four constant temperatures, i.e. 15, 20, 25 and 30 °C, under laboratory settings of: 70 ± 5% RH, and 16:8 h (L: D) photoperiod. A computer simulation was then used to project the population and predation responses with respect to temperatures tested. We found that the development of larvae and adult (male/female) stages of H. axyridis decreased with colder temperatures (i.e., 15 and 20 °C) but increased with warmer temperatures (25 and 30 °C). The intrinsic rate of increase (r) and mean generation time (T) were 0.0662 d−1 and 79.84 d at 15 °C, 0.0843 d−1 and 64.90 d at 20 °C, 0.1067 d−1 and 48.89 d at 25 °C, and 0.1378 d−1 and 35.55 d at 30 °C, respectively. The mean duration of the total pre-adult stage was 44.26, 32.91, 20.63, and 15.39 d at 15, 20, 25, and 30 °C, respectively. At 30 °C. the finite rate of increase (1.1477 d−1) was the highest and the mean generation time (35.55 d) was the shortest. The net predation rate (C0) was 7935.54, 10,466.28, 10,139.38, and 7126.36 eggs at 15, 20, 25, and 30 °C, respectively. Population and predation projections were proportional to temperature. These findings are important for modelling the population responses of H. axyridis to climate change and tailoring integrated pest management strategies to altered climates.

Spodoptera litura (Lepidoptera: Noctuidae) rearing on artificial feed with Chrysoperla carnea predation (Neuroptera: Chrysopidae)

S. litura was reared on artificial meals in a controlled laboratory setting at 26.1°C, 16:8 h L:D, and 65.5% RH at the National Agricultural Research Center (NARC) in Islamabad, Pakistan, to evaluate its premature, mature adult stage characteristics and predation by C. cornea. On the artificial diet, the results for various parameters, including total larval duration (19.1 days, 45 percent), pre-pupal period (3.4 days, 92 percent), pupal period (7.05 days, 83 percent), and total immature duration from eggs to adult stage (33.4 days, 33 percent), as well as percent survival rate, were recorded. On a corn-based artificial diet, data on the pre-oviposition period (2.4 days), oviposition period (5.4 days), post-oviposition period (1.63 days), female fecundity (1366 eggs), and adult longevity (8.66 days) of mature stages of S. litura were collected. When supplied as prey, the predator's biological parameters and predatory capacity, C. carnea, were tested on two stages of S. litura (eggs and 1st instar larvae). The studies indicated that the prey significantly affected the total larval duration, immature duration, and % survival rate. The entire larval period was greatly minimized when C. carnea was offered eggs of S. litura for feeding. Additionally, higher % survival and fecundity were observed feeding with S. litura eggs, followed by 1st instar larvae. C. carnea consumed 443 S. litura eggs and 395 S. litura larvae during its larval development. Daily consumption of C. carnea larvae reached a maximum of 73 eggs and 53 1st instar larvae of S. litura. Comparatively, C. carnea larvae recorded maximum egg predation compared to 1st instar larvae of S. litura and the shorter developmental period when eggs were offered as prey. Moreover, 3rd instar larvae of C. carnea were found more voracious than early instars.

Cold storage of Spodoptera litura eggs and Telenomus remus adults for improving mass‐rearing efficiency

AbstractTelenomus remus (Nixon) has shown promising potential as a biological control agent for the major invasive agricultural pest, Spodoptera frugiperda (J. E. Smith). Application of biological control programmes in the field requires an efficient mass‐rearing system to provide sufficient numbers of beneficial insects. The short longevity of parasitoid adults and limited period of availability of host eggs are two factors affecting the mass‐rearing efficiency of T. remus. Using Spodoptera litura (Fabricius) eggs as an alternative host, the effects of cold storage of S. litura eggs and T. remus adults at 5°C, 8°C and 11°C for different time durations on the fitness of the parasitoid were investigated to identify the most suitable storage conditions. Results showed that T. remus can successfully exploit stored S. litura eggs, but the number of parasitized eggs decreased with increased egg storage duration and/or reduced storage temperature. For refrigerated adults, the survival rate declined gradually with longer storage duration, and the females' survival rate was higher than the males' at any treatment. Similarly, parasitism capacity of stored adults declined significantly with prolonged storage. Female adult longevity was significantly shorter than the control for all treatments. However, the offspring emergence rate and percentage of females were barely affected by cold storage. In conclusion, S. litura eggs can be stored at 11°C for up to 9 days and adult T. remus can be stored at 8°C or 11°C for up to 7 days without significant losses. Data obtained from this study will help coordinate different aspects of T. remus production, decreasing costs and improving the biocontrol materials' availability.

Optimizing Photoperiod, Exposure Time, and Host-to-Parasitoid Ratio for Mass-Rearing of Telenomus remus, an Egg Parasitoid of Spodoptera frugiperda, on Spodoptera litura Eggs.

Telenomus remus (Nixon) is a dominant egg parasitoid of the destructive agricultural pest Spodoptera frugiperda (J. E. Smith), and so is used in augmentative biocontrol programs in several countries. An optimized mass-rearing system is essential to produce biological control products in a timely and cost-effective manner. In this study, the photoperiod, host egg:parasitoid ratio, and exposure time were evaluated to identify the optimal rearing conditions for T. remus on the alternative host Spodoptera litura (Fabricius) eggs. Results showed that increasing photoperiod above 12L:12D remarkably improved parasitoid progeny yield and life table parameters. Overlong photoperiods shortened female longevity, but within acceptable limits. There was a significant negative correlation between parasitism rate and host egg:parasitoid ratio under exposure times of 12 and 36 h, but not 24 h. Percentage of female progeny increased significantly along with increasing the host egg:parasitoid ratio. A significant negative relationship between the number of emerged adults per egg and the host egg:parasitoid ratio was observed at an exposure time of 36 h. It was concluded that T. remus may be mass-reared most efficiently on S. litura eggs using a photoperiod of more than 12L:12D, a 14-20:1 host egg:parasitoid ratio, and an exposure time of 24 h. These findings can be used to produce T. remus more efficiently and at lower costs.

The Biocontrol Agent Pyemotes zhonghuajia Has the Highest Lethal Weight Ratio Compared with Its Prey and the Most Dramatic Body Weight Change during Pregnancy.

Simple SummaryTo explore the biocontrol potential of Pyemotes zhonghuajia, we studied the paralytic process, time to lethality, efficiency, reproductive development, and the ability to search for Spodoptera litura larvae. We found that one newly emerging P. zhonghuajia female could kill a third instar larva greater than 680,000 times her own body weight. An individual P. zhonghuajia adult female was able to kill S. litura eggs and first to third instar larvae. Pyemotes zhonghuajia could develop on eggs, first to sixth instar larvae, and pupae, but only produced offspring on the eggs and pupae. The presence of 50 or 100 P. zhonghuajia resulted in significantly higher mortality rates of first, second, and third instar S. litura larvae in a 2 cm searching range compared with other searching ranges (4.5 and 7.5 cm). Therefore, P. zhonghuajia could potentially be used to control S. litura.Pyemotes spp. are small, toxic, ectoparasitic mites that suppress Coleoptera, Hemiptera, and Lepidoptera plant pests. To explore their potential use as a biocontrol agent, we studied the reproductive development, paralytic process, time to lethality and mortality, and searching ability of Pyemotes zhonghuajia on different developmental stages of the oriental leafworm moth, Spodoptera litura. Pyemotes zhonghuajia gained 14,826 times its body weight during pregnancy. One single P. zhonghuajia female could rapidly kill one S. litura egg and first to third instar larvae, but not fourth to sixth instar larvae, prepupae, or pupae within 720 min. Pyemotes zhonghuajia could develop on eggs, first to sixth larvae, and pupae, but only produced offspring on the eggs and pupae. A single P. zhonghuajia female (an average weight of 23.81 ng) could paralyze and kill one S. litura third instar larvae (an average weight of 16.29 mg)—680,000 times its own weight. Mites significantly affected the hatch rate of S. litura eggs, which reduced with increasing mite densities on S. litura eggs. Releasing 50 or 100 P. zhonghuajia in a 2 cm searching range resulted in significantly higher mortality rates of S. litura first instar larvae within 48 h compared to second and third instar larvae in searching ranges of 4.5 and 7.5 cm within 24 h. To the best of our knowledge, this is the first study to reveal that P. zhonghuajia undergoes the greatest changes in weight during pregnancy of any adult female animal and has the highest lethal weight ratio of any biocontrol agent.

Evaluating the Potential of Using Spodoptera litura Eggs for Mass-Rearing Telenomus remus, a Promising Egg Parasitoid of Spodoptera frugiperda.

Simple SummaryTelenomus remus (Nixon) is an effective egg parasitoid for controlling Spodoptera frugiperda (J. E. Smith), which is a major destructive agricultural pest. Currently, this parasitoid is reared on Corcyra cephalonica (Stainton) eggs in several countries. However, previous studies carried out in China have reported that it cannot parasitize in C. cephalonica eggs. Meanwhile, those works have indicated that Spodoptera litura (Fabricius) can potentially be used as an alternative host. In order to evaluate this potential, our study compared the development and parasitism ability of T. remus on the eggs of S. frugiperda and S. litura at different temperatures in a laboratory. We found that S. litura eggs are more advantageous as an alternative host for the mass-rearing of parasitoid when compared with S. frugiperda eggs. Our results provide a more specific basis and reference for the large-scale production and low temperature storage of T. remus.Although Telenomus remus, a promising parasitoid of Spodoptera frugiperda, had been successfully reared on the eggs of Corcyra cephalonica in some countries, reports from China have argued that it is infeasible. Notably, studies from China have indicated that Spodoptera litura eggs could be a candidate host. Therefore, to further evaluate the potential of using S. litura eggs as hosts, we compared the development and parasitism of T. remus on the eggs of S. frugiperda and S. litura at temperatures between 20–32 °C. Our results showed that T. remus developed successfully on both host eggs at all of the tested temperatures, and the developmental duration and thermal requirements at each stage were similar between the two host species. The number of parasitized eggs was greater for S. litura than for S. frugiperda. Meanwhile, the emergence rate exceeded 86.6%, and it was significantly higher for S. litura than that for S. frugiperda, except at 29 °C. This study is the first time estimating the thermal requirements of T. remus at each stage. Moreover, we also recorded the morphological characteristics of T. remus at each stage. Our results demonstrate that S. litura eggs are more suitable than S. frugiperda eggs as an alternative host for the mass-rearing of T. remus in China. Understanding the thermal requirements and biological parameters contributes greatly to predicting the generation time and providing a reference for the mass-rearing and storage of the parasitoid.

Temperature-Dependent Functional Response of Harmonia axyridis (Coleoptera: Coccinellidae) on the Eggs of Spodoptera litura (Lepidoptera: Noctuidae) in Laboratory.

Simple SummarySpodoptera litura (Fabricius) (Lepidoptera: Noctuidae) is a notorious and polyphagous pest of several economically important agricultural crops. It is worldwide in distribution and primarily managed through typical dependence on insecticides, which resulted in health and the environmental challenges and selected for resistance development in S. litura field populations. Resistance caused chemical control failures and S. litura outbreaks around the world. This necessitated development of eco-friendly alternative approaches such as biological control. With this view, current study investigated the functional response of Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) at various growth stages (i.e., 1st, 2nd, 3rd and 4th instars, and male and female stages) and temperatures (i.e., 15, 20, 25, 30 and 35 °C) against S. litura eggs to enable the recognition of efficient biocontrol stages that could be utilized to suppress S. litura populations. In our findings, egg consumption depended on the growth stage of the predator as well as temperature. All stages consumed S. litura eggs, but more promising stages with active egg consumption were the 4th instar and adults (male and female) typically at higher temperatures (25–35 °C). We conclude that these stages may be exploited to suppress S. litura populations in fields and greenhouses.Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae) is a major pest of several economically important crops with worldwide distribution. Use of insecticides is the principal strategy for its management, which has subsequently led to insecticide resistance and control failures. Functional response of Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) at larval and adult stages was evaluated in this study, using S. litura eggs as the prey at various temperatures varying between 15 and 35 °C. Based on logistic model findings, linear parameters of various predatory stages of H. axyridis at various temperatures were significantly negative, which indicate a type II functional response. The theoretical maximum number (T/Th) of eggs consumed increased with increasing temperature across all predatory stages. According to the random predator equation, the coefficients of attack rate increased and that of handling time decreased as the temperature increased. The 4th instar and adult stages were superior candidates for biocontrol of the target prey, typically at higher temperatures. The maximum attack rate (0.546 ± 0.058 h−1) and lowest handling time (0.189 ± 0.004 h) were exhibited by the females at 30 and 35 °C, respectively, whereas these parameters were inferior for early instars. These findings clearly depict that the 4th instar and adult predators are efficient egg consumers and can serve as potential suppressors of S. litura field populations. The limitations of the predictions formulated by functional response trials are also discussed.

Elucidation of molecular expression associated with abnormal development and sterility caused by electron beam irradiation in Spodoptera litura (F.) (Lepidoptera: Noctuidae)

Purpose: The objective of the present study was to elucidate the mode of indirect action of electron beam irradiation at the molecular level against a quarantine pest, Spodoptera litura (F.).Material and methods: Electron beam irradiation (50–200 Gy) was applied to S. litura eggs, larvae, pupae, and adults, after which the feeding area, body weight, deformity of pupae and adults, ovarian development, expression levels of vitellogenin (Vg) and vitellogenin receptor (VgR) genes, and protein levels were analyzed.Results: The amount of feeding by S. litura larvae and the synthesis level of 70 kDa storage protein significantly decreased as the electron beam dose increased. When larvae were treated with the electron beam, morphological deformities appeared in the pupae, and abnormal wing disc (AWD) expression significantly decreased. Ovarian development was completely inhibited in emerged adults that had undergone 200 Gy electron beam irradiation as pupae. Quantitative real-time PCR (qRT-PCR) assays showed significant downregulation of the Vg and VgR genes due to electron beam irradiation; whereas the synthesis level of Vg protein (190 kDa) did not decrease with time in eggs unlike in non-irradiated (control) S. litura eggs, exhibiting irradiation induced impairment of Vg functioning.Conclusions: These findings of radiation-induced abnormal development and sterility in S. litura together with the correlated changes at the molecular level may facilitate the development of a phytosanitary strategy against this quarantine pest using electron beam irradiation.

Delay in Mating Reduces Reproductivity but Increases Life Span in Tobacco Cutworm, Spodoptera litura Fabricius (Lepidoptera: Noctuidae).

A pheromone-mediated mating disruption is a vital tool in the management of insect population dynamics that not only prevents mating but also delays mating in the target insect. Here, we examined the effect of delayed mating on the longevity and reproductive performance of the global pest, Spodoptera litura Fabricius (Lepidoptera: Noctuidae). Delayed mating was imposed on both sexes simultaneously, males only, and females only. The results showed that a 30-40% reduction in the successful mating rate of S. litura was caused by 7-d delay in mating. Increased mating ages of both sexes of S. litura resulted in a significant decrease in 3-d-old delayed mating, followed by an increase in mean duration of copulation. Furthermore, delayed mating had a significantly negative influence on the number of S. litura eggs produced. Mating delay imposed on both sexes simultaneously had a significantly greater effect on longevity and the number of eggs than when it was applied to either sex alone, and females were more severely affected by delayed mating than males in terms of longevity. Percentage of mating, fecundity, and female longevity were all significantly correlated with the number of days delayed mating. However, the hatching rate of eggs was not significantly affected by an increased delay in mating. Overall, our results indicated that delayed mating in both females and males drastically reduced the females' reproductive output, which itself was affected more by increasing the age at mating of females than males.

Effects of temperature and nonionizing ultraviolet radiation treatments of eggs of five host insects on production of Trichogramma chilonis Ishii (Hymenoptera: Trichogrammatidae) for biological control applications

Trichogramma species are used worldwide as biological control agents. A particularly important application is mass-rearing and release for management of field-crop and warehouse insect pests. Eggs of commonly available hosts, Spodoptera litura, Corcyra cephalonica, Plutella xylostella and Helicoverpa armigera, were exposed to different temperature and nonionizing ultraviolet (UV) radiation treatments to consider whether particular combinations of treatments positively affected T. chilonis development. The treatments had different effects on three measures of parasitoid production: the rate of parasitization, adult emergence, and adult viability. At constant temperature (24, 28, 32°C), the mean percentage of egg parasitization was greatest on treatments of S. litura eggs. However, the mean percentage of adult emergence was significantly greater from C. cephalonica eggs at 28°C than from eggs in other treatments. The mean percentage of adult viability was found to be 83.9% from C. cephalonica eggs at 28°C. Ultraviolet radiation treatments (3, 6, or 9min at 254nm) significantly increased the mean percentage parasitization over that of the non-UV treatments. Also, the mean percentage of adult parasitoid emergence and viability were greater from C. cephalonica eggs exposed to non-ionizing UV radiation than from eggs of other hosts in all other treatments. This information can be used by managers of mass-rearing programs to increase the effectiveness of T. chilonis production for biological control of pest insects.

Functional characterization of SlitPBP3 in Spodoptera litura by CRISPR/Cas9 mediated genome editing

Functional gene analysis by using genome editing techniques is limited only in few model insects. Here, we reported an efficient and heritable gene mutagenesis analysis in an important lepidopteran pest, Spodoptera litura, using the CRISPR/Cas9 system. By using this system, we successfully obtained the homozygous S. litura strain by targeting the pheromone binding protein 3 gene (SlitPBP3), which allowed us to elucidate the role of this gene in the olfaction of the female sex pheromones. By co-injection of Cas9 mRNA and sgRNA into S. litura eggs, highly efficient chimera mutation in SlitPBP3 loci was detected both in injected eggs (39.1%) and in the resulting individual moths (87.5%). We used the mutant moths as parents to obtain the G1 offspring and the homozygous mutant strain in G2. The function of SlitPBP3 was explored by Electroantennogram (EAG) recordings with a homozygous mutant strain. The result showed that the EAG responses were significantly decreased in mutant males than in control males when treated with the major sex pheromone component (Z9,E11-14:Ac) and a minor component (Z9-14:Ac) at higher dosages. The results demonstrate that s SlitPBP3 gene plays a minor role in the perception of the female sex pheromones. Furthermore, our study provides a useful methodology with the CRISPR/Cas9 system for gene in vivo functional study, particular for lepidopteran species in which the RNAi approach is not efficient.

Patogenisitas Beberapa Isolat Cendawan Entomopatogen Metarhizium spp. terhadap Telur Spodoptera litura Fabricius (Lepidoptera: Noctuidae)

Metarhizium spp. merupakan salah satu jenis cendawan entomo-patogen yang dapat digunakan untuk mengendalikan hama Spodoptera litura. Tujuan dari penelitian ini adalah untuk mempelajari patogenisitas isolat Metarhizium spp. terhadap telur Spodoptera litura. Isolat Metarhizi-um spp. dikoleksi dari rizosfer tanaman kubis, bawang merah, bawang daun dan cabai. Hasil penelitian menunjukkan bahwa semua isolat yang diuji bersifat patogen terhadap telur S. litura. Mortalitas telur S. litura berkisar antara19,79%-75,70%, tergantung pada isolat. Larva instar I mati setelah 3 hari keluar dari telur dengan mortalitas tertinggi sekitar 58,65%. Isolat Mt-Kb merupakan isolat yang paling virulen dengan mortalitas telur dan larva instar I tertinggi dibandingkan dengan isolat lain.

Predicting Developmental Timing for Immature Canada Thistle Stem-Mining Weevils, Hadroplontus litura (Coleoptera: Curculionidae).

Predictions of phenological development for insect biological control agents may facilitate post-release monitoring efforts by allowing land managers to optimize the timing of monitoring activities. A logistic thermal time model was tested to predict phenology of immature stem-mining weevils, Hadroplontus litura F. (Coleoptera: Curculionidae), a biological control agent for Canada thistle, Cirsium arvense L. (Asterales: Asteraceae). Weevil eggs and larvae were collected weekly from Canada thistle stems in eastern North Dakota from May through July during 2010 and 2011. Head capsule widths of sampled larvae were measured at the widest point and plotted on a frequency histogram to establish ranges of head capsule widths associated with each instar. We found head capsule width ranges for first-, second-, and third-instar H. litura larvae were 165-324 µm, 346-490 µm, and 506-736 µm, respectively. Logistic regression models were developed to estimate the proportions of H. litura eggs, first-, and second-instar larvae in the weevil population as a function of thermal time. Model estimates of median development time for eggs, first instars, and second instars ranged from 219 ± 23 degree-days (DD) to 255 ± 27 DD, 556 ± 77 DD to 595 ± 81 DD, and 595 ± 109 DD to 653 ± 108 DD, respectively. Based on model validation statistics, model estimates for development timing were the most accurate for eggs and first instars and somewhat less accurate for second instars. These model predictions will help biological control practitioners obtain more accurate estimates of weevil population densities during post-release monitoring.

Seasonality of the common cutworm Spodoptera litura in a soybean ecosystem

Seasonal occurrence of the common cutworm Spodoptera litura (Fab.) (Lepidoptera: Noctuidae) moths captured in synthetic sex pheromone traps and associated field population of eggs and larvae in soybean were examined in India from 2009 to 2011. Male moths of S. litura first appeared in late July or early August and continued through October. Peak male trap catches occurred during the second fortnight of September, which was within soybean reproductive stages. Similarly, the first appearance of S. litura egg masses and larval populations were observed after the first appearance of male moths in early to mid-August, and were present in the growing season up to late September to mid-October. The peak appearance of egg masses and larval populations always corresponded with the peak activity of male moths recorded during mid-September in all years. Correlation studies showed that weekly mean trap catches were linearly and positively correlated with egg masses and larval populations during the entire growing season of soybean. Seasonal means of male moth catches in pheromone traps during the 2010 and 2011 seasons were significantly lower than the catches during the 2009 season. However, seasonal means of the egg masses and larval populations were not significantly different between years. Pheromone traps may be useful indicators of the onset of numbers of S. litura eggs and larvae in soybean fields.

Effect of prey on predation, growth and biology of green lacewing (Chrysoperla zastrowi sillemi)

The larvae of the polyphagous predator, green lacewing [Chrysoperla zastrowi sillemi (Esben-Petersen)] was reared on natural prey including cabbage aphid (Brevicoryne brassicae), bean aphid (Aphis craccivora), nymphs of okra jassid (Amrasca biguttula biguttula), eggs and neonate larvae of Spodoptera litura and eggs of Corcyra cephalonica to study the effect of prey regimes on the predation and the biology of the predator. The lacewing grub preyed significantly highest number of prey units (415.50 eggs/ grub) of C. cephalonica eggs which was significantly more than the S. litura eggs (250.60 eggs/ grub), A. biguttula biguttula (185.00 nymphs/ grub), B. brassicae (127.50 aphids/grub), A. craccivora (119.00 aphids/grub) and neonates of S.litura (62.25 larvae/grub). The larval duration varied from 7.50 to 15.235 days on different preys which was seven day less in the grubs reared on eggs than the grubs fed on insect as prey. Larval survival was significantly highest (97.82%) on C. cephalonica eggs. The pupal period varied from 7.50 days to 8.63 days. The grubs reared on eggs of C. cephalonica and S. litura showed longer pupal period. On insects as prey, the growth index (GI) of larvae was significantly less (5.56–8.58) compared to the larvae reared on egg-hosts. The weight of grubs preying on other hosts was 35–50% less compared to those reared on C. cephalonica eggs. Relative inadequacy of lepidopteran neonates and aphids except B. brassicae as prey for the young larvae adversely affected the larval survival, GI and adult emergence may be due to reduced nutritional support exerting adverse effect on growth and causing moulting distress.

Oviposition and reproductive performance of a generalist parasitoid (Trichogramma pretiosum) exposed to host species that differ in their physical characteristics

The response of generalist egg parasitoids to alternative natural hosts that are present simultaneously is not well known. We investigated the behavior of Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) in relation to two field hosts Helicoverpa armigera Hubner and Spodoptera litura Fabricius, in choice and no choice tests. We quantified the effects of natal host species and post-emergence adult age on the oviposition preference of the parasitoids. H. armigera eggs were consistently preferred over S. litura eggs, regardless of the natal host and adult age. When only S. litura eggs were available as hosts, they were parasitized at statistically similar rates to H. armigera eggs (average of 17 +/- 2.7 vs. 13 +/- 3.0, H. armigera to S. litura). The adult lifespan and lifetime fecundity of T. pretiosum were variable but were affected by natal host species and/or host species to which they were exposed. Mean lifespan and fecundity of parasitoids that had developed in H. armigera eggs and were exposed to H. armigera eggs for oviposition were 13.9 +/- 1.8 days and 98.7 +/- 11.0 adult offspring. By contrast, those that developed in S. litura eggs and were exposed to S. litura eggs for oviposition lived for 7 +/- 0.9 days and produced 53.8 +/- 8.0 adult offspring. The ovigeny index (OI) was significantly lower in the parasitoids exposed to H. armigera eggs than in those exposed to S. litura eggs, regardless of the natal host, indicating that H. armigera eggs sustain the adult parasitoids better than S. litura eggs. These results are used to predict parasitoid behavior in the field when both hosts are available. (c) 2006 Elsevier Inc. All rights reserved.

Structural requirements for activity of juvenile hormone mimetic compounds against various insects

The activity of a set of insect juvenile hormone (JH) mimetics was examined against the metamorphosis of Musca domestica, Spodoptera litura, and Nephotettix cineticeps [cincticeps] larva, the hatching of S. litura eggs, and the propagation of Aphis gossypi nymphs. The structures of the compounds were varied systematically in their dimensions and the position of a functional group. These 4-alkyl-, 4-alkoxy-, 4-benzyl-, and 4-phenoxyphenyl alkyl ether compounds had functions such as ether, oxime, hydroxylamine, ester, amide, carbamate, benzene, and pyridine in the alkane moiety (...)