Spodoptera Frugiperda

This research aimed at studing Telenomus remus Nixon biology reared on Spodoptera frugiperda (J.E. Smith) eggs at different temperatures. Based on the development of the cycle (egg-adult), the thermal requirements and the number of parasitoid generations at constant temperatures were determined. Initially, 24-hour-old S. frugiperda eggs were submitted to parasitism by T. remus during 5 h, being then transferred to acclimatized chambers regulated at 15, 20, 25, 28, 31, and 35°C. The cycle (egg to adult) was influenced by temperature varying from 8.3±0.01 to 47.2±0.01 for females and 8.1±0.01 to 46.8±0.01 days for males at 31 and 15°C, respectively. The emergency (%) was also influenced by temperature. A reduction in emergency was observed at 15°C and no emergency at 35°C. T. remus sex ratio was not influenced by temperature. Sexual rate was not changed by temperature. Regarding to thermal requirements, thermal constant (K) and inferior thermal threshold (Tb) were higher for T. remus females (158.88 degree-days and 12.5°C) when compared to males (154.12 degree-days and 12.6°C). The estimated number of T. remus generation per year for males and females at laboratory conditions was 5.6 and 5.6, 16.9 and 17.3, 28.3 and 29.0, 35.1 and 36.0, 39.6 and 40.7 at 15, 20, 25, 28, and 31oC, respectively.

The fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is a harmful pest of many plants. In Egypt, the presence of S. frugiperda in maize fields was reported in 2019. The aim of this study was to record the parasitoids of S. frugiperda in Egypt. The survey was conducted at Sohag and Qena governorates. Survey studies showed five parasitoids were recorded. In Sohag governorate, from the total samples of fall armyworm collected, four species of parasitoids emerged, three of them belonged to order hymenoptera and one belonged to diptera. Two of the hymenopteran parasitoids were found in samples collected from Shandaweel district, Dinarmus basalis (Rondani, 1877) family Pteromalidae and Cotesia ruficrus (Haliday) family Braconidae. While the third is Microplitis rufiventris (Kokujev) family Braconidae was emerged from samples collected from El-Osyrat district. However, the dipteran parasitoid is Exorista (Tachina) larvarum (Linnaeus), which emerged from samples collected from Shandaweel district. In Qena governorate, one parasitoid species emerged Chelonus intermedius (Thomson) which was found in Abu Tesht district. Up to my knowledge this is the first record of the mentioned parasitoids on S. frugiperda in Egypt.

Spodoptera frugiperda is considered one of the main pest in corn and irrigated rice (fall armyworm) crops, causing high leaf losses. The objective of this study was to obtain an appropriate artificial diet to rear the biotypes "corn" and "rice" of S. frugiperda in laboratory. The insects were collected in areas cultivated with corn and irrigated rice in the meadow ecosystem and the identification was accomplished by the analysis of the DNA genomic. The development of the two biotypes was accompanied on Greene's diet and the same diet modified to 25 ± 1ºC, UR of 70 10% and fotofase of 14 hours. The study was accomplished with 150 larvae by diet individualized in glass tubes containing artificial diet. At emergency 20 couples were individualized and fed with aqueous solution of honey to 10%. The Greene diet made possible better development of the two biotypes, providing larger development speed, larger weight of larvae in the maximum development, weight of pupas and total fecundity, besides higher values of the net reproductive rates, intrinsic and finite rates of increase.

Fall armyworm is an invasive insect pest on maize which is causing huge loss to maize cultivators in Northern Karnataka. The field survey conducted in these areas during kharif 2018 indicated that the entomopathogenic fungi, Nomuraea rileyi is natural occurring on Spodoptera frugiperda with its infection ranging from 1.87 percent in Vijaypur to 18.30 percent in Dharwad district while, the percent damage of fall armyworm on maize ranged between 12.42 in Uttar Kannada and 65.73 percent in Dharwad district. Further, three large scale field evaluation studies conducted on this pathogen against the fall armyworm in maize revealed 58.91 to 62.87 percent reduction of pest infestation in these localities. Similarly, the larval and leaf injury reduction after 15 days of spraying N. rileyi ranged from 62.50 to 66.46 and 66.84 to 73.05 percent, respectively. The studies indicated the high potentiality of N. rileyi in combating the notorious invasive pest, S. frugiperda. This is the first report from India with respect to efficacy of N. rileyi against S. frugiperda under field conditions.

The fall armyworm (FAW) (Spodoptera frugiperda) is a crop pest species that has become global, having spread from its native American distribution to Africa and Asia since 2016. Its rapid spread, plus concerns about potential yield losses, have led to the search for sustainable management options. While most farmers affected by FAW in America have large-scale farm operations, the overwhelming majority of farmers in Africa and Asia are smallholders. This dramatically different context means that different management approaches must be sought. Large-scale producers with high-productivity, access to international market prices, risk-transfer mechanisms and the benefits of government subsidies are able to use technologies unavailable to smallholder farmers without access to those conditions. This review examines these differences and surveys the literature for accessible management options for smallholders, largely based on locally available solutions using ecological knowledge. Innovative digital solutions may also play a role in helping farmers learn about these solutions, and share them locally.

Fall armyworm larvae, Spodoptera frugiperda (J. E. Smith), were collected from sweet corn plants (Zea mays L.) in fields located in three south Florida counties. Fields were sampled from 2010 to 2015 during the fall and spring seasons. Larvae were transferred to the laboratory to complete development. The objective of the study was to identify the common parasitoids emerging from larvae that are present in sweet corn habitats where insecticides are traditionally used. A total of 8353 fall armyworm larvae were collected, of which 60.6% (5062) developed into moths after feeding on corn tissue and artificial diet. Parasitoids emerged from 2365 larvae (28.3%), and parasitism ranged from 1% to 91.7%, depending on site. Parasitism was higher at the University of Florida Everglades Research and Education (EREC) in Belle Glade (50.4 ± 11.8%) than at other locations in south Florida. Parasitism was comparable between fall and spring seasons, but was much higher in unsprayed fields (44.0 ± 9.6%) than in the sprayed fields (15.0 ± 2.5%). The two most common parasitoids that emerged from larvae were the solitary endoparasitoids Cotesia marginiventris (Cresson), found in 23 of the 25 sites sampled, and Chelonus insularis Cresson, found in 18 of the 25 sites sampled. Other parasitoid species that emerged from fall armyworm larvae were Aleiodes laphygmae (Viereck), Euplectrus platyhypenae Howard, Meteorus spp., Ophion flavidus Brullé, and unidentified species of Tachinidae. Techniques to improve the management of fall armyworm in overwintering areas of south Florida using conservation biological control are discussed.

Spodoptera frugiperda is a polyphagous lepidopteran pest that encounters a wide range of toxic plant metabolites in its diet. The ability of this insect to adapt to its chemical environment might be explained by the action of major detoxification enzymes such as cytochrome P450s (or CYP). Forty-two sequences coding for P450s were identified and most of the transcripts were found to be expressed in the midgut, Malpighian tubules and fat body of S. frugiperda larvae. Relatively few P450s were expressed in the established cell line Sf9. In order to gain information on how these genes respond to different chemical compounds, larvae and Sf9 cells were exposed to plant secondary metabolites (indole, indole-3-carbinol, quercetin, 2-tridecanone and xanthotoxin), insecticides (deltamethrin, fipronil, methoprene, methoxyfenozide) or model inducers (clofibrate and phenobarbital). Several genes were induced by plant chemicals such as P450s from the 6B, 321A and 9A subfamilies. Only a few genes responded to insecticides, belonging principally to the CYP9A family. There was little overlap between the response in vivo measured in the midgut and the response in vitro in Sf9 cells. In addition, regulatory elements were detected in the promoter region of these genes. In conclusion, several P450s were identified that could potentially be involved in the adaptation of S. frugiperda to its chemical environment.

Plants respond to insect attack with the induction of volatiles that function as indirect plant defenses through the attraction of natural enemies to the herbivores. Despite the fact that volatiles are induced in response to caterpillar attack, their reciprocal effects on the host location behaviors of the same foraging herbivores are poorly understood. We examined orientation responses of sixth instar fall armyworm [FAW; Spodoptera frugiperda (Smith)] to odors from herbivore-damaged and undamaged maize seedlings (Zea mays var. Golden Queen) in y-tube olfactometer bioassays. While both damaged and undamaged maize seedlings were attractive compared with air, sixth instars preferred odors from damaged maize seedlings over odors from undamaged maize seedlings. Gas chromatography–mass spectrometry analysis of plant volatiles revealed that linalool and 4,8-dimethyl-1,3,7-nonatriene were the major volatiles induced by FAW herbivory 6 hr after initial damage. Given its prominence in induced plants and established attractiveness to adult FAW, linalool was evaluated both as an individual attractant and as a supplemental component of whole plant odors. Volatile linalool was more attractive than air to sixth instar FAW over a broad range of release rates. FAW also responded selectively to different amounts of linalool, preferring the higher amount. The orientation preferences of FAW were readily manipulated through capillary release of linalool into the airstream of whole plant odors. FAW preferred linalool over undamaged plant odors, and linalool-supplemented plant odors over unsupplemented plant odors, indicating that olfactory preferences could be changed by alteration of a single volatile component. These results suggest that although many induced volatiles attract natural enemies of herbivores, these defenses may also inadvertently recruit more larval herbivores to an attacked plant or neighboring conspecifics.

The generalist moth, Spodoptera frugiperda (J. E.
Smith) consists of two genetic subgroups (host strains) that
differ in their distribution among host plant species. The
corn strain prefers crop plants such as corn, sorghum, and
cotton, while the rice strain is found in small grasses such as
Cynodon spp. and rice. Little is known about the physiological
factors that drive this host preference. Here, we report a
feeding study with natural host plants and an artificial diet
containing cyanide. We found that corn, two Cynodon spp.
(bermudagrass C. dactylon (L.) Persoon, ‘NuMex Sahara’,
and stargrass C. nlemfuensis var. nlemfuensis Vanderyst,
‘Florona’), and a hybrid between bermudagrass and stargrass,
‘Tifton 85’, exhibited differences in the concentration
of the cyanogenic precursors or cyanogenic potential
(HCNp) and the release of hydrogen cyanide per unit time
or cyanogenic capacity (HCNc). Corn plants released low
levels of hydrogen cyanide, while stargrass had greater
HCNp/HCNc than bermudagrass and ‘Tifton 85’. Feeding
studies showed that corn strain larvae experienced higher
mortality than the rice strain when fed stargrass or artificial
diet supplemented with cyanide. Also, corn strain
larvae excreted higher levels of cyanogenic compounds
than the rice strain when fed Cynodon spp. These differences
in excretion suggest potential disparities in cyanide
metabolism between the two strains. We hypothesize that
differences in the susceptibility to cyanide levels in various
host plants could play a role in driving strain divergence
and what appears to be the incipient speciation of
this moth.

An isolate of the Spodoptera frugiperda multiple nucleopolyhedrovirus comprises a stable proportion of deletion genotypes (e.g., SfNIC-C), that lack pif1 and pif2 rendering them noninfectious per os, and that survive by complementation with a complete genotype (SfNIC-B) in coinfected cells. To determine whether selection for particular ratios of complete and deletion genotypes occurs mainly during the establishment of the primary infection in insect midgut cells or during subsequent systemic infection, we examined genotype frequencies in insects that fed on OBs comprising different co-occluded mixtures of genotypes. Dramatic changes in genotype frequencies were observed between the OB inoculum and budded virus (BV) samples taken from larvae inoculated with OBs comprising 10% SfNIC-B + 90% SfNIC-C indicating that a marked reduction of SfNIC-C genotype had occurred in the insect midgut due to the immediate elimination of all OBs that originated from cells that had been infected only by SfNIC-C. In contrast, immediate changes were not observed in OBs comprising mixtures of 50% SfNIC-B + 50% SfNIC-C or those comprising 10% SfNIC-B + 90% SfNIC-C as most of the OBs in these mixtures originated from cells that had been infected by both genotypes. Subsequent changes in genotypic frequencies during five days of systemic infection were fairly small in magnitude for all genotypic mixtures. We conclude that the prevalence of defective genotypes in the SfNIC population is likely determined by a balance between host selection against OBs produced in cells infected by SfNIC-C alone and within-host selection for fast-replicating deletion genotypes. The strength of intra-host selection is likely modulated by changes in MOI during the infection period.

We assessed in the laboratory the attraction of the parasitoid Cotesia marginiventris (Cresson) toward odors emitted by conventional maize (Zea mays L. ssp. mays) and Bt (Bacillus thuringiensis) maize seedlings following actual or simulated injury by Spodoptera frugiperda (Smith), the parasitoid’s host, and emitted by the host’s frass, produced following consumption of conventional or Bt maize seedlings. Females of C. marginiventris exhibited similarly strong responses to conventional and Bt maize seedlings injured by the host or with simulated injury, and these were stronger than responses to clean air. In contrast, the responses of C. marginiventris females were consistently weaker toward host frass derived from Bt maize tissue compared to frass derived from conventional maize tissue. We hypothesized that the weakened response was due to a detrimental effect of Bt endotoxins, present in the Bt maize tissue, on the bacterial community present in the host’s gut and frass, including bacteria that produce odors attractive to C. marginiventris. As an initial test of our hypothesis, we compared between the responses of C. marginiventris females to host frass produced following consumption of Bt maize and frass produced from conventional maize which had been treated with an antibiotic (tetracycline) to eliminate host gut bacteria. Our results showed that C. marginiventris females responded similarly weakly to host frass derived from conventional maize tissue treated with antibiotic and to frass derived from Bt maize tissue, treated or untreated with antibiotic, while they responded strongly to frass derived from conventional maize untreated with antibiotic, so provided initial, partial support for our hypothesis. We discussed the weakened response of C. marginiventris females to host frass derived from Bt maize in the context of plausible impacts of transgenic crop cultivars on parasitoid foraging and populations, and the implications for biological control of non-target, polyphagous pests, such as S. frugiperda.

1H/15N and 13C NMR were used to investigate metabolism in Spodoptera frugiperda (Sf9) cells. Labelled substrates ([2-15N]glutamine, [5-15N]glutamine, [2-15N]glutamate, 15NH4Cl, [2-15N]alanine, and [1-13C]glucose) were added to batch cultures and the concentration of labelled excreted metabolites (alanine, NH4+, glutamine, glycerol, and lactate) were quantified. Cultures with excess glucose and glutamine produce alanine as the main metabolic by-product while no ammonium ions are released. 1H/15N NMR data showed that both the amide and amine-nitrogen of glutamine was incorporated into alanine in these cultures. The amide-nitrogen of glutamine was not transferred to the amine-position in glutamate (for further transamination to alanine) via free NH4+ but directly via an azaserine inhibitable amido-transfer reaction. In glutamine-free media 15NH4+ was consumed and incorporated into alanine. 15NH4+ was also incorporated into the amide-position of glutamine synthesised by the cells. These data suggest that the nitrogen assimilation system, glutamine synthetase/glutamate synthase (NADH-GOGAT), is active in glutamine-deprived cells. In cultures devoid of glucose, ammonium is the main metabolic by-product while no alanine is formed. The ammonium ions stem both from the amide and amine-nitrogen of glutamine, most likely via glutaminase and glutamate dehydrogenase. 13C NMR revealed that the [1-13C] label from glucose appeared in glycerol, alanine, lactate, and in extracellular glutamine. Labelling data also showed that intermediates of the tricarboxylic acid cycle were recycled to glycolysis and that carbon sources, other than glucose-derived acetylCoA, entered the cycle. Furthermore, Sf9 cell cultures excreted significant amounts glycerol (1.9-3.2 mM) and ethanol (6 mM), thus highlighting the importance of sinks for reducing equivalents in maintaining the cytosolic redox balance.

Pearl millet [Pennisetum glaucum (L.) R. Br.] is an alternative drought-tolerant grain crop for dryland summer production. Few insecticides are registered for use and insect management has not been extensively studied in pearl millet for grain production. Eleven trails were conducted during 2002-2004 in central and southern Georgia to understand the relative importance of insect pests and to evaluate the efficacy of currently registered insecticides against key pests. The main defoliator species were the fall armyworm [Spodoptera frugiperda (J.E. Smith)] and striped grassworm (Mocis latipes Guenée). Main insects feeding on grain heads were the corn earworm (Helicoverpa zea Boddie), sorghum webworm, (Nola sorghiella Riley), and stink bugs — brown stink bug (Euschistus spp.) and southern green stink bug [Nezara viridula (L.)]. All insects were effectively controlled by cypermethrin at 0.025 lb a.i./acre. The 0.015-lb a.i. rate was effective against sorghum webworm, striped grassworm, ...

The objective of this work was to evaluate the effect of the temperature on the biology of the biotypes "corn" and "rice" of Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae) and to estimate the number of generations per year in laboratory and field. Caterpillars of four populations of S. frugiperda were collected in Rio Grande do Sul State, Brazil, identified by electrophoresis as the biotypes "corn" and "rice" in isolated areas (spaced for more than 300 km), areas of corn and irrigated rice production, as well as in adjacent areas that produces corn and rice irrigated side by side. The most appropriate temperature for the development of the two biotypes was 25ºC. In laboratory, a number between 11.0 and 11.3 generations year-1 for the biotype "corn" can be obtained, originating from isolated and adjacent areas, respectively, and, for the biotype "rice", 12.1 and 12.2 generations year-1 when originating from isolated and adjacent areas, respectively. In the field, the occurrence of 8.3 and 6.1 generations year-1 for the biotype "corn" was estimated, respectively, in isolated and adjacent areas and 8.4 and 7.0 generations year-1 for the "rice" biotype, respectively, in isolated and adjacent areas. In adjacent areas, the "rice" biotype presents an extra generation per year in relation to the "corn" biotype.