Spodoptera Mauritia Research Articles

On the morphogenetic role of juvenile hormone in the prepupal stage ofSpodoptera maurittaBoisd. (Lepidoptera: Noctuidae)

Summary Neck-ligated and thorax-ligated post-feeding (day 4) (last instar larvae of Spodoptera mauritia were treated with ecdysterone alone or in combination with a juvenile hormone analogue, hydroprene. The effects of these treatments on larval-pupal transformation were studied. Sixty three pecent of neck-ligated and 84% of the thorax-ligated larvae injected with ecdysterone (4 μg/larva) (moulted into larval-pupal intermediates. Eighty percent of neck-ligated larvae injected with 4 μg ecdysterone and simultaneously treated with 5 μg hydroprene transformed into headless pupae. By contrast, treatments of same doses of ecdysterone and hydroprene to thorax-ligated larvae induced 60% of the larvae to moult into larval-pupal intermediates only. These results indicate that in S. mauritia the presence of juvenile hormone late in the last instar of larval development is crucial for the successful larval-pupal transformation. Furthermore, since hydroprene and ecdysterone induced pupation is observed only in neck-l...

Effects of anti-juvenile hormone agents and a juvenile hormone analog on neck-ligated post-feeding last instar larvae of Spodoptera mauritia Boisd. (Lepidoptera:Noctuidae)

The ability of three anti-juvenile hormone agents (AJHAs) to prevent the juvenile hormone dependent phase of larval-pupal transformation has been investigated. Neck-ligated post-feeding last instar larvae of Spodoptera mauritia were treated topically with different doses of a juvenile hormone analog (JHA) or the AJHAs, tetra-hydro-4-fluoromethyl-4-hydroxy-2H-pyran-2-one (FMev), ethyl-4-[2-(tert-butyl carbonyloxy)butoxy] benzoate (ETB) and ethyl-[E]-3-methyl-2-dodecanoate (EMD). Untreated ligated larvae or those treated with acetone survived for 12 ± 1 days without showing any sign of pupal cuticle secretion. On the other hand treatments of ligated larvae with different doses of JHA induced pupation. Among the three AJHAs tested treatments of ETB promoted pupation. Treatments of ligated larvae with lower doses of EMD induced the formation of larval-pupal intermediates whereas those treated with higher dose moulted into either pupae or larval-pupal intermediates. FMev-treated larvae exhibited a complete inhibition of moulting and metamorphosis. In order to study whether AJHAs would prevent the JHA induced pupation, neck-ligated larvae were treated simultaneously with different doses of AJHAs and 1μg JHA. Co-application of JHA with different doses of EMD induced pupation in majority of the ligated larvae and thus appears to a certain extent to counteract the effects of treatments of same doses of EMD alone. Co-application of JHA with different doses of ETB elicited pupation in all the surviving ligated larvae. To a large extent co-application of JHA with different doses of FMev failed to induce pupation. The significance of the findings is discussed in the context of the mode of action of these AJHAs. Les trois (AJHAs) ont ete examines son pouvoir qu’ empeche la transformation du Juvenile hormone dependent phase de larvaere-pupae. Ayant nourir derniere stade cou-ligatures larvaire de Spodoptera mauritia sont traite topicalement avec en doses differements du Juvenile hormone analog (JHA) ou AJHAs, tetra-hydro-4-fluoromethyl-4-hydroxy-2H-pyran-2-one (FMev), ethyl-4-[2-(tert-butyl carbonyloxy)butoxy] benzoate (ETB) et ethyl-[E]-3-methyl 2-dodecanoate (EMD). Non traite larvaire ligatures ou celles sont traite avec acetone survie pendant 12 ± 1 jours sans aucune signe de secretion par pupal cuticle. D’ailleurs traitement des larvaires ligatures avec en doses differents de JHA induit pupation. Parmi les larvaire deja traite par trois AJHAs sont induit pupation par ETB. Traitment des larvaires ligatures avec en doses inferieurs du EMD induit la formation de larvaires-pupal intermediares tandisque celles qui sont traites en doses superieurs mue a pupae ou larvaires pupal intermediares. Larvaires traites par FMev montre une inhibition complete du mue et metamorphosis. A fin d’etudier si AJHAs empechevont JHA induit pupation, cou-ligature larvaires sont traite simultanement avec en doses differents des AJHAs et 1μg JHA. En majorite des larvaires ligatures induit pupation par co-traitment de JHA avec en doses differents de EMD. Co-traitment de JHA avec en doses differents de ETB elicit pupation dans toutes les larvaires ligatures survivant. En plus part des cas co-traitment de JHA avec en doses differents de FMev n’induit pas la pupation. Les significances des resultats ont discutes d’une manniere de la mode d’action des AJHAs.

Persistence of the Nuclear Polyhedrosis Virus of the Rice Swarming Caterpillar Spodoptera mauritia (Boisduval) in Soil

Persistence of the nuclear polybedrosis virus (NPV) of Spodoptera mauritia (Boisduval) in soil was studied. The virus when incorporated in soil and kept under field conditions had a half life of 6.46 months, while it was 16.03 months for the virus in soil kept under laboratory conditions. A comparison of the LT 50 values showed that the virus lost its virulence more rapidly when the virus treated soil was kept outdoors. The virus stored in a refrigerator showed only slight loss in original activity even after 18 months.

The high titre of free amino acids in the larval haemolymph of the moth, Spodoptera mauritia boisduval

The pattern and magnitude of the changes in the titre of free amino acids in the larval haemolymph/fat body of Spodoptera mauritia showed marked differences between unit and total volume/weight during development. The free amino acid content of the fat body was about one-tenth of that found in the haemolymph. The changes in the total content of free amino acids in the total tissue (haemolymph and fat body) showed a bell-shaped pattern of variation during the development of the larva. The increase in the total amount of free amino acids was proportional to the growth of the larva and the decrease indicates that there is a positive balance in protein storage. It has been postulated that the characteristic organization of insect cuticle and its lability during the life cycle necessitate a ready supply of a large amount of free amino acids and that the direct relationship between the titre of free amino acids and the evolutionary status of insects lies in the frequency of the remodelling of the integumentary structures.

Age‐dependent responses of last instar larvae of Spodoptera mauritia to precocene II

ABSTRACT. Last instar larvae of Spodoptera mauritia Boisd. (Lepidoptera: Noctuidae) of various ages were treated with a single dose of 80 μg or 160 μg of precocene II (PII) and the effects of larval—pupal transformation were studied. Final instar (sixth) larvae treated on day 0, 1 or 2 with 80 μg P II showed a high mortality; P II treatment during subsequent days of this stadium showed a diminishing tendency for mortality. P II prolonged the larval—pupal period in all larvae but the effect was somewhat reduced in the mid‐stadium.Treatments of 160μg P II to 0‐day‐old, 1‐day‐old, 2‐day‐old and 3‐day‐old larvae were highly toxic. Treatments of 4‐day‐old and 5‐day‐old larvae with 160 μg P II delayed pupation by 1 day, but in addition the larvae often moulted into larval—pupal intermediates. Co‐application of 50μg juvenile hormone analogue (ZR 512) with 160 μg P II restored both normal morphogenesis and a normally‐timed moult.

Armyworm (Lepidoptera: Noctuidae) Resistance in Rice1

A method for screening seedling and older rice plants for resistance to Mythimna separata (Walker) and Spodoptera mauritia acronyctoides (Guenee) was developed. In all seedling stage tests, many entries were readily fed upon, and when the most susceptible entries were consumed, the nonpreferred varieties were also heavily damaged. The most resistant varieties in the seedling stage were those belonging to the wild rice groups, especially group II, which has a different genomic constitution than Oryza sativa. In tests involving older plants, IR20, IR46, and B-441-B-126-1-2-3 were heavily damaged when infested with 2nd- and 3rd-instar larvae

Treatment of larvae with repeated doses of precocene II induces precocious metamorphic changes in Spodoptera mauritia (Lepidoptera: Noctuidae)

AbstractIn Spodoptera mauritia repeated daily treatments of larvae with 40 μg of precocene II throughout the fifth and sixth instar larval period had no effect on the larval‐larval period but prolonged larval‐pupal ecdysis. The resulting pupae showed precocious adult differentiation of mouth parts, wings, eyes, legs, and fat body.

FEEDING PREFERENCES OF LARVAE OF HERPETOGRAMMA LICARSISALIS (WALKER) (LEPIDOPTERA: PYRALIDAE) AND SPODOPTERA MAURITIA (BOISDUVAL) (LEPIDOPTERA: NOCTUIDAE), TWO LAWN PESTS COMMON ABOUT BRISBANE

AbstractLarvae of 2 species of moth, Herpetogramma licarsisalis and Spodoptera mauritia were fed 25 species of lawn and pasture grasses and 32 other wild and cultivated plants. Leaves of few plants except grasses and sedges were ingested, but of these almost any species was eaten. No dicotyledons were eaten by H. licarsisalis while S. mauritia consumed 4 out of 17 dicotyledons. The preference of the larvae for Digitaria didactyla or each of 24 species of grasses and sedges was determined. It appears from the results of tests that there is no connection between the observations that these larvae are now of less concern around Brisbane than formerly and that Axonopus compressus, carpet grass, is becoming increasingly acceptable in lawns.

Invertase activity in the gut of 6th instar larvae of Spodoptera mauritia Boisd. (Noctuidae, Lepidoptera).

Invertase activity has been studied in the fore-, mid- and hindgut of the 6th instar larva of Spodoptera mauritia. The highest activity was in the midgut except during the early hours of the larva period when the foregut showed comparatively increased activity. The hindgut invertase activity may be from the voiding of enzyme along with the undigested food.

The excretion of urea by the larvae ofSpodoptera mauritia boisd. (Noctuidae: Lepidoptera) during development

The concentration of urea in the excreta of the 6th instar larvae of Spodoptera mauritia varies from 4.017 +/- 0.541 to 31.052 +/- 1.193 mumoles/g dry excreta (mean +/- SE). The observation confirms that urea excreted is of metabolic origin.

Control of the armyworms Spodoptera mauritia and Pseudaletia convecta in pastures on the north coast of New South Wales

Chlorpyrifos, methomyl and trichlorphon, at rates of 0.25-1.0 kg ha-1, were evaluated against mixed outbreaks in pastures of Spodoptera rnauritia and Pseudaletia convecta caterpillars in three experiments in New South Wales. Chlorpyrifos was the most effective chemical and at 0.25 kg ha-1 controlled both species in all experiments. Methomyl and trichlorphon each at 0.5 kg ha-1, also gave acceptable control. A comparison of costs of similar levels of control favoured trichlorphon at 0.5 kg ha-1.

Changes observed in hemolymph proteins of the lawn armyworm, Spodoptera mauritia acronyctoides, during growth, development, and exposures to a nuclear polyhedrosis virus

Vertical electrophoresis with acrylamide gel was used to study the effects of a nuclear polyhedrosis virus (NPV) on the hemolymph proteins of Spodoptera mauritia acronyctoides. An electrophoretic pattern consisting of 20 basic bands of proteins was separated in hemolymph of normal larvae which were older than 17 days. These hemolymph proteins increased quantitatively during growth. All 20 proteins could not be detected in hemolymph of younger larvae by the techniques utilized. Additional proteins were separated with metamorphosis. Lethal doses of NPV resulted in a general reduction of hemolymph proteins (hypoproteinemia) in infected larvae. Sublethal doses of NPV elicited an increase in certain hemolymph proteins. Similar increases in proteins were also observed in larvae surviving ostensibly lethal levels of NPV, in larvae subjected to physical stress, and in larvae reared axenically without formaldehyde in their diets. These same proteins, however, were present in approximately the same quantities in mature larvae. Physiopathology of NPV in S. mauritia appears to involve stress factors, host reactions, and the host endocrine system.

Dispersal of 32P-treated larvae of Spodoptera litura and Spodoptera mauritia (Lepidoptera: Noctuidae)

32P-tagged fifth-instar larvae of Spodoptera litura (Fab.) and fourth-instar larvae of Spodoptera mauritia (Boisd.) were released in experimental plots, 10 by 10 m, of clover and grass respectively and traced once a day and once a night for 2 weeks by means of a Geiger counter. The clover had a patchy distribution and was mixed with grass. The dispersal pattern was not random. In the plot with S. mauritia more radiation readings were obtained in the upwind sectors. In the plots withS. litura the majority of the contacts were made in the clover, few in the grass. The results indicate that in both species the direction of the wind may have had an influence on dispersal.

Observations on the armyworm Spodoptera mauritia acronyctoides Gn. (Lep., Noctuidae) in Sarawak (Malaysian Borneo)

Observations were made on the bionomics of Spodoptera mauritia acronyctoides Gn. in Malaysian Borneo (Sarawak) during an outbreak in 1967. The outbreak was discontinuous over about 6 000 sq. miles, affecting 25 000 acres of lowland and upland rice. In the insectary the durations of the various stages were: egg 2·9 days, first- to seventh-instar larvae respectively 3·1, 1·8, 2·2, 2·1, 2·2, 2·3 and 4·9 days, and pupa 8·4 days. Larval instars could usually be distinguished on head width and the width of the faecal pellets. Food consumption of the larvae was greatest during the final instar. During the outbreak the larvae were found mainly on young rice, and also on young maize; wild host-plants included grasses and sedges, but dicotyledonous plants were not attacked.Females generally mated on the night following emergence, and the pre-oviposition period averaged 2·9 days. Fertilised females laid an average of 1 749 eggs, 80% of the potential total. Virgin females laid only 22% of the potential, and resorbed some of their oocytes. The mean longevity of fertilised females was 5·5 days. Fecundity was directly correlated with pupal weight or length, and the weights of pupae produced in wet-rice fields were significantly heavier than those from dry hill-rice sites. There was a significant correlation between the weight of frass produced (hence food consumed) by the seventh-instar larva and the weight of the pupal stage. Pupae from larvae in crowded cultures were significantly lighter than those reared singly.

Interactions between a microsporidian pathogen of the lawn-armyworm and the hymenopterous parasite Apanteles marginiventris

The hymenopterous parasite Apanteles marginiventris oviposited with equal frequency in Nosema-infected and in uninfected lawn-armyworm ( Spodoptera mauritia acronyctoides) when the hosts were exposed in separate containers. When the hosts were exposed together, however, the parasites seemed to prefer the infected hosts although the difference was not statistically significant. Nosema-infected hosts had deleterious effects on their internal parasites. There was high parasite larval and pupal mortality, greatly reduced adult emergence, and those few adults that did emerge were smaller and significantly shorter-lived than the parasites from uninfected hosts. These detrimental effects did not derive from a direct infection of the parasite by Nosema, but rather, because an infected host apparently was not completely adequate for parasite development. There were no observable pathological changes in the tissues of parasites reared in infected hosts. The parasites successfully transmitted the pathogen from severely infected hosts to noninfected hosts during oviposition.

Spodoptera mauritia (Boisduval) and S. triturata (Walker), two distinct Species

In working out a collection of Heterocera made by J. D. Bradley in the Solomon Islands, preparations were made of the genitalia of specimens of Spodoptera mauritia (Boisd.) and they were found to differ from those of African specimens, with which they were compared. Subsequent study of the material in the British Museum has shown that two species have been confused under the one name; S. mauritia, which occurs in Madagascar, Mauritius, the Comoro Islands and from India to the Pacific and which is known from continental Africa from only a single female taken at Lindi on the coast of Tanganyika, and the second species, S. triturata (Wlk.), which occurs throughout continental Africa, south of the Sahara Desert. As both species are of economic importance, it has been decided to describe their differences in a separate paper rather than include them in the faunistic paper dealing with the Heterocera of Eennell Island.

Some experiences with Gammexane (BHC) and DDT in the control of crop pests

The Entomological section has been engaged for some time in studying the effect of the two new insecticides Gammexane (B.H.C.) and D. D. T. on a wide range of crops and pests. The results in most cases have been far beyond expectations. In fact some of the tentative data have been so convincing in the case of a number of major pests like the paddy grasshopper (Hieroglyphus banian), the paddy jassid (Nephotettiz bipunctatus), the paddy swarming caterpillar (Spodoptera mauritia), the rice bug (Leptocorisa acuta), etc., that the information could be passed on straight away to the ryots even without any further confirmatory tests. What is more interesting is that the two chemicals appear to have a definite selective action, each being effective only against a cortain group or category of insects. The response from the ryots also has been very encouraging as a keen demand for these chemicals has now sprung up from farming public. These trials have revealed the possibilities of warding off the damage by many a crop pest, control measures for which were till now either imperfect or non-existent. The insecticides, apart from their high potency, are fairly cheap and easily available with some of the local firms.