Mature Larval Stages Research Articles

Biocontrol potential of native entomopathogenic nematodes against Gonioctena fornicata (Brüggemann, 1873) (Coleoptera, Chrysomelidae) in alfalfa

BackgroundGonioctena fornicata (Brüggemann, 1873) (Coleoptera: Chrysomelidae) inflicts substantial crop damage by consuming alfalfa leaves. The main aim of the study was to develop an efficient, sustainable control method against the pest, considering entomopathogenic nematodes (EPNs) as a potential control agent against soil-dwelling insect pests. This study investigated the impact of two native entomopathogenic nematodes (EPNs), Heterorhabditis bacteriophora (isolate Z-1) and Steinernema feltiae (isolate A-16), on mature larvae and adults of G. fornicata. Concentrations of 250, 500, and 1000 IJs/ml were used for adult and larval stages, and mortality rate was determined at the end of 144 h for larvae and 240 h for adults.ResultsThe highest effect was 94.7% at 120 h for isolate Z-1 and 91.0% at 168 h for isolate A-16 at a concentration of 1000 IJs/ml for adult stages. The highest effect on larval stage was 97.6% at 96 h for isolate Z-1 and 85.8% at 120 h for isolate A-16 at the concentration of 1000 IJs/ml. On the adult stage, isolate Z-1 showed 50.0–67.1% effect at concentrations of 250 and 500 IJs/ml, respectively, while isolate A-16 showed an effect ranging from 46.7 to 63.6%. In the larval stage, isolate Z-1 caused 39.7–77.6% mortality at 250 and 500 IJs/ml concentrations, respectively, while the rate was 32.9–63.9% for isolate A-16. In the trial, isolate Z-1 showed a high efficacy in both stages of G. fornicata.ConclusionsThis study represents the first laboratory investigation encompassing both adult and mature larval stages of G. fornicata. The obtained data offer valuable insights for alternative control strategies targeting G. fornicata.

Determination of Optimum Eri Silkworm Larvae Population Density in Feeding Tray using Shelf Rearing Technique

Population density during the different stages of larval growth and development is one of the crucial issues for successful commercial cocoon crop of silkworms. Using appropriate population density ensures the hygiene of silkworms in order to protect from disease infection and to ensure them good feeding appetite. Different stages of silkworm larvae require different population density or bed space during their growing period in the rearing bed. As worms increase in size, there is overcrowding and overlapping each other that leads to underfeeding, creating a microclimate for disease spread and could also lead to suffocation. Hence, appropriate bed spacing is essential to silkworm larvae, to keep them healthy and productive. The treatments used for examining the appropriate population density of young and medium aged silkworm larvae were 1200, 1000, 800, 600, 400 and 200 per feeding tray (60cm X 90cm size). Another arrangement of population density used for examining the mature aged silkworm larvae were 600, 500, 400, 300, 200 and 100 per feeding tray (60cm X 90cm size) using silkworm shelf rearing technique to evaluate the effects of population density on different larval stages eri silkworm strains. 1 st and 2 nd larval instars/stages as young age, 3 rd and 4 th larval instars as medium age, 5 th larval instar as mature age were considered in the study. Observations on larval mortality, single larval weight, single shell weight, and silk ratio from different eri silkworm strains were carefully noted for each treatment and replications. Three replications were used for each treatment. Statistically significant variation in mean larval mortality rate among population densities was observed in young, medium and mature silkworm larval stages of silkworm strains. Larval mortality rate was significantly reduced when young, medium and mature larval stages of castor feeding eri silkworm strains (Indian eri and Vietnamese eri) reared in a group of 400 to 800 worms, 400 to 600 worms and 300 to 400 worms respectively in a 60 cm X 90 cm feeding tray of shelf rearing method. Bigger Larval weight, bigger shell weight and higher percentage of silk ratio are important cocoon yield quality parameters for silkworm strains. Significant (P < 0.05) variations were observed among population densities for these important variables in all the tested eri silkworm strains. Keywords : Population density, silkworm strains, feeding tray, larval instars, larval mortality, shell weight, silk ratio

A new species of Prosopistoma (Ephemeroptera: Prosopistomatidae) from China with a key to Oriental species.

A new species of the monogeneric family Prosopistomatidae, Prosopistoma ocellatum sp. n., is described and illustrated based on mature larval stages from Guangxi and Hainan, southern China. The new species can be readily distinguished from the other members of Prosopistoma by the following combination of characters: antenna 6-segmented, segment III much longer than segments IV-VI; three bristles at the base of the inner canine; 10-11 pectinate setae on ventral margin of fore tibiae, ventral and basal half surface of all femora with dense scale-like structures, and color pattern of eye-spot on the mesonotum. An update key to the known Oriental species is provided.

Multidendritic sensory neurons in the adult Drosophila abdomen: origins, dendritic morphology, and segment- and age-dependent programmed cell death

BackgroundFor the establishment of functional neural circuits that support a wide range of animal behaviors, initial circuits formed in early development have to be reorganized. One way to achieve this is local remodeling of the circuitry hardwiring. To genetically investigate the underlying mechanisms of this remodeling, one model system employs a major group of Drosophila multidendritic sensory neurons - the dendritic arborization (da) neurons - which exhibit dramatic dendritic pruning and subsequent growth during metamorphosis. The 15 da neurons are identified in each larval abdominal hemisegment and are classified into four categories - classes I to IV - in order of increasing size of their receptive fields and/or arbor complexity at the mature larval stage. Our knowledge regarding the anatomy and developmental basis of adult da neurons is still fragmentary.ResultsWe identified multidendritic neurons in the adult Drosophila abdomen, visualized the dendritic arbors of the individual neurons, and traced the origins of those cells back to the larval stage. There were six da neurons in abdominal hemisegment 3 or 4 (A3/4) of the pharate adult and the adult just after eclosion, five of which were persistent larval da neurons. We quantitatively analyzed dendritic arbors of three of the six adult neurons and examined expression in the pharate adult of key transcription factors that result in the larval class-selective dendritic morphologies. The 'baseline design' of A3/4 in the adult was further modified in a segment-dependent and age-dependent manner. One of our notable findings is that a larval class I neuron, ddaE, completed dendritic remodeling in A2 to A4 and then underwent caspase-dependent cell death within 1 week after eclosion, while homologous neurons in A5 and in more posterior segments degenerated at pupal stages. Another finding is that the dendritic arbor of a class IV neuron, v'ada, was immediately reshaped during post-eclosion growth. It exhibited prominent radial-to-lattice transformation in 1-day-old adults, and the resultant lattice-shaped arbor persisted throughout adult life.ConclusionOur study provides the basis on which we can investigate the genetic programs controlling dendritic remodeling and programmed cell death of adult neurons, and the life-long maintenance of dendritic arbors.

Effect of temperature on the termination of prolonged larval diapause in the chestnut weevil Curculio sikkimensis (Coleoptera: Curculionidae)

Adults of the chestnut weevil Curculio sikkimensis emerged over a 3-year period under laboratory and quasi-field conditions due to a prolonged diapause that occurred at the mature larval stage. Variable proportions of the larvae remained in diapause after a single cold (5 °C) treatment of 120 days. Extension of the chilling period to as long as 540 days did not increase the percentage of diapause termination, and excessively long chilling actually reduced the percentage. Chilling was not indispensable to the termination of larval diapause. Diapause intensity was very high and variable, and more than 1000 days at 20 °C was necessary to reactivate all diapause larvae. When the diapause larvae were exposed to cycles of low (5 °C for 120 days) and high (20 °C for 240 days) temperatures, the percentage of diapause termination reached 100% after two or three such cycles. Thus, the prolonged diapause of C. sikkimensis has characteristics similar to the common short winter diapause in other insects, but has unique characteristics that ensure polymodal reactivation over several years.

Geographic variation in cold hardiness of eggs and neonate larvae of the yellow‐spotted longicorn beetle Psacothea hilaris

SummaryCold hardiness of eggs and neonate larvae of the yellow‐spotted longicorn beetle, Psacothea hilaris (Pascoe) was examined using six geographical populations in Japan. Particular attention was paid to cold hardiness of eggs and neonate larvae of the subtropical population (Ishigaki), because the east Japan populations are considered to have been introduced from a subtropical area, and the overwintering stage in the east Japan populations is incidentally shifted from the original mature larval stage to the egg or neonate larval stages. When the eggs were exposed to low temperatures for 1 h, the decrease in hatchability became significant at –12°C in the southernmost two populations (Ishigaki and Naze), and at –16°C in the northern populations. After 1 h exposure to –20°C, few eggs could hatch in the Ishigaki population, whereas 27–55% of the eggs survived in the northern populations. Pre‐chilling of the eggs at 10°C for 10 days enhanced the cold hardiness in all populations. This effect was particularly distinct in the subtropical population; the eggs of the Ishigaki population became as cold hardy as those of the northern populations after acclimation. These results suggest that the subtropical population is capable of establishing itself in east Japan, where the winter is cold.

Genetic basis of photoperiodic control of summer and winter diapause in geographic ecotypes of the rice stem maggot, Chlorops oryzae

Abstract Chlorops oryzae Matsumura (Diptera: Chloropidae) is bivoltine in northern Japan but trivoltine in the southern part of the country. Larvae of the bivoltine strain (Akita, 39° N) develop without delay under L14:D10 but enter summer diapause in the mature larval stage under L15:D9. In contrast, larvae of the trivoltine strain (Aichi, 35° N) develop quickly under L15:D9 but enter summer diapause under L14:D10. The genetic basis of their different summer‐diapause behavior was analyzed by reciprocal crossing between the two ecotypes and backcrossing to the hybrids. Although a polygenic system seems to be involved, there is a single gene on the X‐chromosome exerting a major effect on summer diapause. The northern bivoltine ecotype has a longer critical photoperiod for the induction of winter diapause in the first larval stage and remains in diapause longer than the southern trivoltine ecotype. The differences in the critical photoperiod and the winter diapause duration between the two ecotypes seem to be controlled by a polygenic system but again a sex‐linked or closely linked gene (or genes) plays a major role. The two geographic ecotypes differ significantly in summer‐ and winter‐diapause traits, both of which are characterized by sex‐linked inheritance. Despite this, no apparent sterility or inviability in hybrids between the ecotypes occurs.

Dermestid beetles and some other insect pests associated with stored silkworm cocoons in India, including a world list of dermestid species found attacking this commodity

A key for the identification of adult and mature larvae of nine species of Dermestidae (Coleoptera) found associated with the Indian silkworm industry is given. The species included are Dermestes ater De Geer, Dermestes leechi Kalik, Dermestes maculatus De Geer, Dermestes undulatus Brahm, Attagenus birmanicus Arrow, Attagenus fasciatus (Thunberg), Orphinus fulvipes (Guérin-Méneville), Trogoderma halsteadi Vijay Veer and Rao, and Anthrenus flavipes (Le Conte). Notes on the biology and distribution are given for all species and detailed morphological descriptions of adult and mature larval stages are presented for D. ater, D. leechi, Att. birmanicus and O. fulvipes. D. ater and Att. fasciatus and T. halsteadi are serious pests of silkworm cocoons which are damaged by larvae boring into them to feed on pupae. Some information is given on damage to silk fabrics. Att. birmanicus and O. fulvipes are recorded for the first time as minor pests of the silkworm industry in India. A world list of 28 dermestid species recorded in association with the silk industry is appended. In addition, brief notes are included on three other beetles, Alphitobius laevigatus (F.), Tribolium castaneum (Herbst) (Tenebrionidae) and Necrobia rufipes (De Geer) (Cleridae), and an earwig, Marava arachidis (Yersin), which were also found associated with sericulture in India.

Taxonomic and biological notes on three Attagenus spp. (Coleoptera: Dermestidae) not previously recorded as pests of stored woollen fabrics in India

The adult morphology of Attagenus birmanicus Arrow is briefly described and detailed morphological descriptions for adult and mature larval stages of Attagenus indicus Kalik and a variety of Attagenus augustatus gobicola Frivaldszky are given. Notes on the biology of the last two species, including new information on A. indicus, are presented. A. augustatus gobicola is recorded from India for the first time and all three species are recorded as new pests of stored woollen fabrics and garments in this country.

Taxonomic and biological notes on Attagenus and Anthrenus SPP (Coleoptera: Dermestidae) found damaging stored woollen fabrics in India

Keys for the identification of the adult and mature larval stages together with morphological description and notes on distribution and biology are given for Attagenus cyphonoides Reitter, Attagenus fasciatus (Thunberg), Attagenus lobatus Rosenhauer, Anthrenus coloratus Reitter, Anthrenus flavipes LeConte, and Anthrenus oceanicus Fauvel. These six species are recorded from stored woollen and other keratinaceous material in India. Anthrenus flavipes, Anthrenus oceanicus, and Attagenus cyphonoides are described as serious pests of woollen goods and Anthrenus coloratus is recorded as a museum pest. Attagenus lobatus and Anthrenus oceanicus are recorded from India for the first time.

Larvae of the formicine ant genus Polyrhachis.

The mature larval stages of 11 species of Polyrhachis from Malaysia are described. For 5 of these species (armata, bihamata, muelleri, scissa and yps i I on) all 5 instars are described. The 17 species that we have described in previous publications are cited but descriptions are not repeated. We are unable to differentiate the larvae of the 10 subgenera studied: the differences among the larvae of the 38 species are not congruent with adult differences and they are not of subgeneric magnitude. We have also stressed the homogeneity of the genera of the tribe Camponotini. The Old World genus Polyrhachis and the cosmopolitan Camponotus both belong to the tribe Camponotini, the former has monomorphic workers, while the latter is highly polymor phic. According to Emery's Genera Insectorum Camponotus is the world's largest genus with 618 species, while Polyrhachis is third with 359 species. Wheeler (1922) recognized 36 subgenera in Camponotus but only 12 in Polyrhachis. The 11 species of Polyrhacis described here for the first time are all from Malaysia, thanks to the very generous donation of Dr. Wolfgang Dorow of Johann Wolfgang Goethe

Biology ofIphiaulax kimballi [Hym.: Braconidae], a parasite ofDiatraea grandiosella [Lep.: Pyralidae

Iphiaulax kimballiKirkland is a gregarious ectoparasite of the mature larval stage ofDiatraea grandiosellaDyar in Mexico. The developmental rate from egg to adult is 16.3±1.0 (x±S.D.) at 29°C. The sex ratio is 1.7∶1 (♀∶♂) in the field. Following host paralysis the female deposits 63.5±2.1 eggs during der 28.6±6.4 day adult-life span; laying 4.6±3.1 eggs on each host. Females held at 10°C lived a maximum of 3 months.

THE RHEUMAPTERA OF NORTH AMERICA (LEPIDOPTER A: GEOMETRIDAE)

AbstractTwo species of Rheumaptera occur in North America: R. hastata (Linnaeus) and R. subhastata (Nolcken). All stages of the two species are described and illustrated. Keys are given to separate the species in the adult and mature larval stages. Additional information on distribution (supplemented by maps), habits, and hosts is provided.

Metabolic reserves of larvae and pupae of the angoumois grain moth, Sitotroga cerealella

The Angoumois grain moth, Sitotroga cerealella, was reared in a refined medium moulded into pellets, and its larval and pupal metabolic reserves were examined. Results showed that lipids and proteins (65–86 per cent larval and pupal dry weights) formed the major reserves of both sexes and that glycogen was only a minor component. Mature female larvae weighed about 44 per cent more than males and therefore contained more reserves, especially in the form of lipids. Although the accumulation of storage materials was found to be essentially complete by the mature larval stage, their in vivo distribution changed during the pharate pupal stage. In mature larvae the haemolymph contained a high protein content and the fat body a high lipid content. Following the larval-pupal ecdysis, however, the fat body became the principal storage centre for protein, lipid, and glycogen. A thin-layer chromatographic study of the neutral lipid classes of whole larvae and pupae of both sexes revealed that both had similar compositions and that triglycerides (70–80 per cent) were the major component. Further investigation of the distribution of the neutral lipids showed that while triglycerides (85 per cent) were the principal neutral lipid class in the fat body, the haemolymph lipids were more evenly divided between triglycerides (38 per cent), diglycerides (15 per cent), free fatty acids (9 per cent), sterols (11 per cent), sterol esters (7 per cent), and hydrocarbons (20 per cent). The results are discussed in relation to the known contents and in vivo distribution of lipid, protein, and glycogen in other insects during metamorphosis.

The Biology and economic Importance of Alomya debellator (F.), a remarkable Parasite of the Swift Moth, Hepialus lupulinus (L.)

While investigating the biological control of certain Hepialids, a very interesting Ichneumonid parasite, Alomya debellator (F.) was reared from the pupae of the Swift Moth, Hepialus lupulinus (L.).The systematic position of this parasite has been thoroughly investigated and the members of the special sub-family, Metopiinae, to which it has been assigned, are characterised by the possession of only one trochanter on each foreleg. A. debellator is the sole representative of the tribe Alomyini.After extensive collecting, and a thorough search of the literature, the conclusion has been reached that the distribution of this parasite is fairly local, but its range in Great Britain and certain other European countries is wide. As a result of the present study H. lupulinus has been definitely proved to be the host of A. debellator.A fairly full account of the life-history of the parasite has been worked out, and amongst other things, a point of special interest is the arrest in development which occurs in the first-instar larva. Possible explanations of this phenomenon are discussed.The morphological and anatomical structure of the larva have been fully investigated and described, and useful diagnostic characteristics both for the primary and mature larval stages, have been discovered.The paper concludes with a discussion on the potential value of A. debellator as a factor in the control of H. lupulinus, and other allied species belonging to the genus Oncopera in Australia. It is maintained, on the evidence collected, that this parasite in some areas is probably the most important single factor of biological control. A note on the feeding habits of Hepialids, and a few remarks about the collecting of parasitised material are appended. Altogether some 7,000 specimens of H. lupulinus larvae and pupae many of which were parasitised by A. debellator were collected from the Willingham area of Cambridgeshire.