Preimaginal Instars Research Articles

An “American” silkmoth endemic to Himalayas, part I: life history and natural distribution of Antheraea compta Rothschild, 1899 (Lepidoptera, Saturniidae)

Females of the uncommon Antheraea compta Rothschild, 1899 were collected at the natural habitat in the Tibetan Sub-Himalayas, descendants of which were reared on Quercus yunnanensis (Fagaceae) successfully, with all the preimaginal instars recorded morphologically. Correlated characters revealed a close relationship between this taxon and New World Antheraea spp., suggesting more attention and protection towards this key species is necessary in the future.

Detailed Taxonomic Redescription, Distribution, and Rediscovery of the Birch Emperor Moth, Rinaca lindia (Moore 1865) (Bombycoidea: Saturniidae) from Jammu & Kashmir, India, After a 38-Year Hiatus

The genus Rinaca Walker 1855 was established with the type species Caligula simla (Westwood 1847) from Simlah (=Shimla), India. Rinaca lindia (Moore 1865) was first reported from northeast, India. During the present study, two specimens of Rinaca lindia (Moore 1865) were collected from the Babareshi region of Jammu and Kashmir (J&K), India, after a 38-year absence. The current study reports the rediscovery of Rinaca lindia (Moore 1865) J&K, India, with description of novel morphological characters and, illustration of the female genitalia. Additionally, information on the preimaginal instars, food plants and species distribution are also provided.

A review of Apha floralis species group (Lepidoptera: Eupterotidae)

5 species of the genus Apha Walker, 1855 are included here under the floralis group, three of which are described as new: A. zephyrussp. nov. (type locality: China, Yunnan, Dianceng Shan, 2.200 m), A. wittisp. nov. (type locality: China, Sichuan, Qionglai Shan, 1.400 m) and A. chloralissp. nov. (type locality: Vietnam, Cha Val, Nam Giang, Quang Nam, 546 m). Types of all species are illustrated, biology and morphology of preimaginal instars are discussed for A. kantonensis Mell, [1930] and A. chloralissp. nov. A new synonymy for Apha Walker, 1855 and Preptothauma Draudt, 1931 (including a single mislabeled species P. oxydiata Draudt, 1931), syn. nov. is established.

First Record of Aleurothrixus floccosus (Mask.) (Homoptera: Aleyrodidae) in Greece and Some Observations οn its Phenology

Aleurothrixus.floccosus was first found in Greece on citrus trees in several urban areas of East Attica, in May 1991. During the following summer and autumn, all preimaginal instars of the insect were found on sample leaves. Adults were captured on yellow sticky traps throughout this period, until mid-December. During the winter (Dec., Jan.) the majority of the population consisted of third and fourth pre-imaginal instars. For control of A. floccosus, the parasitoid Coles noacki (Hymenoptera: Aphelinidae) was imported into Greece from Spain in late 1991. The introduced populations were successfully multiplied in the insectary.

Phylogeny of Myrmeleontiformia based on larval morphology (Neuropterida: Neuroptera)

AbstractThe suborder Myrmeleontiformia is a derived lineage of lacewings (Insecta: Neuroptera) including the families Psychopsidae, Nemopteridae, Nymphidae, Ascalaphidae and Myrmeleontidae. In particular, Myrmeleontidae (antlions) are the most diverse neuropteran family, representing a conspicuous component of the insect fauna of xeric environments. We present the first detailed quantitative phylogenetic analysis of Myrmeleontiformia, based on 107 larval morphological and behavioural characters for 36 genera whose larvae are known (including at least one representative of all the subfamilies of the suborder). Four related families were used as outgroups to polarize character states. Phylogenetic analyses were conducted using both parsimony and Bayesian methods. The reconstructions resulting from our analyses corroborate the monophyly of Myrmeleontiformia. Within this clade, Psychopsidae are recovered as the sister family to all the remaining taxa. Nemopteridae (including both subfamilies Nemopterinae and Crocinae) are recovered as monophyletic and sister to the clade comprising Nymphidae + (Myrmeleontidae + Ascalaphidae). Nymphidae consist of two well‐supported clades corresponding to the subfamilies Nymphinae and Myiodactylinae. Our results suggest that Ascalaphidae may not be monophyletic, as they collapse into an unresolved polytomy under the Bayesian analysis. In addition, the recovered phylogenetic relationships diverge from the traditional classification scheme for ascalaphids. Myrmeleontidae are reconstructed as monophyletic, with the subfamilies Stilbopteryginae, Palparinae and Myrmeleontinae. We retrieved a strongly supported clade comprising taxa with a fossorial habit of the preimaginal instars, which represents a major antlion radiation, also including the monophyletic pit‐trap building species.

First documentation of early preimaginal stages of the blowfly Bengalia (Diptera: Calliphoridae)

Adult blowflies of the large tropical genus Bengalia present a peculiar predacious behaviour, while breeding habits and morphology of their preimaginal instars have remained almost entirely unknown. Light microscopy, scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) were successfully adopted for the first documentation of morphology of eggs and first instar larvae of two species of Bengalia obtained in West Bengal, India. General egg morphology resembles the ground plan known from necrophagous blowflies, with similar form and structure of median area, hatching pleats and micropyle. The structure of the chorion, with subducted central parts of hexagons, is most similar to eggs of parasitic Pollenia and Rhinophoridae. Morphology of the first instar larvae of Bengalia is entirely different from known larvae of necrophagous blowflies. The complex anterior part of the cephaloskeleton in first instar Bengalia is unique within the Calyptratae, although the pseudocephalic sensory organs resemble those found in parasitic species of Calliphoridae and Sarcophagidae with a free-living first instar larva penetrating the soil environment. However, larval biology in Bengalia and in particular the function of their unique mouthhooks need further studies with an integrated field and laboratory approach.

Larva, nymph and naiad – for accuracy's sake

Larva, nymph and naiad – for accuracy's sake

A neotype designation for the bone-skipper Centrophlebomyia anthropophaga (Diptera, Piophilidae, Thyreophorina), with a review of the Palaearctic species of Centrophlebomyia

The European bone-skippers (Diptera: Piophilidae: Thyreophorina), long considered extinct, have recently been the object of much interest by dipterists after their unexpected rediscovery. Considerable faunistic work has been done on these flies in recent years. However, some nomenclatural and taxonomic issues still require attention. A neotype is designated for Thyreophora anthropophaga Robineau-Desvoidy, 1830 (now in the genus Centrophlebomyia Hendel, 1903) to fix the identity of this nominal species. Centrophlebomyia anthropophaga is recognized as a valid species. It is described and illustrated in detail, and information on its preimaginal instars is provided for the first time. Four Palaearctic species of Centrophlebomyia are recognized and reviewed and a key is provided for their identification. Centrophlebomyia orientalis Hendel, 1907 from northern India, is removed from synonymy with Centrophlebomyia anthropophaga and recognized as a valid species of Centrophlebomyia, stat. r. The nominal genus Protothyreophora Ozerov, 1984 is considered a junior synonym of Centrophlebomyia, syn. n.

Parasitoid Niches ofEncarsia formosaandEncarsia Lycopersici(Hymenoptera: Aphelinidae) ExploitingTrialeurodes vaporariorum(Hemiptera: Aleyrodidae)

Encarsia formosa Gahan (Hymenoptera: Aphelinidae) is an aphelinid endoparasitoid of the greenhouse whitefly, Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae). Encarsia lycopersici (De Santis) is a parasitoid of the same host, but it is not known if both parasitoids occupy the same niche. In this study, the duration of development of the parasitoids, and the ability of both species to parasitize the 4 preimaginal instars of T. vaporariorum were determined. Results indicate that both E. formosa and E. lycopersici can parasitize all preimaginal instars of T. vaporariorum, and thus effectively occupy the same parasitoid niches, and they are part of the same parasitoid guild. However, variations in parasitism of the different preimaginal instars were observed. Encarsia lycopersici showed a higher parasitism rate on the first instar than on the third and fourth instars of T. vaporariorum. In contrast to E. formosa, which exhibited a lower parasitism rate on the first instar than on the fourth instar. In addition, E. lycopersici showed higher parasitism rate than E. formosa on the first instar of this host. This suggests that E. lycopersici may have a competitive advantage in exploiting the host, as it is the first to occupy it.

Paradoxical molting process in Orthezia urticae and other coccids (Arthroidignatha: Gallinsecta) with notes on systematic position of scale insects

Process of transformation in legs and antennae, which takes place in Orthezia urticae (Linnaeus, 1758) in course of molt from one instar to another, disagrees with modes of life of these instars. Each molt from one actively feeding instar to another (these are two first instars of male and all instars of female) is accompanied with deep degeneration, dedifferentiation, new differentiation and subsequent growth of each appendage; proximal segment of each appendage newly grows in an unusual inverted condition and everts only during ecdysis. Unlike this, quiescent instars of male molt like most other insects, so that molting processes do not cause immobility of their appendages. Examination of some other coccid species allows to assume that this alternation of molt modes is usual for Gallinsecta. Possibly, this character is initial for Gallinsecta and is connected with existence of leg-less feeding instars in non-related representatives. To describe processes which take place at metamorphosis, new terms for preimaginal instars of Pterygota are introduced. New taxa names PSYLLALEYRODA taxon nov. and APHIDOCOCCA taxon nov. are suggested.

Development of Immature Stages and Comparative Demography of Two Cucurbit-Attacking Fruit Flies in Reunion Island:Bactrocera cucurbitaeandDacus ciliatus(Diptera Tephritidae)

On Reunion Island, two species of Dacini, Bactrocera cucurbitae (Coquillett) and Dacus ciliatus Loew, infest 16 host plant species belonging to the family Cucurbitaceae from sea level to 1,600 m. These two species represent two primary pests of this plant family on the island. Melon fly, Bactrocera cucurbitae, and Ethiopian fruit fly, D. ciliatus, larval development was studied at four different constant temperatures (15, 20, 25, and 30°C) with three host plants (cucumber, pumpkin, and squash). Adult life histories of these two species were studied at 25°C with the three host plants. The results led to the conclusion that B. cucurbitae had a faster egg incubation time. Its preimaginal instars developed significantly faster than those of D. ciliatus independent of temperature. B. cucurbitae and D. ciliatus had similar mean preoviposition duration and egg hatching success. Fecundity was significantly higher for the melon fly on cucumber and pumpkin and lower on squash. Two distinctly different life- history patterns were evident: (1) later onset of reproduction, longer oviposition time, longer life span, and higher fecundity (B. cucurbitae) and (2) early reproduction, lower oviposition time, shorter life span, and lower fecundity (D. ciliatus). These results are useful for improving laboratory-rearing methods and for building simulation models to predict Dacini population dynamics.

Development of Immature Stages and Comparative Demography of Two Cucurbit-Attacking Fruit Flies in Reunion Island: <I>Bactrocera cucurbitae</I> and <I>Dacus ciliatus</I> (Diptera Tephritidae)

On Reunion Island, two species of Dacini, Bactrocera cucurbitae (Coquillett) and Dacus ciliatus Loew, infest 16 host plant species belonging to the family Cucurbitaceae from sea level to 1,600 m. These two species represent two primary pests of this plant family on the island. Melon fly, Bactrocera cucurbitae, and Ethiopian fruit fly, D. ciliatus, larval development was studied at four different constant temperatures (15, 20, 25, and 30 degrees C) with three host plants (cucumber, pumpkin, and squash). Adult life histories of these two species were studied at 25 degrees C with the three host plants. The results led to the conclusion that B. cucurbitae had a faster egg incubation time. Its preimaginal instars developed significantly faster than those of D. ciliatus independent of temperature. B. cucurbitae and D. ciliatus had similar mean preoviposition duration and egg hatching success. Fecundity was significantly higher for the melon fly on cucumber and pumpkin and lower on squash. Two distinctly different life- history patterns were evident: (1) later onset of reproduction, longer oviposition time, longer life span, and higher fecundity (B. cucurbitae) and (2) early reproduction, lower oviposition time, shorter life span, and lower fecundity (D. ciliatus). These results are useful for improving laboratory-rearing methods and for building simulation models to predict Dacini population dynamics.

Morphology of the preimaginal stages of the African emperor moth Bunaeopsis licharbas (Maassen and Weyding): Phylogenetically informative characters within the Saturniinae (Lepidoptera: Saturniidae)

The current classification of African representatives of the family Saturniidae is largely unsatisfactory and needs to be revised following a proper and rigorous phylogenetic analysis. In this regard, the use of characters of preimaginal stages in phylogeny reconstruction was already emphasized in the literature; however, few details are known about the morphology of the eggs, larvae, and pupae of these moths. To fill this gap and to provide a preliminary basis for further phylogenetic studies, the early stages of Bunaeopsis licharbas, a member of the tribe Bunaeini within the Saturniinae, are described. Egg chorionic ultrastructure, chaetotaxy of the larva in every instar, and morphology of the pupa are described and illustrated. A total of 22 previously overlooked characters was found and their potential phylogenetic significance is discussed in the light of a comparative study which includes a large set of representatives of all five tribes in the subfamily. Until further phylogenetic analyses, some characters are considered to be potential synapomorphies supporting, in particular, the monophyly of the tribe Bunaeini, the close relationship between this tribe and part of the Urotini, as well as the existence of an Afrotropical lineage within the Saturniinae uniting the tribes Bunaeini, Urotini, and Micragonini. In a group of moths whose preimaginal instars are among the best known within the Lepidoptera, the unexpected, and relatively high number of potentially informative characters found by the present study stresses the value of minute and exhaustive descriptive studies to make use of morphological characters available for phylogenetic studies.

Seasonal adaptations of green lacewings (Neuroptera: Chrysopidae)

Seasonal adaptations of green lacewings (Neuroptera: Chrysopidae) and their role in the control of aphid populations are discussed. The chrysopids of temperate zones face seasonal changes and must escape cyclic adversity. One way is via the number of broods per year. Most green lacewings are facultatively multivoltine, with the succession of generations most often regulated by photomediated diapause. Others are univoltine and some extend their life-cycle to two years in cold or dry environments. Synchronization is an important feature of seasonality, often starting in spring. In univoltine species, it is sometimes the result of subtle mechanisms, such as double contradictory signals (short plus long day lengths) for reactivation in spring, or a multi-receptivity of the preimaginal instars to photoperiod throughout a year, combined with photo-controlled and synchronized egg laying in late summer. Only one North American species is known to enter a surnumerary food-mediated diapause in summer. Every postembryonic instar may undergo diapause depending on the species. The timing and impact of the spring resumption in aphid consumption depends on their overwintering strategy.As far is known, chrysopids are intolerant of freezing, but their supercooling points are low enough to enable them to endure hard frost. The numbers of overwintering specimens of green lacewings in the field depend on the structure of the assemblages in the previous growing season. Three examples are used to show that the overwintering populations are different in the different biotopes and dependent on the way the dominant species overwinter. Artificial chambers proposed for overwintering adults of common green lacewings afford them protection during diapause and enhance their predatory efficiency in spring.

Larval morphology of Heterogynis (Lepidoptera: Heterogynidae)

The external morphology and chaetotaxy of the larvae of Heterogynidae (Lepidoptera) are described in order to provide information of potential phylogenetic value for the reconstruction of the systematic relationships within the Zygaenoidea. The most outstanding characteristics of heterogynid larvae are their modified habitus during diapause, the presence of an epipharyngeal lamella, the shape of the prothoracic shield, the presence in the first instar of an organ of unknown function on the middorsum of the mesothorax ("Chapman's organ"), the absence of V2, V3 and Va on the head, the absence of V1 on the prothorax and the presence of two primary setae on the inner side of the proleg, the last trait representing an autapomorphy of the family. A number of possible synapomorphies with the Zygaenidae (e.g. presence of cuticular cavities) suggest a close relationship between these two families, but other larval and adult traits are shared only with the "Phaudinae" and limacodid-group families of the Zygaenoidea (viz. absence of V1 on the prothorax with the "Phaudinae", reduced proboscis and absence of ocelli with them all). Nevertheless, a lack of knowledge of the preimaginal instars of species from some zygaenoid families, and of the homology and polarity of given characters of groups within and outside the Zygaenoidea, hamper a thorough comparison of larvae.

Eugymnopeza braueri (Diptera, Tachinidae) as parasitoid of Blaps gibba (Coleoptera, Tenebrionidae), with description of the preimaginal instars

Eugymnopeza braueri, a tachinid known up to now only from the type pair reared from an adult carabid, was rediscovered in Central Italy, where it was bred from adult Blaps gibba (Coleoptera, Tenebrionidae). The first available data on the biology and behaviour of this parasitoid are provided and discussed. A redescription of the species is given, complete with the first description of the preimaginal instars, data on the range of adult variation, and notes on the taxonomy of the genus.

Neurogenesis in adult insect mushroom bodies.

The occurrence of neurogenesis in mushroom bodies of adult insects belonging to several orthopteroid and coleopteran families is described. Using injections of 5-bromo, T2'-deoxyuridine, we showed that neuroblasts, which are progenitors of Kenyon cells during preimaginal instars, continue to divide in adult Acheta domesticus. Their progeny constitute a central column in mushroom body cortices of 3-week-old females. Other Gryllidae, Gryllus bimaculatus and Gryllomorpha dalmatina, show the same pattern of neuroblast activity and migration of their progeny. Immunocytochemical staining of glial cells failed to reveal any immunoreactivity, either in proliferating regions or in the resulting cells. In another orthopteran, Locusta migratoria, discrete clusters of cells, located dorsolateral to the Kenyon cells, incorporated 5-bromo, 2'-deoxyuridine, but we could not detect any neuronal progeny migrating to the mushroom body cortices. These cells were strongly labeled with an antiglial antibody, indicating that the replicating cells are glioblasts rather than neuroblasts. In Periplaneta americana (Dictyoptera), cells replicating their DNA were similarly shown to immunoreact with glial antibodies. In contrast, three coleopterans (Tenebrio molitor, Zophobas species, Harmonia axyridis) have two large neuroblasts located in the middle of the mushroom body cortices. These produce cells which migrate within the group of Kenyon cells, their nuclei having the same shape and size as those of surrounding Kenyon cells. In adult insects, neurogenesis in mushroom bodies occurs in Gryllidae and several coleopteran families, but could not be demonstrated in Dictyoptera and Acrididae. Its occurrence and distribution raise the issue of unexpected plasticity in the adult insect brain.

Statistical Model of Crop Losses Caused by Maize Stem Borers (Lepidoptera: Noctuidae, Pyralidae) in Côte d'Ivoire

Six experiments were conducted in the savanna and forest areas of Cote d'Ivoire to study the influence of stem borers on maize crop yield components and production. Statistical models showed the effect of the oldest preimaginal instars of 2 stem borers, Eldana saccharina Walker (Pyralidae) and Busseola fusca (Fuller) (Noctuidae). Plant destruction was mainly caused by early attack of B. fusca . Attack by both borers on or about the 60th d after emergence induced plant sterility. Stem borers had no direct effect on number of grains per cob-carrying plant: the level of this yield component was set according to the level of the previously determined components through a compensation phenomenon. The last yield component, average weight of grain, decreased with attack by E. saccharina occurring on or about the 80th d after emergence. Effects of borer aggregation, maize variety, and maize streak virus incidence were studied. The statistical model of crop loss, which explains 81.7% of the variation in yield, was validated from the results of 3 trials that were not included in the regression analysis. It enables one to estimate accurately crop losses in most of Cote d'Ivoire with only 2 samplings during the growing season, on the 40th and 80th d after emergence.

The population dynamics of the white peach scale and its parasitoids in a mulberry orchard in Campania, Italy

AbstractWhite peach scale, Pseudaulacaspis pentagona (Targioni-Tozzetti) (Homiptera: Diaspididae), was a serious pest of mulberry until it was the subject of a successful biological control programme in Italy at the turn of the century. Since the 1950s it has returned as a sporadic pest of commercial peach and, more recently, kiwi fruit orchards. We sampled white peach scale in an unmanaged mulberry orchard in coastal Campania over a 17 month period to measure the impact, relative abundance, and interactions of the parasitoids in the absence of pesticides. Sampled scales were dissected, and the immature stages of the parasitoids identified. Mean densities of white peach scale varied with month from 3–15/9 cm2 on primary (interior) branches and 15–100/1.5–2 m secondary (exterior) branch. The generalist ectoparasitoid Aphytis proclia (Walker) was most abundant, followed by two specialist endoparasitoids, Encarsia berlesei (Howard) and Pteroptrix orientalis (Silvestri) (all Hymenoptera: Aphelinidae). Primary parasitism also varied with month from 25–85% on primary branches and 20–90% on secondary branches. Parasitism on primary branches was inversely density-dependent, but was densityindependent on secondary branches. Low levels of superparasitism were generally observed in E. berlesei and P. orientalis (0–6%), but were higher in A. proclia (0–21%). Multiple parasitism of hosts by E. berlesei and A. proclia was fairly common (up to 24% of E. berlesei immatures were found sharing a host with A. proclia), and A. proclia was the probable winner of within-host competitions. The hyperparasitoid Azotus perspeciosus (Girault) (Hymenoptera: Aphelinidae) parasitized late pre-imaginal instars of all three primary parasitoid species. There was no significant difference in hyperparasitism of the three primary parasitoid species, but the rate of hyperparasitism was inversely related to the total density of primary parasitoids.

Ontogenetic studies of flight initiation in Locusta: Wind response of an identified interneurone (TCG)

The tritocerebral commissure giant (TCG) wind-sensitive interneurone is involved in initiation and maintenance of flight in adult locusts. In this paper we study this interneurone in the imago and non-flying larval instars. Cobalt fills show that the TCG establishes its adult morphology by the first larval instar. An accompanying axon, apparently representing the peculiar tritocerebral commissure “dwarf” (TCD) is present, too, at least for the last preimaginal instars. Physiological tests show similar responses of the TCG to wind stimuli in the 4th, 5th instar and adult stages. Spike activity, however, is usually higher in adult compared to larval instars. It is possible that all interneurones, involved in adult-specific motor patterns (such as flight), are present in preimaginal stages and can be activated independently of the function of the final motor system.