Full-grown Larvae Research Articles

Free amino acids of the haemolymph of the cotton leaf-worm,Spodoptera littoralis Boisduval full-grown larvae, infected with nuclear-polyhedrosis virus

Free amino acids in the haemolymph ofSpodoptera littoralis full-grown larvae infected with a nuclearpolyhedrosis virus were compared with those in the haemolymph of normal insects. Amino acids were separated by 2-dimensional paper chromatography and quantified colorimetrically. Most of the amino acids in the haemolymph of diseased full-grown larvae decreased markedly in concentration but proline, lysine, aspartic acid and histidine occurred in greater concentration in the haemolymph of diseased full-grown larvae than in the haemolymph of healthy insects.

Life History and Population Dynamics of Heteroplectron americanum12

The generation time for most individuals of a Heteroplectron americanum population in a Delaware coastal plain stream is one yr. Full-grown male and female larvae attain a mean dry weight of 6.5 and 16.1 mg, respectively, by mid-Apr. Pupation period is ca. 21 days and adults emerge and oviposit from mid-May to mid-June. Gelatinous egg masses were found on submerged branches and logs or attached to tree roots and mosses on the stream bank both above and below the water line. Laboratory studies indicate that fluctuations of water levels after oviposition may cause embryonic mortality due to desiccation and in some years delay the escape of larvae from egg masses isolated on stream banks. First-instar larvae appear in June and most larvae attain the final instar by Dec. A one-yr generation time was confirmed by following the growth of larvae that hatched from egg masses introduced into a stream void of this species.

Larva of the caddisfly Ceraclea dissimilis (Stephens) (Trichoptera: Leptoceridae)

AbstractThe full-grown larva of Ceraclea dissimilis (Stephens, 1836) is described and its morphology compared with other known species of this genus in NW Europe.

Biological and systematic studies of developmental stages inAphytis(Hymenoptera: Aphelinidae): III. Meconia as a possible systematic tool inAphytis

Abstract does not appear. First page follows. Introduction This paper is the third in a series of biological and systematic investigations of developmental characteristics in the genus Aphytis Howard (Hymenoptera: Aphelinidae). The systematics of Aphytis has been based almost entirely on imaginal morphology, which often does not show strong interspecific differences. Other than pupal pigmentation, which has proved useful in certain cases (DeBach, 1959), characteristics of developmental stages have not been utilized as systematic tools in this genus. The first paper in this series (Rosen and Eliraz, 1978) presented the developmental history of the generotype of Aphytis, A. chilensis Howard, as a basic background study, and included detailed descriptions of the various developmental stages. The second paper (Eliraz and Rosen, 1978) presented a comparative study of larval characteristics of several species in five species-groups, and the present paper reports the results of a comparative investigation of meconial pellets in several species of Aphytis. In most parasitic Hymenoptera, fecal material accumulates in the midgut throughout the larval feeding period, and is expelled, in the form of a meconium or meconial pellets, only when the blind midgut becomes linked with the proctodaeum prior to pupation (Hagen, 1964). The meconia of numerous parasitic Hymenoptera have been occasionally described, but have not been used much as a diagnostic character for identification or classification. (Flanders (1942)) briefly discussed the meconia of several species, and concluded that “although larval meconium is of little, if any, value in identifying the species of a genus, it may be of value in the recognition of the species which compose the parasitic fauna of a host in the field.” More recently, Viggiani (1969) has shown that the shape of the meconia may be used to separate certain eulophid parasites of leaf-mining insects. All the known species of Aphytis are ectoparasites of armored scale insects, developing externally on the bodies of their hosts beneath the covering scale (Rosen and DeBach, 1976). Their distinctive meconial pellets are very conspicuous under the scale, and have been noted by some of the early workers. (Quayle (1910)), for instance, described the meconia of A. chrysomphali (Mercet) [erroneously recorded by him as A. diaspidis (Howard)] as follows: “Always accompanying the pupa are from six to ten black or dark brown torpedo like bodies .125 mm. long and .055 mm. broad, which are evacuations from the digestive tract and are expelled by the larva preliminary to pupation.” Similarly, (Taylor (1935)), in his description of (presumably) the same species, wrote: “No excretion occurs until the larva is ready to pupate. The excrement is in the form of small, shiny, black or brown bodies, bluntly pointed at each end—and usually 5 or 6 in number, and uniform in shape. They are deposited inside the scale, round the posterior end of the larva, and are so conspicuous in Aspidiotus destructor that they are very useful as a means of detecting the full-grown larvae or pupae in situ.”

Changes in the blood-brain barrier of the central nervous system in the blowfly during development, with special reference to the formation and disaggregation of gap and tight junctions: I. Larval development

In the central nervous system (CNS) of full-grown larvae of the blowfly Calliphora erythrocephala, the glial-ensheathed nerve cells are completely surrounded by a layer of perineurial cells which form a “blood-brain barrier” between the circulating haemolymph and the CNS. A variety of intercellular junctions, including gap and tight junctions, are found between adjacent perineurial cells and some also between apposing glial cells; these have been characterized by freeze-fracturing as well as by tracer studies and analysis of thin sections. They are found not to be present between such cells in the undifferentiated CNS in the newly hatched larvae, nor are the nerve cells encompassed by glial cells; ionic lanthanum can penetrate to the axonal surfaces at this stage. However, over the 5 days of larval growth and development the glial cells produce attentuated cytoplasmic processes that ensheath the nerve cells, and the perineurium is formed; junctional complexes are assembled and a larval blood-brain barrier is produced which excludes tracers. Freeze-fracture preparations suggest that the inverted gap junctions which develop have done so by migration of individual intramembranous EF particles to form, at first, linear arrays and small clusters and, ultimately, macular aggregations in the perineurium; these lie between the undulating rows of PF particles forming the septate junctions. These septate junctions are formed by the organization of arrays of PF particles into multiple rows. Extensive PF particles fusing into ridges with EF grooves to form perineurial “tight” junctions are also observed, seemingly in the process of development; entry of exogenous lanthanum followed by its exclusion parallels the completion of ridge formation. These ridges are simple linear arrays of particles which may be discontinuous, lying in parallel with one another and the surface. Clustered particle arrays as well as scattered short ridges on the axonal PF, however, appear to be present unchanged throughout larval life; their role may therefore be associated with neural membrane function although there are suggestions that some may form axo-glial junctions. This is the first report on the lateral migration of intramembranous particles as the mode of formation of gap junctions in the nervous system of an invertebrate.

Variation in the Susceptibility of African Acacia (Leguminosae) to Seed Beetle Attack

Summary. This paper is concerned with the apparent infestation anomalies which exist amongst various Acacia species, based on our present knowledge, and the need for further work to highlight the part played by beetles in the ecology of the various species. For those who have not seen either the adults or the damage caused by the larvae it may be useful to describe briefly the life-cycle. In most instances the female selects a ripening pod or, rarely, an already ripened one which has dehisced, and lays an egg, which (depending on the species concerned) is either a round or ovoid flattened structure closely adhering to the surface and held there by a secretion placed over it by the female. Alternatively the egg may be cylindrical and held to the pod by strands of ropelike secretion. The young larva on hatching bores through the pod wall and wanders around until it finds a suitable developing seed. It burrows into this ripening seed and hollows out a chamber, which it enlarges as it grows. When full- grown, it eats away the cotyledon and epidermal layer until a thin circular 'window' of very thin testa is left. The larva then pupates within its feeding chamber and the adult emerges by gnawing at the thin 'window' and pushing its way out. In a few species the full-grown larva leaves the seed and pod through a small circular hole, drops to the ground on a thread of silk and forms a pupal cocoon in the soil under the tree or shrub.

Hormones for the control of livestock arthropods. Effects of 2 juvenile hormone analogues against the screwworm Cochliomyia hominivorax (Coquerel), in vitro and in infested bovine hosts.

Two juvenile hormone analogues, ( E )-6,7-epoxyl-( p -ethylphenoxy)-3,7-dimethyl-2-octene and isopropyl ( E, E )11-methoxy-3,7,11-trimethyl-2,4-dodeca = dienoate, inhibited the emergence of the screwworm, Cochliomyia hominivorax (Coquerel), when they were applied topically to full-grown larvae and pupae and when they were incorporated within the larval diet. Two bovines that were sprayed with a 0.1% concentration of each analogue and then infested with larvae of the screwworms displayed no changes in serum chemistry, and adults emerged from the wound-reared larvae.

Hemocytes of Malacosoma disstria Hübner (Lepidoptera: Lasiocampidae): morphology of the cells in fresh blood and after cultivation in vitro.

Hemocytes of the forest tent caterpillar, Malacosoma disstria, were examined in blood films prepared from full-grown larvae, and in tissue cultures of blood cells maintained by serial passage in vitro up to 148 times. In fresh larval blood, five categories of hemocytes were identified as follows: prohemocytes, plasmatocytes, granular hemocytes, spherule cells, and oenocytoids. The granular hemocytes were the most numerous by far. In the tissue cultures, only three categories were found, prohemocytes, plasmatocytes, and granular hemocytes. and here the granular hemocytes were the least numerous. Each category in culture was autonomous and able to divide. Hemocytes in cultures were larger than the cells in fresh blood, and were mostly round.

Studies on the sterile male technique as a means of control of Adoxophyes orana (Lepidopt., Tortricidae). 3. An evaluation of competitiveness of laboratory-reared moths

Mating competitiveness of an inbred irradiated, mass reared strain ofAdoxophyes was approximately half that of males collected as nearly fullgrown larvae or pupae in the field. This reduction was not caused by irradiation effects. No indications of genetic inferiority of the laboratory strain were found since the difference in competitiveness disappeared after wild moths were reared for one generation on artificial diet. A diet effect on competitiveness seems most likely.

The oxygen consumption of mayfly (Ephemeroptera) and stonefly (Plecoptera) larvae at different oxygen concentration

1. The aim of this investigation was to elucidate how four acquatic insect larvae, from different habitats and having different respiratory organs or types of respiratory regulation, react to a lowered oxygen concentration, and how their oxygen consumption is affected. The species investigated were the stoneflies Taeniopteryx nebulosa, Diura nanseni and Nemoura cincerea and the mayfly Cloeon dipterum. 2. The measurements were performed in a respiratory apparatus of open, flowing-water type. Its design is shown in Fig. 1. Water of known oxygen concentration was allowed to flow past the experimental larvae. The oxygen consumption of the larvae was calculated from the lowering of the oxygen concentration in which ensued. 3. The water used in the experiments was standardized, so that the electrode had the necessary stability (conductivity 470 micromhos/cm). The calcium ion was excluded in order to prevent the precipitation of CaCO3 in the electrode capillary. 4. A large variation in the values of oxygen consumption was found as seen in Fig. 2–5. The reason for that is a corresponding variation in the motor activity of the experimental animals. 5. The physiological reasons for the general form of the curves A and C in Fig. 2–5 are discussed. The curves A and C represent oxygen consumption of the larvae at different degrees of stimulation, entailing different levels of motor activity. Curve A represents intentinally activated animals, curve C non-activated, motionless animals. The curves A and C are boundary curves corresponding to a sort of scope for activity of the animals. Over this scope area a series of curves of the same form could in principal be construed, representing different degrees of stimulation. 6. Within a certain oxygen concentration interval a motor activation was observed caused by a reduced oxygen concentration. The result of that activation can be seen in Fig. 2–5 as a zone with no or very few oxygen consumption values between curve C and D. The more easily activated the species is, the broader the zone will be. Cloen has the most narrow zone and was observed to be less activated than the other species. 7. Small larvae of Cloen (2–4 mm and 42–6 mm) and Nemoura (2–4 mm) showed clearly a greater ability to take up oxygen at low oxygen concentrations than full-grown larvae (see Fig. 8 and 9). 8. The critical point on the curve representing mean oxygen consumption as a function of oxygen concentrations was found to be at 2–5 mg O2/1 for Taeniopteryx and Diura, at 2.2–2.5 mg O2/1 for Cloeon, and at about 2–7 mg O2/1 for Nemoura. The values refer to 8°. Cloeon is the species which is exposed to the greatest variations in oxygen concentration in its natural environment. 9. No influence on the oxygen consumption of starvation for 4 to 5 days was found. No difference between the oxygen consumption values obtained in the presence or in the absence of calcium ions could be observed during the experiments (Fig. 10, 11). 10. The basic picture obtained in this investigation is a set of oxygen consumption values scattered between a curve connecting highest values obtained and a curve of the standard metabolism together with a zone in which the larvae are activated by reduced oxygen concentrations. This picture is presumed to be general in aquatic animals with a well developed motor activity.

Regeneration in transplanted halves of male genital disks and its influence upon duration of development inEphestia kühniella Z.

Herold's organs from full-grown (T7) larvae ofEphestia kühniella were longitudinally bisected and both halves transplanted into a single T7-host. Three classes of results were observed after metamorphosis of the hosts: I. each of the two halves regenerated a complete genital organ, II. only one of the two halves regenerated, III. none of the two halves regenerated the missing parts (cf. Kroeger, 1959, Dewes, 1972).The onset of pupation of the hosts was delayed when one half (average delay 1.7 days) or both halves (average delay 2.5 days) underwent regeneration. No delay was observed in controls or when no regeneration took place (Table 1).

Seasonal Abundance and Natural Mortality of Winthemia manducae (Diptera: Tachinidae) and Degree of Parasitization of Its Host, the Tobacco Hornworm1

Adults from the overwintering generation of Winthemia manducae Sabrosky & DeLoach emerged from May 8 to 31, and produced 3 full and a partial 4th generation on Mandnca sexta (Johannsen). Adults were present until the last week in October, and overwintering larvae were produced beginning in late August. Mortalities for stages in the insectary were 3.7% for eggs, 16.9% for larvae before entering the host, 10.8% for larvae within the host, about 1.3% each for full-grown larvae and pupae, and 1.4% for adults before flying; about 64.6% of the eggs produced adults. Mortality in field cages in the soil was about the same except for a mortality of 27.6% as the adults tunneled up to the soil surface. A physiological reaction of the host killed many larvae when only 1, 2, or 3 entered a host. Intraspecific competition among larvae within the host caused a decrease in size and an increase in mortality as the number per host increased. Competitive parasitism on host larvae previously parasitized by Apanteles congregatus (Say) caused a loss to the overwintering generation of W. manducae estimated at 58-74%. W. manducae killed an estimated 7.59% of the population of host pupae in 1962 and 6.61% in 1963.

Parasites of Oberea brevis (Coleoptera: Lamiidae)1

The girdle beetle, Oberea brevis Swederus, is one of the important insect pests of soybean, Glycine max (L.) in India. It has damaged up to 29% of soybean plants in experimental plantings at Jabalpur, Madhya Pradesh, in Central India, with average annual damage of ca. 13% (Kapoor et al. 1971). The female deposits a single egg in the petiole of a leaf near the top of the plant. The larva feeds into the petiole and on down into the stem, hollowing out the inside of the entire stem. Only 1 larva is present in each infested plant. The mature larva girdles the stem from the inside near the middle of the plant at 2 locations ca. 25 mm apart. The full-grown larva prepares a fibrous cocoon and pupates within the girdled portion of the stem. The plant usually breaks at both points of girdling and the severed section containing the cocoon along with the upper portion of the plant falls to the ground in September or October during the 1–½ months before soybean harvest. The adult emerges from the girdled section in 8–11 days. However, most larvae enter diapause within the cocoon and they remain in diapause until June of the following year when monsoon rains initiate pupation and adult emergence.

Life History of Winthemia manducae (Diptera: Tachinidae), a Parasite of the Tobacco Hornworm1

Winthemia manducae Sabrosky & DeLoach was collected from all tobacco-growing areas of North Carolina but only as far south as Florence, S. C. It was reared from pupae of Manduca sexta (Johannson) and M. quinquemaculata (Haworth). The egg and larva are described. Macrotype eggs were laid on the integument of large last-stadial host larvae, in numbers from 1 to 125 but averaged about 8 per host. Eggs noramlly did not hatch until the host prepupa molted in its cell in the soil, at which time the parasitic larvae entered the host pupa before its integument hardened. The egg stage usually lasted about 7 days, but little hatching occurred unless the host pupated. Multiple parasitism involving Apanteles congregatus (Say) prevented the egg from hatching because A. congregatus killed the host before it pupated. The larvae of W. manducae fed inside the host pupa for 7 days then left the host and pupated within 2 days, largely in the upper 3 inches of the soil. Pupation was greatly delayed, probably by bacterial action, when full-grown larvae were confined with the dead host. Adults emerged 16 days later, the males emerging first. Females began ovipositing in 4 days. Thus a generation required about 37 days in midsummer. The sex ratio of reared adults was 1:1, but males were not found in the field with the females. Larvae required 233 and pupae 500 day-degrees for development above the lower threshold of 8.3°C. A threshold between 18 and 24°C was detected below which pupation of mature larvae was greatly delayed. Only full-grown larvae were observed to overwinter and these were tolerant to experimental exposure to subfreezing temperatures. The egg appeared to be the stage most susceptible to submersion and the pupa the stage most susceptible to high temperature under field conditions.

The effect of nutrition on the susceptibility of larvae of Trogoderma granarium Everts (Coleoptera, Dermestidae) to certain fumigants

The effect of ten natural powdered foods on the susceptibility of full-grown larvae of Trogoderma granarium Everts to four common fumigants was evaluated. In general, methyl bromide was found to be the most toxic fumigant against T. granarium from all foods, followed in a decreasing order of toxicity by ethylene dibromide, carbon disulphide and ethylene dichloride. The insects reared on pulses were, in general, less susceptible to the fumigants than those from cereals. Excepting methyl bromide, where insects from groundnuts were least susceptible, insects from Phaseolus mungo were, as a rule, the least susceptible to the fumigants as compared to those from other foods. The insects from Sorghum vulgare were nearly 3·3 times more susceptible to ethylene dichloride, and those from high extraction wheat flour 1·7 times more susceptible to carbon disulphide, than those from P. mungo. Insects from groundnuts were 4·9 times more susceptible to ethylene dibromide, while insects from wheat flour plus 5% brewer's yeast were nearly 1·5 times more susceptible to methyl bromide, than those from P. mungo. No correlation between the age or body weight of the insects and the ld 50 values of the fumigants could be established.

Notes on the Biology of Tiphia berbereti (Hymenoptera: Tiphiidae), a Parasite of Larval Phyllophaga anxia1,2

The life cycle of a new tiphiid, Tiphia berbereti Allen, is described. T. berbereti larvae were found parasitizing Phyllophaga anxia (LeConte) (Coleoptera: Scarabaeidae) larvae in hay meadows in northcentral Nebraska. There appears to be 1 generation per year with the overwintering stage being the full-grown larva enclosed in a cocoon.

Biology of Cosmobaris amertcana Casey1, a Weevil Attacking Sugarbeets2

Adult and larval feeding on the petioles of sugarbeets, Beta vulgaris L., by Cosmobaris americana Casey, a weevil that attacks betaceous crops and several weeds, chiefly members of Amaranthaceae and Compositae, interfered with the translocation processes; larval feeding also caused injured petioles to wither and die. In the Northwest, adults first appeared in May and lived 3-4 months; eggs were first deposited in feeding pits in late May, and eggs started hatching in June. The larvae developed slowly, but became full grown in August; those that were not full grown by October died during the winter. Full-grown larvae overwintered in old feeding galleries in weed hosts and only rarely in sugarbeets; pupae and adults were both produced mostly in May. There was 1 generation. The suitability of various plants for completion of the weevil's life cycle depended largely on the moisture in the parenchymous tissues mined by the larvae. Larvae feeding in watery petioles of sugarbeets drowned in decomposing tissues or starved after the injured part dried and died; larvae feeding in woody stems of weeds were not so affected.

THE LARVAE OF PRISTIPHORA ACIDOVALVA (HYMENOPTERA: TENTHREDINIDAE) IN ONTARIO

AbstractThe full-grown larva of Pristiphora acidovalva Wong, a newly recognized sawfly on willow, is described and the occurrence of the species in Ontario is discussed.

ON THE BIOLOGY OF HYLASTES NIGRINUS (COLEOPTERA: SCOLYTIDAE) IN WESTERN OREGON

AbstractDuring 1965–66, studies of a large population of Hylastes nigrinus (Mannerheim), breeding in roots and stumps of Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, killed by Dendroctonus pseudotsugae Hopkins in 1964, were conducted on Marys Peak in western Oregon, near the city of Corvallis.The emergence and flight of H. nigrinus were at their maximum in late April and early May. Emergence was strongly influenced by temperature and seldom occurred at temperatures below 61° and above 75°F. Flight behavior was strongly affected by light intensity, peaking at intensities between 300 and 1200 ft-c during the late afternoon or early evening. Maturation feeding was found to take place on small roots of dead, old Douglas-fir and on roots of young Douglas-fir weakened after replanting. Egg-galleries, normally running parallel with the grain of the wood, were initiated in June and eggs were kid from the end of that month. Five larval instars were found. Adult beetles as well as full-grown larvae overwintered in the galleries. The majority of the population completed development in 1 year.The larval population of H. nigrinus was heavily decimated during the fall of 1965 by larvae of the dipteron fly, Medetera vidua Wheeler (Doliohopodidae). Emergence data are presented for scolytid, curculionid, cerambycid, and buprestid species competing with H. nigrinus in stumps or roots.

Wechselseitige Beeinflussung des Entwicklungsablaufs bei entomophagen Parasiten und deren Wirten, erörtert am Beispiel vonColeophora-Arten(Lep., Coleophoridae) undUrophora-Arten(Dipt., Trypetidae)

This study compares the host-parasite relation betweenColeophora ? alcyonipennella andAgathis sp., on the one hand, andUrophora spp. andEurytoma tibialis, on the other hand.Coleophora-Agathis is a striking example for a host-parasite relation where the larval development of the parasitoid is controlled by the endocrine system of the host, which results in an optimal synchronization between the life-cycles of the moth and its specialized Braconid parasite. Attempts to obtain adultAgathis during the winter season for the biological control ofColeophora in New Zealand have met with considerable difficulties because of the hormonal dependence of the parasite on the host. The rearing and the transfer of adult parasites was not possible until the diapause of the host could be ended experimentally. In the complexUrophora-E. tibialis the parasite larvae interferes with the hormonal system controlling the development of the host. In hibernating generations ofUrophora spp. the parasite induces a premature onset of the process of pupation of the host, but consumes the latter when it has formed its puparium. In both hosts the hormonal reactivation of the diapausing full-grown larva results in a change of the position of the larva in its case or gall, before the morphogenetic changes involved in pupation take place. The larvae ofAgathis as well asE. tibialis do not kill their hosts until the latter have reversed their position within the case or gall. In this way the emergence ofAgathis from the case ofColeophora and the emergence ofE. tibialis from the gall ofUrophora is facilitated.