Black Larvae Research Articles

Studies on the abundance, biomass and vertical distribution of larvae and pupae of black flies (Simuliidae, Diptera) on plants of the Grabia river, Poland

Studies on black flies larvae and pupae on water plants demonstrated an abundance, often exceeding 100 000 individuals per m2, in the lotic region of the Grabia river. The biomass of larvae and pupae on water plants constitutes occasionally over 90% of the biomass of all water invertebrates. Aquatic larval stages of Simuliidae occupy preferentially most superficially located plant parts.

A role of juvenile hormone in pupal development of the tobacco hornworm, Manduca sexta

In the tobacco hornworm, Manduca sexta, as in other Lepidoptera, allatectomy of the penultimate instar larva causes precocious pupation. When allatectomized immediately after the initiation of the moult to the fifth instar, the resultant black larvae begin metamorphosis one day sooner than controls. They form pupae which show precocious adult differentiation of the eye and at the base of the forewings, nonextension and nonfusion of the pupal proboscis, and shortened pupal wings. Such adultoid characters appear if the larvae are allatectomized any time in the fifth instar up to the end of the wandering phase. Application of juvenile hormone (either JH I or a mimic, epoxygeranylsesamole) just before the onset of ocellar retraction at the beginning of the prepupal period prevents this precocious adult differentiation (the 50% effective dose of JH I is 3.3 ng/animal).

Histological and chemical observations of the black larva mutant in Anopheles albimanus (Diptera: Culicidae).

Phase contrast and electron microscopy of the lethal mutant black larva of Anopheles albimanus Wiedemann showed an excessive accumulation of a black granular substance in the cytoplasm of the fat body cells. Analyses for lipids and glycogen indicated that the mutants contain as much lipid and glycogen as the normals.

THE GENETICS OF BLACK LARVA, AN AUTOSOMAL RECESSIVE LETHAL MUTATION LOCATED ON CHROMOSOME 3 IN THE MOSQUITO ANOPHELES ALBIMANUS

A spontaneous autosomal recessive lethal mutation, black larva (bl), producing black pigmented larvae that die during the 4th larval instar has been discovered in the mosquito Anopheles albimanus Wiedemann. Genetic investigations using two Y-autosome translocations and a 3rd chromosome dominant marker, St indicate that bl is located on chromosome 3 at a distance of 15 map units from St.

Differences in Light Reactions of Larvae of the Armyworm, Leucania separata Walker, in relation to their Phase Status

THE coloration, rate of development and behaviour of the larvae of the armyworm, Leucania separata Walker, differ when the larvae are subjected to different degrees of crowding during development. Active black larvae appear in crowded conditions and develop more rapidly, feed more voraciously, and tolerate starvation and less palatable food-plants better than the sluggish pale larvae that appear in uncrowded conditions. This phenomenon has much in common with phase polymorphism in locusts1.

Insect population quality and meteorological conditions

Recent studies on the rice stem borer,CHILO SUPPRESSALIS Walker,are presented as an example of some results of spatial variation in population quality.Local differences in the seasonal prevalence of this insect are basically related to the alternative occurrence of a short life-cycle strain which has a strong tendency to multivoltinism, and a long life-cycle strain which has a deep intensity of diapause along the climatic line. Qualitative change in a local population is illustrated by some effects of phase polymorphism in the armyworm,LEUCANIA SEPARATA Walker. The active black larvae that appear in crowded populations and the sluggish pale larvae that appear in sparse populations differ in their daily rhythmic activity and in their resistance to starvation at different humidities.

Transmission of Sacbrood Disease to Individual Honey Bee Larvae1

Sacbrood disease was transmitted experimentally to honey bee, Apis mellifera L. larvae of all ages from hatching to 4 days old by inoculating food in the larval cell with various filtrates of diseased larvae with a micrometer syringe. Up to 90% of the larvae died with symptoms typical of sacbrood. Microscopic examination of dead larvae confirmed the absence of bacteria. Four percent or less of control larvae treated with an equal volume of heat-sterilized filtrate or of water or left undisturbed developed sacbrood. Filtrates prepared from white (recently dead), brown (intermediate stage of decay), or black (late stage of decay) larvae which had died of sacbrood produced successively smaller percentages of infection. A severely infected comb placed in the brood nest of a normal colony did not spread the infection.

Factors Involved in Differential Susceptibility of Corn Earworm Larvae to DDT1

Full-grown corm earworms, Heliothis zea (Boddie), require more than 1,000 times as much DDT on a weight basis as small larvae in order to obtain LD-50 values for topical applications in acetone, Injected DDT in acetone is only slightly less effective on large larvae than on small ones, Chemical and radiometrie analysis showed that lack of penetration by DDT through the integument of the large larvae was the chief factor causing the increase in LD-50 values. Addition of nonvolatile oils to the topically applied material increases the effectiveness of DDT to the larger larvae. Tests with different colored larvae indicate that light yellow larvae are approximately twice as susceptible as the dark red or black larvae.

NOTES ON THE LARVA OF PRIOCYCLA ARMATARTA Herr. Sch

Specimens of a nearly black geometric larva which afterwards proved to belong to this species, were taken last year on the 15th of July on currant and gooseberry bushes, on which they were feeding. They fed on the foliage of the black currant as well as of the red, and in fact seemed to prefer it.When first taken they answered to the following description:Length 45 in. Body tapering a little anteriorly, thicker on middle and hind segments.