Worker Larvae Research Articles

Supplementary studies on ant larvae: Myrmicinae (Hymenoptera: Formicidae).

Supplementary studies on ant larvae: Myrmicinae (Hymenoptera: Formicidae).

Comparative Morphogenic and toxicity Studies on the Effect of Pesticides on Honeybee Brood

SummaryToxicological and morphogenic studies were carried out to determine the potential hazard to honeybee (Apis mellifera) brood of pesticides which have contaminated the food in the hive. Pesticides were added to the food in individual brood cells using a microsyringe. Precise qualitative and quantitative monitoring of the pesticide effect throughout the brood cycle and into the adult stage was possible. Each pesticide was tested at three or more dosages, on worker larvae 1–2, 3–4 and 5–6 days old, for effects on mortality and on amorphogenic changes. Linear regressions were used to construct dosage-mortality curves. Results indicated that mortality may occur at any stage of larval, prepupal or pupal development and to emerging or newly emerged adults. Some adults that survived were light in colour, and of light weight, and often had deformed wings or no wings; they were weak and died soon after eclosion. Of the 31 pesticides tested by the morphogenic technique, six were eventually non-toxic, 19 were s...

Changes in Tissue Polyploidization During Development of Worker, Queen, Haploid and Diploid Drone Honeybees

SummaryCytophotometric measurements were made of DNA content in nuclei stained by the Feulgen method and direct measurements of length and width of nuclei were also made. There was an enormous increase of polyploidization in larvae 4 days old, from an average of 110 n in workers through 112 n and 200 n in haploid and diploid drones to 320 n in queens. Mean DNA content in nuclei of haploid drone, diploid drone, worker and queen larvae were in the ratios 1·0: 1·7: 1·1: 3·1. Since diploids began with twice as much DNA as haploids, polyploidization was about twice as fast in haploid drone larvae as in worker ones and only a little slower in diploid drone larvae than in haploids. A drastic decrease of polyploidization was found in early pupae from 5 n in haploid drones and workers to 8 n in diploid drones and queens. Some increase of average polyploidization was found in imagines, from 7 n in haploid drones through 8 n in diploid drones and workers to 10 n in queens. Relative polyploidization in imagines as de...

Glucose/Fructose Ratio in the Food of Honeybee Larvae During Caste Differentiation

SummaryThe contents of glucose, fructose and sucrose were determined in the natural diets of male and female honeybee (Apis mellifera) larvae reared under various conditions. Glucose was predominant during the early larval stages of workers and drones, but fructose became the main sugar component in the food of older larvae. In the diet of queen larvae, glucose remained the main sugar component throughout the larval period.The abundance of food supplied to worker larvae after a broodless period was characterized by an extremely low glucose content.The significance for caste development of these marked proportional differences in glucose and fructose in larval diets is discussed.

Ecdysteroid production during caste differentiation in larvae of the ant, Plagiolepis pygmaea

ABSTRACT. Variations in ecdysteroids were measured by radio‐immunoassay in worker‐biased and queen‐biased larvae of the ant Plagiolepis pygmaea Latr. (Hymenoptera, Formicidae) during late larval development, i.e. from the end of winter diapause up to the prepupal period. At the end of diapause, larvae are bipotential and, depending on culture conditions, can become either queens or workers. Ecdysteroid profiles revealed that there are striking differences between the two castes: worker larvae showed high titres during their development, queen larvae had low titres over the same period.

Increasing the Acceptance of Transplanted Honeybee Worker Larvae by Queen-Cell Starter Colonies with the use of Partially Drawn Artificial Queen Cups

SummaryChanges in dimensions of artificial queen cups containing transplanted worker honeybee larvae (Apis mellifera) were followed statistically as the cups were drawn by nurse bees for 7–26 h, and percentage acceptance of larvae was correlated with cup size (6 mm or 12 mm) and form (‘undrawn’ or ‘drawn’). Dimensions of empty 6-mm cups of 5·97 ± 0·029 mm internal length, 8·07 ± 0·025 mm opening diameter and 3·00 ± 0·018 mm maximum base-wall thickness were altered by queenless workers over a 24-h period to 3·71 ± 0·025 mm length, 5·47 ± 0·055 mm opening diameter, and 5·75 ± 0·054 mm base-wall thickness. Empty 12-mm cups of 11·97 ± 0·029 mm length, 8·87 ± 0·027 mm opening diameter and 3·10 ± 0·031 mm base-wall thickness were similarly modified to produce corresponding dimensions of 8·89 ± 0·033 mm, 5·34 ± 0·057 mm and 5·28 ± 0·059 mm.Percentage acceptance of transplanted worker larvae 24 h old for 4 types of cups was: 6-mm undrawn, 10·9%; 6-mm drawn, 48·6%; 12-mm undrawn, 63·9%; 12-mm drawn, 78·6%. Percentage acceptance for larvae transplanted into 12-mm cells drawn for different periods was: 7 h, 50%; 14 h, 70%; 21 h, 75%; 26 h, 87·5%. It was concluded that the drawing procedure significantly improved the acceptability of artificial cups, and that any special property acquired from the cups being drawn was less effective in promoting acceptance than an increase in cell length of 8 mm but more effective than an increase of 3 mm.

Acceptance of Transplanted Worker Larvae by Queen-Cell Starter Colonies

SummaryQueen honeybees (Apis mellifera) were reared using undrawn artificial queen cups of 12-mm internal length and 9-mm opening diameter and different conditions of cell priming and larval positioning or orientation. Percentage acceptance (PA) differed significantly (P<0·015) with type of priming, being 55% without royal jelly (RJ) priming, 75% with 8 μl pure RJ and 85% with 8 μl dilute RJ). There was no significant difference in acceptance of larvae transplanted to cells with a candy seal over the entrance (PA = 73%) and larvae placed in a cell without a seal (PA = 80%). The association between larval position and transplant acceptance was significant at P = 0·01. For larvae located centrally, PA = 75–81% with non-inversion of larvae (controls), 50% with complete inversion and 33% with 90° rotation to bring the dorsal surface of the larva into contact with the royal jelly. For larvae located on the cell wall, PA = 24%; the host bees remodelled the queen cup around each larva to produce a new cell at 45...

Seasonal changes in glycogen and trehalose concentration during larval development of worker honey bees ( Apis mellifera)

1. 1. The changes in glycogen and trehalose concentration in honey bee worker larvae during development in different seasons of the year have been studied. 2. 2. The changes in glycogen and trehalose concentration are faster in the summer larvae (May) than in the winter larvae (September). 3. 3. The results are discussed from the aspect of the role of the neurohormones in regulation of the carbohydrate metabolism.

Instars and polymorphism of castes inMacrotermes michaelseni (Isoptera, Macrotermitinae)

Biometric studies and physiological investigations made it possible to propose a scheme of post-embryonic development and polymorphism inMacrotermes michaelseni. An instar hitherto undescribed has been found and designated fourth instar. This instar is comprised of female larvae which moult into major presoldiers. Minor presoldiers moult from some of the third instar female larvae which are morphologically identical to the female worker larvae. Three instars were detected in the case of both minor and major worker development. Workers and soldiers are sterile castes. Nymphs develop from first instar larvae and moult through five instars before imaginal moult.

Imaginal wing discs in larvae of the soldier caste of Pheidole bicarinata vinelandica Forel (Hymenoptera : Formicidae)

In Pheidole bicarinata vinelandica, soldier larvae have prominent mesothoracic wing discs. Imaginal wing discs are suppressed in minor worker larvae. In soldiers, wing discs appear abruptly late in larvae life and are unusually large when compared with wing discs in worker larvae of other ant genera. Once development has been initiated, wing discs of soldier larvae grow at a rate comparable to soldier leg discs. The dynamics of development of soldier wing discs differ fundamentally from those of other holometabolous insects, worker ants and Pheidole bicarinata queens. This unusual developmental pattern may provide a clue to the physiological basis and timing of soldier determination.

Rearing of Honeybee Larvae in Vitro: Effect of Yeast Extract on Queen Differentiation

SummaryFirst instar honeybee larvae (60 per test) were reared in vitro under controlled conditions. The yield of adults was 70–80%, and 10% were queens if royal jelly was used, diluted 1:1 with water and supplemented with D-glucose and D-fructose (2·5 g in 40 g test food). Difco bacto-yeast extract (0·5 g) or charcoal-treated extract (1 g) were added to this basic food. At the same rate of survival, larval growth and queen determination were considerably increased (30% and 50% queens). The charcoal-treated yeast extract was separated by gel chromatography into a salt and an amino acid fraction. The salt component reduced the yield of adults to about 50%, but it increased larval growth rate and differentiation (20% queens). The amino acid fraction reduced the rate of survival to about 30%; growth rate and caste differentiation were below those with the basic food. Addition of both fractions gave the same result as addition of charcoal-treated yeast extract. The average gain in weight of 4th to 5th instar larvae was related to the degree of caste differentiation. For routine tests, use of a mixture of royal jelly, water, sugar and yeast extract yields more than 30% queens, at a survival rate from 1st instar worker larvae near 80%, under controlled in vitro conditions.

Influence of juvenile hormone on gravity orientation in the female honeybee larva (Apis mellifera L.)

The influence of juvenile hormone (JH) on the behaviour of the female honeybee larva (Apis mellifera L.) during ultimate orientation was investigated. The effect of gravity was tested in natural and artificial cells by changing their inclination and by rotation experiments. In queen larvae ultimate orientation (final orientation at the outset of metamorphosis) is controlled by gravity. They display a positive geotaxis under all experimental conditions tested even in reversed natural cells. However, ultimate orientation of worker larvae in natural cells is not affected by gravity. A positive geotactic preference is shown only in long artificial cells whereas larvae in short cells respond indifferently to gravity. The texture of the cell ending has a directing effect. The geotactic indifference is replaced by a positive geotaxis in worker larvae treated with JH-I or JH-III during the third day of larval development (Fig. 5). In JH-treated larvae the evaluation of gravity equals that of queen larvae (Fig. 7). A positive geotaxis is evoked even in individuals that develop rather weak adult queenlike characteristics (Table 2). The juvenile hormone titer not only controls the differentiation of morphological and anatomical caste characteristics but also affects the orientation behaviour of the spinning larva.

Internal anatomy of the fourth instar larva of the imported fire ant, Solenopsis invicta buren (Hymenoptera : Formicidae)

We describe the internal anatomy of fourth instar larvae of the economically important and much studied imported fire ant, Solenopsis invicta Buren to form the basis for studies on their physiology and role in the social organization in the colony. The muscular foregut opens into a blind midgut which fills much of the body cavity. Four malpighian tubules enter the small intestine which opens to a thin-walled rectum bearing 3 rectal pads. The well-developed labial gland system includes a pair of thin-walled reservoirs. The corpora allata are posteroventral to the brain and lateral to the esophagus with anatomical differences between reproductive and worker larvae. The fat body is well developed and contains numerous urocytes. Oenocytes are arranged laterally in dorsoventral rows. The pericardial cells are arranged in parallel rows lateral to the heart. Lateral tracheal trunks connect the 10 pairs of spiracles and 4 anterior tracheal commissures. The body musculature is arranged in groups, including dorsal and ventral longitudinals, dorsoventrals, and lateral and ventral obliques. The antennal, leg, wing (in reproductives) and gonopodal imaginal discs are present. The gonopodal discs are distinctly different in male and female reproductive larvae. The anatomy of reproductive and early instar larvae are compared with the anatomy of fourth instar larvae. The anatomy of larvae of the imported fire ant is compared to that of larvae of other ants and the honey bee. These data reveal the simplification of some organ systems prevalent in larvae of the more sedentary Hymenoptera.

Evidence and Action of Cannibalism Substance inApis Cerana Indica

SummaryOf 26 colonies investigated, 11 were headed by Apis cerana indica queens sibling-mated to several drones. The queens produced diploid drone larvae in about 25% of worker cells. Altogether, 9734 eggs were individually recorded, and the survival rate of brood was monitored on successive days. All the results showed that diploid drone larvae of Apis cerana are not eaten by nurse bees during the first day of larval life as in Apis mellifera. In unfavourable environmental conditions some were eaten in place of worker larvae. Many diploid drone larvae were eaten in their second day of life, but some were reared even until the fourth day, and in favourable conditions some probably reach the adult stage. This suggests that A. cerana diploid drone larvae secrete much less cannibalism substance at the beginning of larval life, but later produce it for a much longer period of life, than do A. mellifera diploid drones.This is another specific difference between the two species of Apis, indicating an earlier ev...

Events following queen removal in colonies of Africanized honeybees in South America

The timing of queen rearing and swarming are described after queens were removed from colonies of Africanized bees. New queens were reared from newly hatched to three day old worker larvae, many of which were moved in the egg or newly eclosed larval stages by workers into newly constructed queen cells. Mortality of worker eggs and larvae following dequeening was high, averaging 50%. When new queens emerged, swarms issued from two-thirds of the colonies. This process of queen replacement and queen-loss swarming differs from that of reproductive swarming in the lack of preparation before queen loss, longer queenless interval, lack of correlation between number of swarms and sealed brood area or number of queen cells, and lack of Congestion in colonies when swarms issued.

Precocene II is no Anti-Juvenile Hormone in the Honey Bee, Apis mellifera

The effect of precocene II on development of the honey bee, Apis mellifera, was studied in vitro. One- to two-day-old worker larvae (body weight 0.5 - 1.0 mg) were removed from the colonies, reared on royal jelly-yeast extract, and after 24 h were topically applied with different amounts (5 - 75 μg/larva) of precocene II. Toxicity was observed only with precocene doses of 50 μg/larva and more. The larval weight-gains declined with the increase of doses. The acetone-treated control had better survival and weight-gain as compared to the no-treatment control. The larval and pu­pal periods in the treated larvae remained unchanged as compared to the controls. The possibility of precocene acting as an antifeedant is discussed.

The role of exogenous JH I, JH III and Anti-JH (precocene II) on queen induction of 4.5-day-old worker honey bee larvae

Worker larvae at an age of 4½ days were fed one of several mixtures of reconstituted royal jelly adjusted to a refractive index of 1.3825 and supplemented with JH I, JH III or Anti-JH (precocene II). In addition, juvenile hormone was topically applied to larvae of the same age. It was readily apparent that caste induction is concentration-dependent and that 4஽-day-old worker larvae can still develop into queens under laboratory conditions, providing that they have not stopped feeding or can be induced to commence feeding again. These findings are contrary to the general belief that queen induction is not possible after a socalled sensitive period of 3–3½ days. Queens resulted only from honey bee larvae exposed to royal jelly containing 1 μg of JH I. In addition, oral application at this concentration resulted in the only case in which the normal mean weights of worker honey bees were exceeded. All other concentrations of juvenile hormone were not sufficient to initiate queen induction, although its lower concentration may have influenced the production of intercastes. Precocene II did not play a role in queen induction and it also did not interfere with the growth of developing larvae or adults. In addition, the lack of malformations in honey bees treated with precocene II indicates that the use of such a compound as a control agent in insect populations will probably not be detrimental to honey bee larvae that are at least 4½ days old. However, large doses of precocene will quickly kill most 3½-day-old honey bee larvae. The evidence presented here clearly indicates that caste determination is regulated by the endocrine system in honey bee larvae. Food intake in honey bee larvae may well be regulated by the endocrine system. Thus, an apparently inhibited corpus allatum (C.A.) could be reactivated by food intake coupled with juvenile hormone. The food intake restriction that worker larvae normally encounter in the hive probably results in a cessation of C.A. activity. The increase in food intake by queen larvae, on the other hand, carries an increase in growth and accompanying morphological changes necessary for queen development. This concept may also explain the development of intercastes encountered in in vitro studies. Only those larvae that follow a normal food intake sequence, i.e. moderate during the first 3–4 days or so, will develop into queens. Conversely, those larvae that take in too much food during the early portion of development may achieve incomplete development of the neurosecretory system and, thus, develop into intercastes.

Identification of Juvenile Hormone 3 as the Only JH Homolog in All Developmental Stages of the Honey Bee

Total extracts from worker larvae, pupae, and adults of the honey bee were analyzed for their juvenile hormone contents. Using the 10-(heptafluorobutyrate)-11-methoxy derivative, the hormone was isolated in yields of 20 - 50% in nanogram quantities as calculated from isotope dilution and from gas chromatography with electron capture detection. The procedure is sensitive enough to isolate the juvenile hormone out of 1-4 grams insect material for qualitative and quanti­tative analysis. Only juvenile hormone 3 (methyl 10.11-epoxy-2-trans, 6-trans-farnesoate) could be detected as the predominant hormone homolog of all the three developmental stages. Juvenile hormone 1 (methyl 3.11-dimethyl-10.11-as-epoxy-7-ethyl-2-trans, 6-trans-tridecadienoate) could, if at all, only be identified in trace amounts, and juvenile hormone 2 was completely absent in all stages. This first systematic analysis of a hymenopteran insect shows a modulation of JH3 titre between zero and 2 ng per gram body weight during imaginal development and a rather constant JH3 titre near 10 ng per gram in the adult.

Queen differentiation and mortality after topical application of different juvenile hormone analogues on worker larvae of the honey bee (Apis mellifera L.)

Queen differentiation and mortality after topical application of different juvenile hormone analogues on worker larvae of the honey bee (Apis mellifera L.)

A Comparative Study of the Endocrine System of the Honey Bee Larvae under Normal and Experimental Conditions

Abstract The endocrine system of the honey bee (Apis mellifera L.) has been studied morphologically through post-embryonic development with several histological techniques. Marked differences in the structure of the neurosecretory complex of queen and worker larvae have been observed during larval stages. In queen larvae, morphogenesis of the neurosecretory cells, their axons and the formation of the chiasma takes place during end of 2nd and beginning of 3rd, in the workers at beginning of 4th larval instar. Stainable neurosecretory material was found in queen larvae at the beginning, in worker larvae at the end of 4th instar. In early larval stages, the corpora allata are more active in the queen. During initial 3 - 5 days of larval development the gland volume is reduced in both castes. After 36 to 48 hours of endocrine retardation, the glands become active again. The same histological effects are found under experimental conditions, where worker larvae of 2nd instar were reared in the incubator on basic food, Royal Jelly and with topically applied juvenile hormone I.