Amount Of Brood Research Articles

Human Factors Facilitating the Spread of a Parasitic Honey Bee in South Africa

Workers of the honey bee subspecies Apis mellifera capensis (Eschscholtz) produce female offspring by thelytokous parthenogenesis and can parasitize colonies of other subspecies. In 1990, translocation of 400 colonies of A. m. capensis into the distribution area of A. m. scutellata by a commercial beekeeper triggered a dramatic parasitic phenomenon. Parasitized colonies died within a few months of infestation, and this resulted in the loss of tens of thousands of colonies by commercial beekeepers in the A. m. scutellata range in South Africa. To deal with the problem and to identify methods that would limit the impact of the social parasite, we investigated the link between beekeeping management and severity of parasitic infestations in terms of colony mortality and productivity. We demonstrate that colonies from apiaries subjected to migrations are very susceptible to infestation and consequently show dramatic mortality. Their productivity is also inferior to sedentary colonies and those in isolated apiaries in terms of honey yield and brood quantity. Furthermore, by concentrating hives in small areas and often in the vicinity of other beekeepers, cross-infestations can easily occur. This can undermine previously parasite-free beekeeping businesses. As a result of our surveys, we propose beekeeping practices based on locally trapped bees, reduced migration, and better control of parasite spread, thus promoting the conservation of these pollinators. If followed by all the South African beekeepers, these measures should limit the spread of the parasite until it is eliminated within a few years, after which full migratory beekeeping practices could resume.

Human Factors Facilitating the Spread of a Parasitic Honey Bee in South Africa

Workers of the honey bee subspecies Apis mellifera capensis (Eschscholtz) produce female offspring by thelytokous parthenogenesis and can parasitize colonies of other subspecies. In 1990, translocation of 400 colonies of A. m. capensis into the distribution area of A. m. scutellata by a commercial beekeeper triggered a dramatic parasitic phenomenon. Parasitized colonies died within a few months of infestation, and this resulted in the loss of tens of thousands of colonies by commercial beekeepers in the A. m. scutellata range in South Africa. To deal with the problem and to identify methods that would limit the impact of the social parasite, we investigated the link between beekeeping management and severity of parasitic infestations in terms of colony mortality and productivity. We demonstrate that colonies from apiaries subjected to migrations are very susceptible to infestation and consequently show dramatic mortality. Their productivity is also inferior to sedentary colonies and those in isolated apiaries in terms of honey yield and brood quantity. Furthermore, by concentrating hives in small areas and often in the vicinity of other beekeepers, cross-infestations can easily occur. This can undermine previously parasite-free beekeeping businesses. As a result of our surveys, we propose beekeeping practices based on locally trapped bees, reduced migration, and better control of parasite spread, thus promoting the conservation of these pollinators. If followed by all the South African beekeepers, these measures should limit the spread of the parasite until it is eliminated within a few years, after which full migratory beekeeping practices could resume.

High Levels of Cotton Pollen Collection Observed for Honey Bees (Hymenoptera: Apidae) in South-Central Louisiana

Honey bees, Apis mellifera L., typically reject pollen of upland cotton, Gossypium hirsutum L., as a resource. This study evaluated the potential of stimulating bees for enhanced pollen collection in overcoming this rejection. In 2002, 16 equal-sized colonies of each of two commercial stocks of bees (Italian and Russian) were placed adjacent to cotton fields at Rosedale, LA, and manipulated so that half of the colonies of each bee type had high stimulus to collect pollen and half had low stimulus. Differential stimuli were achieved by interchanging combs having relatively large amounts of brood with combs having pollen, between colonies of the two treatment groups (i.e., high stimulus colonies donated pollen and received brood, whereas low stimulus colonies had the converse). Stimulus manipulations resulted in more general pollen collection, but not cotton pollen collection, in the high stimulus group on days 1 and 6 after treatment. Foraging responses of the treatment groups equalized by 11 days after treatment. Collection of cotton pollen was minimal (≤2% of all foragers) during this period and was not affected by stimulus treatment. Italian colonies had greater total foraging activity and pollen collection effort on day 1 after treatment, but the bee types foraged similarly on days 6 and 11. There were no interactions of the effects of stimulus treatment and bee type. After the treatment effects dissipated (by day 11, 5 August 2002), collection of cotton pollen increased substantially. Approximately one-fourth of all foragers and 80% of pollen collectors carried cotton pollen pellets during a 2-wk period in midAugust. In 2004, observations of 11 colonies at a cotton planting near Fordoche, LA, showed that foragers again carried notable amounts of cotton pollen during the middle of bloom but little cotton pollen earlier or later. At the peak, a mean of 26% of pollen loads of all colonies and 50–59% of pollen in two colonies were of cotton. The reason for this unexpected willingness to gather cotton pollen is undetermined and warrants investigation because of the potential importance for cotton pollination by honey bees.

The nest architecture of the ant, Camponotus socius

The architecture of subterranean nests of the ant Camponotus socius was studied from casts of plaster or metal. Twenty-four such casts are illustrated using stereo pairs of images. After study, plaster casts were dissolved to retrieve the workers embedded in them, providing a census of the ants that excavated the nest. Nests were up to 60 cm deep, and were composed of descending shafts connecting up to about 10 horizontal chambers. Nest volume ranged up to almost 800 cm3 and total chamber area up to almost 500 cm2. Both volume and area were closely and positively related to the number of workers in the nest. Nest enlargement occurred through the simultaneous enlargement of chambers, deepening of the nest and addition of more chambers. Chamber enlargement contributed most to nest growth. Chambers near the surface were elongate and tunnel-like, while deeper chambers were more compact in outline. As chambers were enlarged, their outlines became more complex and lobed. Workers were polymorphic with clearly distinguishable minor and major workers. The headwidth of minors averaged 1.45 to 1.65 mm, and that of majors 2.30 to 2.80 mm. The mean headwidth of minors increased significantly as the proportion of major workers increased, but the trend of major headwidths fell short of significance. The numerical proportion of majors ranged from 3% to 38% and averaged 15% of the workers, while their biomass proportion ranged from 10% to 75%, averaging about 50%. The queen was recovered in 6 of the 14 plaster nests, suggesting that the average colony of this polydomous species has 2.3 nests. Because of the lateness of the season when casts were made (October), only two nests contained significant amounts of brood. The possible functional roles of nest architecture in ants are discussed.

The nest architecture of the ant, Camponotus socius.

The architecture of subterranean nests of the ant Camponotus socius was studied from casts of plaster or metal. Twenty-four such casts are illustrated using stereo pairs of images. After study, plaster casts were dissolved to retrieve the workers embedded in them, providing a census of the ants that excavated the nest. Nests were up to 60 cm deep, and were composed of descending shafts connecting up to about 10 horizontal chambers. Nest volume ranged up to almost 800 cm and total chamber area up to almost 500 cm. Both volume and area were closely and positively related to the number of workers in the nest. Nest enlargement occurred through the simultaneous enlargement of chambers, deepening of the nest and addition of more chambers. Chamber enlargement contributed most to nest growth. Chambers near the surface were elongate and tunnel-like, while deeper chambers were more compact in outline. As chambers were enlarged, their outlines became more complex and lobed. Workers were polymorphic with clearly distinguishable minor and major workers. The headwidth of minors averaged 1.45 to 1.65 mm, and that of majors 2.30 to 2.80 mm. The mean headwidth of minors increased significantly as the proportion of major workers increased, but the trend of major headwidths fell short of significance. The numerical proportion of majors ranged from 3% to 38% and averaged 15% of the workers, while their biomass proportion ranged from 10% to 75%, averaging about 50%. The queen was recovered in 6 of the 14 plaster nests, suggesting that the average colony of this polydomous species has 2.3 nests. Because of the lateness of the season when casts were made (October), only two nests contained significant amounts of brood. The possible functional roles of nest architecture in ants are discussed.

Influence of brood, vent screening, and time of year on honey bee (Hymenoptera: Apidae) pollination and fruit quality of greenhouse tomatoes.

Greenhouse tomatoes, Lycopersicon esculentum Miller (Solanaceae), are autogamous, but facilitated pollination results in increased fruit size and set. Previous research examining honey bee pollination in greenhouse tomato crops established that fruit quality resulting from honey bee visitation is often comparable to bumble bees (Bombus spp.) and significantly better than in flowers that receive no facilitated pollination. However, management alternatives have not been studied to improve tomato fruit quality when honey bees are the only pollination option available for the high-value greenhouse industry. We investigated whether the quantity of brood (eggs, larvae, and pupae) in a honey bee colony in the winter and screening on greenhouse vents in the summer would encourage honey bee foraging on tomato flowers. We also established the influence of time of year on the potential for honey bees to be effective pollinating agents. We constructed small honey bee colonies full of naive forager bees with either two frames of brood ("brood colonies") or two empty frames ("no-brood") and compared total fruit set and the number of tomato seeds resulting from fruit potentially visited by honey bees in each of these treatments to bagged flowers that received no facilitated pollination. There was no significant difference in the quality of fruit resulting from honey bees from "brood" and "no-brood" colonies. However, these fruits produced significantly more seeds than bagged flowers restricted from facilitated pollination. Honey bees from brood and no-brood colonies also resulted in 98% fruit set compared with 80% fruit set in bagged flowers that received no facilitated pollination. During the summer, the number of seeds per fruit did not differ significantly between unbagged flowers potentially visited by honey bees in screened greenhouses and unscreened greenhouses and bagged flowers that received no facilitated pollination. However, time of year did have a significant influence on the quality of fruit produced by honey bees compared with flowers that received no facilitated pollination, because no difference in seed number was observed between the treatments after mid-April. The results from this study demonstrate that the management of brood levels and vent screening cannot be used to improve the quality of fruit resulting from honey bee pollination and that honey bees can be a feasible greenhouse pollination alternative only during the winter.

Effects of clothianidin on Bombus impatiens (Hymenoptera: Apidae) colony health and foraging ability.

We conducted laboratory experiments to investigate the lethal and sublethal effects of clothianidin on bumble bee, Bombus impatiens Cresson, colony health and foraging ability. Bumble bee colonies were exposed to 6 ppb clothianidin, representing the highest residue levels found in field studies on pollen, and a higher dose of 36 ppb clothianidin in pollen. Clothianidin did not effect pollen consumption, newly emerged worker weights, amount of brood or the number of workers, males, and queens at either dose. The foraging ability of worker bees tested on an artificial array of complex flowers also did not differ among treatments. These results suggest that clothianidin residues found in seed-treated canola and possibly other crops will not adversely affect the health of bumble bee colonies or the foraging ability of workers.

RELATIONSHIPS BETWEEN PHENOTYPE, MATING BEHAVIOR, AND FITNESS OF QUEENS IN THE ANT LASIUS NIGER

Considerable attention has focused on why females of many species mate with several males. For social hymenopteran insects, efforts have primarily concentrated on determining whether multiple mating increases colony performance due to the increased genetic diversity. Most of these studies are correlative because it is difficult or impossible to experimentally mate queens in most species. Thus, the positive associations found between multiple paternity and colony fitness in some cases may not be due to direct effects of genetic diversity but could, in theory, arise from high-quality queens having more mates. Here we show that in the ant Lasius niger variation in the number of matings covaries with queen phenotype. Young queens that were heavier at the time of the mating flight were significantly more likely to mate with several males. As a result, heavier queens stored more sperm. The initial weight of queens was significantly associated with the probability of surviving mating flights during the two years of the study, with queens of intermediate weight having the highest across-year survival. Queen initial weight was also significantly and positively associated with the quantity of brood at the time of the first worker eclosion as well as colony productivity at the time of hibernation. By contrast, there was little evidence for a positive effect of the number of matings on colony performance when the effect of mate number and queen initial weight were considered simultaneously.

Periodic mass flights of the giant honey bee, Apis dorsata

SUMMARYThis article reports observations conducted in Rampur, Chitwan, Nepal, during March-April and October—December 1999. 14 continuous observations were carried out from 08:00 h to 19:00 h on 6 to 48 nests of Apis dorsata in different seasonal conditions. Detailed observations of 410 periodic mass flights (PMFs) were recorded. During the day, A. dorsata workers made 0–6 PMFs, each of which lasted about 5 min. Worker bees from 52% to 100% of colonies performed PMFs within a day. About 55% of colonies performed a second PMF and about 25% a third flight. Percentage of colonies performing PMFs and the number of PMF activities per colony were highest when the largest amount of brood was present in colonies. In cool conditions (average temp. 20.9 °C), PMF activity lasted between 4 and 7 h and peaked around noontime. In warm conditions (average 26–28 °C), the duration of this activity extended up to 9 h with no PMFs at noon. In hot conditions (average 33.6 °C), the duration of PMF activities was extended to 11 h; however, flights were made only in the morning between 8:00 h and 10:00 h and in the evening between 16:00 h and 18:00 h, with a 6-h gap of no PMF in between. The duration and distribution of PMF activities during the day were correlated with average daily temperatures. On the warmest days, more PMF activities (63–67%) were performed after the hottest midday hours were over. We suggest that both the short duration of 5 min of PMF activity as well as the distribution of PMFs during the day are strategies to avoid thermal disruption of the protective bee curtain.

How raiders of the slave-making ant Polyergus rufescens (Hymenoptera Formicidae) evaluate a target host nest

Raiding activity is a crucial task of the slave-making ant Polyergus rufescens, during which colonies of the host species are attacked in order to pillage the resident brood and obtain a slave work force. The features of the host colony influencing the organization of P. rufescens raids were investigated by laboratory experiments which allow the analysis of behavioural patterns unlikely to be observed in the field. In particular, the mechanism of evaluation of the target nest was studied. By providing P. rufescens the possibility to sack different host nests, we found that a greater number of raiders was recruited when a greater amount of brood was present inside the attacked nest. The hypotheses that raiding activity is performed in accordance with the “optimal foraging theory” and that raiders prefer to sack colonies where the residents are more aggressive are discussed.

Effects of Nosema bombi and its treatment fumagillin on bumble bee ( Bombus occidentalis) colonies

We examined the effects of Nosema bombi (Microsporidia: Nosematidae) on colonies of bumble bees, Bombus occidentalis Greene (Hymenoptera: Apidae), used to pollinate tomatoes in commercial greenhouses. We assessed methods of detecting N. bombi and tested the effectiveness of fumagillin to control this parasite. N. bombi did not affect adult population size or amount of brood in B. occidentalis colonies. Fumagillin was not effective against N. bombi at the doses we tested, and frass samples did not provide accurate estimates of the intensity of N. bombi infections. The number of N. bombi spores per bee was highly variable among bumble bees within colonies, and accurate estimates could only be obtained by sampling a large proportion of bees in each colony. Therefore, whole bee and frass sampling is useful for determining if N. bombi is present or absent, but not for obtaining accurate estimates of the intensity of N. bombi infections.

Effects of Novel Pesticides on Bumble Bee (Hymenoptera: Apidae) Colony Health and Foraging Ability

Abstract Two experiments were conducted testing for lethal and sublethal effects of the transgenic proteins Cry1Ac and chitinase, and the chemical seed and soil treatment imidacloprid on bumble bees (Bombus occidentalis Greene and B. impatiens Cresson, Hymenoptera: Apidae). In the first experiment, B. occidentalis colonies were exposed to realistic residue levels of Cry1Ac, chitinase, and imidacloprid found in pollen. There were no effects on pollen consumption, bumble bee worker weights, colony size, amount of brood, or the number of queens and males produced. In the second experiment, using B. impatiens, we tested the effects of Cry1Ac and two levels of imidacloprid. Similar colony health measures were collected as in the first experiment, but in addition foraging ability of individual bees was tested on complex artificial flowers. There were no differences in colony characteristics among treatments. However, bees in the high-imidacloprid treatment had longer handling times on the complex flowers than b...

Managing Honey Bees (Hymenoptera: Apidae) for Greenhouse Tomato Pollination

Although commercially reared colonies of bumble bees (Bombus sp.) are the primary pollinator world-wide for greenhouse tomatoes (Lycopersicon esculentum Mill.) previous research indicates that honey bees (Apis mellifera L.) might be a feasible alternative or supplement to bumble bee pollination. However, management methods for honey bee greenhouse tomato pollination scarcely have been explored. We 1) tested the effect of initial amounts of brood on colony population size and flight activity in screened greenhouses during the winter, and 2) compared foraging from colonies with brood used within screened and unscreened greenhouses during the summer. Brood rearing was maintained at low levels in both brood and no-brood colonies after 21 d during the winter, and emerging honey bees from both treatments had significantly lower weights than bees from outdoor colonies. Honey bee flight activity throughout the day and over the 21 d in the greenhouse was not influenced by initial brood level. In our summer experiment, brood production in screened greenhouses neared zero after 21 d but higher levels of brood were reared in unscreened greenhouses with access to outside forage. Flower visitation measured throughout the day and over the 21 d the colonies were in the greenhouse was not influenced by screening treatment. An economic analysis indicated that managing honey bees for greenhouse tomato pollination would be financially viable for both beekeepers and growers. We conclude that honey bees can be successfully managed for greenhouse tomato pollination in both screened and unscreened greenhouses if the foraging force is maintained by replacing colonies every 3 wk.

Evaluation of three concentrations of tebufenpyrad for the control of Varroa destructor (Acari: Varroidae).

We evaluated three concentrations of tebufenpyrad (17.5, 15 and 12.5%) in strip formulations for controlling varroa mites, Varroa destructor Anderson and Trueman (2000), in honey bee colonies. We also included colonies treated with Apistan, CheckMite+, and untreated colonies in our evaluation. The three concentrations we evaluated reduced varroa populations but also reduced the amount of brood and adult bees when compared with untreated colonies and colonies treated with Apistan or CheckMite+. Alternative delivery methods, lower concentrations of tebufenpyrad, and the evaluation of related compounds are logical next steps in evaluating the varroacidal potential of tebufenpyrad and related compounds.

The within-nest behaviour of honeybee pollen foragers in colonies with a high or low need for pollen

Numerous studies have documented that honeybee colonies can rapidly adjust the number of foragers collecting pollen in response to changes in quantities of brood, pollen and nectar in the nest. However, few studies have examined the behaviour of individual pollen foragers while in the nest between trips. Thus, little is known about how a pollen forager actually assesses its colony's needs. To understand this process better, we observed the behaviour of 319 pollen foragers while in their nests between foraging trips. We observed foragers in two types of nest environments: one with a relatively high need for pollen and one with a relatively low need for pollen. Foragers performed as many as 14 activities during two phases demarcated by the unloading of pollen loads. They inspected empty cells and cells with pollen, and performed the waggle dance at higher relative frequencies before unloading ( P≤ 0.0004 each act). They antennated nestmates, autogroomed and received trophallaxis at higher relative frequencies after unloading ( P≤ 0.0004 each act). All acts were performed both before and after unloading, but not always by each bee. Pollen foragers discriminated among cells based on cell contents in two contexts. First, they inspected cells already containing pollen more often than expected by chance. Second, their pattern of inspecting cells with different contents differed from their pattern of unloading pollen loads in those cells. Pollen foragers performed 42.3±4.6% (least square mean±SE) of preunloading inspection events on empty cells, but unloaded in them only 19.9±4.6% of the time. They performed 42.2±4.6% of preunloading inspection events on cells already containing pollen, but unloaded in them 79.4±4.6% of the time ( P< 0.0001). Our data show that pollen foragers can determine the contents of cells in the nest and suggest that the regulation of pollen collection involves direct assessment of colony need by pollen foragers. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.

Mortality of Varroa destructor in honey bee (Apis mellifera) colonies during winter

The change in infestation levels of the mite Varroa destructorAnderson and Trueman on adult bees during periods with little or no brood rearing (late October/early November to early Febru- ary) was investigated in 10 colonies for two consecutive years in a Swedish climate (N57°06'E18°16'). The results do not support the hypothesis that mites become concentrated on the remaining bees as bees die off from the winter cluster. When the number of all mites recovered from dead bees or from debris was used to calculate mites per dead bee, the level of infestation per bee was not signif- icantly different between samples of live bee and dead bees. For modelling purposes, we presently find no reason to differentiate the mortality rates of bees and mites during periods when there is no or limited amounts of brood in the colonies, although the connection between bee mortality and mite mortality may not be as direct as previously assumed.

Thermoregulation of dancing bees: thoracic temperature of pollen and nectar foragers in relation to profitability of foraging and colony need

The thorax surface temperature of dancing honeybees ( Apis mellifera carnica) recruiting nestmates to natural sources of nectar and pollen around Graz (Austria) was measured by real-time infrared thermography without touching them or disturbing social interactions. Thorax temperature during dancing was quite variable (31.4–43°C). In the course of a foraging season it varied considerably and was always lower than in bees foraging from a highly profitable food source (2 molar sucrose 120 m from the hive). It averaged 38.0°C (SD=2.24, n=224 dances) in the nectar foragers and 37.4°C (SD=1.64, n=171) in the pollen foragers, resembling that of dancers foraging 0.5 molar sucrose from feeders with unlimited flow. Hive air temperature accounted only for about 3–8% of total variation. Foraging distance modulated dancing temperature in a way that, according to the decrease of the profitability of foraging with distance, maximum temperatures decreased and, in accordance with the increase of the dancing threshold with distance, minumum temperatures increased with distance, this way providing new support for the hypothesis that the dancing temperature is modulated by the profitability of foraging and the dancing and foraging motivation of the bees. Dancing temperature of both nectar and pollen dancers correlated with several parameters of the hive status, increasing with the amount of brood and decreasing with the amount of honey and pollen. These correlations are discussed with respect to literature reports on a colony's need for pollen and nectar, in particular the effect of brood and the amount of pollen on pollen foraging, and the effect of honey stores and demand for nectar on nectar foraging.

Regulation of pollen foraging in honeybee colonies: effects of young brood, stored pollen, and empty space

Pollen storage in a colony of Apis mellifera is actively regulated by increasing and decreasing pollen foraging according to the “colony's needs.” It has been shown that nectar foragers indirectly gather information about the nectar supply of the colony from nestmates without estimating the amount of honey actually stored in the combs. Very little is known about how the actual colony need is perceived with respect to pollen foraging. Two factors influence the need for pollen: the quantity of pollen stored in cells and the amount of brood. To elucidate the mechanisms of perception, we changed the environment within normal-sized colonies by adding pollen or young brood and measured the pollen-foraging activity, while foragers had either direct access to them or not. Our results show that the amount of stored pollen, young brood, and empty space directly provide important stimuli that affect foraging behavior. Different mechanisms for forager perception of the change in the environment are discussed.

Adaptation of hypopharyngeal gland development to the brood status of honeybee ( Apis mellifera L.) colonies

We studied pollen consumption, head weight, hypopharyngeal gland (HPG) acini diameter, and protein synthesis and transfer in honeybee workers reared in colonies with normal and with decreasing amounts of brood. We found that head fresh weight is correlated with size of the glands and that pollen consumption is positively correlated with gland development. An effect of brood on size of the glands could be confirmed, but was not as profound as in previous studies. Similarly, no difference in the amount of protein synthesized or transferred in workers living under the two brood conditions was found. We suspect this is due to the fact that HPGs also supply food to young bees and in our study young bees were always present while in previous studies, colonies often lacked both brood and young bees.

Honey bee colony population in relation to brood rearing and stored pollen

The present work was carried out to study the relationship between brood rearing activity, bee density and stored pollen grains. Fifteen colonies, 1st. Carniolan hybrid nearly in equal strength were put under investigation from June 1994 to May 1995. The results revealed that the major peak of brood activity and higher rate of stored pollen were in May, consequently the maximum number of house bees was recorded during June and July. However no correlation existed, the lowest production of brood, bees and gathered pollen occurred during February. It was found that high significant differences were in quantity of brood and house bees, while low significant differences were in quantity of stored pollen. Correlations between brood activity, house bees density and stored pollen were observed in winter.