Brood Development Research Articles

Variation in season length and development time is sufficient to drive the emergence and coexistence of social and solitary behavioural strategies.

Season length and its associated variables can influence the expression of social behaviours, including the occurrence of eusociality in insects. Eusociality can vary widely across environmental gradients, both within and between different species. Numerous theoretical models have been developed to examine the life history traits that underlie the emergence and maintenance of eusociality, yet the impact of seasonality on this process is largely uncharacterized. Here, we present a theoretical model that incorporates season length and offspring development time into a single, individual-focused model to examine how these factors can shape the costs and benefits of social living. We find that longer season lengths and faster brood development times are sufficient to favour the emergence and maintenance of a social strategy, while shorter seasons favour a solitary one. We also identify a range of season lengths where social and solitary strategies can coexist. Moreover, our theoretical predictions are well matched to the natural history and behaviour of two flexibly eusocial bee species, suggesting that our model can make realistic predictions about the evolution of different social strategies. Broadly, this work reveals the crucial role that environmental conditions can have in shaping social behaviour and its evolution and it underscores the need for further models that explicitly incorporate such variation to study the evolutionary trajectories of eusociality.

Microbial community structure variability over the development of healthy and underperforming oyster larval hatchery broods

Microbial community structure variability over the development of healthy and underperforming oyster larval hatchery broods

Evaluation of Some Pollen Substitutes on Productivity of Honey bee Colonies (Apis cerana F.)

This study examined the effects of different pollen substitutes on the performance of honey bee colonies in Assam, India. Natural Corbicula pollen (CPF) and six artificial diets were compared with a sugar syrup control for 15 days. CPF consistently outperformed other treatments in all parameters. Regarding the honey area, the CPF reached 22.63 cm2 and 22.65 cm2 in 2021 and 2022, respectively, while in the control group it was 15.61 cm2 and 15.72 cm2, respectively. CPF also had the highest pollen area (15.59 cm² and 15.68 cm²) and brood area (20.19 cm² and 20.35 cm²) in both years. Colony strength was maximized in the CPF (7.55 and 7.59 for frames 2021 and 2022). Among artificial foods, OUAT-PS (soy flour, honey, yeast, multivitamin) generally performed best, with no significant difference from CPF in colony strength. All pollen substitutes stimulated honey production and brood development with foods rich in proteins, vitamins and amino acids, and significantly improved colony performance compared to controls. These results can help beekeepers select appropriate additional nutrients in times of pollen shortage.

Phenology, voltinism, and brood development of Xylosandrus (Coleoptera: Curculionidae) ambrosia beetles in New York.

The ambrosia beetles Xylosandrus germanus (Blanford) and Xylosandrus crassiusculus (Motschulsky) are nonnative pests in orchards and nurseries in North America. They construct galleries in the sapwood of stressed woody hosts and culture a symbiotic fungus as food for their offspring. Preventing attacks is preferred but a better understanding of their biology may elucidate additional avenues for control. Recent phenological studies are lacking for X. germanus that is common in New York, and biological information on brood and gallery development is lacking for the less abundant X. crassiusculus. We conducted both outdoor rearing and laboratory studies to better understand the timing of key events in the maturation of their galleries, particularly associated with the symbiotic fungi. Two and a partial third summer generation were consistently observed over 2 yr for X. germanus; and thus, 3 flights of adult females (foundresses) occurred each summer from mid-April to late September. In both the field and laboratory, initial growth of the symbiotic fungus occurs within a few days of gallery initiation. The rapid development of the reproductive tract and oviposition by X. germanus appears to be stimulated by the presence of the fungus. Fungal, reproductive, and brood development are similar for the related X. crassiusculus in laboratory studies; the 2 species mainly appear to differ in size. The lag between beetle colonization and reproduction currently seems too brief to be exploited for management. Disruption of other stages in gallery development should also be explored to minimize the beetle damage if attacks cannot be prevented.

Honey bee larval toxicity study designs: Applicability of the current study protocols and endpoints asa predictor of pesticide hazard for pollinators.

The assessment of pesticide risks to bees in North America currently relies in part on Tier 1 honey bee laboratory toxicity studies to support the registration and registration review processes for crop protection chemicals. For immature stages, the studies follow two standardized test designs recommended by the Organization for Economic Cooperation (OECD), evaluating acute (seven-day single-dose, TG OECD 237) and chronic (22-day repeated-dose, GD OECD 239) toxicity in bee larvae. In this article, we aim to evaluate the current approach for generating and interpreting honey bee larval toxicity data, enhancing pesticide risk assessment for pollinators. First, by considering that the repeated-dose larval study covers all stages of honey bee brood development up to adult emergence, we compared endpoints (larval LD/ED50 and LC/EC50 values) from seven-day acute exposure studies with the 22-day chronic exposure studies. Our goal was to identify the study design offering greater sensitivity in assessing pesticide toxicity to immature bees. Our second objective involved analyzing available weight data from emerged adults and comparing it to survival endpoints (e.g., NOEL and LD50) to determine if the weight after adult emergence would accurately represent a sensitive indicator of pesticide effects on developing honey bees. Our analysis determined that the use of a single 22-day chronic exposure study adequately covers all immature stages and that the toxicity values based on cumulative dose are more accurate and representative measures of exposure for immature bees than using endpoints based on estimated daily doses. Furthermore, our analysis suggests that measuring the weight of emerged adults was a more sensitive indicator than mortality of treatment-related effects in 22% of the compounds included in our analysis. Here we also discuss the importance of standardized protocols for proper collection of weight after emergence and the need for further discussion on the relevance of this parameter at risk assessment scheme. Integr Environ Assess Manag 2024;20:2283-2293. © 2024 Pollinator Research Task Force. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

The 'Goldilocks Grub': reproductive responses to leafroller host development in Goniozus jacintae, a parasitoid of the light brown apple moth.

Many parasitoids alter their reproductive behaviour in response to the quality of encountered hosts. They make adaptive decisions concerning whether to parasitise a potential host, the number of eggs laid on an accepted host, and the allocation of sex to their offspring. Here we present evidence that Goniozus jacintae Farrugia (Hymenoptera: Bethylidae), a gregarious ectoparasitoid of larval tortricids, adjusts its reproductive response to the size and developmental stage of larvae of the light brown apple moth (LBAM), Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae). Goniozus jacintae parasitises instars 3-6 of LBAM, but most readily parasitises the later, larger, instars. Brood sizes were bigger on larger hosts and brood sex ratios were female biased (proportion of males = 0.23) with extremely low variance (never >1 male in a brood at emergence), perhaps the most precise of all studied bethylids. Host size did not influence brood development time, which averaged 19.64 days, or the body size of male offspring. However, the size of females was positively correlated with host size and negatively correlated with brood size. The sizes of individual males and females were positively related to the average amount of host resource available to individuals within each brood, suggesting that adult body size is affected by scramble competition among feeding larvae. Average brood sizes were: 3rd instar host, 1.3 (SE ± 0.075); 4th instar, 2.8 (SE ± 0.18); 5th instar, 4.7 (SE ± 0.23); 6th instar, 5.4 (SE ± 0.28). The largest brood size observed was 8 individuals (7 females, 1 male) on the 6th instar of LBAM. These results suggest that later instars would give the highest yield to optimise mass-rearing of G. jacintae if used for augmentative biological pest control.

Assessing the Efficacy of Organic and Chemical Treatments for Varroa Mite Control in Macedonian Apiaries

Varroa destructor infestations pose a significant global threat to honeybee colonies, affecting bee populations and honey production. The purpose of this study is to assess the performance of Apis mellifera L. honeybee colonies under various control methods with a particular focus on critical parameters like mite dewdrop, honey production and colony growth. The study took place in a normal apiary in the Pelister district for a year from April 2021 to March 2022. There were three treatment groups: Group A got Amitraz (a chemical treatment), group M got formic acid (an organic treatment) and group K got nothing (a control group) to see how the treatments affected the bees. Regular monitoring assessed parameters including dropped mites and Varroa infestation levels with honey production evaluated seasonally. The results showed that both chemical and organic treatments successfully decreased the levels of Varroa mite infestation compared to the control group, while also noting differences in colony growth and honey production. The Amitraz treatment did prevent the mites from dropping, but it also slowed down the young's development. On the other hand, the formic acid treatment kept the brood's development healthy, suggesting that it might be a better way to get rid of varroa. This study shows how important it is to think about how treatments affect important colony parameters. It also calls for more research like longterm observations, to fully understand how treatments affect the health, development and longevity of bee families which will eventually lead to the creation of more effective combined pest control methods.

Distribution of brood of the acorn ant Temnothorax crassispinus in artificial nests after forced migration

Nest sites are important for social insects, as they provide refuge against enemies and ensure optimal conditions for the brood development. In large nests, the different chambers can be used for different reasons; for example, for food storage or as a brood chamber. Acorn ants from the genus Temnothorax dwell in small cavities in acorns and wood; however, even such small chambers can have a high degree of spatial heterogeneity. During this study, the distribution of brood items of the acorn ant Temnothorax crassispinus inside artificial nest cavities composed of three chambers in a linear system was analysed. 29 ant colonies were photographed 13 times during a period of approximately one month: during three consecutive days, and after forced migrations. I found that the distribution of the brood inside the nest cavity was similar during the consecutive days; however, after the forced migration, the distribution typically changed. Almost all the brood items were kept farther from the entrance. Keeping the brood farther from the entrance could be explained as a safer option.

Variation in season length and development time is sufficient to drive the emergence and coexistence of social and solitary behavioral strategies.

Season length and its associated variables can influence the expression of social behaviors, including the occurrence of eusociality in insects. Eusociality can vary widely across environmental gradients, both within and between different species. Numerous theoretical models have been developed to examine the life history traits that underlie the emergence and maintenance of eusociality, yet the impact of seasonality on this process is largely uncharacterized. Here, we present a theoretical model that incorporates season length and offspring development time into a single, individual-focused model to examine how these factors can shape the costs and benefits of social living. We find that longer season lengths and faster brood development times are sufficient to favor the emergence and maintenance of a social strategy, while shorter seasons favor a solitary one. We also identify a range of season lengths where social and solitary strategies can coexist. Moreover, our theoretical predictions are well-matched to the natural history and behavior of two flexibly-eusocial bee species, suggesting our model can make realistic predictions about the evolution of different social strategies. Broadly, this work reveals the crucial role that environmental conditions can have in shaping social behavior and its evolution and underscores the need for further models that explicitly incorporate such variation to study evolutionary trajectories of eusociality.

Recapping behavior in Apis cerana: does it contribute to resistance against Varroa spp.?

The invasion of the ectoparasitic mite Varroa destructor into European honey bee, Apis mellifera, populations has contributed to the collapse of most wild populations and economic losses in beekeeping operations. Understanding how some A. mellifera populations survive infestation by this parasite is of great fundamental and practical interest and has led to numerous studies of potential resistance mechanisms. One such mechanism is the uncapping and recapping of comb cells containing infested brood by nurse bees. Recapping has been observed in most surviving populations, but its link to V. destructor resistance remains unclear. Investigating the occurrence of recapping in the Eastern honey bee, Apis cerana, the original host of the parasite, could provide a better understanding of the evolution and function of this behaviour in the Apis genus. Here, we determined the frequency of recapping in two A. cerana populations in China and Thailand at different stages of brood development and compared them with a sympatric A. mellifera population in China. The species, which differ in their susceptibility to infestation, did not show significant differences in recapping frequency. A specific association between recapping and resistance to Varroa spp. in A. cerana is therefore not supported. We discuss possible functions and evolutionary scenarios for this behavior.

Understanding the Impact of Heat Stress on Honeybee Populations: Insights into Thermoregulation, Colony Dynamics, and Environmental Interactions

Nowadays, heat stress is emerging as a significant issue for honeybees in apiculture due to its potential to negatively impact the honey bees' health, the bee colony, and the economic stability. This review aims to thoroughly analyze the impact of heat stress on honeybee populations by consolidating existing research to provide accurate information. The thermoregulation process in honeybees and associated behavioral and molecular adaptations in worker bees, specific to Apis mellifera. Additionally covers the various ways that individual bees respond to heat stress, including changes in their metabolic rate and feeding habits. Furthermore, the paper provides a comprehensive analysis of how heat stress affects the entire bee colony, including detrimental effects on brood development, decreased productivity, and heightened susceptibility to illnesses and parasites. Also, it investigates the correlation between heat stress and other stressors, such as pesticide exposure, nutritional stress, biotic pressures, habitat loss, and the combined effects on bee health. To safeguard these important pollinators from the negative effects of climate change, this review stresses the need of interdisciplinary research and the need of identifying health stress as a major component influencing honeybee populations.

Ontogenesis of honey bees (Apis mellifera) under the influence of temperature stress

The productivity of bee colonies mostly depends on the influence of exogenous factors. The most significant ones include: the presence of a honey base, climatic conditions, environmental temperature, etc. The stability of microclimate indicators in the nest significantly affect the growth of families and nest. The vital temperature range in the post-embryonic period ranges from 30–38 °С. For normal brood development, the incubation temperature should be 34–35 °С. The intensity of growth during this period is largely determined by the influence of climatic conditions, including temperature. As a result of decrease in temperature, there is a densification of the placement of bees, which are more concentrated in the central, breeding part of the nest. Under these conditions, hypothermia of individual areas of the brood, located on the peripheral parts of the honeycombs, beyond the healthy temperature range, is sometimes noted. This is manifested by a sharp drop in the ambient temperature, when there is a numerous brood in the family, or if the nest is not expanded properly. In order to study the influence of cold stress on the development of offspring, two groups were formed. The group incubated at a temperature of 35 ºС was considered the control group. The experimental group was a group which was grown at a temperature of 32 ºС. After the brood was sealed, pupae were selected every 2 days. At the same time, their mass, the content of total lipids and the ratio of their individual classes were determined. It was found that under the influence of cold stress during brood development, the duration of the incubation period increases by 35–42 hours. It has been established that the adaptation of bees to cold includes a complex of physiological and biochemical processes, among which changes in the mass and composition of lipids play a significant role. The dynamics of triacylglycerides under optimal and stressful conditions of incubation were studied. Taking into account their functional purpose as the main element of energy supply of metabolic pathways, such dynamics indicate profound changes in the processes of energy exchange. When studying the mechanisms of adaptation to cold, a change in the ratio of phospholipid classes, the expression of which is induced by the effect of cold, was revealed. The results of this study bring a deeper understanding of the adaptation mechanisms of honeybees' response to changes in brood incubation temperature. They expand data on the biology of bees during critical periods of growth and development.

Hybrids of two destructive subterranean termites established in the field, revealing a potential for gene flow between species.

Hybridization between invasive pest species may lead to significant genetic and economic impacts that require close monitoring. The two most invasive and destructive termite species worldwide, Coptotermes formosanus Shiraki and Coptotermes gestroi (Wasmann), have the potential for hybridization in the field. A three-year field survey conducted during the dispersal flight season of Coptotermes in Taiwan identified alates with atypical morphology, which were confirmed as hybrids of the two Coptotermes species using microsatellite and mitochondrial analyses. Out of 27,601 alates collected over three years, 4.4% were confirmed as hybrid alates, and some advanced hybrids (>F1 generations) were identified. The hybrid alates had a dispersal flight season that overlapped with the two parental species 13 out of 15 times. Most of the hybrid alates were females, implying that mating opportunities beyond F1 may primarily be possible through female hybrids. However, the incipient colony growth results from all potential mating combinations suggest that only backcross colonies with hybrid males could sometimes lead to brood development. The observed asymmetrical viability and fertility of hybrid alates may critically reduce the probability of advanced-hybrid colonies being established in the field.

Urban abiotic stressors drive changes in the foraging activity and colony growth of the black garden ant Lasius niger

Changes in habitat characteristics are known to have profound effects on biotic communities and their functional traits. In the context of an urban-rural gradient, urbanisation drastically alters abiotic characteristics, e.g., by increasing environmental temperatures and through light pollution. These abiotic changes significantly impact the functional traits of organisms, particularly insects. Furthermore, changes in habitat characteristics also drive changes in the behavioural traits of animals, allowing them to adapt and thrive in new environments. In our study, we focused on the synanthropic ant species Lasius niger as a model organism. We conducted nocturnal field observations and complemented them with laboratory experiments to investigate the influence of night warming (NW) associated with Urban Heat Islands (UHI), light pollution (ALAN), and habitat type on ant foraging behaviour. In addition, we investigated the influence of elevated temperatures on brood development and worker mortality. Our findings revealed that urban populations of L. niger were generally more active during the night compared to their rural counterparts, although the magnitude of this difference varied with specific city characteristics. In laboratory settings, higher temperatures and continuous illumination were associated with increased activity level in ants, again differing between urban and rural populations. Rural ants exhibited more locomotion compared to their urban counterparts when maintained under identical conditions, which might enable them to forage more effectively in a potentially more challenging environment. High temperatures decreased the developmental time of brood from both habitat types and increased worker mortality, although rural colonies were more strongly affected. Overall, our study provides novel insights into the influence of urban environmental stressors on the foraging activity pattern and colony development of ants. Such stressors can be important for the establishment and spread of synanthropic ant species, including invasive ones, and the biotic homogenization of anthropogenic ecosystems.

Automated precision beekeeping for accessing bee brood development and behaviour using deep CNN.

Bees play a significant role in the health of terrestrial ecosystems. The decline of bee populations due to colony collapse disorder around the world constitutes a severe ecological danger. Maintaining high yield of honey and understanding of bee behaviour necessitate constant attention to the hives. Research initiatives have been taken to establish monitoring programs to study the behaviour of bees in accessing their habitat. Monitoring the sanitation and development of bee brood allows for preventative measures to be taken against mite infections and an overall improvement in the brood's health. This study proposed a precision beekeeping method that aims to reduce bee colony mortality and improve conventional apiculture through the use of technological tools to gather, analyse, and understand bee colony characteristics. This research presents the application of advanced digital image processing with computer vision techniques for the visual identification and analysis of bee brood at various developing stages. The beehive images are first preprocessed to enhance the important features of object. Further, object is segmented and classified using computer vision techniques. The research is carried out with the images containing variety of immature brood stages. The suggested method and existing methods are tested and compared to evaluate efficiency of proposed methodology.

Quantification of heritable variation in multiple lodgepole pine chemical and physical traits that contribute to defense against mountain pine beetle (Dendroctonus ponderosae)

Bark beetles are major causes of conifer mortality worldwide. We quantified genetic contributions to key chemical and physical traits in lodgepole pine that contribute to defense against mountain pine beetle, a native tree-killing herbivore. Assays were conducted with mature trees in replicated provenance trials. Among chemical defenses, monoterpene composition (relative proportions of various compounds) had higher genetic variability than monoterpene concentration (absolute quantities). Additionally, constitutive concentrations had higher genetic variabilities than induced concentrations elicited by simulated attack. Resin flow elicited by mechanical wounding likewise showed very low genetic variability. In previous studies with this and related systems, induced monoterpene concentration and resin flow are the two best predictors respectively of which trees will survive outbreaks under natural conditions. This means that expression of the most efficacious defense traits is strongly influenced by environmental factors. These low heritabilities despite their survival values likely arise from specific life history and ecological aspects of this system, such as the lengthy period between when lodgepole pines begin cone production and become large enough for brood development, the extended viability of serotinous cones post-mortem, the high heterogeneity of both resources and stressors that trees experience across landscapes, and a strong proximate-neighbor effect on tree mortality arising from beetle aggregation pheromones. However, low heritability values do not preclude long-term evolvability and coadaptation of defenses, for which there is extensive mechanistic and associational evidence in this system. Among other traits we evaluated, sesquiterpenes had higher genetic variability than monoterpenes. Sesquiterpenes are not known to influence conifer-bark beetle interactions but have anti-herbivore properties in some other plant-insect systems. The lengths of lesions formed in response to simulated attack showed no heritable component and likewise do not predict tree survival in nature. Bark texture was highly heritable and is known to influence beetle post-landing orientation and colonization patterns, but whether it influences survival patterns at the whole-tree level is unknown. Relationships between tree defenses and growth were generally positive, suggesting that environmental heterogeneity in resource quality among trees supersedes potential underlying substrate allocation processes within trees. Similarly, relationships between various defense traits were generally positive rather than showing trade-offs, suggesting conifer resistance to native bark beetles entails coordinated defense syndromes. Implications to tree breeding, forest management, and coevolution between long-lived plants and rapidly reproducing herbivores are discussed. The extent to which these trends may apply to other bark beetle systems is evaluated, along with specific priorities for future research.

Lithium chloride treatments in free flying honey bee colonies: efficacy, brood survival, and within-colony distribution

The efficacy of various lithium chloride (LiCl) applications in eradicating the parasitic mite Varroa destructor in honey bee colonies was investigated, with a specific focus on its impact on brood development. In broodless colonies (3 weeks post queen caging), the highest efficacy of 98% was achieved with a 9-day treatment of 2.5 kg of candy spiked with 50 mM LiCl. A shorter 5-day treatment with 2 kg of 50 mM LiCl candy resulted in an efficacy of 78%. In colonies with brood, a repeated short-term application of 4 × 0.5 kg 50 mM LiCl candy yielded an efficacy of 88%. LiCl treatment led to a removal of the first batch of brood reared after release of the queen. However, no long-term effects on colony growth were observed, and the colonies successfully overwintered. Additionally, the study demonstrated that lithium is rapidly distributed among the bees of a colony within 2 days, yet only low concentrations were detected in stored food samples. This suggests that the bees efficiently absorb and distribute lithium within the colony. The harvested honey in the following spring revealed a lithium concentration of 0.1–0.2 mg/kg, which is below naturally occurring lithium levels in honey. Based on these findings, LiCl can be considered an effective and easy-to-apply acaricide in broodless colonies, and even in colonies with brood, it had good efficacy and no long-term effects on colony survival. Further research may be necessary to determine the optimal treatment period for achieving an efficacy over 95%.

Efficacy and trade-offs of an innovative hyperthermia device to control Varroa destructor in honeybee colonies

For decades, the honeybee, Apis mellifera, has suffered from severe colony losses due to the ectoparasitic mite Varroa destructor. Various strategies based on chemicals fail to adequately control varroa mite populations, and often comprise side-effects on the host, parasite resistance and residues in hive products. Reduced temperature tolerance of V. destructor compared to its host has long been recognised and accordingly, the potential of hyperthermia to disrupt mite reproduction within honeybee brood cells or even kill adult parasites. Yet, earlier studies on hyperthermia remain largely anecdotal, and readily implementable solutions have so far been lacking. This study investigates autonomously controlled interval heating from within brood combs throughout the season compared to control colonies maintained according to good apicultural practice. We documented treatment-dependent colony growth dynamics and honey production at three apiaries, complemented by regular monitoring of varroa mite levels and comprehensive digital assessments of brood development over time. Our one-year field trial suggests the evaluated hyperthermia device efficiently suppresses mite populations below critical thresholds until autumn. Whilst a general winter reference-curing revealed similar mite infestations of colonies previously treated with hyperthermia versus formic acid (control), only the latter imposed substantial overwintering burdens indirectly through frequent late-season queen supersedure. However, relative to targeted pupae, increased mortality particularly of heat-treated non-target brood stages (eggs and larvae) appeared to trigger compensatory colony-level responses, translating into temporarily decreased numbers of adult workers coupled with increased pollen foraging and overall lower honey harvests. Valuable insights into previously unrecognised side-effects of hyperthermia and mitigation thereof may ultimately permit successful routine applications of this chemical-free approach to combat the major threat to honeybees worldwide.

Substances in the mandibular glands mediate queen effects on larval development and colony organization in an annual bumble bee.

Social organization is commonly dynamic, with extreme examples in annual social insects, but little is known about the underlying signals and mechanisms. Bumble bee larvae with close contact to a queen do not differentiate into gynes, pupate at an earlier age, and are commonly smaller than siblings that do not contact a queen. We combined detailed observations, proteomics, microRNA transcriptomics, and gland removal surgery to study the regulation of brood development and division of labor in the annual social bumble bee Bombus terrestris. We found that regurgitates fed to larvae by queens and workers differ in their protein and microRNA composition. The proteome of the regurgitate overlaps significantly with that of the mandibular (MG) and hypopharyngeal glands (HPG), suggesting that these exocrine glands are sources of regurgitate proteins. The proteome of the MG and HPG, but not the salivary glands, differs between queens and workers, with caste-specificity preserved for the MG and regurgitate proteomes. Queens subjected to surgical removal of the MG showed normal behavior, brood care, and weight gain, but failed to shorten larval development. These findings suggest that substances in the queen MG are fed to larvae and influence their developmental program. We suggest that when workers emerge and contribute to larval feeding, they dilute the effects of the queen substances, until she can no longer manipulate the development of all larvae. Longer developmental duration may allow female larvae to differentiate into gynes rather than to workers, mediating the colony transition from the ergonomic to the reproductive phase.

Foraging activity and role of stingless bee Tetragonula iridipennis Smith (Hymenoptera: Apidae) in bitter gourd

In the bitter gourd cropping system, honey bees were the primary pollinators. In the Coimbatore district, a field study was conducted to record the foraging activity and pollination efficiency of the stingless bee Tetragonula iridipennis in bitter gourd. Bee foraging activity was recorded separately in male and female flowers, with the number of foragers/flower/min recorded. Fruit set and yield were assessed under three different conditions: pollinator exclusion, bee pollination, and open pollination. Abundance of Pollinators and foraging rate of stingless bees observed on male flower 1.71 bees/ flower/ minute and flower handling time in seconds was (37.86 sec) was higher than female flowers 1.22 bees / flower/ minute and (25.73 sec) respectively. The peak foraging activity of stingless bees was observed between 08:00-10:00 hours with 3.30 bees/ 5 mins. The pollination efficiency index of stingless bees in bitter gourd flowers was 41600. The foraging activity of bees at the hive entrance was at its peak at 08:00 to 10:00 hours. T. Iridipennis colony growth parameters show increased honey sealed area 1464.5 g and brood development. The experiment results show that yield was higher in the managed bee-pollinated condition in terms of number of fruits/plant was (18.2 fruits) and fruit yield per hectare (44.08 t/ha) than in the open pollinated condition (16.5 fruits) and (38.30 t/ha), and with pollinators excluded, no fruit set was recorded.