The recognition of larvae by worker honeybees

SUMMARYVitellogenin, an egg-yolk protein precursor common to oviparous animals, is found abundantly in honeybee workers -a caste of helpers that do not usually lay eggs. Instead, honeybee vitellogenin (180kDa) participates in processes other than reproduction: it influences hormone signaling, food-related behavior, immunity, stress resistance and longevity. The molecular basis of these functions is largely unknown. Here, we establish and compare the molecular properties of vitellogenin from honeybee hemolymph (blood) and abdominal fat body, two compartments that are linked to vitellogenin functions. Our results reveal a novel 40kDa vitellogenin fragment in abdominal fat body tissue, the main site for vitellogenin synthesis and storage. Using MALDI-TOF combined with MS/MS mass-spectroscopy, we assign the 40kDa fragment to the N terminus of vitellogenin, whereas a previously observed 150kDa fragment corresponded to the remainder of the protein. We show that both protein units are N glycosylated and phosphorylated. Focusing on the novel 40kDa fragment, we present a homology model based on the structure of lamprey lipovitellin that includes a conserved b-barrel-like shape, with a lipophilic cavity in the interior and two insect-specific loops that have not been described before. Our data indicate that the honeybee fat body vitellogenin experiences cleavage unlike hemolymph vitellogenin, a pattern that can suggest a tissue-specific role. Our experiments advance the molecular understanding of vitellogenin, of which the multiple physiological and behavioral effects in honeybees are well established. Supplementary material available online at

Section: Discussionmentioning

confidence: 99%

Deconstructing honeybee vitellogenin: novel 40 kDa fragment assigned to its N terminus

Havukainen

Halskau

Skjærven

et al. 2011

“…Experimentally food-deprived larvae are inspected more frequently than untreated controls, indicating that there are signals or cues providing the nurse bees with information about the nutritional state of the larvae (Huang and Otis, 1991a). Chemical signals produced by the eggs and brood of honeybees are known to be used by worker bees in a variety of contexts (Koeniger and Veith, 1983;Ratnieks and Visscher, 1989;Le Conte et al, 1990;Trouiller et al, 1991;Huang and Otis, 1991b;Le Conte, 1994;Le Conte et al, 1995;Châline et al, 2005). Cuticular hydrocarbon patterns of honeybee larvae provide information about the age and caste of the larva (Aumeier et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

Mechanisms of food provisioning of honeybee larvae by worker bees

Heimken

Aumeier

Kirchner

2009

SUMMARYAlthough it has clearly been demonstrated in previous studies that honeybees inspect their worker brood in a non-random fashion, it is still unclear which signals and cues worker bees use to monitor the nutritional state of their brood. Here we show that worker bees can recognize and quantify the larval food present in a brood cell olfactorily and identify potential mechanical signals produced by the brood. There is no evidence for additional chemical hunger signals produced by the larvae. However, the pattern of movement of larvae within their cells changes with their nutritional state and might provide additional information to nurse bees.

“…This proposition builds on previous work by Omholt (Omholt, 1988), who suggested that the nurse load of young honeybee workers affects longevity: a low nurse load can increase lifespan whereas a high nurse load has the opposite effect. In addition to consuming colony resources, however, larval brood secrete a primer brood pheromone, a blend of 10 fatty acid methyl and ethyl esters (Le Conte et al, 1994) produced by the salivary glands (Le Conte et al, 2006). This pheromone affects worker brain gene expression (Alaux et al, 2009), gland physiology (Pankiw et al, 2008) and behavior (Pankiw, 2004).…”

Section: Introductionmentioning

confidence: 99%

Brood pheromone suppresses physiology of extreme longevity in honeybees (Apis mellifera)

Smedal

Brynem

Kreibich

et al. 2009

SUMMARYHoneybee (Apis mellifera) society is characterized by a helper caste of essentially sterile female bees called workers. Workers show striking changes in lifespan that correlate with changes in colony demography. When rearing sibling sisters (brood), workers survive for 3-6 weeks. When brood rearing declines, worker lifespan is 20 weeks or longer. Insects can survive unfavorable periods on endogenous stores of protein and lipid. The glyco-lipoprotein vitellogenin extends worker bee lifespan by functioning in free radical defense, immunity and behavioral control. Workers use vitellogenin in brood food synthesis, and the metabolic cost of brood rearing (nurse load) may consume vitellogenin stores and reduce worker longevity. Yet, in addition to consuming resources, brood secretes a primer pheromone that affects worker physiology and behavior. Odors and odor perception can influence invertebrate longevity but it is unknown whether brood pheromone modulates vitellogenin stores and survival. We address this question with a 2-factorial experiment where 12 colonies are exposed to combinations of absence vs presence of brood and brood pheromone. Over an age-course of 24 days, we monitor the amount of vitellogenin stored in workers' fat body (adipose tissue). Thereafter, we track colony survival for 200 days. We demonstrate that brood rearing reduces worker vitellogenin stores and colony long-term survival. Yet also, we establish that the effects can result solely from exposure to brood pheromone. These findings indicate that molecular systems of extreme lifespan regulation are integrated with the sensory system of honeybees to respond to variation in a primer pheromone secreted from larvae. Supplementary material available online at