In Vitro Rearing Changes Social Task Performance and Physiology in Honeybees

In vitro rearing of honeybee larvae is an established method that enables exact control and monitoring of developmental factors and allows controlled application of pesticides or pathogens. However, only a few studies have investigated how the rearing method itself affects the behavior of the resulting adult honeybees. We raised honeybees in vitro according to a standardized protocol: marking the emerging honeybees individually and inserting them into established colonies. Subsequently, we investigated the behavioral performance of nurse bees and foragers and quantified the physiological factors underlying the social organization. Adult honeybees raised in vitro differed from naturally reared honeybees in their probability of performing social tasks. Further, in vitro-reared bees foraged for a shorter duration in their life and performed fewer foraging trips. Nursing behavior appeared to be unaffected by rearing condition. Weight was also unaffected by rearing condition. Interestingly, juvenile hormone titers, which normally increase strongly around the time when a honeybee becomes a forager, were significantly lower in three- and four-week-old in vitro bees. The effects of the rearing environment on individual sucrose responsiveness and lipid levels were rather minor. These data suggest that larval rearing conditions can affect the task performance and physiology of adult bees despite equal weight, pointing to an important role of the colony environment for these factors. Our observations of behavior and metabolic pathways offer important novel insight into how the rearing environment affects adult honeybees.

Effect of Larval Food Amount on in vitro Rearing of Indo-Malayan Stingless Bee Queen, Heterotrigona itama (Hymenoptera: Apidae; Meliponini)

The demand for stingless bee colonies in Malaysia has considerably increased due to the rapid advance of meliponiculture in using the stingless bees as agricultural pollinators, as well as the commercialization of stingless bee products (i.e. honey, bee bread and propolis). Thus, in vitro queen rearing for a large scale and rapid colony multiplication must be developed in order to fulfil the public requirements in a short period. Little is known about the in vitro rearing of native stingless bee queen, Heterotrigona itama. Therefore, in this study, we investigated the amount of larval food required by H. itama queen by comparing three different amounts of larval food, viz., 100 µL, 120 µL and 150 µL. All treatments were controlled under 100% relative humidity for the first 6 days, and 75% relative humidity for the rest of larval development until queen adult emergence, under 30 °C incubator temperature. The results showed that larvae of H. itama treated with the highest amount of larval food (150 µL) led to 78% of the queen’s emergence, whereas larvae treated with 120 µL and 100 µL of larval food resulted in 40% and 0% of queen emergence. The dynamic survival curve showed that most of the larvae died before the pupation phase and reached constant stability afterward. The queen’s body and abdominal length were significantly greater than wild workers. Microscopy analysis showed that in vitro queen had well-developed reproductive system with a huge ovary and spermatheca, whereas wild worker had much smaller ovary without spermatheca. Outcomes from this study could help increase the number of colonies on a large scale, allowing for their use both ecologically and economically, and contribute to conservation efforts in native species of stingless bees.

In vitro biology of pigeon louse Colpocephalum turbinatum (Amblycera: Phthiraptera)

In vitro rearing of amblyceran Phthiraptera is a challenging task. A look on the literature reveals that negligible information exists on the in vitro bionomics of avian Amblycera. Present report furnishes information on the in vitro biology of an amblyceran louse, Colpocephalum turbinatum, reared at 35 ± 1˚C, 75-82% Relative Humidity, at feather diet. The incubation period of the eggs of louse was determined as 5.37±0.67 days. The duration of first, second and third nymphal instars remained 5.04±0.65, 5.12±0.89 and 5.0±0.57 days, respectively. The longevity of adult female (13.04 ± 3.67 days) was comparatively longer than that of males (9.6±2.87 days). An adult female laid an average of 0.63 egg/day in vitro condition (35±1oC and 75-82% RH, at feather diet).