Karolina Kuszewska

Effect of the Internet Commerce on Dispersal Modes of Invasive Alien Species

The spread of invasive alien plants has considerable environmental and economic consequences, and is one of the most challenging ecological problems. The spread of invasive alien plant species depends largely on long-distance dispersal, which is typically linked with human activity. The increasing domination of the internet will have impacts upon almost all components of our lives, including potential consequences for the spread of invasive species. To determine whether the rise of Internet commerce has any consequences for the spread of invasive alien plant species, we studied the sale of thirteen of some of the most harmful Europe invasive alien plant species sold as decorative plants from twenty-eight large, well known gardening shops in Poland that sold both via the Internet and through traditional customer sales. We also analyzed temporal changes in the number of invasive plants sold in the largest Polish internet auction portal. When sold through the Internet invasive alien plant species were transported considerably longer distances than for traditional sales. For internet sales, seeds of invasive alien plant species were transported further than were live plants saplings; this was not the case for traditional sales. Also, with e-commerce the shape of distance distribution were flattened with low skewness comparing with traditional sale where the distributions were peaked and right-skewed. Thus, e-commerce created novel modes of long-distance dispersal, while traditional sale resembled more natural dispersal modes. Moreover, analysis of sale in the biggest Polish internet auction portal showed that the number of alien specimens sold via the internet has increased markedly over recent years. Therefore internet commerce is likely to increase the rate at which ecological communities become homogenized and increase spread of invasive species by increasing the rate of long distance dispersal.

Ecological stoichiometry of the honeybee: Pollen diversity and adequate species composition are needed to mitigate limitations imposed on the growth and development of bees by pollen quality

The least understood aspects of the nutritional needs of bees are the elemental composition of pollen and the bees’ need for a stoichiometrically balanced diet containing the required proportions of nutrients. Reduced plant diversity has been proposed as an indirect factor responsible for the pollinator crisis. We suggest stoichiometric mismatch resulting from a nutritionally unbalanced diet as a potential direct factor. The concentrations and stoichiometric ratios of C, N, S, P, K, Na, Ca, Mg, Fe, Zn, Mn, and Cu were studied in the bodies of honeybees of various castes and sexes and in the nectar and pollen of various plant species. A literature review of the elemental composition of pollen was performed. We identified possible co-limitations of bee growth and development resulting mainly from the scarcity of Na, S, Cu, P and K, and possibly Zn and N, in pollen. Particular castes and sexes face specific limitations. Concentrations of potentially limiting elements in pollen revealed high taxonomic diversity. High floral diversity may be necessary to maintain populations of pollen eaters. Single-species crop plantations, even if these species are rich in nectar and pollen, might limit bee growth and development, not allowing for gathering nutrients in adequate proportions. However, particular plant species may play greater roles than others in balancing honeybee diets. Therefore, we suggest specific plant species that may (1) ensure optimal growth and production of individuals by producing pollen that is exceptionally well balanced stoichiometrically (e.g., clover) or (2) prevent growth and development of honeybees by producing pollen that is extremely unbalanced for bees (e.g., sunflower). Since pollen is generally poor in Na, this element must be supplemented using “dirty water”. Nectar cannot supplement the diet with limiting elements. Stoichiometric mismatch should be considered in intervention strategies aimed at improving the nutritional base for bees.

Sedentary antlion larvae (Neuroptera: Myrmeleontidae) use vibrational cues to modify their foraging strategies

Learning abilities are exhibited by many animals, including insects. However, sedentary species are typically believed to have low capacities and requirements for learning. Despite this view, recent studies show that even such inconspicuous organisms as larval antlions, which employ an ambush predation strategy, are capable of learning, although their learning abilities are rather simple, i.e., limited to the association of vibrational cues with the arrival of prey. This study demonstrates, for the first time, that antlion larvae can use vibrational cues for complex modifications of their foraging strategies. Specifically, antlion larvae rapidly learn to differentiate between the vibrational cues associated with prey of different sizes, and they save resources by ignoring smaller prey in favour of larger, more energetically profitable prey. Moreover, antlion larvae can learn to associate vibrational cues with the loss of their prey, and they respond by burying their victims under the sand more often and more rapidly than do individuals with no opportunities to form such associations. These findings provide not only new insights into the cognitive abilities of animals but also support for the optimal foraging strategy concept, suggesting the importance of maximizing fitness output by balancing the costs and benefits of alternative foraging strategies.

Age at Which Larvae Are Orphaned Determines Their Development into Typical or Rebel Workers in the Honeybee (Apis mellifera L.)

In the honeybee, diploid larvae fed with royal jelly develop into reproductive queens, whereas larvae fed with royal jelly for three days only and subsequently with honey and pollen develop into facultatively sterile workers. A recent study showed that worker larvae fed in a queenless colony develop into another female polyphenic form: rebel workers. These rebel workers are more queenlike and have greater reproductive potential than normal workers. However, it was unclear whether larvae orphaned at any time during their feeding period can develop into rebels. To answer this question, the anatomical features of newly emerged workers reared in queenless conditions at different ages during the larval period were evaluated. Our results showed that larvae orphaned during the final four or more days of their feeding life develop into rebel workers with more ovarioles in their ovaries, smaller hypopharyngeal glands, and larger mandibular and Dufour’s glands compared with typical workers with low reproductive potential that were reared with a queen or orphaned at the third to last or a later day of feeding life.

Risky robbing is a job for short-lived and infected worker honeybees

Researchers in many fields would like to understand the determinants of risk-taking. Social insects are an excellent model for examining them since the tasks they perform bear different risks. Some honeybee (Apis mellifera) workers do not forage for nectar or pollen; instead, they take on the extreme risk of robbing honey from other bee nests. In this paper, we show that robbers live shorter lives than foragers under the same cage conditions, and that they are more often and more heavily infected with the intestinal parasite Nosema than foragers are. This finding supports the theoretical prediction that risky tasks should be undertaken by shorter-lived individuals.

Honeybee worker larvae perceive queen pheromones in their food

Honeybee workers develop from fertilised eggs, but those reared in a queenless colony develop into ‘rebel’ workers, which are more queen-like than typical workers. Rebels develop after an old queen leaves with a swarm and before a new queen hatches. We hypothesised that larval food lacking queen mandibular pheromones trigger the rebel phenotype. Larvae reared under queenright or queenless conditions were additionally fed with water or a drop of macerated queen mandibular glands. After following development of the bees and subjecting them to dissection, we found that those reared with a queen or fed the macerated glands under queenless conditions developed into typical workers. Only those workers reared without a queen and without macerated glands added to their food developed into rebels; these rebels had more ovarioles, smaller hypopharyngeal glands, and larger mandibular and Dufour’s glands than did typical workers. This is the first evidence that larval perception of the presence or absence of queen pheromones causes an alternative development strategy.

Larval antlions with more pronounced behavioural asymmetry show enhanced cognitive skills.

Brain lateralization is hypothesized to improve the efficiency of information processing. Here, we found that some Myrmeleon bore antlion larvae showed individual asymmetry in righting from a supine to normal position over one side of their body, which can be considered a reflection of greater brain lateralization. We demonstrated that these behaviourally asymmetrical individuals showed improved learning abilities, providing novel evidence that brain lateralization leads to beneficial effects on cognitive functions.

Secretions of mandibular glands are not involved in the elicitation of rescue behaviour in Formica cinerea ants

Certain ants perform rescue behaviour for other ants that require help, and the expression of rescue behaviour is hypothesized to depend on signals (“calls for help”) sent by the imperilled individuals. We studied whether the mandibular glands were involved in the elicitation of rescue behaviour in Formica cinerea Mayr ants. In the first experiment, we determined the occurrence and characteristics of rescue behaviour directed towards nest mates with impaired mandibular gland communication. We did not observe any difference in rescue behaviour directed towards individuals who were untreated, treated with paint over the mandibles, or sham-treated with paint over the thorax. In the second experiment, we determined whether rescue behaviour would occur towards dummy ants coated with the contents of the mandibular glands. Compared with the control untreated nest mates, we found that rescue behaviour was not directed towards either the untreated dummy ants or the dummy ants covered with crushed mandibular glands. Our results indicated that the “call for help” signal does not originate from the mandibular glands. Therefore, we propose that gaster-tip glands represent a plausible alternative source of rescue-eliciting pheromone(s) for the F. cinerea ants examined in this study.

Honeybee workers with higher reproductive potential live longer lives

ABSTRACT Social insects, especially honeybees, have received much attention in comparative gerontology because of their peculiar and flexible ageing patterns that differ across genetically similar individuals. The longevity of honeybee individuals varies and depends on patterns of gene expression during development; females developing into reproductive individuals (queens) live longer than facultatively sterile workers. Here, we show that rebel workers, which develop under queenless conditions after swarming and have high reproductive potential, live approximately 4 days longer in hives and approximately 3 days longer in cages than individuals that develop in queenright colonies and have lower reproductive potential; this difference in longevity occurs in both free‐flying and caged workers. Moreover, we show that both rebel and normal workers live longer when their ovaries contain more ovarioles. Longer‐living rebel workers can benefit the colony because they can fill the generation gap that emerges between workers after queen exchange during swarming. Our findings provide novel evidence that the fecundity of workers in a social insect colony impacts their intrinsic longevity. HighlightsRebel honeybee workers have higher reproductive potential than normal workers.Rebel workers have a longer lifespan under both caged and free‐flying conditions.The reproductive potential of both types of workers influences their longevity.Longer‐living rebel workers can fill the generation gap after swarming.

Reproduction of rebel workers in honeybee (Apis mellifera) colonies

The honeybee is one of several eusocial species in which the queen is typically the only reproductive member of the colony; worker reproduction is mostly restricted to queenless colonies. Because workers cannot mate, they lay unfertilized eggs, which develop into males. A recent study showed that in queenless colonies, which arise after swarming, worker larvae develop into rebel workers that have greater reproductive potential than do workers reared in queenright colonies, as measured by the number of ovarioles and degree of ovary activation. However, there was no evidence that rebels had an opportunity to produce male offspring. Here, we show for the first time that rebel workers not only activate their ovaries but also produce significantly more male offspring in queenright colonies than do normal workers. Moreover, our results show that the level of rebel reproduction in queenright colonies is similar to the reproduction of normal workers in queenless colonies. This finding suggests that the ultimate factor favouring the evolution of the rebel strategy is the decrease in relatedness between the old-generation workers and the new queen’s offspring that occurs after queen exchange at swarming.