Plants interact with many visitors who consume a variety of plant tissues. While the consequences of herbivory to leaves and shoots are well known, the implications of florivory, the consumption of flowers prior to seed coat formation, have received less attention. Herbivory and florivory can yield different plant, population and community outcomes; thus, it is critical to distinguish between these two types of consumption. Here, we consider the ecological and evolutionary consequences of florivory. A growing number of studies recognize that florivory is common in natural systems and in some cases surpasses leaf herbivory in magnitude and impact. Florivores can affect male and female plant fitness via direct trophic effects and through altered pathways of species interactions. In particular, florivory can affect pollination and have consequences for plant mating and floral sexual system evolution. Plants are not defenceless against florivore damage. Concepts of resistance and tolerance can be applied to plant‐florivore interactions. Moreover, extant theories of plant chemical defence, including optimal defence theory, growth rate hypothesis and growth differentiation‐balance hypothesis, can be used to make testable predictions about when and how plants should defend flowers against florivores. The majority of the predictions remain untested, but they provide a theoretical foundation on which to base future experiments. The approaches to studying florivory that we outline may yield novel insights into floral and defence traits not illuminated by studies of pollination or herbivory alone.

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Florivory: the intersection of pollination and herbivory.

Foraging behaviour is one of the distinctive behaviours of honey bees, Apis mellifera. This behaviour is the link between the honey bee colony and the ambient environment. Therefore, various in-colony and out-colony factors have an impact on this behaviour, and many studies have been employed to investigate these factors. Foraging behaviour is not advantageous only for the colony and for plant pollination but also has other benefits. In contrast, some disadvantages have also been discovered to be linked with foraging activity. Practically speaking, the control over this behaviour is very important to maximize colony products as well as to increase other agricultural benefits. This paper presents a review on foraging activity including; the regulation of foraging tasks, factors impacting this behaviour, foraging preference, variations between subspecies, monitoring methods as well as the possible methods for controlling this behaviour. As concluded from this review, more work needs to be performed in order to elucidate certain aspects of foraging behaviour.

The foraging behaviour of honey bees, Apis mellifera: a review.

Variation in flower size is an important aspect of a plant’s life history, yet few studies have shown how flower size varies with environmental conditions and to what extent foliar responses to the environment are correlated with flower size. The objectives of this study were to (1) develop a theoretical framework for linking flower size and leaf size to their costs and benefits, as assessed using foliar stable carbon isotope ratio (δ13C) under varying degrees of water limitation, and then (2) examine how variation in flower size within and among species growing along a naturally occurring moisture availability gradient correlates with variation in δ13C and leaf size. Five plant species were examined at three sites in Oregon. Intra- and inter-specific patterns of flower size in relation to moisture availability were the same: the ratios of the area of flower display to total leaf area and of individual flower area to leaf area were greater at sites with more soil moisture compared to those sites with less soil moisture. The increase in flower area per unit increase in leaf area was greater at sites with more soil moisture than at sites where water deficit can occur. Values of δ13C, an index of water-use efficiency, were greater for plants with larger floral size. The patterns we observed generalize across species, irrespective of overall plant morphology or pollination system. These correlations between flower size, moisture availability, and δ13C suggest that water loss from flowers can influence leaf responses to the environment, which in turn may indirectly mediate an effect on flower size.

Correlated variation of floral and leaf traits along a moisture availability gradient

Pollen beetles (Meligethes aeneus) are pests that feed and oviposit in the buds and flowers of oilseed rape. Honey-bees foraging from a hive fitted with an inoculum dispenser at the entrance effectively delivered dry conidia of the entomogenous fungus, Metarhizium anisopliae , to the flowers of oilseed rape in caged field plots. In both winter- and spring-sown rape experiments, a greater mortality of pollen beetles occurred in treated plots than in control plots. The mortality (61% on winter rape, 100% on spring rape) was greatest during peak flowering, when the feeding activity of both bees and beetles from the flowers was maximal, providing optimal conditions for inoculum dissemination and infection. Conidial sporulation occurred on a significant proportion of the dead pollen beetles. There was no evidence of any adverse effect on the honey-bee colonies.

Honey-bee-mediated infection of pollen beetle (Meligethes aeneus Fab.) by the insect-pathogenic fungus, Metarhizium anisopliae

Plants experience damage to both their vegetative and their reproductive parts. Loss of leaf area can affect subsequent photosynthesis and resources available for growth and reproduction; damage to flowers can result in loss of ovules and seeds by consumption, but herbivory may also disfigure flowers, interfering with their functions of attracting and rewarding pollinators. We examined natural populations of the butterfly pea, Centrosema virginianum, in pine rockland habitat in Everglades National Park (intact habitat) and a pine rockland fragment in suburban Miami‐Dade County to answer the following questions: (1) What is the breeding system of C. virginianum? (2) What are the pollinators of this species in southern Florida pine rocklands? And (3) how are flower herbivores affecting pollinator visitation and subsequent fruit set? Controlled hand‐pollination experiments revealed this species to be self‐compatible but requiring visitation/pollination for fruit set. Cross‐pollinated flowers and open‐pollina...

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Effects of florivory on the pollination of flowers: an experimental field study with a perennial plant

The amount of herbivore damage to the petals of 41 species of herbaceous plant was surveyed from April to September in a limestone grassland in central England. Damage was recorded as the percentage of the petal area removed. Most damage was caused by invertebrates, particularly slugs. The amount of invertebrate damage differed significantly between plant species and with time of year. The mean damage across all species was only 2 %, ranging from an average of 0 % in Galium sterneri to 8 % in Primula vulgaris. In most species, less than a quarter of flowers received any damage, so those that were damaged were often severely affected. Species flowering early or late in the season received more damage, possibly because of greater slug activity. Hypotheses to explain the inter-specific variation in the amount of herbivory were examined by testing for correlations with a range of plant variables. No correlations with flower-stem length, flower-stem thickness or the longevity of flowers were apparent. The amount of petal damage correlated strongly with flower size and petal thickness. This appeared to result from the prevalence of large-flowered species early and late in the season rather than from a preference for flower size and petal thickness per se. The evolutionary significance of floral herbivory is discussed.

Factors affecting floral herbivory in a limestone grassland

SUMMARYAdults and larvae of the pollen beetle Meligethes aeneus (Nitidulidae) are abundant in flowers of oilseed rape (Brassica napus) in the UK. Their effects on the foraging behaviour of honey bees (Apis mellifera) were investigated in the field. Bees foraged predominantly from fully open flowers, but landed on fully open flowers containing adult beetles less often than would be expected from the proportion of flowers with beetles in them. Of 107 flowers visited by bees, 99 had no adult beetles, whereas of 100 flowers selected at random, 81 had no beetles; the difference was significant. Simulated adult beetles (black spots on the petals) deterred nectar-foraging bees from landing. Bees given a choice between flowers with four black or four clear spots and one black or one clear spot were 2.5 times and 2.4 times, respectively, more likely to visit flowers with clear spots. Flowers with real adult beetles had as much nectar as those without, so there was no evidence that the avoidance of simulated beetle...

Karen N. Breadmore

Papers

Factors affecting floral herbivory in a limestone grassland

The effects of pollen beetles on the foraging behaviour of honey bees