The Flower Visitors
http://arizonabeetlesbugsbirdsandmore.blogspot.com.au/2013_03_01_archive.html
Figure 8. Bug feeding on inflorescence
Insects and plants have been strongly linked evolutionarily since the Cretaceous period, when both groups had a significant co-radiation (Grimaldi, 1999). Anteriorly, in the late Jurassic, the emergence of flowering plants, called angiosperms, led to the evolution of insects adapted to pollinate flowers. They had a general and basic bouplan of mouthparts (Labandeira, 2002). In contrast, current living insects associated with plants have evolved several types of mouthparts to become adapted and able to feed on specific floral structures (Barth, 1991).
Nowadays, many taxa of insects rely on flowering plants not only as a source of food but also as a place to shelter, mate and prey. Furthermore, flowers might provide pollen and nectar to insects that are usually attracted by colors and fragrances. Some of them may even feed on petal tissues. Hence, Insect orders such as hymenoptera, Coleoptera, Lepidoptera and Diptera, are strictly reliant on Angiosperms as well as these plants rely on insects to be pollinated and eventually protected (Thompson, 1989; Lunau, 2004).
Apart from particular specializations of mouthparts, the general feeding mechanisms and therefore types of oral appendages of insects that visit plants can be classified into three types, according to what they feed on: nectar feeding, pollen feeding and petal feeding.
Figure 8. Bug feeding on inflorescence
Insects and plants have been strongly linked evolutionarily since the Cretaceous period, when both groups had a significant co-radiation (Grimaldi, 1999). Anteriorly, in the late Jurassic, the emergence of flowering plants, called angiosperms, led to the evolution of insects adapted to pollinate flowers. They had a general and basic bouplan of mouthparts (Labandeira, 2002). In contrast, current living insects associated with plants have evolved several types of mouthparts to become adapted and able to feed on specific floral structures (Barth, 1991).
Nowadays, many taxa of insects rely on flowering plants not only as a source of food but also as a place to shelter, mate and prey. Furthermore, flowers might provide pollen and nectar to insects that are usually attracted by colors and fragrances. Some of them may even feed on petal tissues. Hence, Insect orders such as hymenoptera, Coleoptera, Lepidoptera and Diptera, are strictly reliant on Angiosperms as well as these plants rely on insects to be pollinated and eventually protected (Thompson, 1989; Lunau, 2004).
Apart from particular specializations of mouthparts, the general feeding mechanisms and therefore types of oral appendages of insects that visit plants can be classified into three types, according to what they feed on: nectar feeding, pollen feeding and petal feeding.
http://www.thebutterflysite.com/what-butterflies-eat.shtml
http://en.wikipedia.org/wiki/Mandible_(arthropod_mouthpart)#mediaviewer/File:Bullant_head_detail.jpg
Figure 9 and 10. Adaptations of mouthparts: Adapted to fight (left); adapted to suck fluids (right)
1.nectar feeding
Floral nectar is the resource that is most utilized by insects that are reliant on Angiosperms. It is a substance rich in sugar secreted by existing glands present on some flowers. However, the
concentration of sugar present in the nectar broadly varies as well as its composition. Nectar can be made up of amino acids, fructose, glucose and other several types of nutrients and sugars (Baker and Baker, 1983). This substance may be secreted in different regions of the flower, called nectaries. In some species, nectaries are exposed, facilitating its access by insects. In contrast, in others, nectaries may be partially concealed or completely hidden. Concealed nectaries are the most difficult to be accessed by insects, since they are usually present at the base of elongated and narrow corolas ( Jervis and Vilhelmsen,2000). For those, some groups of insects need complex mouthparts, such as long proboscis, in order to reach the base of flower tubes (Nilsson, 1988; Jervis, 1998). In contrast to this distinct type of mouthpart, highly specialized in extracting concealed nectar, many other insects have unspecialized mouthparts such as piercing or sucking mouthparts used to feed on non-hidden nectaries.
The uptake of nectar from flowers is based on two basic principles: adhesion and suction (Kingsolver and Daniel, 1995). Even though these principles function together, some types of mouthparts work better in accordance with one of these properties. Thus, if the property is adhesion, the mouthparts will perform licking or sponging the nectar. If it is suction, mouthparts are usually long and narrow food canals without motion. Nectar is sucked up into the mouth as if the feeding appendages were straws.
2. Pollen feeding
Pollen is a floral structure rich in nutrients, since it is made up of proteins, lipids, amino acids and other substances. However, different from nectar, only a few groups of hexapods feed exclusively on pollen, even though it can be easily accessed on flowers. Such obligate pollen feeders can be found in a few orders such as Coleoptera, Diptera, Hymenoptera and Lepidoptera. In contrast, several taxa of insects feed occasionally on it, such as Mantodea and
Collembola (Kevan and Baker, 1983). The mouthparts of these obligate pollen feeders are broadly varied and sometimes highly specialized.
3. Petal feeding
Several orders of insects have been reported to use petals of flowers as part of their diets. Most
of them do not seem to be beneficial to plants, since they end up destroying floral tissues. However, it has been noticed that even though some species of beetles destroy some flowers when feeding on them, they help pollination. The petal feeding mechanism varies according to the taxa, but the mouthparts of the majority of them seem to be simple and in general not specialized.
Some insects belonging to the order Thysanoptera have piercing mouthparts. The maxilla is modified into stylets and is used to pierce the petal tissue and consequently cells that there exist. Once cells are damaged, insects will be able to suck fluids into their mouths (Hunter and Ullman, 1989).
Some families of beetles also have representatives that have been reported to feed on floral tissue. The strong and fruity smell of some types of fleshy flowers attracts them. Once attracted, they are trapped inside the flower, where they have to stay for a period of time before escaping. Meanwhile, their bodies and appendages become covered with pollen as they move around and feed inside the flower. Hence, they contribute with the process of pollination (Gottsberger, 1989). The mouthparts of these animals are adapted to chew. Mandibles are hard and sclerotized in order to bite fleshy petal tissues and chew them. The other oral appendages such as maxilla and labium are used to move and hold the food near the mouth (Proctor et al., 1996). Some types of beetles have also been reported to feed exclusively on petal tissues and they possess a general and unspecialized chewing mouthpart type.
It is not common for species belonging to the order Hymenoptera to feed on floral tissues, even
though it has been reported in some families (Linston, 1980).
http://en.wikipedia.org/wiki/Mandible_(arthropod_mouthpart)#mediaviewer/File:Bullant_head_detail.jpg
Figure 9 and 10. Adaptations of mouthparts: Adapted to fight (left); adapted to suck fluids (right)
1.nectar feeding
Floral nectar is the resource that is most utilized by insects that are reliant on Angiosperms. It is a substance rich in sugar secreted by existing glands present on some flowers. However, the
concentration of sugar present in the nectar broadly varies as well as its composition. Nectar can be made up of amino acids, fructose, glucose and other several types of nutrients and sugars (Baker and Baker, 1983). This substance may be secreted in different regions of the flower, called nectaries. In some species, nectaries are exposed, facilitating its access by insects. In contrast, in others, nectaries may be partially concealed or completely hidden. Concealed nectaries are the most difficult to be accessed by insects, since they are usually present at the base of elongated and narrow corolas ( Jervis and Vilhelmsen,2000). For those, some groups of insects need complex mouthparts, such as long proboscis, in order to reach the base of flower tubes (Nilsson, 1988; Jervis, 1998). In contrast to this distinct type of mouthpart, highly specialized in extracting concealed nectar, many other insects have unspecialized mouthparts such as piercing or sucking mouthparts used to feed on non-hidden nectaries.
The uptake of nectar from flowers is based on two basic principles: adhesion and suction (Kingsolver and Daniel, 1995). Even though these principles function together, some types of mouthparts work better in accordance with one of these properties. Thus, if the property is adhesion, the mouthparts will perform licking or sponging the nectar. If it is suction, mouthparts are usually long and narrow food canals without motion. Nectar is sucked up into the mouth as if the feeding appendages were straws.
2. Pollen feeding
Pollen is a floral structure rich in nutrients, since it is made up of proteins, lipids, amino acids and other substances. However, different from nectar, only a few groups of hexapods feed exclusively on pollen, even though it can be easily accessed on flowers. Such obligate pollen feeders can be found in a few orders such as Coleoptera, Diptera, Hymenoptera and Lepidoptera. In contrast, several taxa of insects feed occasionally on it, such as Mantodea and
Collembola (Kevan and Baker, 1983). The mouthparts of these obligate pollen feeders are broadly varied and sometimes highly specialized.
3. Petal feeding
Several orders of insects have been reported to use petals of flowers as part of their diets. Most
of them do not seem to be beneficial to plants, since they end up destroying floral tissues. However, it has been noticed that even though some species of beetles destroy some flowers when feeding on them, they help pollination. The petal feeding mechanism varies according to the taxa, but the mouthparts of the majority of them seem to be simple and in general not specialized.
Some insects belonging to the order Thysanoptera have piercing mouthparts. The maxilla is modified into stylets and is used to pierce the petal tissue and consequently cells that there exist. Once cells are damaged, insects will be able to suck fluids into their mouths (Hunter and Ullman, 1989).
Some families of beetles also have representatives that have been reported to feed on floral tissue. The strong and fruity smell of some types of fleshy flowers attracts them. Once attracted, they are trapped inside the flower, where they have to stay for a period of time before escaping. Meanwhile, their bodies and appendages become covered with pollen as they move around and feed inside the flower. Hence, they contribute with the process of pollination (Gottsberger, 1989). The mouthparts of these animals are adapted to chew. Mandibles are hard and sclerotized in order to bite fleshy petal tissues and chew them. The other oral appendages such as maxilla and labium are used to move and hold the food near the mouth (Proctor et al., 1996). Some types of beetles have also been reported to feed exclusively on petal tissues and they possess a general and unspecialized chewing mouthpart type.
It is not common for species belonging to the order Hymenoptera to feed on floral tissues, even
though it has been reported in some families (Linston, 1980).
http://www.bio.georgiasouthern.edu/bio-home/harvey/lect/lectures.html?ccode=en&mda=scrn&flnm=en_morph&ttl=Arthropod%20morphology
Figure 11. Lapping mouthparts of flies
Figure 11. Lapping mouthparts of flies