Insect ecology presentation

This presentation contains insectivorous plants and their ecology.

1. Term Paper Presentation on INSECTIVOROUS PLANTS AND THEIR ECOLOGY Presented By BIPIN KARKI ENT-07M-2019 Department of Entomology AFU, Rampur, Chitwan

2. Insectivorous plants Introduction Insectivorous means insect-eating, insectivorous plants derive most of their nutrition from the insects by trapping them. Sometimes called Carnivorous plants. However, carnivorous plants capture insect as well as other animals. Plants are autotrophic in nature. However insectivorous plants are devoid of nutrition and food synthesizing capabilities. To be accepted as carnivorous, a plant must not only have a mechanism for trapping, but the trap must be specifically designed to extract food from the prey (Temple, 1993 ).

3. Only plants possessing following traits should be considered as carnivorous/insectivorous plants (Ellison & Adamec , 2018 ): Capturing or trapping prey in specialized, usually attractive traps . Killing the captured prey . Digesting the prey . Absorption of metabolites (nutrients) from the killed and digested prey . Use of these metabolites for plant growth and development.

4. Plant characteristics Nitrogen Deficiency -These are found in nitrogen deficient soil. They entrap insects and digest them to fulfil their nitrogen requirement. Attractive nature - These plants are colorful and shiny in appearance to attract insects. They often have nectars and a pleasant odor to attract insects. Inescapable traps - They have hair-lined edges that shut as soon as the insect touches the hair, thereby trapping the insects inside. Have digestive enzymes - Some insectivorous plants secrete digestive enzymes that dissolve the insect for absorption. Life on wet and damp places - These plants exist in damp, humid, wet and acidic soil that is deficient in nutrients. Such places includes coastal plains, bogs, wetlands etc.

5. Some examples Drosera They have sticky digestive enzyme which fakes and attracts the insects. These plants trap and digest insects. Venus flytrap These plants have a wide mouth lined with hair which have sensitive structures As soon as an organism touches this hair, the mouth shuts uo trapping the insect inside. Once the organism is digested, the leaves of this plant open up again to trap another prey.

6. Nepenthes/Pitcher plant These plant consist of the pitcher which produces a liquid on its own. The insects are attracted by the odour of the plant. Once the insect is trapped, the plant starts secreting the digestive liquid. The organism is then digested and the nutrients are absorbed.

7. Pinguicula / butterworts They produce bright, colourful   flower   to attract prey and have dewy sticky leaves to trap the insects. These plants are dormant during the winter season.

8. Genlisea / corkscrew plant It contains the Lobster pot trap that has small hair lined at the entrance. It is made up of two types of leaves- the underground leaves is specially designed for insect trap. These underground leaves form hollow tubes. With the aid of water flow, the insects enter these tubes but cannot come out.

9. Types of traps in insectivorous plants Generally two types of traps: Active traps: H ave movement in the process of trapping and digesting their prey. Eg Dionaea , Drosera Passive traps: U tilize no movement either in trapping or during digestion . prey move towards the plant and trapped, by falling into a pit or being stuck with a gluey substance. Eg . Pinguicula , Sarracenia

10. Ecology of insectivorous plants Have wide range of habitats and found in wind-whipped mountain tops to lowland . The wide range of habitats has an equally large range of potential prey( Darnowski , Bauer, Mendez, Horner, & Plachno , 2018). Most abundant and diverse in tropical to subtropical regions of all continents(warm to hot, humid to wet climates) Grow in fresh-waters, marshy ponds, and swamps with low nitrogen content . Have high plant diversity in wet, unshaded and nutrient poor habitats.

11. Centre of diversity of some insectivorous plants according to (Brewer & Schlauer , 2018 ). Nepenthes in tropical Asia Drosera in Australia Pinguicula in Central America and the Mediterranean (predominantly at elevated altitudes ) Genlisea in tropical South America and Africa Utricularia in tropical America, Africa, and Australia

12. Some examples of carnivorous plants with their habitat Venus flytrap grows in soils with almost immeasurable nitrate and calcium levels.   Drosophyllum lusitanicum grows in dry soil and generally found in desert. Pinguicula valisneriifolia is found in limestone cliff(calcium rich soil). most species are associated with open, herbaceous habitats, and are poor competitors for light (Juniper et al. 1989, Givnish 1989 ).

13. Prey selection by insectivorous/carnivorous plants Shape and size of the trap of plant sets the limit for size and type of the prey. Large trap-large prey small trap- small prey Likewise, chemical composition of mucilage also useful in prey selection. Differentiation among Drosera species in growth form, leaf shape, glandular hairs or chemical composition of the trapping mucilage could indicate a separation of trophic niches. Upright sundew species significantly differ in their prey composition compared to more horizontal species, with the former capturing more aerial arthropods and the latter more terrestrial arthropods. Some select prey with their motile traps. For example, Aldrovanda uses a snaptrap to capture prey ranging from very small crustaceans to occasional small tadpoles. Some select with their non-motile traps. For example Genlisea can attract and trap various protozoan, crustaceans, annelids and mites in their non-motile traps.

14. Interactions between insectivorous plants and insects Plant-insect interactions have been presented in the context of insects serving as prey. But the associations can be much more varied and complex . For example: spiders often can be found prowling on the mouth of pitcher plants, lowering themselves on the silken strands to retrieve prey from the pitcher well . The pitcher plant mosquito ( Wyeomyia smithii ) lays eggs on inner surface of leaf. The larvae hatch and feed on detritus from trapped insects, bacteria and protozoans. During winter-goes into dormant stage spring-exits from pitcher as a adult mosquito Exyra moths use pitcher leaf to shelter their young.

15. Seed morphology, germination biology and seed dormancy M ajority of carnivorous genera produce seeds that are small to minute (<5.0 mg per seed except Triphyophyllum peltatum (large and unique seed ). P hysiological dormancy (PD) is seen in all genera of carnivorous plants except Paepalanthus , Roridula , Darlingtonia , Heliamphora , Sarracenia , Genlisea , and Utricularia . But seeds of some species with physiological dormancy i.e. Drosera and Dionea germinate readily when sown, suggesting no dormancy is present . Seeds of Heliamphora germinate readily several weeks after dehiscence and thus appear to have morphological dormancy (MD ). S eeds of Darlingtonia californica and Sarracenia do not germinate because they have morphophysiological dormancy (MPD).

16. Two techniques that can alleviate PD/MPD: C ycles of wetting and drying E xposure of seeds to high temperatures for short periods but these methods have not yet been tested widely on carnivorous plant seeds . Once dormancy has been alleviated, seeds remain quiescent until exposed to environmental conditions suitable for germination. exogenous chemical stimulant such as smoke, nitrates, or ethylene acts as germination stimulants.

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