1. المحاضرة الثانية Insect-Plant Interactions Plpt343@hotmail.com

2. Numbers of herbivorous species in different orders Herbivorous species Total no. of species Insect order %No. 35122000349000Coleoptera 100119000119000Lepidoptera 3035700119000Diptera 111050095000Hymenoptera 905300059000Hemiptera 1001990020000Orthoptera 9045005000Tysanoptera 10020002000Phasmida HM

3. Specialization vs Generalization Specialization vs Generalization Monophagous Insects feed on one or a few closely related species. Many lep. Larvae, hemi. and coleopt. Insects feed on one or a few closely related species. Many lep. Larvae, hemi. and coleopt. Oligophagous feed on a number of plant species belonging to the same plant family example Pieris brassicae feeds on plant of Brassicaceae

4. Specialization vs Generalization Polyphagous Insects feed on many plant species belonging to different plant families. Insects feed on many plant species belonging to different plant families. Myzus persicae Myzus persicae

5. Specialization vs Generalization Limitations!

6. Limitations Monophagous and Oilgophagous Individuals of the same insect species may show different host-plant preferences in different area of its distribution, and even individuals belonging to same population may be much more restricted in their choice. Individuals of the same insect species may show different host-plant preferences in different area of its distribution, and even individuals belonging to same population may be much more restricted in their choice. It is more convenient to distinguish only specialist (Monophagous and Oilgophagous ) and generalist (Polyphagous) It is more convenient to distinguish only specialist (Monophagous and Oilgophagous ) and generalist (Polyphagous)

7. Specialization vs Generalization Host-plant specialization is the rule rather than the exception. Host-plant specialization is the rule rather than the exception. An inventory (list) of about 5000 British herbivorous insects species show that 80% of them should be regards as specialists. An inventory (list) of about 5000 British herbivorous insects species show that 80% of them should be regards as specialists. 76% of all British aphids are mnophagous, 18% are oligophagous, and only 6% are polyphagous. 76% of all British aphids are mnophagous, 18% are oligophagous, and only 6% are polyphagous.

10. Specialization vs Generalization Generalists seem to be privileged compared with specialists because they have access to a much broader food range! BUT, specialists need to make decisions based on a smaller number of options than generalists, thereby increasing the efficiency of decision-making process in the former group.

11. Specialization vs Generalization Polyphahous insect species prefer certain plant species. So they are discriminate in what they choose from their acceptable host plant range. Oilgophagous species are indscriminate ….

12. Specialization vs Generalization The gypsy moth exhibits more discrimination prefers full-grown leaves, leaves grown on sunny side, in southern side of tree Age of the leaves Exposed to sunlight Direction

13. Specialization vs Generalization

14. It has been argued that some polyphagous insects should be considered as monophagous when their host plant selection based on a specific type of plant chemical. 1. Larvae of cabbage white butterfly feed on plants of different families but they contain glucosinolate. One can say that cabbage white butterfly is monophagous on glucosinolate-containing plants. (Limitations!)

15. Specialization vs Generalization 2- Similar, larvae of the brown tail, Euproctis chrysorrhoea, 2- Similar, larvae of the brown tail, Euproctis chrysorrhoea, attack trees with tannins in their leaves.(Limitations!)

16. Specialization on plant parts

19. Food-plant range and host-plant range

20. Oviposition female selects the plant on which its offspring will feed The diet breath of the larvae is often wider than the range of plants acceptable as oviposition substrate to the adult female 2.6

22. Food-plant range and host- plant range The oviposition female is governed by different part of genome than those coding to for food selection behaviour in the larvae. There is a positive correlation between …..

23. Food-plant range and host- plant range Different females of same population of the butterfly Euphydryas editha showed host different plant preference for oviposition. Larval performance correlated positively with it. 2 Tipworm Crovidosema plebbejana on different plant stages of cotton and Malva showed that there is a strong correlation between the acceptable level of a plant as an oviposition substrate and larval performance. 2.7

25. Food-plant range and host- plant range Thus, larvae grew best on the plants that their mothers had selected.

26. Specialization on plant parts In addition to host plant specialization, also show specialization with regard to the feeding sites they occupy on their host. different leaf parts taste different and possess different physical properties. Grass hopper many lepidoptera and Coleoptera larvae are leaf foragers (folivores), ingesting large chunk of leaf material. Plant bugs penetrate epidermal cell Aphids suck from the sap flow in phloem Leaf-hoppers tap (hit) the xylem Leaf miners HM Leaf miners HM

27. Specialization on plant parts Compound leaves Larvae of Catacala spp. Can discriminate between the basal, alteral and terminal leaflets of their compound leaved food plant, and they showed a dislike the basal leaflets. 2.10

29. Specialization on plant parts Stem borers Fig 2.11

30. Specialization on plant parts Conclusion These examples show how all parts of plant are shared out and can support some insect or others.

31. Below-ground herbivory The total biomass of the life beneath our feet is mach more than above the ground. The subterranean life of forest consists of 100 000 to 500 000 insects and other arthropods per square meter The subterranean life of forest consists of 100 000 to 500 000 insects and other arthropods per square meter

32. Below-ground herbivory The interactions of insect and plant below ground surface are likely to mirror the above-ground interactions. Examples Grubs eat rootlets Larvae of onion flies, carrot flies, and cabbage root flies are root borers. Sap feeders like aphids

33. Below-ground herbivory Root-infesting insect may affect their above-ground counterparts (and vice versa) via changes in their host's chemistry and physiology. The rice water weevils that feed on rice` roots reduced the growth rate of the fall armyworms.

34. Below-ground herbivory Herbivore damage to roots may also affect indirect plant defence. Example Cotton plants exposed to root-feeding wirworms (Agriotes sp.) increased their extrafloral nectar production 10- fold. extrafloral nectar recruits predators

35. Number of insect species per plant species No. plant species vs herbivorous insect species An insect species occur on more one plant species. Number of insects species attacking a single plant species Not necessary competition Spatial separation Spatial separation Temporally separated because of differences in phenology between insects Temporally separated because of differences in phenology between insects Behavioral separations Behavioral separationsExample Plant of Urtica dioica is the host plant of eight species. 2.12

36. Number of insect species per plant species

37. 143 different insect species were found upon Tansy Plant, Tanacetum vulgare,

38. Number of insect species per plant species

39. Host Plant is more than food plants Fed on Lived on Housing facilities provided by host plant: biotic and abiotic factors other than foods

40. Host Plant is more than food plants Larvae of platyprepia virginalis were parasitized by a tachinid fly in 83% and in 50% on hemlock and lupin plants in the same habitat, respectively. The avoidance reaction

41. hemlock plant lupin plant (legume) Apiaceae or Umbelliferae Host Plant is more than food plants

42. Nutritionally optimal host Nutritionally suboptimal host survival rates

43. Host Plant is more than food plants Nutritionally optimal host Nutritionally suboptimal host Insect may prefer the suboptimal host that not visited by some of their natural enemies. Such plant provide better overall survival rates

44. Host Plant is more than food plants Microclimate around plants The upper leaf surface may be warmer or cooler than ambient level, depending on the rate of transpiration. The lower surface of a leaf is usually cooler and more humid than the upper surface

45. Host Plant is more than food plants Microclimate around plants The temperature of the leaf surface may be up to 10 c, and even more, above or below the air temperature. Fig 2.15; Table 2.6

48. Host Plant is more than food plants Microclimate around plants The microclimates may also be studied at level of whole plants or within natural vegetations Fig. 2.16 2.17