3.2. Diversity analysis
Collected numbers of leafhopper species (Plate 5; Plate 6; Plate 7; Plate 8; Plate 9; Plate 10 and Plate 11) were analyzed for various diversity parameters to generate spatio-temporal distribution of the group especially based on agroclimatic zonations.
3.2.1. Shannon-Weiner Index value when approaches zero, the composition of the species found in the various zones shows certainty, whereas, higher values indicated that the composition of each species was highly unpredictable. Shannon-Weiner Index of Diversity (H′) which takes into account the richness and evenness was more than 1 in all the four zones indicating that the composition of the species in various zones was somewhat unpredictable. The Shannon Diversity Index (Table 6) was 3.5 for the mid hill zone II (651-1800 m amsl) with highest species richness (66) and relative abundance (822). This directs towards more variation in species encountered in mid hills. High hills wet temperate zone III (1801-2200 m amsl) was recorded with second highest Shannon Diversity Index (2.94) with abundance of 749 individuals and 48 species. While in high hills dry temperate zone IV (above 2200m amsl) and low hills zone I (350-650m amsl) the index was 2.74 and 2.63 with 39 and 35 species, respectively (Fig II).
3.2.2. Evenness of leafhopper species for each zone was evaluated using Shannon-Weiner Index. All the zones surveyed had less variation in the evenness value but close to zero, indicating that leafhoppers were unevenly distributed. The evenness value was 0.835 for mid hills zone II (651-1800m amsl) and 0.760 for high hills wet temperate zone IV (above 2200 m amsl), while, 0.742 and 0.749 for low hills zone I (350-650m amsl) and high hills dry temperate zone IV (above 2200m amsl) (Table 6; Fig II).
3.2.3. Dominance is the measure of the numerical importance of the most abundant species. Dominance value (Table 6) was found to be for 0.250 for high hills dry temperate zone IV, 0.239 for hills wet temperate zone III, 0.164 for mid hills zone II and 0.257 for low hills zone I. Decreasing dominance values is the indicative of higher diversity for example, in high hills dry temperate zone IV dominance value of 0.250 indicates that 25 percent of 39 recorded speciesi.e. approximately 10 species were dominant in zone IV (Table 3) that constituted of leafhopper species viz ., Platymetopius fidelis (Distant) (Plate 8l), Aconurella erebrus (Distant) (Plate 10e), Amrasca biguttula biguttula (Ishida) (Plate 11d),Amrasca motti (Plate 11f), Empoasca sp. 1 (Plate 11m),Austroagallia sinuata (Mulsant & Rey) (Plate 5a),Typhlocyba sp. 1 (Plate 11b), Morphospecies 4 (Plate 11c),Psammotettix emarginata Sawai Singh (Plate 8g),Pseudosubhimalus bicolor (Pruthi) (Plate 8i),Pseudosubhimalus sp. 2. (Plate 8j). In hills wet temperate zone III the value of 0.239 implied 12 dominant species among 49 recorded,Typhlocyba sp. 1 (Plate 11b), Amrasca motti (Plate 11f), Amrasca biguttula biguttula (Ishida) (Plate 11d),Detocephalus maculates (Pruthi) (Plate 10d), Durgades aviana Viraktamath (Plate 5b), Empoasca sp. 1 (Plate 11m), Pseudosubhimalus bicolor (Pruthi) (Plate 8i), Pseudosubhimalussp. 2 (Plate 8j), Jilinga gopi (Pruthi) (Plate 8e),Evacanthus sp. 1 (Plate 5k) and Exitianus indicus(Distant) (Plate 6c) and Mimotettix sp. 1 (Plate 6e) standing out. In the mid hills zone II, the value of 0.164 stands for 11 dominating species out of 66 comprising of Exitianus indicus(Distant) (Plate 6c), Amrasca motti (Plate 11f), Amrasca biguttula biguttula (Ishida) (Plate 11d), Austroagallia sinuata(Mulsant & Rey) (Plate 5a), Empoasca sp. 1 (Plate 11m),Evacanthus convolutus Viraktamath & Webb (Plate 5l), Mimotettix sp. 1 (Plate 6e), Morphospecies 5 (Plate 10l),Osbornellus confuscus (Pruthi) (Plate 6h), Psammotettix emarginata Sawai Singh (Plate 8g) and Scaphoidieus sp. 1 (Plate 6l). Value of 0.257 recorded in low hills zone I implied 9 out of 30 dominating species to be Exitianus indicus (Distant) (Plate 6c),Amrasca motti (Plate 11f), Amrasca biguttula biguttula(Ishida) (Plate 11d), Cofana spectra (Distant) (Plate 5j),Empoasca sp. 1 (Plate 11m), Balclutha sp. 1 (Plate 10k),Stirellus indra (Distant) (Plate 9a), Morphospecies 2 (Plate 10h) and Idioscopus nitidulus (Walker) (Plate 9f) a well known pest of mango (Fig. II).
3.2.4. Margalef’s Index measured the species richness in each of the agro-climatic zones. A perfect linear relationship between the Margalef Index and Shannon-Weiner Diversity Index was observed. The Margalef Index value was found to be 9.684, highest for the mid hills zone II, which showed highest species richness with a maximum species diversity of 3.50 followed by high hills wet temperate zone III with value of 7.252 and Shannon Diversity of 2.956. This indicated that Zone II and Zone III ecosystem were rich with a greater diversity of leafhopper species, followed by richness value of 6.049 in the low hills zone I and 5.954 in the high hills dry temperate zone IV with comparatively less diverse leafhopper fauna (Table 6; Fig II).
3.2.5. Simpson Yule Diversity Indices was measured as the dominance of species, adding the total number of species recorded in an area, along with the relative abundance of each species. Simpson index was found to be the 0.101 for high hills dry temperate zone IV as well as for high hills wet temperate zone III which means that the probability of encountering an individual belonging to the same species among two randomly collected specimens shall be 0.101.In the mid hills zone II the value was 0.043 and in the low hills zone I it was 0.078. Different Simpson Yule Index value in the four agro-climatic zones (Table 6) signals towards variations in leafhopper diversity. Consequently, the higher diversity was attained at mid and low hills zones as compared to the high hills wet and dry temperate zone, thereby, decreasing the chances of encountering a particular species due to the greater relative abundance of different species.