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.