Studies on phytophagous white grubs in Mandi district of Himachal Pradesh
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Date
2021-03-11
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palampur
Abstract
The studies on biodiversity of phytophagous scarab beetles were conducted by using light traps and
also by sampling them directly from their host trees at Sundernagar, Jogindernagar, Chailchowk,
Pangna, Bagsaid and Janjehli in Mandi district of Himachal Pradesh from May-September 2019. At
Sundernagar, Jogindernagar, Chailchowk and Pangna, Holotrichia longipennis Blanchard and
Anomala lineatopennis Blanchard were recorded to be the predominant species. The relative
abundance of H. longipennis varied from 13.45-23.36 per cent, and A. lineatopennis contributed to
14.19-24.41 per cent of total beetle catch. The predominant species at Bagsaid were Anomala
dimidiata Hope and Anomala rufiventris Redtenbacher and these species comprised 14.90 and 14.60
per cent, respectively. Brahmina coriacea (Hope) and Brahmina flavosericea Brenske were found to
be the other predominant species at Bagsaid and Janjehli, and their relative abundance was 14.23-
14.85 and 12.41-15.39 per cent at both these locations, respectively. The pooled analysis of data from
six locations revealed that H. longipennis was the most predominant species comprising 16.31 per cent
of total beetle catch on light trap. The Pielou’s evenness index was maximum at Pangna (J'= 0.86) and
minimum at Sundernagar (J'= 0.73). The value of Shannon index (H') was computed to be maximum
at Pangna (H'= 2.54), and minimum at Sundernagar (H'= 2.18). The Simpson’s index of diversity was
maximum at Pangna (D= 0.90) and minimum at Chailchowk (D= 0.85). The Fisher plots indicated few
common and more rare species at most of the locations. The Whittaker rank/ abundance curves
showed greater evenness of scarab assemblage at Chailchowk and Pangna. The Beta diversity
exhibited maximum similarity between Sundernagar and Chailchowk, whereas maximum dissimilarity
between scarab communities was recorded between Jogindernagar and Janjehli. The survey of scarab
beetles on host trees indicated the occurrence of 17 species on different fruit plants, forest trees, field
crops, vegetables and ornamental plants. The five most leading species on different host plants were H.
longipennis (23.13 %), B. coriacea (19.61%), B. flavosericea (12.43 %), Holotrichia sikkimensis
Brenske (7.41%) and Maladera insanabilis (Brenske) (6.59 %). H. longipennis beetles exhibited
distinct preference for rose, beans, toon, whereas B. coriacea and B. flavosericea beetles were
collected only on apple in high hills. The value of Shannon index and Pielou’s evenness index was
calculated to be maximum at Bagsaid (H'= 1.95) and Pangna (J'= 0.91), respectively. The Simpson’s
index of diversity was computed to be maximum at Jogindernagar (D= 0.82). In the present study, five
species viz. Asactapholis microsquamosa (Frey), Anomala variivestis Arrow, Anomala aureoflava
Arrow, Holotrichia assamensis Brenske and Polyphylla fullo (Linnaeus) are new records from
Himachal Pradesh. In potato, the tuber infestation of white grubs was very high (34.44 - 44.91 %). In
peas, the plant mortality varied from 10.59 - 20.40 per cent. In garlic, 23.20 per cent bulbs were found
to be infested by the grubs at Rohanda