EFFECTS OF COMBINATION OF SYNERGISTS WITH CRUDE ETHANOLIC HERBAL EXTRACTS OF CLERODENDRUM PHILIPPINUM AND LEUCAS LAVANDULIFOLIA AGAINST RHIPICEPHALUS (BOOPHILUS) ANNULATUS
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Date
2022-02-15
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COLLEGE OF VETERINARY AND ANIMAL SCIENCES POOKODE
Abstract
The objective of the present study was to compare the anti-tick activity due to
addition of the synergists viz., piperonyl butoxide (PBO) and S, S, S-tributyl
phosphotrithioate (DEF) with crude ethanolic extract of Clerodendrum philippinum and
Leucas lavandulifolia against Rhipicephalus (Boophilus) annulatus and to evaluate the
effects of these treatments on the reproductive organs of R. (B.) annulatus
L. lavandulifolia (Family: Lamiaceae) and C. philippinum Schauer (Family:
Verbenaceae) are generally annual spreading herbs seen in cultivated fields, wastelands and
roadsides throughout India. Acaricidal effects of these plants were reported earlier. In order
to increase the acaricidal activity, inhibition of fecundity and inhibition of hatching of eggs
laid by treated ticks, the synergists like piperonyl butoxide (PBO), S, S, S-tributyl
phosphotrithioate (DEF) and tripheny phosphate (TPP) were added along with crude
ethanolic extracts of L. lavandulifolia and C. philippinum at a ratio of 0.5:1.
The addition of TPP, PBO and DEF to the crude ethanolic extract of L.
lavandulifolia increased the adult tick mortality to 2.95, 2.95 and 0.51-fold respectively. In
addition, the inhibition of fecundity increased 2.00, 1.98 and 1.65 times after addition of
these synergists to the crude extract. The addition of TPP, PBO and DEF to the crude
ethanolic extract of C. philippinum increased the adult tick mortality 1.90, 1.77 and 1.36
fold respectively. The inhibition of fecundity also increased 1.56, 1.54 and 1.49 times
respectively. The present investigation revealed that the synergists TPP and PBO were the
ideal synergists for producing adulticidal effects when combined with crude ethanolic
extracts.
The effect of extracts, sysnergists and synergised extracts were testedagainst
the larvae of R. (B.) annulatus using larval packet test (LPT). The extracts of L.
lavandulifolia alone exhibited larval mortality of 1.81 per cent at 1.1 per cent(IFD50)
concentration. Similarly, at 0.55 per cent PBO, DEF and TPP exhibited 33.41, 88.57
and 33.58 per cent larval mortality. The highest larval mortality (99.09
± 0.91 per cent) was seen when 1.1 per cent L. lavandulifolia synergised with 0.55
per cent DEF, PBO and TPP synergized extracts caused 97.66 ± 0.78 per cent and
71.97± 3.70 per cent mortality respectively. The crude ethanolic extract of C philippinum alone exhibited larval mortality of 0.36 ± 0.36 per cent at 0.4 per cent
(IFD50 concentration). Similarly, when synergist alone was tested at 0.20 per cent
concentration each, DEF, PBO and TPP exhibited 92.50, 76.94, and 0.00 per cent
larval mortality respectively. The highest larval mortality (93.71 ± 2.00per cent)
was seen when 0.4 per cent C. philippinum synergised with 0.2 per cent DEF.
However, the larval mortality induced by the DEF synergised extract did not
significantly increase when compared with DEF alone. Though PBO synergized
extract also caused significantly high mortality, it was only 26.49 ± 7.37 per cent.
However, TPP synergized extract of C. philippinum could not induce any larval
mortality. Larval mortality caused by L. lavandulifolia. extract increased 39.76, 53.95 and
55.10 fold after addition of TPP, PBO and DEF respectively. Similarly, larval mortality
caused by C. philippinum. extract also increased 0.00, 73.58 and 260.30-fold respectively.
Hence, DEF was identified as better synergist causing larvicidal activity in combination
with crude ethanolic plant extracts.
Histological changes observed in the oocytes of ticks treated with
synergized extract were reduction in size of oocytes, reduced basophilia of type I
oocytes, vacuoles in the cytoplasm, reduced the amount of yolk granules, irregular
shape, presence of vacuoles in the germ vesicle, decrease in the content of yolk
droplets. Possible acaricidal bioactive molecules identified using GC-MS analysis in the
crude ethanolic extracts of L. lavandulifolia and C. philippinum were benzaldehyde,
caryophyllene, Octadec-9-enoic acid and hexadecanoic acid.
Description
Submitted in partial fulfillment of the requirement for the degree of
MASTER OF VETERINARY SCIENCE in Veterinary Parasitology