The gravid female lays eggs inside encrustation and first instars larvae hatch out which crawls and settle at suitable sites on succulent stem of host plant. The settlement of the first instar crawlers takes place within a period of a week or two of the hatching. The observations of mean initial density of settlement of crawlers recorded 7 days after the inoculation of broodlac and there were a difference in a mean initial density of settlement of first instar crawlers on lower, middle and upper portion of plant. The observed mean initial settlement of first instar crawlers of
Rangeeni strain of lac insect on Pigeon pea in
Baisakhi season during 2019-20 and 2020-21 were 79.37, 77.10, 66.37 and 84.20,81.30,67.53 crawlers per sq.cm respectively on lower, middle and upper portion of host plant in three set of experiment. The mean final density of settlement of first instar crawlers were recorded 72.97, 70.13, 59.53 and 76.90,73.13,60.00 crawlers per sq.cm in both year, respectively on lower, middle and upper portion of host plant in three set of experiment. The data reveal that maximum mean final density of settlement of crawlers observed were 76.90 crawlers per sq.cm; while, minimum mean final density of settlement of crawlers of
Rangeeni strain of lac insect were 59.53 crawlers per sq.cm on lower portion of Pigeon pea in during
Baisakhi season of 2019-20. The mean per cent settlement of crawlers in three set of experiments were observed 91.78, 90.73, 89.16 and 91.15, 89.89, 88.83 on lower, middle and upper portion of plant in 2019-20 and 2020-21, respectively (Table 1).
The results of present investigations are in alignment with the findings of
Divakara (2013), who recorded maximum density (77.8 crawlers/cm2) of insect settlement in
F.
macrophylla as intercrop in understorey of
Dalbergia sissoo after 21 days of brood lac inoculation. Similarly,
Mohanta et al (2014) who reported that initial density of settlement of larvae ranged between 92.58-126.74 crawlers per sq.cm and 93.12-109.62 crawlers per sq.cm of lac strain on Kusum and Ber trees, respectively.
The first instar crawlers which could not find suitable sites for settlement on host plant could not survive and dies due to starvation within a week or two of its emergence. The observations on per cent initial mortality of first instar crawlers recorded at 21 days after inoculation of brood lac of
Rangeeni strain of lac insect in
Baisakhi season on Pigeon pea during 2019-20 and 2020-21. The per cent mean mortality was observed to be 8.06, 9.04, 10.30 and 8.67, 10.05, 11.15 from lower, middle and upper portion of the plants in three set of experiment in both year, respectively (Table 2). The results of the present investigation confer the findings of
Divakara (2013) who recorded minimum per cent mortality of
Rangeeni strain of lac insect in
C.
calothyrsus (12.48%) and
D.
assamica (22.36%) and maximum per cent mortality of
Kusmi strain in
Jethwi season in
F.
semialata (27.88%) followed by ber (24.91%) and kusum (18.75%).
Kalahal et al., (2017) reported that mean mortality of Rangeeni strain of lac insect in Pigeon pea were 7.55%, 8.12%, 10.39%; 7.70%, 6.46%, 7.49% and 9.09%, 12.27%, 12.58% at lower, middle and upper portion of plant in three plots respectively; confirming the present findings.
The duration of sex differentiation of
Rangeeni strain of lac insect on lower, middle and upper portion of plants in three set of experiments were 49.10, 48.83, 48.23 and 48.97, 48.60, 48.70days, 2019-20 and 2020-21, respectively (Table 2). The present investigation close conformity with findings of
Swami et al., (2017), who reported that time elapsed between date of inoculation to male and female differentiation of lac insect recorded as duration of pre sexual stages (days) varied from 47 to 51 days on 10 pigeon pea plants in three set of plots.
The mean density of female cell recorded at crop maturity were 4.27, 4.97, 4.57 and 5.27, 4.93, 5.20 female cells per sq.cm in 2019-20 and 2020-21, respectively on lower, middle and upper portion of plant in three set of experiment. The maximum mean density of female cells of
Rangeeni strain of lac insect on pigeonpea, ranged from 4.27 to 4.97 per sq.cm and 4.93 to 5.27 per sq.cm during
Baisakhi season of both year, respectively (Table 1). The results of present investigation are in full alignment with the findings of
Mohanta et al., (2014) who also recorded average density of living female cells at crop maturity were 3.38-12.67 cells per sq.cm on palas plant for
Rangeeni strain of lac insect. Similarly,
Kalahal et al. (2017), who reported that the density of female cells during maturity ranged from 01-11 cells per sq.cm on Pigeon pea for
Rangeeni strain of lac insect.
The mean plant height, number of branches per plant, number of pods per branch, number of seeds per pod, seed yield per plant and weight of 100 seeds in lac inoculated were 161.30 cm, 11.53, 4.40, 3.57, 24.13 gm and 7.63 gm in first year and 161.06 cm, 11.63, 4.37, 3.70, 24.00 gm and 7.27 gm, observed in second year, respectively (Table 3). The mean seed yield in lac inoculated experiment and control experiment 2019-20 and 2020-21 were 603.33, 603.33 and 895.00, 752.50 kg/ha, respectively. The per cent decrease in both year plant height, number of branches per plant, number of pods per branch, number of seeds per pod, seed yield per plant and weight of 100 seeds in first year lac inoculated pigeonpea were 6.60, 3.08, 4.35, 3.60, 32.59 and 12.26% respectively and in second year lac inoculated pigeonpea were 5.75, 5.42, 9.03, 9.96, 19.82 and 12.45% respectively.
The findings of present investigation are almost similar as observed by
Ghosh et al., (2014), Lohot et al., (2018) and
Ghosh et al., (2018). Gosh et al., (2014), who reported that rearing of lac insect on Pigeon pea reduced weight of 100 seeds (13.03%) and grain yield per plant (12.08%) significantly. Similarly,
Lohat et al., 2018) observed that lac culture decreased 100 seed weight (5.4%) and seed yield (10.5%) of Pigeon pea.
The Benefit cost ratio of lac inoculated experiment was more (1.95 and 2.09) than sole seed crop of Pigeon pea (1.84and 1.35) in both year, respectively
i.
e. lac inoculation gave maximum profit (Table 4). The result was found similar to the finding of
Lohot et al., (2018), who reported that additional income from lac cultivation and income from selling seed as sole crop Assam local-1 (12.8%), Assam local-2 (17.1%) and RCMP-5 (27.2%) had significantly higher profit per cent as compared to control (sole seed crop). The present findings are in agreement with the findings of
Kumari et al., (2019) and
Kandasamy et al., (2020) who reported Pigeon pea,
Cajanus cajan (L.) Millsp. is one of the good host plants for lac cultivation after the correct identification of genotype.
