The present study revealed that the EPF, I. fumosorosea (ICAR-NBAIR Pfu-5), had significant virulence and fungal mycelia development on RSW eggs, nymphs and adults. I. fumosorosea infection affects egg hatching, and nymphal mortality especially fourth-instar nymph (pupae), which led to a severe reduction in adult emergence and further perpetuation of RSW population. Substantial mycosis and deformation were seen in newly emerging adults from I. fumosorosea-treated nymphs, which led to a drastic reduction of adult emergence that may result in less perpetuation of the pest in the coconut ecosystem (Fig. 1). Further, the combination of I. fumosorosea (ICAR-NBAIR Pfu-5) @ 5 ml /l sublethal dose of profenophos 50 EC@ 2 ml/l was superior to all other treatments after 7 and 15 days, with significantly lower RSW population on coconut palms.
Infestation of RSW per palm (%)
Pre-treatment per cent infestation was uniform in all the treatments as indicated by non-significant differences, ranging from 43.44 to 51.99% (Fig. 2). However, after 7 days of topical application, I. fumosorosea (ICAR-NBAIR Pfu-5) @ 5 ml/l + profenophos 50 EC @ 2 ml/l (T7) showed the lowest infestation (13.84%), followed by I. fumosorosea (ICAR-NBAIR Pfu-5) @ 5 ml/l + buprofezin 25% SC @ 1.25 ml/l (T3) with (16.72%), I. fumosorosea (ICAR-NBAIR Pfu-5) @ 5 ml/l + azadirachtin10000 ppm @ 2 ml/l (T6) with (18.47%) and I. fumosorosea (ICAR-NBAIR Pfu-5) @ 5 ml/l + buprofezin 25% SC @ 0.6 ml/l (T2) with (24.53%) over I. fumosorosea (ICAR-NBAIR Pfu-5) @ 5 ml/l alone (T1) with (26.74%), while the highest RSW infestation was recorded in I. fumosorosea (ICAR-NBAIR Pfu-5) @ 5 ml/l + pongamia soap @10 g/l (T4) with (29.60%) followed by I. fumosorosea (ICAR-NBAIR Pfu-5) @ 5 ml/l + fish oil rosin soap @ 2 ml/l (T5) with (28.89%), whereas untreated control, (T8) with (49.90%) infestation (Fig. 2).
Similarly, after 15 days, T7 dominated all other treatments with the lowest infestation (4.95%), followed by T3 with (6.06%), T6 with (8.75%) and T2 with (13.35%) over I. fumosorosea (ICAR-NBAIR Pfu-5) alone (T1) with (14.16%), while the highest RSW infestation was recorded in T4 with (18.77%) followed by T5 with (17.98%), whereas untreated control, T8 with (60.44%) infestation (Fig. 2).
However, after topical application of T7 showed the lowest mean infestation (9.40%), followed by T3 with (11.39%) and T6 with (13.61%) over I. fumosorosea (ICAR-NBAIR Pfu-5) alone (T1) with (20.45%), while the highest RSW infestation was recorded in T4 (24.18%) followed by T5 (23.43%), whereas untreated control, T8 with 55.17% infestation (Fig. 2).
The application of T7 resulted in the highest reduction of RSW infestation (82.97%) over I. fumosorosea (ICAR-NBAIR Pfu-5) alone, T1 with (62.93%) and untreated control. Following that, T3 with (79.35%) and T6 with (75.33%) (Fig. 2).
Intensity of RSW infestation (%)
Pre-treatment RSW intensity was uniform across all treatments, as evidenced by non-significant differences ranging from 47.32 to 59.79% (Fig. 3). After applying I. fumosorosea (ICAR-NBAIR Pfu-5) @ 5 ml/l + profenophos 50 EC @ 2 ml/l (T7), the percentage intensity of RSW was drastically reduced.
After 7 days of topical application, T7 showed the lowest (16.64%) intensity, followed by T3 with (20.39%), T6 with (23.37%) and T2 with (24.97%) over I. fumosorosea (ICAR-NBAIR Pfu-5) alone (T1) with (27.88%), while the highest RSW intensity (30.59%) was recorded in T4 followed by T5 with (30.01%), whereas untreated control, T8 with (51.35%) intensity (Fig. 3).
Similarly, after 15 days, T7 showed the lowest (4.05%) intensity, followed by T3 with (6.34%), T6 with (7.30%) and T2 with (10.60%) over I. fumosorosea (ICAR-NBAIR Pfu-5) alone (T1) with (11.84%), while the highest RSW intensity was recorded in T4 with (15.62%) followed by T5 with (14.08%), whereas untreated control, T8 with (54.71%) intensity (Fig. 3).
Palms treated with T7 surpassed all other treatments with the lowest (10.34%) mean per cent intensity followed by T3 with (13.37%) and T6 with (15.33%) over I. fumosorosea (ICAR-NBAIR Pfu-5) alone, T1 with (19.86%). While RSW intensity in T5 with (22.04%) and T4 with (23.11%) was recorded. Whereas, untreated control T8 with (53.03%) intensity (Fig. 3).
The treatment of T7 resulted in the greatest reduction (80.49%) of RSW intensity over I. fumosorosea (ICAR-NBAIR Pfu-5) alone, T7 with (62.55%) and untreated control. The next best treatments are T3 with (74.79%) and T6 with (71.09%) (Fig. 3).
Mean live colonies of RSW/leaflet
The pre-treatment mean live colonies of RSW were uniform in all the treatments as indicated by non-significant differences, ranging from 11.92 to 12.56 colonies/ leaflet (Fig. 4). The RSW mean live colonies were drastically reduced after palms were treated with I. fumosorosea (ICAR-NBAIR Pfu-5) @ 5 ml/l + profenophos 50 EC @ 2 ml/l.
After 7 days, T7 showed the lowest (4.25 mean live colonies/leaflet), followed by T3 with (5.04 mean live colonies/leaflet), T6 with (5.60 mean live colonies/leaflet) and T2 with (5.88 mean live colonies/leaflet) over I. fumosorosea (ICAR-NBAIR Pfu-5) alone (T1) with (6.15 mean live colonies/leaflet). However, the highest RSW mean live colonies/leaflet were recorded in T4 with (6.80 mean live colonies/leaflet) followed by T5 with (6.48 mean live colonies/leaflet), whereas untreated control, T8 with 12.84 mean live colonies/leaflet (Fig. 4).
After 15 days, T7 showed the lowest (1.23 mean live colonies/leaflet) followed by T3 with (1.91 mean live colonies/leaflet), T6 with (2.40 mean live colonies/leaflet) and T2 with (2.78 mean live colonies/leaflet) over I. fumosorosea (ICAR-NBAIR Pfu-5) alone (T1) with (3.23 mean live colonies/leaflet), while the highest RSW mean live colonies were recorded in T4 with (4.11 mean live colonies/leaflet) followed by T5 with (3.80 mean live colonies/leaflet) and, however, untreated control T8 with 14.10 mean live colonies/leaflet (Fig. 4).
Palms treated with T7 were significantly superior to all other treatments with the lowest (2.74 overall mean live colonies/leaflet) followed by T3 with (3.48 mean live colonies/leaflet), T6 with (4.00 mean live colonies/leaflet) over I. fumosorosea (ICAR-NBAIR Pfu-5) alone (T1) with (4.69 mean live colonies/leaflet), while T5 with (5.14 mean live colonies/leaflet) and T4 with (5.38 mean live colonies/leaflet) were recorded and, however, untreated control (T8) with 13.47mean live colonies/leaflet (Fig. 4).
In general, palms treated with T7 showed the greatest reduction (79.68%) mean number of RSW live colonies over I. fumosorosea (ICAR-NBAIR Pfu-5) alone (T1) with (65.20%) and untreated control. This was followed by T3 with (74.20%) and T6 with (70.30%) reduction (Fig. 4).