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The study entitled “Field efficacy of biocapsules of entomopathogenic fungi
for the management of vegetable pests” was conducted at the Biocontrol Laboratory
for Crop Pest Management, Department of Agricultural Entomology, College of
Agriculture, Vellayani, Thiruvananthapuram, during the year 2018-2021. The
objective of the study was to evaluate the efficacy of biocapsules of
Beauveria bassiana (Balsamo) Vuillemin, Metarhizium anisopliae (Metschnikoff)
Sorokin, Lecanicillium lecanii (Zimmermann) Zare and Gams and
Lecanicillium saksenae (Kushwaha) Kurihara and Sukarno for the management of
major groups of vegetable pests. The study also intended to standardize the dose of
biocapsules in managing amaranthus leaf webber Spoladea (Hymenia) recurvalis F.,
okra shoot and fruit borer Earias vittella F. and cowpea aphid Aphis craccivora Koch.
The biocapsules of fungi were formulated at a higher spore load of 1010 with HPMC
coating and chitosan as carrier, following the protocol developed by Remya and Reji
(2019).
In the first field experiment to evaluate the efficacy of biocapsules in
managing defoliators in amaranthus, it was revealed that, Metarhizium and Beauveria
capsules @ 3 L-1
sprayed twice (at weekly intervals) was effective causing 83.69 and
69.97 per cent reduction in population of S. recurvalis respectively. Lower doses of 2
and 1 capsules L -1 were less effective causing, 47.39 to 66.5 per cent reduction in
larval population. Spraying spore suspensions of these fungi @ 108 mL-1 resulted in
91.27 to 100 per cent reduction, while in flubendiamide 39.35 SC, it was 89.84 per
cent. Treatment with Metarhizium and Beauveria capsules did not affect the natural
enemy population significantly, the mean population being 2.33 to 3.67 plant-1
. The
corresponding population was 1.44 in flubendiamide 39.5 SC and 3.67 in untreated
control. The yield recorded in the plots treated with Metarhizium and Beauveria
capsules @ 3 L
-1 was high (2.67 and 2.30 kg plot-1
) when compared to that in
untreated plot 0.80 kg plot-1
.
Results of the second experiment to evaluate the efficacy of biocapsules in
managing fruit and shoot borer E. vittella in okra concluded that, Beauveria capsule
@ 3 L
-1
and Metarhizium capsule @ 3 L-1 were equally effective when sprayed at
weekly intervals leading to 84.96 and 79.64 per cent reduction in the shoot damage
respectively. The percentage reduction in shoot damage was only 65.32 to 73.86 per
cent reduction in lower doses of capsules. In plots treated with spore suspensions, the
mean shoot damage recorded was 90 to 95 per cent. Percentage reduction in
chlorantraniliprole 18.5 SC was 90.71. Considering the fruit damage, Metarhizium
capsule @ 3 L-1 was found to be the best treatment causing 100 per cent reduction in
damage caused by E. vittella, while it was 89.75 per cent with Beauveria capsule@ 3
L
-1
. Reduction in fruit damage ranged from 67.82 to 82.81 per cent in the lower doses
of capsules. Highest reduction in the fruit damage observed with spore suspensions of
Beauveria and Metarhizium @ 108 mL-1 (93.16 and 100 per cent, respectively).
Similar results were obtained in the case of okra leaf roller, Metarhizium @ 2 L-1
and
Beauveria capsule @ 3 L -1 were found to be the best treatment causing 96.38 and
85.80 per cent reduction in population of Sylepta derogata F., while it was 80.23 per
cent with Metarhizium capsule @ 3 L-1
. Reduction in population ranged from 41.35 -
68.72 per cent in the lower doses of capsules. Highest reduction in the population of
S. derogata observed with spore suspensions of Beauveria and Metarhizium @ 108
mL-1 (100 per cent). Percentage reduction in chlorantraniliprole 18.5 % SC was 93.41.
Treatment with biocapsules capsules did not cause any adverse affect on natural
enemy population, in okra field. The yield obtained from different treatments did not
vary significantly.
Third experiment in cowpea field revealed that, foliar application of
L. saksenae capsule @ 3 L
-1
and L. lecanii capsule @ 3 L-1 were equally effective to
A. craccivora when sprayed twice (at weekly intervals) causing 94.38 and 92.28 per
cent reduction in the population respectively. Reduction in population noted was
57.54 to 63.96 per cent with lower dose @ 2 capsules L-1 while it was least with single
capsule treatment (37.51 to 44.73 per cent). The spore suspensions were more
effective resulted than the lower doses (78.73 - 83.53 per cent reduction). The
chemical check thiamethoxam 25 WG recorded 95.79 per cent reduction in
population. Biocapsule treatment did not affect natural enemy population
significantly. The yield recorded in the plots with L. saksenae capsules @ 2 and 3 L-1
was high (1.85 and 1.56 kg plot-1
) when compared to other treated plots and untreated
plot (1- 1.45 kg plot-1
).
Therefore, it is concluded that biocapsules of Metarhizium and Beauveria, can
effectively manage defoliators in amaranthus and borers in okra and those of
L. lecanii and L. saksenae can be recommended for pea aphids, without affecting the
natural enemies and yield significantly.

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