New Horizons in Insect Science Towards Sustainable Pest Management

Development, Characterization and Field Assessment of Multiple Insecticides ... 333

trade-off in performance at different temperature
and phenotypic plasticity in maternal selection
may con-population evolution of the thermal
niche in Trichogramma. To avoid genetic trade-
off, a variable temperature of 32–38 °C was taken
as one of the treatments.
The results of percent parasitism by laborato-
ry population and field-collected population are
presented in the Table 2. The result indicated that
in general efficacy of T. chilonis was reduced in
the high temperature. At 32 °C, parasitism by lab-
oratory population was slightly higher compared
to the field-collected population, but at all other
higher temperature of 36, 40, 45 °C and at vari-
able temperature of 32–38 °C percent parasitism
by field-collected population was significantly

more. At 40 and 45 °C, very low parasitism was

recorded mainly due desiccation of the host eggs

as humidity recorded was < 20 % at these tem-

perature. Most surprisingly at variable tempera-

ture, percent parasitism by field-collected popu-

lation was > 63.3 % compared to no parasitism by

laboratory population. The results indicated that

though lab population is capable of surviving in

the temperature at 32–38 °C but it fails to parasit-

ize its host. Thus, if releases of Trichogramma

are to be considered during hotter months, ordi-

nary lab population may not give any appreciable

control of the pest.

Trichogrammatids are known to perform bet-

ter in temperature range 20–32 °C. The effec-

tive pest control is determined by many factors

Table 1 Dose mortality response (LC) of T. chilonis to three insecticides
Insecticide Period for
exposed (h)

LC 50 95 % Fiducial limit LC 90 95 % Fiducial limit Slope ± SE χ^2
Lower Upper Lower Upper
Laboratory population to
Endosulfan 6 0.08 0.05 0.11 0.19 0.14 0.42 3.51 ± 0.36 18.8
Monocrotophos 6 0.003 – – 0.01 – – 2.06 ± 0.36 0.2
Fenvalerate 6 0.01 0.01 0.02 0.04 0.02 0.07 3.15 ± 0.24 17.6
Field-collected population to
Endosulfan 6 1.07 0.65 1.64 3.71 2.21 16.46 2.38 ± 0.19 23.1
Monocrotophos 6 0.70 0.48 0.95 1.76 1.22 4.84 3.19 ± 0.24 23.9
Fenvalerate 6 0.04 – – 0.003 – – 1.07 ± 0.27 185.1

Table 2 Response of field-collected and laboratory-reared T. chilonis to high temperature and variable temperature
regime
Temperature (°C)Mortality (%) Parasitism (%)
6 h Mean (B) 24 h Mean
(B)

Mean
LP FP LP FP LP FP (B)
32 0.0 (1.3) 0.0 (1.3) 0.0 (1.3) 47.7
(43.7)

45.6

(42.5)

46.6

(43.1)

54.0 46.7 50.4

36 4.1 (11.7) 0.9 (1.9) 2.5 (9.1) 96.9
(79.9)

77.7

(61.8)

97.3

(80.5)

6.7 45.0 25.9

40 59.7 (50.6) 0.0 (0.0) 29.8
(33.1)

100.0

(90.0)

90.7

(72.2)

95.3

(77.5)

0.0 18.3 9.2

45 96.1 (78.6) 9.2 (17.7) 52.7
(46.6)

100.0

(90.0)

97.1

(80.2)

98.6

(78.9)

0.0 2.3 1.2

32–38 1.8 (7.7) 0.0 (0.0) 0.9 (5.4) 98.5
(83.0)

57.1

(49.1)

77.8

(61.9)

0.0 63.3 36.1

Mean (A) 32.3 (34.6) 2.0 (8.1) 88.6
(70.3)

73.6

(59.1)

12.1 35.2

A factor B factor A x B A factor B factor A x B A factor B factor A x B
SEM ± 1.26 2.00 2.83 3.40 5.38 7.61 3.34 4.52 7.62
LSD ( P = 0.05) 3.74 5.92 8.37 7.60 15.80 24.40 NS 14.8 19.4
Data in parentheses represent arcsine transformed values; LP laboratory population, FP field-collected population