Abstract
Studies on the life parameters of Trichogramma chilonis at different environmental conditions,
its field efficacy and sustainable use against eggplant shoot and fruit borer, IÆucinodes
orbonalis were carried out at IPM laboratory and experimental farm of Department of
Entomology, Bangladesh Agricultural University, Mymensingh and farmers field of Gazipur
during August 2015 to July 2018. Temperature and rainfall, two important abiotic factors
affected the performance and establishment of the parasitoid, T. chilonis in the field. Constant
and cycling temperature influenced significantly the parasitism performance, adult
emergence, female progeny and adult longevity of the parasitoid. Cycling temperature was
found better for egg parasitism than constant temperature. Highest parasitism (90.5%), adult
emergence (94%), female percentage (753%), number of adult emerged per egg (0.94) were
found at 300C:250C cycling temperature. Second highest parasitism was 91 % at 250C:200C and
further increase of temperature decreased parasitism performance. Rainfall frequency and
release of parasitoids affected parasitism significantly showing increased parasitism and
decreased the shoot and fruit infestation. Parasitism was not affected with 50 mm of water
application as mimic of rainfall. Parasitism of T. chilonis in ESFB egg was density dependent.
Parasitoid number ranging from 500 to was found most effective at 250C:200C
temperature, rainfall against the eggs of 7 female ESFB. At extreme high temperature
of 400C:350C and rainfall of 110mm, a higher numbers Of parasitoids needed for
similar performance. Highest shoot infestation of 56% was in control treatment i.e. in absence
of parasitoid and rainfall and the lowest fruit infestation of 15.67% was evident in the field
with released parasitoid at no rainfall conditions. Single time released parasitoid could not
contribute significantly to reduce the ESFB infestation in the field for longer period due to its
less sustainability. Pesticide toxicity to T. chilonis indicated highest mortality of 76% in
Emamectin Benzoate followed by Spinosad (3.9%) and Azadirachtin (2.2%). Parasitism
performance was highly affected (79%) with Emamectin Benzoate treatment. Azadirachtin a
neem based biopesticide was found to be less harmful for T. chilonis as considerably high
parasitism (50.85%. Longevity of the parasitoid was adversely affected by the pesticide
Emamectin Benzoate showing only 1.25 days as compared to 8.1 days. Difference in
parasitism and longevity of T. chilonis in 3 regions indicates that sustainability of this
parasitoid is higher in Khagrachari compared to Mymensingh and Gazipur. Parasitism and
adult emergence of parasitoid was influenced by this storage duration as highest parasitism
(95.6%) was found in O weeks stored eggs compared to lowest (57%) from the 12 weeks
stored eggs. Release of parasitoid in the form Of mummy through Trichocard provides a
maximum of parasitism compared to 53.3% when as adults. Release of immature
parasitoid as parasitized eggs On paper strip incurs 4 folds' higher expenses than the adults.
Release of parasitoid through bvisted paper chocklet chips is preferred for its high parasitism
performance and cost effectiveness.