To study the effect of natural enemy Trichogramma chilonis ( Ishii ) against spotted bollworm ( Earias Vittella F . ) on okra

The present study was conducted at the Pussia Goth near Tandojam during the year 2016, to study the effect of natural enemy Trichogramma chilonis (Ishii.) against spotted bollworm (Earias Vittella Fabricius) on okra. Observations on spotted bollworm population were recorded at once per week. Pre-treatment observation was recorded one day before release and post-treatment observation was recorded three and five days after release. The reduction percentage was also calculated. The maximum population of spotted bollworm recorded in 6 week was (17.66±1.72) and minimum population in 10 week was (14.33±0.29) in control plot during 1 to 10 weeks duration, respectively. The natural enemies were released at the interval of 10 days. However, the population in treated plot after 3 days of (T. chilonis) releases the maximum population of spotted bollworm was recorded in 2 week (8.89±1.24) and minimum population in 10 week (6.19±0.29) during 1 to 10week duration, respectively. Peak level of spotted bollworm was observed during 1 and 2 weeks afterward the spotted bollworm population was declined in a linear sequence from 3 to 10 weeks. Similarly, after 5 days (T. chilonis) releases, the maximum population of spotted bollworm was recorded in 1 week (10.16±1.33) and minimum population in 10 week (8.00±0.41) during 1 to 10 week duration, respectively. Peak level of spotted bollworm was observed during 1 and 2 weeks afterward the spotted bollworm population was declined in a linear sequence from 3 to 10 weeks. Moreover, the results showed that spotted bollworm populations were considerably declined in treated plots due to the presence of T. chilonis as compare to control plot.


Introduction
Okra, Abelmoschus esculentus (L.) belongs to family Malvaceae is Kharif season vegetable as well as cash crop of Pakistan.It is originated from Africa and Asia.This is famous vegetable used as human food in the country with great interest.This vegetable almost grown throughout the world during warm season [1-3].A number of factors which influenced the productivity of okra crop.Among them, insect pests are the major factor which destroyed the okra crop and produced almost 69 percent damaged in yield losses [4, 5].Among insects, bollworms, spotted bollworms and American bollworms are dominant pests which damaged the okra in early and late developmental stages.The magnitude of infestation and the nature of extent of injury vary with plant variety, seasons and localities [5].Despite massive applications of broad-spectrum insecticides, the action of natural enemies plays an important role in reducing insect pest infestation, both through inundative releases or as natural control agents

Materials and methods
The experiment was carried out at the experimental area of Pussia Goth near Tandojam during 2016 to monitor the effect of natural enemy Trichogramma chilonis (Ishii.)against spotted bollworm of okra.The variety (Sabzpari) of okra was sown on area of 106' x 66' ft.By drilling method of sowing with all other agronomical practices were carried out as usual for this experiment.Observations on spotted bollworm population were recorded once per week.Six releases were made during the cropping season at the rate of 6 cards per acre.Trichogramma were released (as pupae) inside the host eggs ready to emerge as adults and they were glued to cards.Trichogramma wasps were emerged from cards in two to five days.Selected five plants for each treatment for recording spotted bollworm population and 05 leaves were observed from top, middle and bottom for spotted bollworm infestation.Pre-treatment observation was recorded one day before release and Posttreatment observations were recorded 3 and 5 days after release.

Calculating reduction percentage
The reduction percentage was calculated according [16] by the following formula:

Results and discussion
In order to study the effect of natural enemy Trichogramma chilonis (Ishii.)against spotted bollworm of okra, the experiment was carried out at the Pussia Goth near Tandojam during the year 2016.The results are presented in (Table 1, 2, 3) their analysis of variance as shown as (Table 4,5).

Mean population of spotted bollworm on okra crop after Trichogramma chilonis cards releases
The data ( , 2 nd , 3 rd , 4 th , 5 th , 6 th , 7 th , 8 th , 9 th and 10 th weeks duration, respectively.The population of spotted bollworm in okra crop was observed as zigzag trend in control plot (where no biological control) was applied.The data further demonstrated that the observation between weeks was found non-significant (P>0.05)difference in spotted bollworm population in okra crop.The maximum population was recorded in 6 th week (17.66±1.72) of observation and minimum population of spotted bollworm was observed in 10 th week (14.33±0.29) in control plot.Values in the column with same letters did not differ significant at P-value <0.05 The data (  9.77±1.43, 9.62±1.63, 8.81±1.50, 8.69±0.72, 8.20±0.71and 8.00±0.41during 1 st , 2 nd , 3 rd , 4 th , 5 th , 6 th , 7 th , 8 th , 9 th and 10 th weeks duration, respectively.Peak level of spotted bollworm was observed during 1 st and 2 nd weeks afterward the spotted bollworm population was declined in a linear sequence from 3 rd to 10 th weeks.Moreover, statistical analysis showed significant (P<0.05)difference in spotted bollworm population between the different observation weeks in okra crop.The maximum population was recorded in 1 st week (10.86±1.71) of observation and minimum population of spotted bollworm was observed in 10 th week (8.00±0.41) in treated plot after 5 days.The results further showed that spotted bollworm populations were considerably declined in treated plots due to the presence of Trichogramma chilonis (Ishii.)as compare to control plot.Values in the column with same letters did not differ significant at P-value <0.05 of spotted bollworm in the treated plots before treatment.Ta = Number of spotted bollworm in the treated plots after treatment.Cb = Spotted bollworm population in the control plots before treatment.Ca = Spotted bollworm population in the control plots after treatment.The data of pests and natural enemies were also recorded from control plot for comparison.Collected data were interpreted in spreadsheet of Microsoft excel.Then further data analysis ANOVA was carried out through software Statistix 8.1 [17].
These tiny parasitoids lay their eggs in eggs of other species.Trichogramma represent around 80 genera from the Trichogrammatidae family with over 800 species worldwide [12-15].Keeping in view the above facts and figures this study was conducted to equate the efficacy of Trichogramma chilonis against spotted bollworm (Earias Vittella F.) on okra.