Effect of Natural Enemy ( Chrysoperla carnea Stephens ) against Sucking Insect Pests of Okra

An experiment effect of natural enemy (Chrysoperla carnea Stephens.) against sucking insect pests of Okra was carried out at Latif Farm, Sindh Agriculture University, Tando Jam during 2014.The results showed that overall maximum mean population of jassids (1009.5 ± 78.12/plant) was recorded in pre-treatment treated plot followed by thrips (706.17 ± 34.26/plant), mites (572.5± 33.00/plant) and whiteflies (209.83 ± 19.76/plant) respectively. Whereas, the overall maximum mean population of jassids (1322.44 ± 8.6/plant6) was recorded in pre-treatment control plot, followed by thrips (828.05 ± 6.77/plant), mites (640.55 ± 5.95/plant) and whiteflies (267.38 ± 4.74/plant) respectively. However, the overall maximum mean of jassids (434.27 ± 4.91/plant) were recorded in post-treatment control plot, followed by thrips (278.11 ± 3.93/plant), mites (134.11 ± 2.63/plant) and whiteflies (18.83 ± 0.99/plant), respectively. The results further revealed that the statistical analysis of data through paired T-test between treated and control plot of jassids, whiteflies, thrips and mites showed significantly different at (P<0.05) level. Whereas, the statistical analysis of data through paired T-test between pre-treatment and post-treatment of jassids, whiteflies, thrips and mites also showed significantly different at (P <0.05) level.


INTRODUCTION
Okra, Abelmoschus esculentus L. (Family: Malvaceae) is a warm-season, annualkharif vegetable of Pakistan.The origin of this vegetable is considered as Africa and Asia. .In the present world, okra is grown in almost all parts of the tropics, and during summer in the warmer parts of the temperate region [1].Okra is a good source of vitamins, minerals, salts and has good calories values.The edible portion contains 89.8, 0.8 0.2, 7.4 and 1.8 percent water, protein, fat, carbohydrate and ash, respectively.It has 175 calories per pound.It is one of the cash crops of Sindh [2].
Okra is attacked by number of insect pests right from germination to harvest [3].Sucking pests in the early stage and the fruit borers in the later stage cause extensive damage to fruits and the yield losses have been recorded up to 69 percent [4].Among these thrips, whiteflies, jassids, aphids, mites are consider as major insect pests of okra [4].Therefore there is great need to develop alternates strategy for handling such economically important pests approach.Farmers extensively used insecticides for the management of insect pests.Insecticides are costly and indiscriminate use has induced insect resistance to the insecticides and caused environmental pollution [5].Despite *Address correspondence to this author at the Department of Entomology, Faculty of Crop Protection, Pakistan; E-mail: alisyedshahzad75@gmail.com 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 [6].
Biological control is often viewed as a promising alternative or complement to pesticides in integrated pest management programs [7].Green lacewings are proven broad-spectrum biological control agents, devouring eggs and young larvae of Colorado potato beetles, flea beetles, most caterpillar (worm) pests (armyworms, budworms, bollworms, borers, corn earworms, cabbage loopers, codling moths, etc.), aphids, spider mites, scales, psyllids, mealy bugs, whiteflies, thrips, leafhoppers and other pests [8].Adult green lacewings are pale green, about 12-20 mm long, with long antennae and bright, golden eyes.They have large, transparent, pale green wings and a delicate body [9].Chrysoperla carnea and C. rufilabris (Neuroptera: Chrysopidae), are active predators fed on many insect pests infesting field crops [10].Green lacewings are common in agricultural fields and their adults feed only on nectar, pollen, and aphid honeydew, but their larvae are active predators.C. carnea occurs in a wide range of habitats and C. rufilabris may be more useful in areas where humidity tends to be high such as greenhouses and irrigated crops [11].In present study the effect of natural enemy (Chrysoperla carnea Stephens.)as biological controlling agents were released in field against sucking insect pests of okra.This will help to manage sucking insect pests on okra crop.

MATERIALS AND METHODS
The present experiment was conducted at the experimental field of Latif Farm, Sindh Agriculture University, Tando Jam during July to November of 2014 to determine the effect of natural enemy (Chrysoperla carnea Stephens) against sucking insect pests of Okra.The experiment was designed in RCBD (Randomized Complete Block Design).The variety (Sabzpari) of okra was sown on area of 106 x 66 ft by drilling method of sowing.All agronomical practices were carried out as usual for this experiment.The observations on Jassids, Thrips, Whiteflies and mites population was recorded at once per week.Chrysoperla carnea (Stephens) second in star larvae were released at the rate of 1500 larvae/ acre.The natural enemies were released at the interval of 10 days.Six releases were made during the cropping season.Pre-treatment observation was recorded one day before release and Post-treatment observations were recorded 3 and 6 days after release.The data of pests and natural enemies were also recorded from control plot for comparison.Yield of okra was also recorded from treated and control plots.Finally the data were statistically analyzed by paired T-test method of analysis between pest populations of treated and control plots and also between pest population of pre and post-treatment.

RESULTS
The study was carried out the effect of natural enemy (Chrysoperla carnea Stephens) against sucking insect pests of Okra at Latif Farm, Sindh Agriculture University, Tando Jam during the winter season of 2014.In the present study, the data shown in Table 1 depicted that maximum jassids, whiteflies, thrips and mites population (1750, 340, 985 and 790/ plant) was recorded in pre-treatment plot during 3 rd week of July, respectively.While, the minimumper plant population of Jassids, whiteflies, thrips and mites (521, 95, 420 and 291/plant) was recorded in 4 th week of November, respectively.The data (Table 1) revealed that overall maximum mean population of Jassids (1009.5 ± 78.12)The statistical analysis of data through paired T-test between treated and control plot of Jassids, whiteflies, thrips and mites showed significantly different at (P < 0.05) level.Whereas, paired T-test between pretreatment and post-treatment of Jassids, whiteflies, thrips and mites showed significantly different at (P =< 0.05) level (Appendix VII-XI).

DISCUSSION
The present study on effect of natural enemy (Chrysoperla carnea Stephens) against sucking insect pests of Okra was carried out at Latif Farm, Sindh Agriculture University, Tando Jam during July to November, 2014.The results of present study agree with those of Rosenheim and Wilhoit [12] who concluded that since one lacewing can produce 40,000 progeny in 60 days, maximum benefits are obtained by starting releases very early in the season.A rough release rate is 5,000 to 50,000 green lacewings per acre per season or 1,000 per 2,500 square feet of garden.At least two early season releases two weeks apart are needed to faster overlapping generations (larvae, the pest-eating stage, are then most likely to be present).Daane et al. [13] concluded that lacewing larvae (Chrysoperla carnea) could potentially be one of the most important biological control agents for psyllid pests of box plants.Daane and Yokota [14] evaluated three aspects of release strategies used to augment green lacewings (Chrysoperla spp.); the delivery system, the release rate and timing, and the lacewing developmental stage released.
The results of present study also agree with those of Yolde et al. [15] who released native strain of predator Chrysoperla carnea (Stephen.)against whiteflies, spider mites and aphids, respectively.E. formosa and P. persimilis were found to be effective in a release ratio of 1/5 parasitoid l whitefly and 1/20-40 predator/red spider mite, respectively, on tomatoes and cucumbers, but ineffective on eggplants.C. carnea was not able to control aphids.Hochmuth and Davis [16] reported that the effective control of insect pests was achieved with a combination of plastic insect screening materials and the release of biological control agents.
The results of present study are also partially agreed to those of Hassanpour et al. [17] who evaluated the response of three larval instars of the green lacewing, Chrysoperla carnea (Stephens), preying upon eggs and first instar larvae of the cotton bollworm, Helicoverpa armigera Hübner.The present study showed that effect of Chrysoperla carnea (Stephen) on suppuration of pest population of okra pests mainly sucking complex proved best in reducing the pest population from the field This shows that this study can be exploited for pest control in different crops, fruits and vegetables.Release of natural enemies against insect pests of okra may be included as best IPM strategy so that adverse effects on pesticides may be excluded for the coming generations.

CONCLUSIONS
It was concluded from the present study that the effect of release of Chrysoperla carnea (Stephen) on suppuration of pest population of okra pests mainly sucking complex proved best in reducing the pest population from the field.The Jassid population can be reduced greatly by releasing of Chrysoperla carnea (Stephen) predator.This shows that this study can be exploited for pest control in different crops, fruits and vegetables.It was also concluded that due to reduction in pest population after the release of natural enemies, the yield of treated plot was increased thrice than control plot.