Egg parasitism caused by Trichogramma spp . against maize stem borer, Chilo partellus.

-Present study was carried out to determine the numbers of egg batches and eggs per batch in the maize fields of selected sites of Indore. Moreover, discovery efficiency and parasitism efficiency was also determined. The result revealed that highest mean discovery efficiency rates of Trichogramma spp. was found from Mhow and was therefore having low parasitism per field and lowest mean discovery efficiency rate was recorded from Mangliya and was having high parasitism per field. There was generally a high variation in the numbers of egg batches and eggs per batch among the sites surveyed. The predominant parasitoid species was Trichogramma spp . This study showed that although egg parasitoid species diversity was higher, egg parasitism was considerably lower in selected sites of Indore.


INTRODUCTION
Maize production is severely affected by number of biotic and abiotic factors. Among biotic factors stem borer (Chilo partellus, Swinhoe) is the most notorious and destructive pest. Maize (Zea mays, L.) is an important cereal crop of India. Because of pesticides use, problems have increased, thus it has stimulated renewed interest in biological control as a control method by itself or as a part of integrated pest control system. Among biological techniques, inundative releases of Trichogramma spp. have led to commercially successful programs against Chilo partellus Swinhoe) [1]. Inareas where Trichogramma spp. has been released continuously for years, has resulted in large ecological and economic benefits [2]. Trichogramma spp. is a tiny (5mm long) parasitoid, which attacks the eggs of its host. As a biological control agent, T. chilonis wasp are reared and released in the affected fields [3]. The larva (T. evanescens) goes through three developmental stages and pupate inside the host egg that cause host eggs turn black [4]. Trichogramma species have been reported from various hosts i.e., Acigona steniellus, Helicoverpa armigera, Chilo partellus, Chilo infuscatellus, and Emmalocera depressella [5]. Present study was designed to evaluate the parasitism caused by Trichogramma species on the host eggs of Chilo partellus. This study showed that although egg parasitoid species diversity was higher, egg parasitism was considerably lower in selected sites of Indore.

II. RELATED WORK
Trichogramma spp. as the pest egg parasitoid whose abundance decreases the population of stem borers at the very initial stage [6]. In the present study, the distribution of egg batches was regular to random, corroborating findings by [7][8][9]. Parasitoids locate borers by laying eggs into them while feeding inside the plant stems. When they will hatch, the larvae of theparasitic wasp will be feeding internally in the pest and kill it and then exit to spin cocoons [10].

Experimental work:
The collection of pest, Egg masses of Chilo partellus and the predators were done in maize fields and rearing and rest of the bio-assays were done in laboratory.

Egg parasitism
Parasitoids were calculated per egg mass by the method described by [11].
Three kinds of parasitization were calculated by for egg parasitoid: (a) The ratio of Percent of eggs parasitized (individual egg batch), to all egg batches observed in the maize fields calculated as Mean egg parasitism per maize field. (b) "Discovery" efficiency, the percentage of egg batches with parasitoids per field. (c) The percentage of eggs parasitized within discovered egg batches, averaged over all egg batches per field called as "parasitism efficiency".

IV. RESULTS
During 2015, In the selected regions of Indore where eggs were collected, overall mean number of egg batches were

V. DISCUSSION
The highest mean discovery efficiency rates of Trichogramma spp. was found from Mhow and lowest mean discovery efficiency rate was recorded from Mangliya. The above mentioned result thus showed that because of the lowest discovery efficiency rates of parasitoids in Mangliya region, maize stem borers were highest.
Trichogramma spp. as the pest egg parasitoid whose abundance decreases the population of stem borers at the very initial stage [6]. In the present study, the distribution of egg batches was regular to random, corroborating findings by [7][8][9]. Parasitoids locate borers by laying eggs into them while feeding inside the plant stems. When they will hatch, the larvae of the parasitic wasp will be feeding internally in the pest and kill it and then exit to spin cocoons [10]. The above mentioned biologists are also in agreement with present study.
[12] also worked on Suitable Trichogramma spp. and dosage for the management of Chilo partellus (Swinhoe) in maize and found that the screening of various Trichogrammatids against Chilo partellus (Swinhoe) eggs revealed that Trichogramma chilonis Ishii gave significantly higher parasitism of 43.9%. Egg parasitoids of the genus Trichogramma, including T. brassicae, have been successfully used to control mainly lepidopteran pests in biological control worldwide [13]. Thus the result is in agreement with the present investigation.

VI. CONCLUSION AND FUTURE SCOPE
The highest mean discovery efficiency rates of trichogramma spp. was found from Mhow and lowest mean discovery efficiency rate was recorded from Mangliya. Therefore, because of the lowest discovery efficiency rates of parasitoids in Mangliya region, maize stem borers were highest. For sustainable low cost maize production, it is necessary to have a low cost technique of pest control. The control of pest by Trichogramma spp. is economical, more productive.