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Madhulika Srivastava ¹, A. K. Singh ²

Affiliations
1 Division of Entomology, Indian Agricultural Research Institute, New Delhi 110012, IN
2 Department of Zoology, Delhi University, New Delhi 110008, IN

Abstract

Chemical signals play an important role in communication between different organisms determining the ecological balance between host plants, insect pests and their natural enemies. Some organic acids present in host insects and plants influence host habitat location and host location by insect natural enemies. Kairomonal response of Trichogramma chilonis Ishii to seven organic acids, viz., triacontanoic, docosanoic, octocosanoic, tricosanoic, pentadecanoic, heptacosanoic and hexacosanoic acids, was studied by laboratory bioassay. Among the acids tested, triacontanoic acid elicited the highest response from T. chilonis, followed by docosanoic and octocosanoic acids. Triacantonic acid at 10 ppm concentration and docosanoic acid at 20 ppm concentration could be used successfully in IPM programmes for enhancing the activity of T. chilonis in different agroecosystems.

Keywords

Kairomone, Organic Acid, Trichogramma chilonis.

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Madhulika Srivastava ¹, A. K. Singh ²

Affiliations
1 Indian Agricultural Research Institute, New Delhi 110 012, IN
2 Central Agroforestry Research Institute, Jhansi (U.P), IN

Abstract

Adaptation to climatic conditions (more importantly the temperature) of an area play a decisive role in influencing the parasitoid efficiency in controlling pests. Besides, the optimal conditions for inundative release of parasitoid e.g. Trichogramma, may also depend on strain. A strain of Trichogramma chilonis tolerant to high temperature was developed in the Biological control laboratory of IARI (PUSA), New Delhi and effect of temperature was studied on parasitoid efficiency. The biological traits viz., fecundity, emergence, survivability (male&female) and female populations were studied at 25, 27, 29, and 31ºC. The fecundity and emergence were recorded highest at 27 ºC. An increase of 107.23% (fecundity), 184.50% (emergence) and 15.65% (female survival) was observed from base to 35th generation, while male survival and female population decreased by 8.2 and 1.2%, respectively. The survival of immature stages of tolerant strain of Trichogramma proved their ability to withstand the temperature.

Keywords

Emergence, Fecundity, Parasitoid, Longevity, Trichogramma, Sex Ratio.

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Madhulika Srivastava ¹, A. V. N. Paul ¹, Prem Dureja ², A. K. Singh ³

Affiliations
1 Division of Entomology, IARI, New Delhi, 110012, IN
2 Division of Agricultural Chemicals, IARI, New Delhi, 110012, IN
3 Department of Zoology, Delhi University, Delhi, 110007, IN

Abstract

Kairomones emanating from males and females of three different host insects, viz., Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae) Spodoptera exigua (Hubner) (Lepidoptera: Noctuidae) and Chilo auricilius (Dudgeon) (Crambidae: Lepidoptera) that tend to influence the parasitic potential of Trichogramma chilonis Ishii was studied. Whole body extracts of male and female moths were analysed separately by gas liquid chromatography for determining their hydrocarbon profile, which showed the presence of straight chain saturated hydrocarbons ranging from C₉ to C₅₀, Different host insects showed variation in number and concentration of these chemicals, which were responsible for influencing parasitoid activity and parasitism. The concentration of these hydrocarbons ranged from 4 ppm to 1215280 ppm. The foraging activity of the parasitoid as indicated by parasitoid activity index (PAI) was highest (14.63) in S. exigua female body extract at highest concentration (60, 0000 ppm). Per cent mean parasitism rates recorded for S. litura male and S. exigua male and female body extract were significantly different from that for the body extract of C. auricilius. Both kairomonal interactions observed in the male body extract of S. litura could be due to the presence of appreciably very high amounts of favourable hydrocarbons docosane and heneicosane and comparatively high amount of octosane and pentaeosane as compared to its female body extract. Similarly, female body extract of S. exigua also showed comparatively higher amounts of favourable hydrocarbons tricosane, docosane, pentacosane, heneicosane and hexacosane as compared to its male body extract. Based on the hydrocarbon profile of body washings of males and females of the three host insects and quantity of favourable and unfavourable hydrocarbons present in individual extract body, it may be coneluded that heneicosane and hexacosane exerted significantly higher level of kairomonal effect on the parasitoid as compared to other hydrocarbons. The response elicited by the male extract body of S. litura was significantly higher, whereas the body extract of male C. auricilius elicited the least response from T. chilonis. These favourable hydrocarbons at the appropriate concentration of body extract of spent adults of S. litura males and S. exigua females could be used for enhancing parasitization by T. chilonis.

Keywords

Chilo auricilius, Host Body Extract, Kairomones, Spodoptera exigua, S. litura, Trichogramma chilonis.

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Usha ¹, Radhey Shyam ², Madhulika Srivastava ³, B. S. Rajput ¹

Affiliations
1 Rani Lakshmi Bai Central Agricultural University, Jhansi (U.P.), IN
2 Bihar Agricultural University, Sabour (Bihar), IN
3 Central Agroforestry Research Institute, Jhansi (U.P.), IN

Abstract

Pollinators provide an essential ecosystem service, namely pollination. Indeed, One-third of world's agricultural crops depends upon pollination by animals, including birds, bats, lizards and other animals - but the main pollinators are insects. Insect pollinators include bees, (honey bees, solitary species, bumblebees); pollen wasps (Masarinae); ants; a variety of flies including bee flies and hoverflies; lepidopterans, both butterflies and moths; and flower beetles.

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