J Bu'! (',,1/[1( ,I. l.~: 1,)·2.<. 19<)9 Survey and tritrophic interactions between host plants, Helopeltis alltollii Signoret (Heteroptera: Miridae) and its egg parasitoids D. SUNDARARAJU* and P. C. SUNDARA BABU Department of Agricultural Entomology Tamil Nadu Agricultural University Coimbatore 641 003, Tamil Nadu, India ABSTRACT: The egg parasitoids ofHelopeltis antonii Signoret existing in neem endemic area (coastal and hinterland of Tamil Nadu) and in non-neem endemic area (western ghats of Tamil Nadu and coastal Karnataka) are Telenomus sp. laricis group (Scelionidae), Erythmelus helopeltidis Gahan (Mymaridae), Chaetostricha Spa and VIens sp. (Trichogrammatidae). Telenomus Spa is very much dominant in non­ Deem endemic areas, whereas Ufens sp. is quite prominent in neem endemic areas. When the eggs of R. antonii laid on neem were exposed for natural parasitism, neem has not exerted any adverse interaction on Telenomus sp. KEY WORDS: Egg parasitoids, Helopeltis antonii Helopeltis antonll Signoret undertaken to identify the species of egg (Heteroptera: Miridae) is the serious pest parasitoids of H. antonii existing in the on cashew and neem. Even though, the egg neem endemic and non-neem endemic areas parasitoids of H. antonii on cashew viz., of Tamil Nadu and to document their Telenomous sp. laricis group, Erythmelus tritrophic interactions. helopeltis Gahan, Chaetostricha sp. and Gonatocerus sp. have been documented MATERIALS AND METHODS from coastal Karnataka on cashew Survey of egg parasitoids of H. antonii (Sundararaju, 1996), the species in Tamil Nadu composition of egg parasitoids of H. antonii on neem has not been studied Plant samples of neem (Azadirachta so far. Hence, present studies were indica A. Juss), cashew (Anacardium * Present address: National Research Centre for Cashew, Puttur 574 202. Karnataka, India. SUNDARARAJU and SUNDARA BABU occidentale L.), guava (Psidium guajava . exposed for natural egg parasitism as a host L.) and drumstick (Moringa oleifera enrichment technique (Luck et al., 1988) Lamark.) containing eggs of H. antonii at during 1994-97. In each occasion, different locations in neem endemic area minimum of one hundred eggs were (coastal and hinterland) and non-neem exposed for natural parasitism and the endemic area (eastern slopes and western shoots containing eggs were severed from ghats) of Tamil Nadu during 1993-96. At respective host plant and the extent of each location, at least 75 eggs were parasitism was estimated on or before examined mainly to find out whether egg sixtieth day by dissection method as parasitism exists or not. Sampling of eggs explained earlier. In the neem endemic was repeated twice on same host plant, areas, the eggs were exposed on neem, wherever, egg parasitism was absent in the cashew, drumstick, guava, cotton first instance. For this purpose, the plant (Gossypium hirsutum L.) and silk cotton parts containing the eggs were either [Ceiba pentandra (L.) Gaetrn.] in dissected immediately or on or before hinterland (Coimbatore) and cashew and sixtieth day after maintaining them in adult neem in Vridhachalam and Villupuram (east parasitoid emergence cage (Sundararaju, coast region of Tamil Nadu), respectively. 1993) for collection of adult parasitoids and In non-neem endemic area at Puttur finally percentage of parasitism was worked (coastal Karnataka), the eggs were exposed out. The total parasitism was classified on neem, cashew and guava. Neem trees into two main groups based on the were specially raised for this study in this characteristics of different species of region. Similarly, at Coimbatore, as parasitoids. The two groups were cashew never existed due to antagonistic categorized as Telenomus group (TG) of soil condition, cashew grafts/seedlings Scelionidae and non-Telenomus group were raised for this purpose with adequate (NTG) belonging to Trichgammatidae and amelioration. Mymaridae (Sundararaju. 1996). Tritrophic interactions between host RESULTS AND DISCUSSION plants,H. antonii and its egg parasitoids Survey of egg parasitoids of H. antonii The tritrophic interactions were studied in Tamil Nadu to find out whether host plants influence In this study. both groups (TG and the extent of parasitism of egg parasitoids NTG) were encountered. In total three and which type of egg parasitoid is more species of solitary egg parasitoids viz., prevalent on a particular host plant. For Telenomus sp. laricis group (Hymenoptera: this purpose, the gravid females of Scelionidae), Ufens sp. (Hymenoptea: H. antonii were caged for oviposition on Trichogrammatidae) and Erythmelus tender shoots of respective host plants. helopeltidis Gahan (Hymenoptera: After 24h, the cages were removed and Mymaridae) were reported for the first time those shoots having eggs of H. antonii were in Tamil Nadu. The Chaetostricha sp. 20 Survey and tritrophic interactions - reported from coastal Karnataka was found Tritrophic interactions between host to be absent whereas the occurrence of plants,H. antonii and its egg parasitoids Telenomus sp. and E. helopeltidis (Sundararaju, 1993) has also been From the eggs of H. anton;; laid in different host plants at Coimbatore (neem confirmed in this study in Tamil Nadu. The endemic area), occurrence of Telenomus egg parasitism was observed in all host sp. was more prominent on other host plants surveyed except guava and the plants (cashew, drumstick, silk cotton and highest extent of parasitism on different cotton) than on neem and it ranged from host plants ranged from 19.1 to 61.9 per 11.0 to 48.7 per cent, whereas on neem its cent (Table 1). Occurrence of three species occurrence was noticed to a max.imum (Vfens sp., E. helopeltidis and Telenomus extent of 6.3 per cent. But on neem, sp.) and one species (Vfens sp.) were occurrence of NTG parasitoids was quite observed on neem at hinterland prominent and ranged from 7.5 to 91 .8 per (Coimbatore) and coastal region (Chennai), cent (Table 2). The low occurrence of respectively. On cashew, the dominant egg Telenomus sp. on neem may be due to parasitoid (Telenomus sp.) recorded from interspecific competi tion between NTG coastal Kamataka (Sundararaju, 1993) was parasitoids rather than any adverse detected in western ghat region influence of host plant (tritrophic (Pechiparai) of Tamil Nadu, whereas in the interaction), since its occurrence was east coast, it was absent and only Ufens highest (22.7%) on neem and was quite sp. was recorded. On drumstick, only dominant than NTG parasitoids at Puttur Telenomus sp. was detected at Coimbatore. (neem non-endemic area). Table 1. Survey on natural egg parasitism of H. antonii in Tamil Nadu Range of egg parasitism (%) Period of Host plant Location sampling Species composition Total NTG TG Azadirachta indica Coimbatore Nov. -Dec., 93 50.0-61.9 50.0-61.9 0.0-4.8 Azadirachta indica Chennai April, 95 18.9 18.9 0.0 Anacardium. occidentale Vridhachalam April-May, 95 15.4-47.4 15.4-47.4+ 0.0 Anacardium occidentale Pechiparai July, 96 70.8 0.0 70.8 Moringa oleifera Coimbatore Aug., 95 19.1 0.0 19.1 Psidium guajava Periyakularn Dec., 94 & 0.0 0.0 0.0 Jan., 96 Psidium guajava Coimbatore Oct., 95 & 0.0 0.0 0.0 Nov., 95 . NTG (Vfens sp. and Erythmelus he{opeltidis); TG (Telellomus sp. lancls group); + only Ufens sp . 2 1 UNDARARAJU and SUNDARA BABU f In fable 2. Extent of parasitism of exposed eggs 0 H . antonii neem endemic and non-endemic areas Range of egg parasitism (%) Period of Species composition Host plant Location sampling Total NTG TG Neem endemic area 7.5-91.9 7.5-91.9 0.0- 6.3 Azadirachta indica Coimbatore Nov., 94 to Oct., 95 56.7+ Azadirachta indica ViIlupuram Dec., 95 56.7 0.0 Anacardium occidentale Coirnbatore Dec., 94 & 1.8 - 11.0 0.0- l.8 0.0 -11.0 Jan., 95 Anacardium occidenlale Vridhachalam Jan., 95 45.2 45.2+ 0.0 Moringa oleifera Coimbatore Nov., 94- 23.7 - 50.0 0.0- 2.9 23.7 -48.7 Jan., 95 Gossypium hirsutum -do- Aug. 94 & 95 & 5.8 - 22.2 5.8-16.3 0.0 -22.2 Nov., 94 Ceiba pe/ltandra -do- Dec., 95 25.2 0.0 25.2 Psidium guajava -do- Oct. & 0.0 0.0 0.0 Nov., 95 Neem non-endemic area A. indica Puttur Mar., 97 37.7 15.1 H 22.7 A. occidentale -do- -do- 60.1 23.7" 36.5 P. guajava -do- -do- 50.0 19.2" 30.8 NTG (Vfenssp. and Erythmelus helopeltidis); ++ Chaetostrichasp. and E. he/opeltidis + only Vfens sp.; TG (Telenomus sp. laricis group) Even though in the neem endemic area, (Vridhachalam). Since, Tele1l0mllS sp. was occurrence of any egg parasitoids was recorded on a number of host plants in host totally absent on guava, their occurrence enrichment technique. it may very well on neem in the non-endemic area (Puttur) establish especially on cashew in the east was recorded to a maximum extent of 50 coast and it is worth while to introduce it per cent on the same host plant (Table 2) in the cashew belt of east coast of Tamil and it needs further study in Tamil Nadu. Nadu. In fact, the influence of host plants This study again confirms that Telenomus has affected the parasitism by sp. is absent in the cashew belt of east coast Trici10gramma and i:.:llcorsia sp. on other 22 Survey and tritrophic interactions host insects (Yadav, 1980; Yadav and Patel , Management in Horticultural 1981; Srinivasa et al., 1999) and no such Ecosystems, 5: 59-61. adverse effect of host plant has been recorded in the present study. Sundararaju, D. 1993. Studies on . parasitoids of tea mosquito bug, Helopeltis antonii Sign. (Heteroptera: ACKNOWLEDGEMENTS Miridae) on cashew with special reference to Telenomus sp. Journal of The first author expresses his gratitude Biological Control, 7: 6-8. to the Director, National Research Centre for Cashew (leAR), Puttur for providing Sundararaju, D.