Collection Methods of Pimplini (: Ichneumonide: ) Parasitoids and their Species Composition...

INTERNATIONAL JOURNAL OF TROPICAL AGRICULTURE

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Volume 36 • Number 3 • 2018

Collection Methods of Pimplini (Pimplinae: Ichneumonide: Hymenoptera) Parasitoids and their Species Composition in Selected Districts of Tamil Nadu, India

C. Kathirvelu* and S. Manickavasagam** * Asst. Professor, **Professor, Department of Entomology, Faculty of Agriculture, Annamalai University, Annamalainagar, Tamil Nadu - 608 002, India, E-mail: [email protected]

Abstract: In the present study, a survey was conducted to determine the species composition of Pimplini parasitoids in selected districts of Tamil Nadu state, India using three different methods of collections viz., sweep net, Malaise trap and host rearing. The species composition of Pimplini recorded from different sites and the collection methods were compared. Of the collection methods employed, use of sweep net yielded highest species composition of Pimplini whereas Malaise traps were effective in collecting ichneumonids other than Pimplini. Among the districts surveyed, Cuddalore recorded more Pimplini and other ichneumonids than other eight districts. In the tribe Pimplini, the genera Xanthopimpla and Pimpla were recorded from the study area. In the genus Xanthopimpla, eight species; X. flavolineata, X. punctata, X. stemmator, X. exigua, X. konowi, X. tricapus, X. pedator and X. nigritarsis were recorded. Xanthopimpla flavolineata was the predominant species while in the genus Pimpla, only a single species P. duplicauda was recorded. Key Words: Species composition, Host rearing, Malaise trap, Net sweep, Pimplini Parasitoids.

INTRODUCTION (1997) divided the family into 37 With over 1, 00,000 described species, the order subfamilies, and this number varied greatly over the Hymenoptera is ranked fourth in the Class Insecta. past few decades according to different authors and In the order Hymenoptera, the superfamily is still debated. Among them, Pimplinae is one of Ichneumonoidea contains the two largest families, the vital subfamilies that include parasitoids of Ichneumonidae and Braconidae (Wahl, 1993). Gauld agricultural importance. The Pimplinae is the most

International Journal of Tropical Agriculture 545 C. Kathirvelu and S. Manickavasagam biologically diverse and moderately large group with the agriculturally important parasitoid species of the several big, strikingly coloured common parasitoid tribe, Pimplini in select districts of Tamil Nadu state, species (Gauld, 1991). They are diverse, ecologically India as well as to compare three methods of significant and economically important. It is often collection used in the study. numerically the best represented subfamily in general collections of Ichneumonidae (Fitton et al., 1988). MATERIALS AND METHODS The classification of Pimplinae has undergone many changes by different authors and presently the Study Area subfamily is divided into four tribes; Ephialtini, The present survey was carried out for a period of Pimplini, Delomeristini and Perithoini (Gauld et al., three years in three districts each representing a 2002). All species of Pimplini are generalist different habitat, a coastal belt (Cuddalore, parasitoids (rather than specialists) that have more Nagapattinam and Villupuram), a central tropical than one species of host. The most primitive region in Tamil Nadu (Namakkal (Kolli hills 1200 ft pimplines are idiobionts (kill or paralyze their host) above MSL), Karur and Salem (Yercaud hills 4970 ft of the endopterygote . Typically the hosts of above MSL) and one each representing rice these parasitic are concealed within plant monocropping (Thanjavur) and multicropping (rice, tissues (Salt, 1941 and Fitton et al., 1988). pulses, flowers, vegetables, etc.,) (Coimbatore) Studies on the biosystematics of these practiced districts (Figure 1). important parasitoids would provide information required for undertaking biological control or Collection Methods integrated pest management programmes. The Pimplini parasitiod wasps were collected using Application of biocontrol agents against pests three methods; net sweeping, Malaise trapping and has had a major resurgence in the recent years. through host rearing at different sites of the above Parasitic Hymenoptera including pimplines are mentioned districts. The sweep net collected among the most important agents for biological specimens were removed using an aspirator. control and are abundant in most tropical terrestrial Sweeping was done in different sites of the entire habitats. Numerous instances where outbreaks of a study area covering 2000 sq km once a week including pest have been suppressed by Ichneumonidae barren field. Malaise traps made according to Townes suggested the use of these parasitic insects in the (1972) were used. Two Malaise traps each were set management of pests (Narendran, 2001). The species up in Cuddalore, Nagapattinam, Namakkal and composition of Pimpline ichneumonids was seldom Salem representing agro and forest ecosystems in studied. It was done in Costa Rica with Malaise trap Tamil Nadu. Catches were emptied once a week for collections by Kavin and Gauld (1993). Despite their three years and specimens were diagnosed up to species composition, taxonomy of the group remain genus/ species level using the keys of Townes and poorly known and their identification is still difficult Chiu (1970) and Fitton et al. (1988) during the study and debatable (Huber, 1993). This leads to undue period. delays in documenting the fauna of a locality. Many species may become extinct before they are brought One of the host insects of Pimplini is the rice to light. Further, lack of knowledge in the parasitoid pink stem borer, Sesamia inferens Walker. Its pupae fauna, their taxonomy and distributions in particular were collected from rice fields of Annamalai area will result in bio-control failures. Keeping this University farm premises of Cuddalore district and in view, the objective of the study was to document held either individually or in clusters in Petri dishes

546 International Journal of Tropical Agriculture Collection Methods of Pimplini (Pimplinae: Ichneumonide: Hymenoptera) Parasitoids and their Species Composition...

Figure 1: Sampling areas of Pimplini parasitoids in Tamil nadu, India lined with cotton roll. The pupae were collected Pimplini. In the genus Xanthopimpla, eight species during an outbreak of S. inferens in Annamalai were identified. They are X. flavolineata Cameron, X. University farm premises during the Navarai rice punctata Fabricius, X. stemmator Thunberg, X. exigua season (February to April). They were maintained Krieger, X. konowi Krieger, X. tricapus Townes, X. under laboratory conditions at 27±2o C and 65±5% pedator Cameron and X. nigritarsis Cameron. From RH) for continuous observations for emergence of the genus Pimpla, only a single species P. duplicauda Pimplini parasitoids. Heinrich was identified. From the number collected (1886), it was evident that X. flavolineata is the RESULTS AND DISCUSSION dominant species followed by X. punctata (697) and X. stemmator (248). Xanthopimpla pedator and X. Sweep Net Collection nigritarsis were recorded only from Coimbatore The Pimplini parasitoids collected by sweep netting district numbering 30 and 54 respectively, whereas in the select districts of Tamil Nadu are presented X. konowi (19), X. tricapus (12) and X. exigua (8) were in Table 1. A total of 9,486 other ichneumonids and recovered only from Namakkal, Karur and Salem 3,029 Pimplini parasitoids were collected. Among districts respectively. In the genus Xanthopimpla, the the Pimplini, the two genera Xanthopimpla Saussure predominant species X. flavolineata was represented and Pimpla Fabricius were recorded from the study by 62.3% of the total Pimplini collected. Xanthopimpla area. Of them, Xanthopimpla was the predominant punctata was represented by 23.0%. The findings are genus 97.5 % occurring in almost all the habitats in accordance with those findings of Menakadevi that were surveyed in selected districts while the (2006) and Mahendran (2007) who also reported that genus Pimpla was represented by on ly 2.5% of the predominant and potential species is X.

International Journal of Tropical Agriculture 547 C. Kathirvelu and S. Manickavasagam flavolineata. The districts surveyed using sweep net predominant species X. flavolineata, X. stemmator and revealed that maximum number of Pimplini in X. punctata are mainly associated with agro Cuddalore (654) followed by Nagapattinam (472) and ecosystems. Hence, Pimplini collection through Thanjavur (464). Karur district recorded the least Malaise traps proved less effective than that of number (129) of Pimplini. This is likely due to the sweeping. Moreover, Malaise trap is suitable for the multicropping system practiced in the district. Low collection of insects of forest and orchard number of Pimplini and other ichneumonids ecosystems where sweeping is comparatively difficult recorded from Karur, Villupuram, Salem and and labour intensive. Findings of the study in Namakkal districts may be due to the unavailability agreement with Bartlett (2000) who compared of host insects coupled with the dry climate of the Malaise trap collections and host rearing. Namakkal districts. Absence of certain groups of and Salem districts recorded higher number of other Ichneumonidae in the tropics has been explained by ichneumonids over other two districts viz., Cuddalore the absence of their host groups (Gauld, 1987). The and Nagapattinam. The other two districts recorded number of specimens representing X. pedator, X. maximum numbers of Pimplini. The former districts nigritarsis, X. konowi and X. exigua was low because represented forest habitats and the latter districts of their narrow host range and host unavailability in represented rice based habitats. Of the two genera the study area as reported by Townes and Chiu collected, Xanthopimpla (97.7 %) outnumbered Pimpla (1970). The number of P. duplicauda reported from (Table1). The results are in accordance with the Cuddalore was 14 and from Namakkal was 59 and report that Malaise traps are generally considered to two specimens of Pimpla from Salem. This may be better for collecting ichneumonids in tropical areas be due to the preference of this parasitoid for (Mathews and Mathews, 1970) in forest ecosystem forests dense vegetation as reported by Fitton et al. (Gauld, 1991). (1988). Host Rearing for Parasitoid Collections Malaise Trap Collection The natural parasitism levels of Xanthopimpla The numbers of Pimplini parasitoids collected from species on S. inferens pupae in rice fields is presented Malaise trap in the four districts of Tamil Nadu are in Table 2. Significantly high (28.9%) emergence given in Table 1. A total of 1,461 Pimplini and 6,702 was recorded from pupae collected in March other ichneumonids were collected. A total of 615, followed by May, April, January and February with 332, 292 and 222 of Pimplini were collected from levels of 21.8, 21.6, 21.4 and 19.1 % respectively. Cuddalore, Namakkal, Nagapattinam and Salem The highest parasitoid emergence was recorded in respectively. In the genus Xanthopimpla, X. flavolineata, pupae collected in March. This may be due to the X. punctata and X. stemmator were recorded from all availability of the active tillering and flowering stage the four districts whereas X. exigua, X. tricapus and of the rice crop when the pre-pupae and pupal X. konowi were recorded only f rom Salem, stages of S. inferens was present in plenty. T he Nagapattinam and Namakkal districts respectively. population build up of the host is less during the Xanthopimpla pedator and X. nigritarsis were not early stages of the crop and it increased during and recorded from Malaise trap collections. The genus after tillering and to decline again at the end of the Pimpla was represented by P. duplicauda (33) in season coinciding with steady increase in Cuddalore and Namakkal districts only. Malaise traps temperature upto harvest in May. This is evident were found to be more suitable for the collection of from the number of host pupae collected and the other ichneumonids than Pimplini because the emergence of the parasitoids.

548 International Journal of Tropical Agriculture Collection Methods of Pimplini (Pimplinae: Ichneumonide: Hymenoptera) Parasitoids and their Species Composition... 0 0 5 0 22 15 33 MT 847 198 341 1461 6702 8163 total 8 2 30 54 19 12 73 NS 248 697 Cumulative 1886 3029 9486 12515 MT Not Erected u Karur* 3 5 0 0 0 0 0 0 12 NS 109 129 309 438 MT Not Erected 0 0 0 0 0 21 46 30 54 Coimbatore* NS 250 401 961 1362 ted districts of ted districts Tamilnad MT Not Erected 9 0 0 0 0 0 0 0 97 NS 162 268 941 Villupuram* 1209 MT Not Erected 0 0 0 0 0 0 0 Thanjavur* 40 NS 280 144 464 1386 1850 Malaise traps from selec from traps Malaise Table 1 Table 0 0 5 0 0 0 26 61 27 MT 213 332 1895 2227 Namakkal* 0 0 0 0 0 17 77 19 59 NS 176 348 1263 1611 0 0 0 0 0 0 30 14 22 MT 156 222 1762 2022 years Salem* 0 0 0 8 0 0 2 ected by net sweeps and ectedsweeps by net 12 56 NS 215 293 1495 1828 0 0 0 0 0 0 49 64 15 MT 164 292 1578 1870 0 0 0 0 0 0 0 61 NS 303 108 472 1315 1787 Nagapattinam* ids collected in 3 years in collected ids 3 years in collected ids 0 0 0 0 0 6 0 k 3 for years 93 counted once a week for 3 for a once week counted MT 314 202 615 1467 2082 Pimplini parasitoids coll parasitoids Pimplini 0 0 0 0 0 0 Cuddalore* 85 14 NS 391 164 654 1816 2470 . Districts sp Pimplini Methods flavolineataX. stemmator X. punctata X. pedator X. nigritarsis X. konowi X. X.exigua tricapus X. duplicauda P. Pimpla Pimplini Total Other ichneumonids Total NS – Net sweep of number * Total parasito a wee once made * Sweeps Malaise trapMT – of number * Total parasito and emptied * Collections

International Journal of Tropical Agriculture 549 C. Kathirvelu and S. Manickavasagam c a b b cd 10.7 13.1 12.3 15.2 18.1 0.78 1.61 Host pupae dead* (21.21) (25.18) (25.98) (22.95) (25.53) a c c b ab 48.7 49.6 41.5 45.5 38.5 0.92 1.98 Adult (44.77) (40.11) (38.35) emerged* (42.42) (44.26) S. inferensS. c a b bc bc thod) 19.2 18.2 17.3 18.7 21.6 0.67 1.33 Other (24.58) (27.69) (25.98) emerged* (25.25) (25.60) parasitoids a b b b b 21.4 19.1 28.9 21.6 21.8 1.73 3.52 group Pimplini (32.52) emerged* (27.56) (25.91) (27.69) (27.83) in rice (Host rearing me rice in 2.7 1.9 3.7 2.3 2.8 d pupae

inferens

X. punctata+ X. 1.2 1.5 2.0 0.9 1.2 level by LSD by level

Sesamia on on Table 2 Table 1.8 2.1 3.5 1.5 1.7 species per month collecte month per species X. stemmator+ X. 0.7 1.2 2.0 0.3 1.1 analyzed using CRDanalyzed ignificantly different at 5% different ignificantly implini Parasitoids implini Xanthopimpla Parasitoid emergence % Parasitoid 8.4 11.2 11.5 10.3 10.0 X. flavolineata+X. 3.8 4.0 6.2 6.3 5.0 arc sine transformed arc sine and ut from emergence ofut from emergence Natural parasitism by P by parasitism Natural a common letter are s anot common 149 101 202 283 125 Total SE.d pupae of host number collected CD (p =0.05) (p CD Month January February March April May are parentheses in * Values by *followed Mean values o worked values Percent +

550 International Journal of Tropical Agriculture Collection Methods of Pimplini (Pimplinae: Ichneumonide: Hymenoptera) Parasitoids and their Species Composition...

With regard to the other groups of parasitoids, showed its supremacy in places where sweeps could 21.6% emergence was found from host pupae not be made. Noyes (1989) also compared net collected in May followed by January (19.2%), April sweeping, Malaise trapping and other collection (18.7%), February (18.2%) and March (17.3%), while methods and found both the methods are efficient the % emergence of S. inferens was found to be high in the collection of Ichneumonidae. in February (49.6) followed by January (48.7) and April (45.50). The other parasitoids that emerged ACKNOWLEDGEMENT were mainly, Brachymeria lasus and Tetrastichus sp. The The authors are grateful to the authorities of Annamalai unemerged host pupae were 18.1 % in May followed University for their permission to carry out this by 15.2 in April. Among the Pimplini parasitoids, investigation. emergence of X. flavolineata was more in all months. The results are in accordance with the findings of CONCLUSION Kanagarajan (2008). Wherever, there was no From the study, it is evident that the net sweeping emergence of either the host moth or the parasitoids method is more effective than Malaise trapping and from pupae, many dead immature stages of host rearing in collecting Pimplini group of parasitoids were found on dissection. This may be parasitoids, while Malaise trapping is better for due to competition among developing parasitoids collecting ichneumonids other than Pimplini. (some times belonging to different species). Similar Regarding the species composition of Pimplini levels of emergence of X. nana nana during the peak parasitoids, Cuddalore yielded more Pimplini because incidence of its host Opisina arenosella in October to of the habitats representing multiple cropping December was reported by Pillai and Nair (1983). system. Comparison of Collection Methods The tribe Pimplini is represented by two genera Among the methods employed to recover Pimplini viz., Xanthopimpla and Pimpla in the study area, with parasitoids from Cuddalore district, net sweep was the genus Xanthopimpla represented by eight species found better than Malaise trap and host rearing. It and the genus Pimpla by only one species. was easy to make sweeping with net in the crop canopy as well as in adjoining weeds. Generally, the REFERENCES flight activity of Pimplini is associated with crop Bartlett, R. (2000). Efficiency of collection methods and canopy and also the parasitoids rest on the surface flight activity of Ichneumonidae (Hymenoptera) in of leaves whereas in Malaise trapping, the parasitoids three sites in Guanacaste, Costa Rica. M.Sc. Thesis, have to be trapped while on flight. The third method The University of Georgia, Athens, Georgia. viz., host rearing is laborious, though this would be Fitton, M.G., Shaw, M.R. and Gauld, I.D. (1988). Pimpline useful to determine host - parasitoid association. The – Ichneumon flies. Hymenoptera, Ichneumonidae collection of pupae of host insect S. inferens is also (Pimplinae). Handbook for the Identification of laborious as it is hidden within the stem. The findings British Insects. 7 (1), 110 p. are in accordance with Mahendran (2007) who Gauld, I.D. (1987). Some factors affecting the adopted similar methods for the collection of composition of tropical ichneumonid fauna. Biol. ichneumonids. In addition, Bartlett (2000) and J. Linn. Soc., 30: 299-312. Prabhu (2006) also reported that sweep net is Gauld, I.D. (1991). The Ichneumonidae of Costa Rica, practicable and easier and host rearing is an effective 1. Mem. Amer. Entomol. Inst., 47: 1- 589. method for host specific parasitoids. Malaise trap

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