J. BIOI. Control. 12 (2): 101-106 _ 1998

Life table of the Mexican , bicolorata Pallister on and sunflower

B_ S. BHUMANNAVAR, C. BALASUBRAMANIAN and S. RAMANI Project Directorate of Biological Control P. B. No. 2491, H. A. Farm Post, Bellary Road Hebbal, Bangalore 560 024, Karnataka,

ABSTRACT: Life-table of the Mexican beetle, Zygogram11ll1 bicolorata Pallister feeding on parthenium leaves, parthenium leaves smeared with sunflower extract, sunflower leaves and sunflower leaves smeared with parthenium leaf extract have been constructed. The longevity and

intrinsic rate of natural increase (rm ) varied with extract treated and their respective hosts. The intrinsic rate of natural increase did not change considerably when fed on parthenium leaves and parthenium leaves smeared with sunflower extract (rm = 0.44). The fed on sunflower leaves (r = 0.37) and sunflower leaves smeared with m parthenium extract (rm = 0.35) were also not very different. Shorter generation time was obtained when fed with parthenium and parthenium leaves smeared with sunflower extract.

KEY WORDS: Intrinsic rate of natural increase, life table, , sunflower,

Parthenium hysterophorus L. addition to reducing land productivity, the () is an annual weed, native to weed causes acute allergic dermatitis and semi-arid and sub-humid regions of the rhinitis in susceptible human beings America. This weed got accidentally (Towers and Subba Rao, 1992). introduced into India in early 1950's along with imported food grains (Vartak, 1968). The Mexican beetle, z,vgogramma It is an aggressive invader, distributed on bicolorata Pallister was introduced into cultivated and open land and was declared India in 1984 for biological control of the as a noxious weed in India in the 1970's. In weed and released in the field after host I3lll:MANNAVAR et al.

specificity tests in 1985 (Jayanth, 1987). unit (comprising a male and a female) was The beetle has spread to about 200,000 terminated with the natural death of the square kilometre area in Karnataka, Tamil female. Life table parameters were Nadu, parts of Andhra Pradesh and in computed to study the natural mortality certain pockets of Madhya Pradesh and rate in relation to the age of the individual Punjab (Jayanth and Ganga Vishalakshy, as well as the growth rate of biocontrol 1994). Eventhough, the beetle is well agent, Z. bieolorata on natural host, established on parthenium, it has been P hysterophorus, non-host sunflower reported feeding on sunflower in isolated leaves and their extracts smeared on the plots in Karnataka viz., Arsikere leaf surface of each other. (Chickmagalur District), Kolar (Kolar District), Javagal and Yemmadoddy RESULTS AND DISCUSSION (Hassan District). The beetle, after The results indicated that the longevity complete defoliation ofparthenium, moved of Z. bie%rata showed a significant to the adjoining area of sunflower and fed variation when fed with parthenium, on border row (Anon., 1997). This parthenium leaves smeared with sunflower work was carried out to know the pest extract, sunflower leaves and sunflower leaf potential of Z. bieolorata and the possible smeared with parthenium leafextract, mean threat to sunflower. values being 27.11, 13.44, 12.88, and 13.29 MATERIALS AND METHODS weeks, respectively. The maximum net reproductive rate (R) was 702.62, 702.0 Hundred freshly laid eggs were used for 130.06 and 370.58 and the mean generation each experiment. Freshly emerged larvae time was 16.13, 16.13, 13.52 and 13.69 were reared in rectangular (1 Ox4.5cm) weeks, respectively, in the above mentioned plastic containers with copper wire mesh treatments. The mortality occurring among windows on all the sides. To study the cohorts is depicted in Figure la to d. A fecundity, freshly emerged adults were comparative analysis of survivorship curves reared in pairs (1M: IF) and provided with of Z. bie%rata indicated that the female mature (:::; 10 days old) parthenium leaves, mortality occurred late when reared on parthenium leaves smeared with sunflower parthenium and parthenium leaves smeared leaf extract (100/0 aqueous), sunflower with sunflower extract and sudden increase leaves and sunflower leaves smeared with in mortality was recorded in sunflower fed parthenium leaf extract. The experiment individuals. was carried out under laboratory conditions ± (28 1°C; 45-65%> RH ) at the Project The innate capacity for increase (rc ) and Directorate of Biological Control, intrinsic rate of natural increase (r ) of m Z. Bangalore during 1996-97. The number of bicolorta on different treatments are given eggs laid daily by the females, were noted. in Table 1. A comparison of the value In case of death of the male partner, another r ' indicates that the' m value and the male was substituted. Each experimental generation time were higher on parthenium 102 r ;;; ~ 0- il ..,o ,~ Table 1. Life table studies on Z. bicolorata on different host plants :r;: ~ .... ""~ § ::: t:t ~" Reproductive Mean Innate capacity Conneetedrm Connected Finite rate >: rate (Ro) generation for natural I:lxmx generation of increase ~ Host time Increase X=1096.6 log.R IS' o Antilogc (in weeks) log.Ro (fifweek) T=-- )=- Llxmx r = -- r c m Tm

T=-c Tc Ro o Parthenium leaves 702.62 16.13 0.406 0.437 15.00 1.548 'J-J Parthcnium leaves smeared with sunflower extract 702.00 16.13 0.406 0.437 15.00 1.548

Sunflower leaves 130.06 13.52 0.360 0.374 13.00 1.454

Sunflower leaves smeared with parthenium extract 370.58 13.69 0.432 0.348 17.00 1.416 I BHUMANNAVAR el til.

80 150 l> (;'CC ;'#.(J - 60 n CD 100 c en "u ~ ;:3"0 CI) C!I 40 Q.CD Q.> -.0 I/) '- _. CI) E:: 50 '<- :::!% CI:::l 20 0 < I/) 0 0 5 7 9 11 13 15 17 19 21 23 25 27 29 31 _Suvivd Fig. 1 a: Fed on parthenium Time in weeks (X) _Fa::trdty

120 60 100 50 l>o ;:tf!..(J - cc ocr CD -u ~ 80 40 CI) C!I c en Q.> 60 30 :::l"O en - C._ 0CD CI) E:: 40 20 CI:::l '< :::!% - 0 < I/) 20 10 0 0 5 7 9 11 13 15 17 19 21 23 25 27 29 31 Time in weeks (X) Fig. 1 b: Fed on parthenium leaves srreared with sunfbw er extract

100

0""" ;,;:-;1: 80 -(3 '=:' CD C!I 60 Q.> I/) .- 40 CI) E:: CI:::l < I/) 20 0 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 Time in weeks (X) Fig.1c: Fed on sunflower lea~s

120 ~------~ 40 0- 100 "-13~~ 30 -~ (1)- 80 ~ (J) c.~ 60 I/) '- 20 § ~ (I) E:: c.(J)_. 0 CI:::l 40 en 10':< ::; < 20 o 0 5 6 7 8 9 10 11 12 13 14 15 16 17 18 192021 222324252627 Time in weeks (X) Fig.1d: Fed on sunflower leaves smeared with parthenium extract

Fig. I. Age specific survival and parthenium of Z. bicolorata

]04 Lite table of Zygogramma bicolorata and parthenium leaves smeared with course become a pest in natural conditions sunflower leaf extract than that on by modifying their trophic levels to suit the sunflower and sunflower smeared with host (Bemays and Chapman, 1994). Kumar parthenium l~af extract. The onset of egg (1992) reported feeding of the Mexican laying and egg laying period was influenced beetle, Z. bieolorata on Xanthium more by natural host than the non-host or strumarium and also on its ability to non-host smeared with host leaf extract. oviposit and complete its life cycle, which The egg laying pattern in relation to host indicates the expanding host range (as and non-host leaves are presented in Figure stenophagy)by the Mexican beetle. The 1. Early reproduction was evident when results call for further studies on reared on natural host namely parthenium allelochemical interactions of Z. bicolorata leaves or parthenium leaves smeared with with several members of the family sunflower extract. Asteraceae to resolve the conflict of the ability of this to become a pest of Life tables of chrysomelids have- been sunflower under field conditions. studied on the natural host by Jayanth and Bali (1994). In the present investigation, ACKNOWLEDGEMENTS life table parameters of an insect were analysed and compared on natural host and The authors are thankful to the Project non-host (sunflower). Parthenium was Director, Dr. S. P. Singh, Project highly preferred to sunflower and Directorate of Biological Control, sunflower leaves smeared with parthenium Bangalore for his encouragement and extract. Zygogramma bieolorata can ICAR, New Delhi for the financial support. clearly discriminate between natural host, REFERENCES non-host and host smeared with non-host and non-host smeared with host extract. Anonymous, 1997. The pest potential of Jayanth and Ganga Vishalakshy (1994) the Mexican beetle, Zygogramma reported that among 1 5 different varieties bicolorata introduced for biological of sunflower evaluated in the field for control of parthenium. ICAR Annual susceptibility to Z. hie%rata, the beetle Report 1997, 18 pp. was able to feed (5 - 1 5%) only on certain varieties viz., MSFH-8, EPRO-l and IAHS-l and laid only negligible number of Bernays, E. A. and Chapman, S. D. 1994. eggs. The basis of discrimination has not Host selection by phytophagous Chapman and Hall, New York. been studied. In the context of chemical . co-evolution hypothesis, the secondary plant metabolites are capable of altering the Jayanth, K. P. 1987. Introduction and suitability of host plants for herbivores and establishment of Zygogramma bicolo­ consequentially affecting plant-herbivore rata on Parthenium hysterophorus at interactions. Specialist herbivores may Bangalore, India. Current Science, sequester such compounds and in due 56: 310-311. 105 BHUMANNAVAR et al.

Jayanth, K. P. and Ganga Vishalakshy, P. (Coleoptera: Chrysomelidae) expanding N. 1994. Field evaluation of sunflower its host range? Curre!?t Science, 63: 729 varieties for susceptibility to the -730. parthenium beetle, Zygogramma bieolorata. Journal of Biological Towers, G. H. N. and Subba Rao, P. V. Control, 8: 48-52. 1992. Impact of the pan-tropical weed, Parthenium hysterophorus L. on human Jayanth, K. P and Geetha Bali. 1994. Life affairs. In: Richardson, R. G. (Ed.). table of the parthenium beetle, Proceeding of the First International Zygogramma bicolorata Pallister "Weed Control Congress, Melbourne: (Coleoptera: Curculionidae) in Weed Science Society of Victoria, Bangalore, India. Insect Science and its 9: 171-179. Application, 15: 19-23. Vartak, V D. 1968. Weed that threatens Kumar, A. R. V 1992. Is the Mexican crop and grasslands in Maharashtra. beetle Zygogramma bicolorata Indian Farming, 18: 23-24.

106