Net reproductive rates and cohort generation times are tabulated for pearl millet head miner (Heliocheilus albipunctella) reared on 4 diets (Bio-Serv® 9782 and 3 pearl millet-based diets) at 24, 26, 28 or 30°C. The highest R0 values of 5.84 and 4.33 females per female were estimated when the head miners were fed Bio-Serv® at 30° and early exserted millet at 24°, respectively. Tc tended to be shortest at 26 and 28°

Gilstrap, F E

Kadi, H A K

Pendleton, B B

Teetes, G L

Youm, O

ICRISAT Open Access Repository

untreated plots for each entry were paired in plots 0.9-mwide and 5.9-m long. One, 3-dichloropropene (1,3-D)Telone II was injected at 56.1 L ha-1 through a singlechisel in one row per plot and bedded. The other row ineach plot was left untreated and served as a control. Tencores of soil (2.5-cm diameter x 25-cm deep) were col-lected from each row of each subplot on 9 July, 28 Au-gust (data not presented), and 8 October, and nematodeswere extracted from a 150-cm3 subsample for each plotby centrifugal flotation (Jenkins 1964), identified, and re-corded.Results and discussionNumbers of nematodes in the soil were low on 9 July(2 weeks after the pearl millet was sown) in both treatedand untreated plots, but as expected, tended to have lowervalues in Telone II treated plots (Table 1). Both M. in-cognita and P. minor numbers tended to increase at the 8 October sampling (more so in untreated than treatedplots, as expected), but significant differences (P = 0.05)were only observed for M. incognita between treated anduntreated plots of pearl millet hybrid 97-107 x 115.Numbers of M. incognita tended to increase more in thesoil of plots growing hybrids with 115 as the male parentthan those with 117 as the male parent. Plants in thetreated plots were taller and greener than those in the un-treated plots during the first month after sowing, but thedifferences gradually disappeared by anthesis. Signifi-cant grain yield differences were observed betweentreated and untreated plots for 9 of the 14 hybrids. Plantsin untreated plots of 5 of the 9 hybrids yielded more grainthan plants in the treated plots. Telone II treatment didnot significantly affect grain yield in 5 of the hybrids. Thedata indicated differences existed for resistance toM. incognita and P. minor nematodes among the 14 pearlmillet hybrids. The fibrous rooting system of pearl milletprobably allows this crop to flourish under certain popu-lations of nematodes as the plants matured, due to in-creased root branching, but this hypothesis needs furtherstudy.ReferencesJenkins, W.R. 1964. A rapid centrifugal-flotation tech-nique for separating nematodes from soil. Plant DiseaseReporter 48: 692.Johnson, A.W. and Burton, G.W. 1977. Influence ofnematicides on nematodes and yield of sorghum-sudangrass hybrids and millets. Plant Disease Reporter61 : 1013-1017.McGlohon, N.E., Sasser, J.N., and Sherwood, R.T.1961. Investigation of plant-parasitic nematodes associ-ated with forage crops in North Carolina. N.C. Agricul-tural Experiment Station Technical Bulletin 148. Raleigh,USA: N.C. State University.AcknowledgmentThis research was supported in part by a special grantfrom the Georgia Feed Grain Initiative.Population Reproductive Statistics ofMillet Head Miner (Lepidoptera:Noctuidae) Reared in a Laboratory inNigerH A Kadi Kadi1, F E Gilstrap2, G L Teetes2, O Youm3,and B B Pendleton2 ( 1 . Institut national de recherchesagronomiques du Niger ( I N R A N ) BP 429, Niamey,Niger; 2. Department of Entomology, Texas A & M Uni-versity, College Station, TX 77843-2475, USA; and3. International Crops Research Institute for the Semi-Ar id Tropics ( lCRISAT) , BP 320, Bamako, Mal i ) .I n t r o d u c t i o nMillet head miner (Heliocheilus albipunctella de Joannis)significantly damages pearl millet [Pennisetum glaucum (L.) R. B r ] grown in the Sahel. Young larvae cut and feedon flowers and perforate the glumes of pearl millet. Late-instar larvae bore and create tunnels in the kernels onpearl millet panicles (Gahukar et al. 1986). Cultural andchemical management tactics have been used to reducedamage by millet head miners in West Africa, but areimpractical and expensive. A life table was used to studycohort development and assess the number of millet headminers surviving or dying in each life stage.Materials and methodsLife table parameters, including reproduction, develop-ment, and survival, were assessed for millet head minersreared using 4 temperatures and 4 diets in a laboratory.Cohorts were reared only on Bio-Serv® 9782 diet or on3 pearl millet-based diets, i.e., spike parts at early exser-tion, mid-flowering, or soft-dough stages. Mil let headminer adults ( l f : l m ) from a laboratory colony wereplaced with freshly cut pearl millet panicles into oviposi-tion cages. Eggs were counted and kept in a petri dishuntil they hatched. Each neonate larva was put into a 60 ISMN 40, 1999plastic cup containing 15 mL of an artificial or a millet-based diet. Cups were distributed among 4 incubatorsmaintained at 24, 26, 28, or 30 ± 1°C; a photoperiod of12:12 (L:D) h; and 70% relative humidity (RH). Num-bers of surviving and dead larvae were recorded and usedto construct life tables. Standard techniques developedby Southwood (1978) and Price (1997) were used to cal-culate the net reproductive rate of multiplication in termsof females produced per generation (Ro = alx mx) and co-hort-generation time, a period during which offspringwere produced (Tc = al mx x /alx mx ).Results and discussionThe population reproductive statistics estimated from thefecundity and life table data (Kadi Kadi 1999) are sum-marized in Table 1. When millet head miners were fedBio-Serv® diets, Ro increased from 3.53 females per fe-male at 24°C to 5.84 females at 30°C. Mean net repro-ductive rate was 4.09 females per female at the 4 tem-peratures. Tc ranged from a low of 21.51 days at 28°C toa high of 33.04 days at 30°C. Mean Tc at the 4 tempera-tures was 25.02 days. When millet head miners were fedearly exserted millet panicles, Ro and Tc were greatest at24°C. Ro at 24°C was 4.33 females per female and Tc was 23.86 days. Mean Ro was 3.64 females and Tc was 22.93days at the 4 temperatures. When a mid-flowering milletdiet was used, Ro and Tc were greatest at 24°C (3.77 fe-males and 24.95 days) but least at 28°C (2.89 femalesand 16.98 days). Mean Ro was 3.34 females and Tc was 21.44 days at the 4 temperatures. Using soft-dough stagemillet as a diet, Ro and Tc generally increased as tempera-ture increased. Ro increased from 3.26 females per femaleat 24°C to 3.86 at 30°C. Mean Ro of 3.52 females wasestimated at the 4 temperatures. Mean Tc was 19.79 days,higher than the Tc values recorded at 24 or 30°C.In summary, the highest Ro values of 5.84 and 4.33 fe-males per female were estimated when millet head minerswere fed the Bio-Serv® diet at 30°C and the early exertedmillet diet at 24°C. Overall mean Ro tended to be highestat 24°C (3.72 females) and 30°C (4.35 females). Thesevalues were lower than the Ro values of 21.09-71.17 fe-males per female, Srinivasaperumal et al. (1992) reportedfor immature stages of the noctuid, Earias vittella (Fabri-cius), reared on 3 hosts in a laboratory. Mean Tc valueswere 20.29-24.86 days at the 4 temperatures when millethead miners were fed the 4 diets. Tc tended to be shortestat 26 and 28°C and was only 16.98 days when millet headminers were fed mid-flowering millet diets at 28°C.Srinivasaperumal et al. (1992) reported Tc values of34.24-39.22 days when E. vittella was reared on threehosts in a laboratory. The Tc of 33.04 days for millet headminers fed the Bio-Serv® diet at 30°C was similar to the34.24 days Srinivasaperumal et al. (1992) reported forE. vittella reared on okra, [Abelmoschus esculentus (L.)Moench] at 27°C. Tc was shortest (mean of 19.78 days)when millet head miners were fed soft-dough stage milletdiets. The suitability of their food affected millet headminer population abundance and reproductive capabilityin the laboratory.T a b l e 1 . N e t r e p r o d u c t i v e rates a n d cohor t genera t ion t imes f o r p e a r l m i l l e t head m i n e r r e a r e d o n B io -Serv® 9 7 8 2 a n d th ree p e a r l mi l le t -based diets a t I C R I S A T S a h e l i a n C e n t e r , S a d o r e , N i g e r , 1996 a n d 1997 .D i e tB i o - S e r v® 9 7 8 2Pan ic le parts at ear ly exser t io rM i d - f l o w e r i n g stage pan ic lesS o f t - d o u g h stage pan ic lesM e a nReproduc t i vevalueR0T cR0T cRT cR0T cR0TcTempera tu re ( ° C )243.53 ± 0.0322.13 ± 0 . 0 14.33 ± 0.0323 .86 ± 0 . 0 43.77 ± 0.0724.95 ± 0.053.26 ± 0 .0618.37 ±0 .0 .43.72 ± 0 .2022.33 ± 0.94263.49 ± 0 .0223 .38 ± 0 .022.98 + 0.0120 .36 ± 0.04——3.23 ± 0.0320.53 ± 0.033.23 ± 0 . 1 0 .21 .42 ± 0 . 6 1283.48 ± 0.0221.51 ± 0 . 0 13.60 ± 0.0521.58 ± 0 . 0 22.89 ± 0.0916.98 ± 0 . 0 23.72 ± 0.0221 .10 ± 0 . 0 53.42 ± 0 . 1 220 .29 ± 0.723 05.84 ± 0 .0233 .04 ± 0 . 0 1——3.35 ± 0 . 0 522 .40 ± 0 . 1 03.86 ± 0 .0619.13 ± 0 . 0 34.35 ± 0 .5024 .86 ± 2 .70M e a n4.09 ± 0 .0425 .02 ± 1.803.64 ± 0 .2422.93 ± 0 .643.34 ± 0 .2021 .44 ± 1.503.52 ± 0 .1119.78 ± 0 . 4 1ISMN 40,1999 61References Notes a n d N e w sGahukar, R.T., Guevremont, H., Bhatnagar, V.S.,Ndoye, M. , and Pierrard, G. 1986. A review of the peststatus of pearl millet spike worm, Raghuva albipunctella de Joannis (Noctuidae: Lepidoptera), and its managementin the Sahel. Insect Science and its Applications 7: 457-463.Kadi Kadi, H.A. 1999. Laboratory life-fertil ity table as-sessment and field biology of millet head miner (Lepi-doptera: Noctuidae) in Niger. M.S. Thesis, Texas A & MUniversity, College Station.Price, P.W. 1997. Insect ecology. 3rd edition. New York,USA: John Wiley.Southwood, T.R.E. 1978. Ecological methods: with par-ticular reference to the study of insect populations. Lon-don, UK: Chapman and Hall.Srinivasaperumal, P., Samuthiravelu, P., andMuthukrishnan, J. 1992. Life tables and energetics ofEarias vittella (Fab.) (Noctuidae: Lepidoptera) reared onthree hosts. Insect Science and its Applications13:749-754.News ItemsR Bandyopadhyay Receives AwardRanajit Bandyopadhyay of the Genetic Resources andEnhancement Program, ICRISAT was presented with anOutstanding Achievement Award by the National GrainSorghum Producers Board (NGSP) and the Sorghum Im-provement Conference of North America (SICNA) dur-ing the 21st Biennial Grain Sorghum Research and Ut i l i -zation Conference, on 22 February 1999 at Tucson,Arizona, USA. The award is presented occasionally torecognize significant contributions towards improvementof sorghum industry in North America. The award is nor-mally given to individuals, but in 1999 it was given to aninternational team of three scientists for their work onsorghum ergot, a devastating disease that took the sor-ghum industry in the Americas by surprise. The teamconsisted of D E Frederickson (University of Zimbabwe,Harare; currently a Visit ing Scientist at Texas A & M Uni-versity, College Station), N W McLaren (Grain CropsResearch Institute, Potchefstroom, South Africa) andR Bandyopadhyay. After the arrival of sorghum ergot inthe U.S. in 1997, Bandyopadhyay worked for 10 monthsin 1998 at Texas A & M University (with R A Fred-eriksen) and the United States Department of Agriculture(USDA) (with J A Dahlberg) on various aspects of thedisease. One of the key areas of his work was dissemina-tion of appropriate research information andadvice to various sections of the sorghum industry.Bandyopadhyay's posting was covered by a Memoran-dum of Understanding on collaborative research betweenTexas A & M University and ICRISAT.NGSP is the national body representing the interest ofsorghum trade in the U.S. and elsewhere. Its membershipincludes growers, researchers, extentionists, seed compa-nies, and people associated with different facets of sor-ghum trade. SICNA is an organization of sorghum re-searchers that prepares a general program of research,education, and developmental activities in the U.S.SICNA is a co-publisher (with ICRISAT) of the Interna-tional Sorghum and Mil lets Newsletter.Previous Outstanding Achievement awardees associ-ated with ICRISAT include H Dogget (1981) and L R House (1993). Other awardees include such sorghumstalwarts such as R A Frederiksen (1995), G L Teetes(1995), D T Rosenow (1993), F R Mil ler (1989), L W Rooney (1985), J C Stephens (1963) and J R Quinby(1963).62 ISMN 40, 1999

Population Reproductive Statistics of Millet Head Miner (Lepidoptera: Noctuidae) Reared in a Laboratory in Niger

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Population Reproductive Statistics of Millet Head Miner (Lepidoptera: Noctuidae) Reared in a Laboratory in Niger

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