Proceedinqs of the 7th Internaiunuil Workmg Conference an Stored-pvoduci Protectioa - Volume 1

Study on the population dynamics of the angoumois grainmoth Sitotroga cerealla (Olivier)

Fan Imgan'

Abstract

The population dynamics of the angoumois gram mothSiiotroco. cerealla (Ohvier ) was studied at 28'C and 75 %r h The results showed that the growth of adult populationstarted increasmg m 30 days after moculation , and reached apeak m 150 days The growth of adultoid population (larvaand pupa) had a small peak m 30 days after inoculation, andpeak m 120 days The population growth under the lmutedcondition (space and food) accorded with the LOgiStiCSGrowth Model

1142 33N, = 1+ e6 549-0 0'549t

The instantaneous rate of population increase (r) waso 0549 Under the condition of lmuted space and food, thedensity of insect restncted the further growth of population

Introduction

Siictroqo. cerealella (Olrvier , 1819) is an important pestdamaging the storage gram worldwide It is mainlydrstnbuted over Bntam, France, German, RUSSian,Holand , Indian, Pakistan, Japan, all countries of thewesteastern Asia, Chma , countries in Norht-South America,Egypt, Sudan, Kenya and Australia, etc Besides quantity,the harm caused the decrease of gram quality The starchand protem, gluten and ash content of wheat, thegermination percentage and so on reduced The insectbrought about 5 - 60 75% of loss of gram (Harukawa 1938,Moore 1966, Shahjahan 1974, El-Desstuki 1976)Due to the senous harmfulness, many scholars worldwide

studied on its biology, ecology and control (G A Dean, NSachorov, A Gibson, G Storey, P K Note, F SBedenhermer , G M LiS, L B Danuiels, J Davidson, JIByha-cobuur , A C Crombie, L 0 Waren, V R Adler, ASavescu, G Chippendeha, P E Boldt, Budnnr , E NCorry, R C Srmt, A I Baize, E H Eloyd, F Beccaar, SA Mostafa, L B Daniels, J Laing, V A Tyumeneva , BCornwell, Z A Qureshi, L L Sower, W H Me-

"Chengdu Ammal and Plant Quarantme Bureau. Chengdu 610041, P

R Chma

Gauyhey ) Reported researches were focused on thepopulation dynamics of the insect, but this study establishedthe population growth model based on the research of

population dynamics under the expenmental condition

Material and Method

The trial insect came from the last wheat harvested m theMeihuashan Mountains. Berber, Chongqmg City, and wasfed 3 generations With the wheat contammg water of 16% at28'C and 80% r h (Relative humidity) The trial wheat

was disinfected for 6 hours at 60'C after bemg washed Withwater The tnal bottle (diameter of 7cm, volume of525cm2), desicator (diameter of 40cm) and gauze were

disinfected for 2 hours at 100'C A bottle was filled 150g ofwheat All of the tnal wheat was kept for 2 weeks at 24'Cand 75% r h before test, and thus the contammg water of

13%The treatments were set up m the test One was ck The

other was maculated the insect A bottle was mocu1ated a parr ofadults (female + male) All treatment was repeated 3 times

The msect was fed m desiccator at 24'C and 75% r h

Results and Analysis

The population dynamics of adult

The result showed that the population quantity of hvmg adultstarted mcreasmg m 45 days after maculation, and had a peak m129 days Then it began to decrease (see Fig 1) The totalquantity of adult (mcludmg Irving and dead) began to increase m

30 days, and had a peak 150 dayst See Fig 2)

3!~ ...L.L...l-.-...-L._--J.-.J~X) ~20 t?V !IJ'J

Fig. 1. The populatIon dynarmcs of adult

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Proceedl~ of the 7th Iniernaiumal WOIkuu; Conference on Stored-product Protection. - Volume 1

FIg. 2. The population dynarrucs of the total adultst live +dead)

The population dynamics of larva + pupa

The population quantity of larva and pupa had a small peakm 30 days, and a peak m 120 days Then it decreased (SeeFig 3)

18 l:r , 1 1is t-

12 -

Fig. 3. The population dynamics of the adultoid (larva +pupa)

The population growth model

Fig 1 showed that the population growth of adult underthe luruted condrtion (space and food) basically accordedWith the logistics Growth Model

1142 23N, = 1+ e6 549 0 05491

In the formula, N, was the population quantity of adultchanged With the time t , t was the time (day)According to the logistics Growth Model, the

instantaneous rate of population mcreasei r ) was 0 0549

Discussion

The rapid increase of population quantity m initial stageshowed that the innate capacity increase (rm) was greaterunder the fittest condition The decrease of populationquantity after the peak showed that the space and food wererelatively short The rapid reproduction dunng the mitralstage was the cause that the favorable existence conditionwas turned into an unfavorable one, and thus the decrease ofthe population quantityThe regulanty of the population dynamics showed that the

density of insect restricted the further growth of populationunder the condition of hmited space and food

References

Zhang Zhenxiang and Chen Yong 1957 A mrtial survey onthe habits and charactenstics of S~totroga cerealell aeInsect Knowledge, 1957(6) 256 - 262Dmg Yanqm 1980 The pnnciple and application ofmathematical ecology on msect population SCience Press,BeijingChen Yaoxi 1984 Warehouse pests Agricultural PubhshmgHouse, BeijmgZhao Zlumo and Zhou Xmyuan 1984 An introduction toecology Chongqmg Branch of Science-technologyDocuments Pubhshmg House, Chongqmg

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