Starvation survival and effects of chlorpyrifos-methyl and deltamethrine on...
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Proceeduuis of the 7 til, International Workmg Conference on Stored-product Protecuon - Volume 1 Starvation survival and effects of chlorpyrifos-methyl and deltamethrine on Sitophilus granarius L Petar KIJaJIc l , Radmila Almasr' and IlIJa Penc l Abstra,ct Effects of starvation of granary weevil adults were determmed in laboratory, and individuals that survived LT so starvation mterval were exposed to the msecncides chlorpynfos-methyl and deltamethrine. Insecticidal effects were tested by the so-called film method m glass vessels The adults that were not fed after the penod of starvation and those recovenng from starvation on untreated wheat for 24 and 48 hours were exposed to the msecttcides The mortality percentages for the starvation penod and the penod of exposure to insecticides were corrected to mdude the mortality of control msects, and the results were subjected to probit analysis The results show that the lethal effect of starvation IS slower for granary weevil adults ongmatmg from densities of all population which were placed m separate vessels, WIth total mortahty of starved adults occurnng withm 6 - 8 days In all tnal variants, death from starvation occurred more slowly for insects ongmatmg from populations WIth the highest density. The results showmg the effect rate of chlorpynfos-methyl on unrecovered granary weevil adults and those that recovered from starvation for 24 and 48 hours showed that tlus msecticide had a slower effect on the previously starved adults, and that the lengh of recovery penod had no effect on Its tOXICIty.Nodifferences were observed concermng the vanants of recovery, but the difference from the control IS slight but statistically srgruhcant. The tOXICItyofdeltamethnne to granary weeviladults that were not fed after starvation and the ones recovenng for 24 hours was found to be sImIlar. However, deltamethnne was slgmflcantly more tOXIC to granary weeVil adults recovenng from starvatIOn for 48 hours, and less tOXIC to control adults than to any other vanant of starved msects. 1 Agncultural. Research InstItute 'Serbia' - PestICIdes and Envtronmental Research Centre Banatska 31 b, P 0 B 163, 11080 Belgrade-Zemun, Yugoslavta 2Faculty of Agnculture, InstItute for Plant Protection, Trg DosIteJa Obradovlc 8, 21000 Novt Sad, YugoslaVia Introduction Successful protection of stored products from mfestation by insects and other pests requires the application of Integrated Pest Management (IPM) concept, which mc1udes all measures available to prevent pest occurrence and curative interventions durmg storage of products (Bond, 1984; Cuperus and Platt, 1996; Scholler et al., 1997) The apphcatton of this concept requires considerable knowledge of the properties of each msect species and their populations under different environmental conditions, particularly their reactions to pesticides under different environemntal condrtions (Busvme , 1971; Penc and KIJaJlc, 1997) Lack of nourishment, L e. starvation, has rarely been investigated for pest insects occurnng in stored products, especially the mfluence of different starvation mtervals on msecticidal tOXICItyCitmg results of other authors, Busvme (1971) noted that granary weevil (S. qronuirius') adults were more tolerant to carbon disulphide (CSz) on the first day of starvation and more susceptible to the fumigant after four and particularly eight days ThIS expenment aimed to determme effects of starvation on granary weevil adults ongmatmg from different initial population densities , and effects of the msecticides chlorpynfos-methyl and deltamethrme on mdrvtduals that survived specific starvation periods. Materials and Methods We used a laboratory stram of granary weevIls normally susceptlble to msectlCldes, reared m msectanum accordmg to methods proposed by Harem and Soderstrom (1966), and DaVISand Bry (1985) The msects were reared on wheat grams, at room temperature measurmg 26 ± rc and relative air humidity of 60 ± 5 %. We used granary weevil adults aged about two weeks. Effects of starvation were momtored m three replications WIth the followmg vanants: one msect per each of 25 vessels, five adults per each of 10 vessels, and 10 mdlVldualsper each of 10 vessels. The msects were supplIed from three mitIal population denSIties: 500 , 1, 000 and 2,000 adults per 1,500 wheat grams InseCtiCIdaleffects on granary weeVIls followmg speCIfIC 826
Transcript of Starvation survival and effects of chlorpyrifos-methyl and deltamethrine on...
Proceeduuis of the 7til, International Workmg Conference on Stored-product Protecuon - Volume 1
Starvation survival and effects of chlorpyrifos-methyl anddeltamethrine on Sitophilus granarius L
Petar KIJaJIcl, Radmila Almasr' and IlIJa Pencl
Abstra,ct
Effects of starvation of granary weevil adults weredetermmed in laboratory, and individuals that survived LTsostarvation mterval were exposed to the msecncideschlorpynfos-methyl and deltamethrine. Insecticidal effectswere tested by the so-called film method m glass vesselsThe adults that were not fed after the penod of starvationand those recovenng from starvation on untreated wheat for24 and 48 hours were exposed to the msecttcides Themortality percentages for the starvation penod and thepenod of exposure to insecticides were corrected to mdudethe mortality of control msects, and the results weresubjected to probit analysisThe results show that the lethal effect of starvation IS
slower for granary weevil adults ongmatmg from densitiesof all population which were placed m separate vessels, WIthtotal mortahty of starved adults occurnng withm 6 - 8 daysIn all tnal variants, death from starvation occurred moreslowly for insects ongmatmg from populations WIth thehighest density.The results showmg the effect rate of chlorpynfos-methyl
on unrecovered granary weevil adults and those thatrecovered from starvation for 24 and 48 hours showed thattlus msecticide had a slower effect on the previously starvedadults, and that the lengh of recovery penod had no effecton Its tOXICIty.No differences were observed concermng thevanants of recovery, but the difference from the control ISslight but statistically srgruhcant.The tOXICItyof deltamethnne to granary weevil adults that
were not fed after starvation and the ones recovenng for 24hours was found to be sImIlar. However, deltamethnne wasslgmflcantly more tOXICto granary weeVil adults recovenngfrom starvatIOn for 48 hours, and less tOXICto control adultsthan to any other vanant of starved msects.
1 Agncultural. Research InstItute 'Serbia' - PestICIdes and
Envtronmental Research Centre Banatska 31 b, P 0 B 163,11080 Belgrade-Zemun, Yugoslavta
2Faculty of Agnculture, InstItute for Plant Protection, Trg DosIteJaObradovlc 8, 21000 Novt Sad, YugoslaVia
Introduction
Successful protection of stored products from mfestation byinsects and other pests requires the application of IntegratedPest Management (IPM) concept, which mc1udes allmeasures available to prevent pest occurrence and curativeinterventions durmg storage of products (Bond, 1984;Cuperus and Platt, 1996; Scholler et al., 1997) Theapphcatton of this concept requires considerable knowledgeof the properties of each msect species and their populationsunder different environmental conditions, particularly theirreactions to pesticides under different environemntalcondrtions (Busvme , 1971; Penc and KIJaJlc, 1997)Lack of nourishment, L e. starvation, has rarely been
investigated for pest insects occurnng in stored products,especially the mfluence of different starvation mtervals onmsecticidal tOXICItyCitmg results of other authors, Busvme(1971) noted that granary weevil (S. qronuirius') adultswere more tolerant to carbon disulphide (CSz) on the firstday of starvation and more susceptible to the fumigant afterfour and particularly eight daysThIS expenment aimed to determme effects of starvation
on granary weevil adults ongmatmg from different initialpopulation densities , and effects of the msecticideschlorpynfos-methyl and deltamethrme on mdrvtduals thatsurvived specific starvation periods.
Materials and Methods
We used a laboratory stram of granary weevIls normallysusceptlble to msectlCldes, reared m msectanum accordmgto methods proposed by Harem and Soderstrom (1966), andDaVISand Bry (1985) The msects were reared on wheatgrams, at room temperature measurmg 26 ± rc and relativeair humidity of 60 ± 5%. We used granary weevil adultsaged about two weeks.Effects of starvation were momtored m three replications
WIth the followmg vanants: one msect per each of 25vessels, five adults per each of 10 vessels, and 10mdlVldualsper each of 10 vessels. The msects were supplIedfrom three mitIal population denSIties: 500 , 1, 000 and2,000 adults per 1,500 wheat gramsInseCtiCIdaleffects on granary weeVIls followmg speCIfIC
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penods of starvation were tested at LTso mterval , the lethaltime obtained m previous starvation trials for the vanant of10 insects x 10 vessels We used the film method oftOXICIty test, applying 3 ml acetone solution of techmcalgrade msecticides to each glass vessel of 720 ml volume.After drymg off the deposits, we placed onto them theimmediately starved insects and adults recovenng fromstarvation on untreated wheat grams for 24 and 48 hours.Chlorpynfos-methyl was apphed m 0.03 p.g/cm2 dose, anddeltamethrine m 0.18 p.g/cm2 doseThe obtained mortahty rate, corrected according to
Abbott (1925) to include the mortahty in control, wassubjected to probit analysis based on the method descnbed byFinney (1971) and processed by computer software designedby Raymond (1985)The LTso values were assumed to be sigmficantly different
only when 95% confidence intervals did not overlap.
Results and Discussion
Our results of the effects of starvation on granary weeviladults m different tnal vanants and from different mitialpopulation densities are given in Tables 1- 3
Table 1. Starvation effects on granary weevils ongmatmgfrom population density of 500 adults / 1,500 gwheat grams
Vanant LTso(No of vessels x adults) (days)
Fiducial hrmts LT9Sfor LTsoa (days)
25 x 1 4.97 4.81-5.13 7.17
10 x 5 4.30 4.14-4.44 5.75
lOx 10 3.99 3.86 - 4. 12 5.43
a 95% level
Table 2. Starvation effects on granary weevils origmatmgfrom population densIty of 1,000 adults / 1, 500 gwhea t grams.
Vanant LTso(No of vessels x adults) (days)
FIdUCial hmI ts LT9Sfor LTsoa (days)
25 x 1 5.02 4.85 - 5 . 19 7.25
10 x 5 4 00 3.85 - 4 . 14 5.78
lOx 10 4.11 3.96 - 4.26 6.03
a 95% level
Table 3. Starvation effects on granary weevils originatingfrom populationdensity of 2,000 adults / 1, 500 gwheat grams.
Vanant LTso(No of vessels x adults) (days)
Fiducial hrruts LT9Sfor LTsoa (days)
25 x 1 5.83 5.65 - 6.01 8.6810 x 5 4.50 4.29 -4.70 7.00lOx 10 4.74 3.99 - 5.60 6.58
a 95% level
The results presented m Tables 1 - 3 indicate that thelethal effect of starvation for all mitral population densitieswas slower for adults placed m individual vessels, WIth fullmortahty occurnng withm 6 - 8 day period. Death fromstarvation was slower m all tnal vanants for mdrvidualsoriginating from the high-density population (2, 000 adultsper 1,500 wheat grams)Effects of prehmmary starvation of granary weevil adults
on the manifestation of tOXICIty of chlorpynfos-methyl anddeltamethnne following different vanants of recovery areshown in Tables 4 and 5
Table 4. Effect rate of chlorpynfos-methyl (0.03 p.g/cm2)on granary weevil adults after different vanants ofrecovery from starvation.
Recoveryvanant
LTso(rrunutes)
Fiducial hrmts LT9Sfor LTsoa (minutes)
No recovery
24 - hour recovery48 - hour recoveryControl"
108.57108.10107.95103.10
106.22-110 93 162.72105.83- 110.42 160.58105.49-110.41 164.70100.85-105 .33 153.34
a 95% levelb no preVIOUSstarvation
Table 5. Effect rate of deltamethnne (0.18 p.g/cm2) ongranary weevil adults after different vanants ofrecovery from starvation.
Recoveryvanant
LTso(mmutes)
FIdUCIal hmits LT9Sfor LTsoa (mmutes)
No recovery
24 - hour recovery48 - hour recoveryControlb
72.0072.7557.1375.09
68.15 -76.0770.65 -74.9254 06 - 60.4072.80 -77.48
138.23126.49104.81134.84
a 95% levelb no preVIOUSstarva tlon
The results gIven in Table 4 show that the insecticIdechlorpyrifos-methyl had slower effect on previously starvedmsects, regardless of the length of theIr recovery penod.
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No difference between the recovery variants was observed,and the difference with control was found to be slight butstatistically sigruficant. However, preliminary starvationevidently had very little influence on the tOXICIty ofchlorpyrifos-methyl to granary weevil adults in any of therecovery variantsWe found the effect rates of deltamethnne (Table 5) on
msects unrecovered from starvation and those fed onuntreated wheat grains for 24 hours to be similar. Theinsecticide showed SIgnificantly higher toxicity to granaryweevil adults recovering from starvation for 48 hours, ascompared With control.
Conclusion
Granary weevil adults were found to be susceptible tostarvation as full mortahty of the exposed individuals fromall mrtial population densities occurred withm 6 - 8 days.Significantly slower lethal effects of starvation were foundfor insects placed in individual vessels.Prelimmary starvation of granary weevils had little effect
on the manifestation of toxicity of chlorpyrifos-methyl,while deltamethrine showed greater tOXICIty to insectsrecovering from starvation for 48 hours
References
Abbott, W. S. 1925. A method of computing theeffectiveness of an insecticide. Journal of EconomicEntomology, 18, 265 - 267.Bond, E. J. 1984. Manual for fumigation for msect control.
Rome, FAO Plant Production and Protection Paper, 54,432 p.Busvine, J. R. 1971 A cntical review of the techniques fortestmg insecticides. London, Commonwealth AgnculturalBureau, 345 pCuperus, G. and Platt, R 1996. Stored Product Pests PushPCO Treshold. Pest Control, 5, 44 - 48.Davies, R. and Bry, R. E. 1985. Suophilu« granarius,Sitophilus oryzae and Sitophtlus zaenuus , Trtbouusn.conjusum and Tribolium casumeum In: P. Singh andR. F. Moore ed. , Handbook of insect reanng, Amsterdam-Oxford-New York-Tokyo, Elsevier, Vol. I, 287 - 293.Fmney, D.J. 1971. Probit Analysis Cambridge, University
Press, 333 p.Harein, P K and Soderstrom, E L 1966. Coleopteramfestmg stored products. In: C. N. Smith ed., Insectcolornzation and mass production, New York, London,Academic Press, 241 - 257.
Peri c, I. and Kljaji C, P. 1997 Dezmsekcija u razli citimuslovima sredme Zbornik radova sa VIII simpozijuma IZoblasti dezmfekcije , dezmsekcije I deratizacije u zastitizivotne sredine, Subotica, mal 1997, 45 - 51.Raymond, E. J. (1985): Presentation d ' un programme d'analyse log-probrt pour rmcro-ordinnateur. Cah.ORSTOM, Ser Ent. Mad. et Parasitol. , 22, 117 -121.Scholler, M., Prozell, S., Al-Kirshi, A. -G andReichmuth, Ch. 1997. Towards Biological Control as aMajor Component of Integrated Pest Management m StoredProduct Protection, Journal of Stored-Products Research,33,81-97
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