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1/I\J -Al~~!IVi "'-{i g d- -J -:t ~...... J '7°3 tfSI Efficacy of Chlorpyrifos in Soil in 'Florunner' Peanut Fields to .Lesser Cornstalk Borer (Lepidoptera: Pyralidae)

T. P. MACK, J. E. FUNDERBURK,! R. E. LYNCH,2 E. G. BRAXTON,3 AND C. B. BACKMAN Department of Entomology, Alabama Agricultural Experiment Station, Auburn University, Alabama 36849

J. Econ. Entomol. 82(4): 1224-1229 (1989) ABSTRACT Survival of lesser cornstalk borer, Elasmopalpus lignosellus (Zeller), larvae in soil from conventionally tilled and planted

KEY WORDS Insecta, Elasmopalpus lignosellus, efficacy

THE LESSER CORNSTALK BORER, Elasmopalpus lig that technical phorate was inactivated in air-dry nosellus (Zeller), is a key pest of peanuts in the sand. Chlorpyrifos residues that weathered under southeastern United States (Smith & Barfield 1982). high temperatures disappeared faster than residues Population outbreaks occur in hot, dry climates in exposed to lower temperatures (Getzin 1985), and peanuts grown in sandy soils (Luginbill & Ainslie the half-life of chlorpyrifos in water decreased by 1917, King et al. 1961, Dupree 1965, Leuck 1966, 75% when temperature was increased from 20 to Mack & Backman 1987). First and second instars 37.5°C (Freed et al. 1979). Effectiveness of some damage vegetative buds, leaves, and plant stems soil insecticides declines more rapidly with in at the ground level; older instars feed on pegs (gy creased temperature. The degradation rate of car nophores) and pods (Leuck 1966, Lynch 1984, Mack bofuran increased from IS to 3SoC (Ou et al. 1982); et a!. 1988). Suber et al. (1982) estimated lesser Bromilow et al. (1980) reported that the degra cornstalk borer damage to the Georgia peanut crop dation rate of aldicarb and oxamyl increased with to be $25 million in 1980. temperature within the range of S-1S°C. Insecticides are commonly used to manage the Studies were begun in Alabama and Florida to lesser cornstalk borer, and chlorpyrifos is the in measure the residual efficacy of chlorpyrifos over secticide most widely used. However, the efficacy time against lesser cornstalk borer in peanuts, and of chlorpyrifos against the lesser cornstalk borer in to examine timing of treatments in relation to res peanuts has not been reported. Furthermore, no idue efficacy. We document survival of first-instar studies have examined the loss of insecticide effec lesser cornstalk borer exposed to soil treated with tiveness on the lesser cornstalk borer with time, chlorpyrifos and the change in survival with time. and the effects of hot, dry conditions on efficacy. Soil moisture and soil temperature greatly affect Materials and Methods insecticide performance (Harris 1972). Harris & Turnbull (1977) reported that the effectiveness of Conventionally tilled and planted 'Florunner' carbofuran, chlorpyrifos, and terbufos was reduced peanuts were used in the study. Standard agro in air-dry soil. Harris & Chapman (1980) noted nomic practices for fertilization and for weed and disease management were used. One soil sample was collected from each plot 1 North Florida Agricultural Research and Education Center, approximately every 2 wk for bioassay with first University of Florida, QUincy, Fla. 32351. instars. Each soil sample (30 em wide by 10 cm 2 Insect Biology and Population Management Research Lab, USDA-ARS, Coastal Plains Experiment Station, Tifton, Ga. 31793. long by 2.S cm deep in Alabama or 40 cm wide 3 Florida Department of Agriculture and Consumer Services, by 10 cm long by 2.5 cm deep in Florida) was Bureau of Pesticides, Tallahassee, Fla. 32399. taken by collecting two (Florida) or three (Ala-

Table I. Mean percentage of survival of first-ins tar lesser cornstalk borer in Alabama, 1986a

Chlorpyrifos Sample date (days after planting) treatment, kg 27 12 18 25 2 2 8 8 22 5 20 26 Plant- 27 Mayb May June June June Julyb July Julyb July July Aug. Aug. Aug. ing Flower Pegging (0) (16) (22) (29) (36) (36) (42) (42) (56) (70) (85) (91) None None None 85.2a 81.5a 66.7a 77.8a 85.2a 85.2a 74.1ab 74.1a 92.6a 2.2 None None 70.4a O.Oa O.Ob O.Ob 3.7b 50.0a 33.3b 74.1ab 77.8a 66.7a 85.2a 2.2 None 2.2 81.5a 7.4a O.Ob O.Ob 22.2b 55.6a O.Oc 22.2c 25.9c 18.5b 48.2b 2.2 None 1.1 81.5a 3.7a O.ob O.Ob 7.4b 55.6a O.Oc 29.6bc 51.9b 70.4a 59.3ab None 2.2 None 70.4 O.Ob 3.7c 29.6bc 55.6ab O.Ob 48.2b None None 2.2 77.8 O.Oc 33.3bc 51.9b 22.2b 77.8ab

a Chlorpyrifos applied as granules (15G formulation). The flowering time application occurred at beginning bloom, and the pegging time applications occurred approximately 10 d after approximately 50% of the plants began pegging. Means in each column followed by the same letter are not significantly different (P > 0.05, Duncan's multiple range test [SAS Institute 1985]). b Samples taken before treatment to estimate mortality before chlorpyrifos application.

bama) subsamples from within each plot. Soil sam each plot, so 100 larvae (four replicates times five ples were put in plastic bags, labeled, and refrig cups per replicate times five larvae per cup) were erated (Alabama) or frozen (Florida) until the tested for each treatment. Treatments were the bioassays were conducted. same as in the Alabama tests, but the 2.2 kg (AI)/ Alabama. Tests were conducted in 1986 and 1987 ha at planting plus 2.2 kg (AI)/ha at pegging treat on peanuts planted in a Dothan sandy loam soil ment was not included. Each plot was four rows (0.5% organic matter) at the Wiregrass Substation wide (91 cm row spacing) and 9.8 m long. Soil of Auburn University, Headland, Ala. Six treat samples were air dried for 6 to 30 h until individual ments were replicated three times in a randomized soil particles separated easily when shaken. complete block design. One soil sample was taken Bioassay. The toxicity of chlorpyrifos was eval from each plot, so 27'larvae (three replicates times uated by testing first instars in plastic cups (30 ml) three cups per replicate times three larvae per cup) that were filled to a depth of 1 cm with soil. Sor were tested for each treatment. The treatments ghum seedlings were germinated in dishes lined were an untreated control, and chlorpyrifos 15G with paper and moistened with a solution contain (Dow Chemical Company, Midland, Mich.) ap ing a fungistat (benomyl or amphyl depending upon plied at 2.2 kg (AI)/ha in a 25- to 30-cm band at the state in which the bioassay was done). Three planting; 2.2 kg (AI)/ha at planting plus 2.2 kg (Alabama) or five (Florida) larvae were placed in (AI) /ha at pegging (R2 plant growth stage, as de each cup, with three (Alabama) or five (Florida) fined by Boote [1982]); 2.2 kg (AI)/ha at planting cups used for each soil sample. Sorghum seedlings plus l.1 kg (AI)/ha at pegging; 2.2 kg (AI)/ha at were placed in each cup to provide a continuous pegging; and 2.2 kg (AI)/ha at flowering (Rl plant supply of food for the larvae. All cups containing growth stage). Each plot was eight rows wide (91 soil, lesser cornstalk borer larvae, and the sorghum cm row spacing) and 15.2 m long. Treatments were seedlings were kept in a controlled environment applied with a small-plot granular applicator (Pre chamber at 30°C with a 14:10 (L:D) photoperiod cision Machine Company, Lincoln, Nebr.); sam and approximately 50% RH. The effectiveness of pled areas within each plot were marked with a each treatment was evaluated after 72 h by count flag to prevent resampling. ing the living larvae found in each cup. Soil samples were not dried before use in the Data Analysis. Bioassay data were analyzed with 1986 bioassay. Soil moisture content was measured analysis of variance and a Duncan's multiple range by determining its mass before and after drying at test (P =::; 0.05) by comparing the mean percentage 30°C for 1 wk. Soil moisture in 1986 ranged from of living larvae from each treatment on each sam o to 4.0%, with 6 of the 10 sample dates having ple date (SAS Institute 1985). Bioassay data for each 0% moisture. In 1987, all soil samples were dried year and location were analyzed separately. Treat at 35°C to <5% soil moisture before use. Soil was ment effectiveness was defined as a significant de dried in 1987 to maintain a constant moisture level crease in survival compared with that of larvae in the bioassays. exposed to untreated soil on the same date. Florida. Tests were done in Jackson County, Florida, on peanuts planted in a Tifton loamy sand Results (2-3% organic matter) at the Dozier School for Boys in 1986 and in Orangeburg sandy loam soil Alabama. In 1986, 66-93% of first instars sur at the Marianna Agricultural Research Center in vived a 72-h exposure to soil from untreated plots 1987. Four treatments and ali untreated control (Table 1). All chlorpyrifos treatments reduced lar were replicated four times in a randomized com val survival to <7.5% on the sample date after plete block design. One soil sample was taken from application. Chlorpyrifos applied only at planting 1226 JOURNAL OF ECONOMIC ENTOMOLOGY Vol. 82, no. 4

significantly reduced larval survival at 0, 16, 22, ;>. .... 29, and 42 d after application. Larval survival in ]~ ~~ ~..8'Ev~~ ~ v this treatment from 56 to 91 d after application ...... ""'0)0""'''' S bO <~ ""';""';ar.io~a) ... c 1C~ >< ~ was not significantly different from survival in un- C'I t-""'C'I 10 o ... 5...s! treated plots. Both treatments containing planting 0..0.. bh ~:c and pegging applications reduced larval survival ::l- ~~..c~..c..c ...V -::l "'CO C'I 000000 until 36 d after application. Treatment with 2.2 kg <~ a) a) ohx; ...,,; ...,,; .:::: S ~~ ICC'lC'I"' ...... !oO:.~ '" (AI)/ha at planting plus 2.2 kg (AI)/ha at pegging &l ; reduced larval survival for the remainder of the ~ g ;>. v ::l study. This treatment was more effective in re- ~c;, ~..c.,g'E.,g"'O ...... t- co ...... t-"''''''C'I so. dueing larval survival than treatment with 2.2 kg t-~ tcitX5oc.;""';o;i "'010 C'I CO ""''''''''''''''C'I ...~~ 0 (AI)/ha at planting plus 2.2 kg (AI)/ha at pegging All of the pegging and flowering treatments sig- ;>. e" "'3(0 gc.. ~G~a;~~ "'~ nificantly reduced larval survival immediately af- ...... co a)a)~ar.i~...,,; c .... o~ ICC'I"'C'I"' ...... o C ter application; however, the activity of each treat- C'I ::: ~ ~ v .S:l::t= ment varied with time (Table 1). Application at ..c_ 0...:0 the time of flowering significantly reduced larval ::l'" Q §'..c ...... !e. ~ ~..c..c Q"'O v .... survival up to 55 d after application, and the ap- t- C'I 00"''''''' co"'" S ; u:i~~tX5a)~ ... Q plication at pegging reduced survival at 0, 14, and cot-"''''''C'I .... .:d bO'"C C 43 d after application. Decreased survival occurred v ... bO c_ bO'" in three of the four pegging and flowering treat- bO ::lco bO'"v .... .5 ...... "'" ~~..c~ Q 0.. 0 C o~ 10 ...... 100"'" C ments on 20 August. The soil moisture at this time ~ "';""';u:ic.;~ ~ ~ was 4% and was the greatest percentage of moisture 0.. '" COt-lOCO .... ~ ... ~ "'0 ... c- c v recorded during the growing season. Soil moisture ~ ::lCO 1:3 ~:::: ~ ...... :!. I I I I co e"..s! from 18 June until 22 July was 0% . ~ g v In 1987, 59-85% of first instars survived a 72-h ~ _8 S ~ v ..c ~ c_ bO'" exposure to soil from untreated plots (Table 2). All t-" v ~~..c..c..c C v co ~ ::l~ 0"'1C~0 ... ..c chlorpyrifos treatments significantly reduced sur- 0\.... "'0 ...... '" f2c.;tX5u:io c ...... s! C'I"'~ "' ...... C'I '~$ vival on the sample date after application. Chlor- cU 0.. v "'0 e s ..c v pyrifos applied at planting did not reduce larval ec ~ v .:a en ~~..c..c Q ~ ~ survival at 33, 39, or 46 d after application, but ec §c;, t-1C"'t-t- "'0= ...... v 0 did decrease survival at 66, 73, and 102 d. The ~~'" tciu:ic.;oc.; t::-- < COlO"'''''' ::l C .S sudden decline in percentage of survival on 20 July ..t) 8 S ~ a. v 0_ .9 in the planting applications may have been caused c- c 0 ~ ::l'" o Q ~ by an increase in biologically-available chlorpyri- 0 ...... ~ I I I I; I ".C..,c .S:l .:a "'" ~ Q 0.. fos in the soil as the result of 3.04 cm of rainfall ..III ~ ~ ~ 0.. v ~ on 14 July. Application at flowering consistently S c- 2::.5 III ::l1C 1~~tX? ~ '" E ...... e Ot-;::!: I I v C ~ reduced larval survival for approximately 70 d, and 0 0) S ~ ;>. application at pegging reduced survival for ap- ~ :;::~ a. bO e- ~ v ..9 proximately 41 d. III c- It-:~~ .§ ~ ..c III ::lCO 00)0) Q Florida. In 1986, 75-93% of first ins tars survived ...... ,=. ""'C'IC'I I I ~ C'I ~~ ~ 0"'" a. t;l ...... a 72-h exposure to soil from untreated plots (Table ;>. .e s V C V III ~- ..co ..c 3). All treatments remained effective for at least :::;::: I~~~t-oo E-o"'O co~ ·V £ 55 d after planting. Chlorpyrifos applied at plant- 'rIII C'I c; a. ;>. '2c 1:: ing reduced larval survival 3, 14, 28, 41, 55, 87, ;.:: ~ 0 ... ~§: I~~~ 1 1 ~-a e and 102 d after application. Application at planting 0 000 "'3 v v and pegging reduced larval survival for 139 d, so '; ~..t) e ~ ~ ~ s ~ .~ ;>. the second application of chlorpyrifos extended ef- ~ ...... a. C,.')o'" :8 :::; ...,,; -- ~ ficacy until the end of the study. Treatment at t- I I I I I III= ~o.. .8 ... ~ ~= flowering reduced larval survival on all sample dates 0 ~< c ~ "'3bh v except 8 August, and the applications at flowering bIl bO C C e ec c v V v ~ ... and at pegging reduced survival for III and 98 d, bO C C C ... bO ~ ...!oO: 'So OOC'l ...... OC'l bObO -=~ bO ~ respectively. Application at pegging was less ef- ~ v ZZo;i",;Zo;i ~ a. c p., 8- ~ v "'Oc ~ fective than application at flowering on the last two g" v ~ 0 .- b.Cl ~ e 0.. v.....:.. v sample dates. Increased survival in all treatments ~ ...v v v v v v = c c c c c 0....clC'..c =~ ~ occurred on 8 August. Samples on this date were ~ 0 OOOOC'lO ~ '" 00 c ~ ~ ZZZZo;iZ .e§~~ collected by different personnel than any of the ..: "'a~ oW ~ ~;>. other dates, but very dry conditions during this 0.. bO 2~ :8] ~ .5 v v v 8 oW 1;; ~ time probably account for the observed increase. ::a S c c c ec :2 c OC'lC'lC'lOO :2~.s~ All chlorpyrifos applications, regardless of when E-o U ~ Zo;io;io;iZZ U~enen ~ " o<..t) they were applied, decreased in activity between 1C.~ 9 and 19 September (102 to 112 d after planting). August 1989 MACK ET AL.: SURVIVAL OF E. lignosellus IN TREATED SOIL 1227

Table 3. Mean percentage of survival of first-instar lesser cornstalk borer in Florida, 1986a

Chlorpyrifos Sample date (days after planting) treatment, kg 2 13 27 27 10 10 24 8 25 9 19 3 16 Plant- June June June Juneb Julyb July July Aug. Aug. Sept. Sept. Oct. Oct. ing Flower Pegging (3) (14) (28) (28) (41) (41) (55) (70) (87) (102) (112) (126) (139) None None None 93.3a 90.0a 75.0a 90.0a 92.5a 82.5a 90.0a 80.0a 92.5a 87.5a 80.0a 2.2 None None o.ob O.Ob O.Ob o.ob o.ob 73.7a 7.5b 7.5b 77.5b 77.5ab 87.5a 2.2 None 1.1 O.Ob O.Ob O.Ob 2.5 O.Ob 2.5b 42.5b O.Ob 2.5b 27.5c 62.5bc 37.5b None 2.2 None 90.0 O.Ob O.Ob O.Ob 77.5a O.Ob O.Ob 7.5d 5.od 10.Oc None None 2.2 90.0 O.Ob O.Ob 56.2b O.Ob O.Ob 7.5d 47.5c 32.5b

a Chlorpyrifos applied as granules (15G formulation). The flowering time application occurred at beginning bloom (Rl), and the pegging time applications occurred 13 d later (R2). All plots were planted on 30 May. Means in each column followed by the same letter are not significantly different {P > 0.05, Duncan's multiple range test (SAS Institute 1985]). b Samples taken before treatment to estimate mortality before chlorpyrifos application.

The application of chlorpyrifos at planting showed was probably caused by accelerated degradation the greatest decline in activity. in the hot and dry weather during the growing In 1987, 53-95% of first instars survived a 72-h season. In 1986, July was much hotter in Alabama exposure to soil from untreated plots (Table 4). All than in 1987, with 268 h in which the hourly soil chlorpyrifos applications reduced larval survival to temperature 2.5 cm below the soil surface was <5% on the first sample date following application. > 35°C, and zero hours in 1987 (Fig. 1). Freed et The application at planting significantly reduced al. (1979) reported that the half-life of chlorpyrifos larval survival until 30 July (73 d after application). decreased from 53 to 13 d when incubated at 20 Application at planting and at pegging reduced and 37.5°C, so a decrease in effectiveness in 1986 survival until 31 August, or 32 d longer than ap is consistent with this previous report. plication at planting. The application at flowering Because less rain fell on the plots in Alabama in was effective for at least 60 d, whereas application 1986 than in 1987, a greater frequency of low soil at pegging was effective for only 32 d. After 32 d, moisture was observed in July and August of 1986 larval survival in soil from the pegging application than in 1987 (Fig. 2). Whitney (1967) found that plots was at least as great as survival in untreated the control of the confused flour beetle, Tribolium soil. confu8um Jacquelin du Val (Coleoptera: Tene brionidae), with chlorpyrifos changed from 0% at 2% moisture to 100% at 7.5% moisture. Reduced Discussion effectiveness of soil insecticides in dry conditions Survival of lesser cornstalk borer larvae in un also has been noted for carbofuran, terbufos, and· treated soil was generally good, ranging from 59 phorate (Harris & Turnbull 1977, Harris & Chap to 93% in the Alabama tests, and from 53 to 95% man 1980). in the Florida tests. Larvae are known to be can Lesser cornstalk borer damage to seedling pea nibalistic, so survival of 53 to 95 % is not. surprising. nuts is rare (Morgan et al. 1982), but it is common Survival was significantly reduced at some point during flowering, pegging, and pod production. An by chlorpyrifos applications in all of the tests, and insecticide applied for management of this insect the effectiveness of treatments varied with timing must protect the plant from flowering to late pod of application, location, and year. For example, fill (i.e., R1 to R7) to reduce yield losses. Application application at planting in 1986 and 1987 was ef at planting was not effective during this period in fective in Alabama for 42 and 102 d, and in Florida Alabama in 1986 or in Florida in 1987. Effective for 102 and 73 d, respectively. The decrease in ness of the application at planting declined when effectiveness of chlorpyrifos in Alabama in 1986 the plants were growing pods, indicating that sig-

Table 4. Mean percentage of survival of first-instar lesser cornstalk borer in Florida, 1987a Sample date (days after planting) Chlorpyrifos treatment, kg 18 May I June 19 June 2 July 15 July 30 July 18 Aug. 31 Aug. 14 Sept. 28 Sept. Planting Flower Pegging (0) (14) (32) (45) (58) (73) (92) (105) (119) (133) None None None 86.8a 73.7a 67.5a 82.5a 87.5a 72.5a 57.5b 52.5b 95.0a 2.2 None None O.Ob O.Ob 7.5b 12.5bc 40.0b 40.0b 81.2a 97.5a 75.0a 90.0ab 2.2 None 1.1 O.Ob 1O.0b 15.0b 22.5b 52.5b 5.Oc 40.0c 57.5c 70.0ab 80.0ab None 2.2 None O.Oc 5.Oc 40.0b 41.2c 55.0c 62.5ab 70.0b None None 2.2 O.OC 16.2d 22.5d 75.0a 85.0ab

a Chlorpyrifos applied as granules (15G formulation). The flowering time application occurred at beginning bloom (RI), and the pegging time applications occurred 24 d later (R2). All plots were planted on 18 May. Means in each column followed by the same letter are not Significantly different (P > 0.05, Duncan's multiple range test [SAS Institute 1985]). 1228 JOURNAL OF ECONOMIC ENTOMOLOGY Vol. 82, no. 4

(J) (J) L 250 D 1986 I- [2]1986 ::::::l :::J 400 0 rn 1987 200 0 I I 1987 4- 300 4- 0 150 0 L (J) 100 I- 200 ...0 (j) ..0 E 50 ::::::l E 100 Z :::J 0 Z June July August 0 Month June JUly August Fig. 1. Comparison of the number of hours per month Month in Alabama in 1986 and 1987 in which the hourly mean Fig. 2. Comparison of the number of hours per month soil temperature 2.5 cm below the soil surface under the in Alabama in 1986 and 1987 in which the hourly mean peanut canopy was > 35°C, as determined by a com soil moisture 2.5 em below the soil surface under the puterized environmental monitor. peanut canopy was < -10 bars, as determined by a com puterized environmental monitor. nificant pod damage could have occurred because ing; both these applications would provide ade of the decline in efficacy. Residual efficacy was quate control of the lesser cornstalk borer during probably related to environmental conditions. Ap pod-fill. plication at planting provided season-long control during normal moisture and temperature condi tions (e.g., Alabama in 1987), but not during hot, Acknowledgment dry climatic conditions (e.g., Alabama in 1986). Thus, application at planting provided sufficient We thank D. Spurgeon and L. Buckelew for collection efficacy from flowering to late pod-fill when con of field samples, and we thank Doris Paroonagian of Dow Chemical Company, Wayside, Miss., for her assistance ditions were not favorable for lesser cornstalk borer in developing the laboratory methods. This paper is Al outbreaks, but not when conditions were favorable. abama Agricultural Experiment Station Journal Series A second application during flowering or early peg No. 17-881802P. ging would be required when the hot, dry condi tions that are favorable for lesser cornstalk borer outbreaks (Mack et al. 1987) occurred. Application References Cited at both planting and pegging effectively reduced lesser cornstalk borer survival from flowering to Boote, K. J. 1982. Growth stages of the peanut (Ar late pegging in our study. However, two chlor achis hypogaea L.). Peanut Sci. 9: 35-39. pyrifos applications are not currently recommend Bromilow, R. H., R. J. Baker, M. A. H. Freeman & K. ed (French & Weeks 1988) Gorog. 1980. The degradation of aldicarb and ox amyl in soil. Pestic. Sci. 11: 371-378. Application at flowering was more effective for Dupree, M. 1965. Observations on the life history of a longer period of time than treatment at pegging the lesser cornstalk borer. J. Econ. Entomol. 58: 1156- in Florida in 1986 and in Alabama in 1987, and 1157. efficacy was equivalent to application at pegging Freed, V. H., C. T. Chiou & D. W. Schmedding. 1979. in the other two tests. Peanut plants are typically Degradation of selected organophosphate pesticides smaller at first flowering than at pegging, so gran in water and soil. J. Agric. Food Chern. 27: 706-708. ules are· not physically deflected as much by the French, J. C. & J. R. Weeks. 1988. Peanut insect plant as they are dropped. A greater concentration control, pp. 71-74. In Alabama pesticide handbook. Alabama Cooperative Extension Service Circular of granules at the base of the plants may increase ANR-500, Auburn University. effectiveness. Insecticides used for lesser cornstalk Getzin, L. W. 1985. Factors influencing the persis borer management are usually applied at pegging tence and effectiveness of chlorpyrifos in soil. J. Econ. (Le., R2-R3). Mack et aI. (1988) found Significant Entomol. 78: 412-418. yield losses from lesser cornstalk borer feeding at Harris, C. R. 1972•. Factors influencing the effective the V9 and R1 plant growth stages, so an insecticide ness of soil insecticides. Annu. Rev. Entomol. 17: 177- application before R2 could improve insecticide 198. effectiveness and protect peanuts from earlier dam Harris, C. R. & R. A. Chapman.· 1980. Insecticidal age. Smith & Holloway (1979) also reported that activity and persistence of phorate, phorate sulfoxide, larval damage to developing Spanish peanut flower and phorate sulfone in soils. Can. Entomol. 112: 641- 653. tissue and the destruction of minute flower buds Harris, C. R. & S. A. Turnbull. 1977. Laboratory concentrated in the root crown area were more , assessment of the potential of 16 experimental com significant than later damage to pods. However, pounds as soil insecticides. Can. Entomol. 109: 1109- application of chlorpyrifos at flowering or pegging 1114. would be more effective than a treatment at plant- King, D. R., J. A. Harding & B. C. Langley. 1961. August 1989 MACK ET AL.: SURVIVAL OF E. lignosellus IN TREATED SOIL 1229

Peanut insects in Texas. Texas Agricultural Experi borer Elasmopalpus lignosellus (Zeller). Georgia Ag ment Station Miscellaneous Publication 550, College ricultural Experiment Station Special Publication 17, Station. Tifton. Leuck, D. B. 1966. Biology of the lesser cornstalk Ou, L. T., D. H. Gancarz, W. B. Wheeler, P. S. C. Rao borer in south Georgia. J. Econ. Entomol. 59: 797- & J. M. Davidson. 1982. Influence of soil tem 80L perature and soil moisture on degradation and me Luginbill, P. & G. G. Ainslie. 1917. The lesser corn tabolism of carbofuran in soils. J. Environ. Qual. 2: stalk borer. USDA Entomological Bulletin 529. 293-298. Lynch, R. E. 1984. Damage and preference of lesser SAS Institute. 1985. SAS user's guide: statistics. SAS cornstalk borer (Lepidoptera: Pyralidae) larvae for Institute, Cary, N.C. peanut pods in different stages of maturity. J. Econ. Smith, J. W., Jr., & C. S. Barfield. 1982. Management Entomol. 77: 360-363. of preharvest insects, pp. 250-325. In H. H. Pattee Mack, T. P. & C. B. Backman. 1987. Density of the & C. T. Young [eds.], Peanut science and technology. lesser cornstalk borer, Elasmopalpus lignosellus (Zel APRES, Yoakum, Tex. ler), in peanut fields: endemic and outbreak popu Smith, J. W. & R. L. Holloway. 1979. Lesser cornstalk lation configurations. Peanut Sci. 14: 61-66. borer larval density and damage to peanuts. J. Econ. Mack, T. P., J. W. Smith, Jr., & R. B. Reed. 1987. Entomol. 72: 535-537. A mathematical model of the population dynamics Suber, E. F., D. C. Sheppard & W. A. Gardner. 1982. of the lesser cornstalk borer, Elasmopalpus lignosel Summary of economic losses due to insect damage· Ius (Lepidoptera: Pyralidae). Ecol. Modell. 39: 269- and costs of control in Georgia, 1980. Georgia Agri 286. cultural Experiment Station Special Publication 20, Mack, T. P., C. B. Backman & J. W. Drane. 1988. Tifton. Effects of lesser cornstalk borer (Lepidoptera: Pyrali Whitney, W. K. 1967. Laboratory tests with dursban dae) feeding at selected plant growth stages on peanut and other insecticides in soil. J. Econ. Entomol. 60: growth and yield. J. Econ. Entomol. 81: 1478-1485. 68-74. Morgan, L. W., M. H. Bass & H. Womack. 1982. Lesser cornstalk borer as a pest of peanuts, pp. 56- Received for publication 25 August 1988; accepted 9 64. In A review of information on the lesser cornstalk December 1988.