A SURVEY OF EARLY-SEASON HOST PLANTS AND PARASITES OF HELlOTHIS SPP. I IN ARIZONA 2

Robin J. Rathman and T. F. Watson Department. of Entomology

College of Agriculture University of Arizona

Tucson, AZ 85721

Abstract: Surveys wcre conducted in 1979 8nd1980 to determine the species of wild and cultivated plants utilized llS hosts by the tobacco budworm, Heliothis uiresc('r1s (Fabricius), and the cotton bollworm. /-lelia/his zen (Boddie), in cenlral Arizona before colton begins squaring.

During April and May in 1979 Heliothis spp. wcrc abundant on redstcm filarce. Erodium cicularium (Linnaeus), a common desert annunL Yellow bird-of· paradise. Cat'snlpitmia giUiesi; Wall.. and garbanzo bean. Cicf!r arielinum Linnacus. were primlll)' spring hosts in 1980. An obscllre species, Heliothis plllnxiplmga (Grote ond Robinson), was collected on daisy l1eabane. E.'rr'ldervll diucrgcns Torr. und Grlly, in 1979 und on K ciClitariwn in 1979 lind [980.

Sevcll species of hymenopterous parasites IRo,l,'as PCI1)I(!xu.~ Gahnl\, C{/l'(liflchile.~ semini1!CI' (Cresson), Campo!etis MJlIO!'In~i,~ (Cameron). n'b;loll1cnl,~ spill (ItOI' (Fabricius). HYIIt!.~nter exif{ua(!

(Viereck). Microplil,:<; cmccipcs (Cresson) and Spi/ochrtlcis sp.1 were reared from Jleliflth':~ spp. in 1979 and 1980, FoUl' species of Diplera Il.cspcs;o arr!JipfJivora <Riley). HlIce!atoria J"p"

Chaelogacdia sp. and Areilyta... marmoratus (Townsendll emerged from collected larvae.

Key Words: Heliothis "pp., host plants, parasites.

J, Agric, l~ntomoL 2(4): 388-394 (October 1985)

In Arizona, the tobacco budworm, J-Ieliolhis uirescells (Fabricius), rirst became a major pest of cotton in 1972 (Watson 1974). The subsequent det.ermination of methyl parat.hion resistance in this insect (Crowder et a1. 1979) and the potential for developing resistance to synthetic pyrethl'oids made it critical to implement new management strategies. Additional data were needed on factors influencing populat.ion dynamics of /-I. uirescens and relat.ed species.

Lincoln (l972) noted t.hat seasonal abundance of f1e1iolhis zell (Boddie) (bollworm) and tobacco budworm (TBW) is strongly influenced by the sequent.ial availability of favorable host plants. A continuous series of cultivated and non­cultivated plants sUI>ports these species during their active period (Snow and Brazzel 1965)_ The objective of this research was to survey spring host I}!ants, especially ornamentals and desert annuals, for I-Iefiolhis spp. in central Alizona.

MATERIALS AND METHODS

Surveys for early-season host plant.s of I-Idiothi... spp. were made from Pebruary unt.il June in 1979 and 1980 in Pinal County. Arizona. Major crops grown in this area include sugarbeet, alfalfa and lettuce in the winter. and alfalfa, coiton and corn in the summer.

LEPIDQIYfERA: ~octuidne

'2 Collc~e of Agricuhure. Ariz. A}::ric. EXI). Sta. ,Journal SericJ" :'-lo, :l9:l8, Received for publication Ii August 1984: acceplCd :Ul .11I1IUIU)' 191Ui.

"88

BATHMA:-J nnd WATSON: Host Plants and Pnrllsitc!\ of J-Ir/iOl!Jis spp. 389

Hdiolhis spp. larvul populations developing on uniform stands of spring host plant.s were sampled with a 38.1 em sweep net. With plant speciel:i not growing in dense stands, visual examinations of ent.ire plants were made to locate eggs and larvae. After Heliathis spp. were found associated with a particular plant species in a given 'area, weekly and biweekly samples were taken until plants reached senescence or unt il no eggs and larvae were found. Sites where f-Ie/iot.his spp. were found in J979 were resampled in 1980. The number of sweep samples and number of plants examined to establish population levels varied among collection dates and locations because of manpower. host availability and infestation levels. These conslraints limited this study to a host survey. and statistical analyses were not conducted.

Collected material was taken to the laboratory on the University of Arizona campus in Tucson for sorling. /-Idiolhis spp. were separated from other genera and placed individually in 30 ml, clear plastic cups approximately two-thirds full of modified lima bean-agar diet (Patana 1969). I~ggs and larvae were reared in the laboratory at 25°C under ambient daylength for identification and parasite emergence.

Bollworm and TBW larvae were separated, under magnification, by the characters listed by Boyer et al. (1977) and Brllzze) et al. (1953). Heliolhis ph/oxipll(lga (Grole and Robinson) were distinguished from 1-1. zea by larval descriptions (Hardwick 1965) and by adult emergence. TBW and bollworm eggs were distinguished by the structure of the micropyle (Phillips 1978).

Between 13 l\:lay and 20 May 1980, unit area samples were tuken of f-Ieliothis spp. larvul populations developing on redstem fLiaree, Erodium cicutariwn (Linnaeus). A 0.5-m 2 circular area was marked within a uniform stand of plants; vegetation was clipped at ground level, placed in plastic bags and returned to the laboratory. Samples were checked carefully for Heliolhis spp. eggs and larvae. Scattered host availability and low infestation levels in 1980 limited the usefulness of this technique. Sweep net samples allowed coverage of a more extensive area/unit time.

RESULTS

Field Samples - /979 and 1980 A summary of field collections from 1979 and 1980 is presented in Table J. In

mid-April, 1979, Neliolhis spp. populations on Coulter's glohemallow, Sphaeralcea coulterj (Watson) reached a peak of 17 bollworms and 3 TBW larvae in 400-sweep samples. Spring He/jothis spp. populations on E. cicutarium reached a level of 26 TBW. 8 J-I. phloxiphaga and 3 bollworm larvae/400 sweeps before declining in early June. Daisy neabane, Erigeron divergens Torr. and Gray. was also infested with He/iothis spp. during this same sampling period. On 15 May 1979, on this host, IOO-sweep samples netled 132 H. phloxip/wga larvae and L TBW larva. _ umbers decreased considerably afler this date.

[n the spring of 1980, f-Ie!iol!lis spp. larvae were found feee/ing OIl cultivated garbanzo bean, Cicer arietillum Linnaeus. at two localions near Eloy. On 22 May, 20 bean plants were visually examined, and 86 TBW larvae collected. Numbers declined after this date, Abundance of E. cicutariwn was limited in 1980 to canal and irrigation ditch banks. Sample densities were highest in late May; in 100 sweep-net samples 8 H. ph/oxiphaga. 8 TB\V and 2 bollwonn Iwvae were coUected Populations on yellow bird-of-paradise, Caesalpirlllia gillies;i Wall., an introduced ornamental, peaked in mid-June; ca. 30 plants were examined for fleliolhis spp., and 85 TBW larvae collected.

390 J. Agric. Enlomol. Vol. 2, )lo. 4 (1985)

Table 1. Relative abundance of Heliothis sPI>. larvae on different spring host plants in Pinal County, Arizona.

Collection % of total Host plant. period Number collected

H. viresccns collected 1.97.9

S. coulteri 4/16·4/21 5 3.4 C. arvensis 5/1 1 0.7 E. cicutarium 5/12 - 6/12 135 93.8 E. diverge"s 5/12 - 5/22 3 2.1

1.980 E. cicutarium 5/10 - 6/5 L3 3.2 C. ariet.inwn 5/10·5/29 209 50.8 C. giUiesi; 5/27 - 6/26 171 41.6 P. parviflora 6/18-6/26 18 4.4

H. zen collected 1.97.9

S. coulteri 4/16 - 5/1 31 59.6 C. arvensis 5/1 5 9.6 E. cicutarium 5/12 - 6/1 7 13.5 C. tin.cturius 5/12 4 7.7 L. sativa 4/12-511 4 7.7 M. sativa 5/3 1 1.9

1980 E. cicut.arium 5/10 - 5/27 8 34.8 C. arietilHl m. tl/l5·5/13 15 65.2

H phloxiphaga collected /97.9

E. ciclIlarilirTI 5/12 - 6/12 65 11.1 E. divercens 5/12 - 6/21 52l 88.9

1980 E. cicutarium. 5/10·6/5 26 100.0

Parasitism The percentage of parasit.ism for Heliothis spp. on sampled host plants is

shown in Table 2. The most significant information provided is a comparison between levels of parasitism on different host plants utilized by Heliothis spp. Table 3 lists parasite/host. plant!Heli(J(his spp. associations. Parasites common to TBW and fI. phJoxiphaga larvae on redstem filaree included t.he following species: Campoleli....· sunorensis (Cameron). Pristomellls sp,iwtor (Fabricius), Hyposoler exigllae (Viereck), Lespesia archippivfJra (Riley) and !\4ic:ropJitis croceipes (Cresson).

RATHMAN and WATSON: Host Plants and Parnsi1.Cs of Nf'liothis spp. 39]

Table 2. Relative parasitization of lhree Heliothis spp. on different host plants in cenlral Arizona in 1979 and 1980.

Plant species Sample period H. zea

Percent parasitization· H. uiresccns H. phloxiphaga

1979 Erodium cieutarium Sphaeraleea coulteri Lactuea satiua ;{1edicago sativa Erigeron divergens

5/12 - 6/12 ·1/24 - 5/1 4/12 - 4/19 5/3 5/] 2 - 6/21

0.0 (6) 5.0 (20) 0.0 (4) 0.0 (I) 0.0 (0)

55.0 (100) 0.0 (3) 0.0 (0) 0.0 (0)

66.; (3)

34.9 (43) 0.0 (0) 0.0 (0) 0.0 (0)

23.4 (32)

1980 Cicer arietinum 4/15 - 5/27 26.7 (15) 16.8 (167) 0.0 (0) Erndium cieutarium 51l0· 6/5 25.0 (8) 63.6 (I I) 31.2 (16) Proboscidea paruiflora 6/18 - 6/26 0.0 (0) 16.; (18) 0.0 (0) Caeso{pirlllia gilliesii 5/2; - 6/26 0.0 (0) 0.; (133) 0.0 (0) • :"J\lmb~r of lor"'"!! obsclV~d in l) only includes I/ln:ae thlll died from pornsilizlltion.

Miscellaneous Plants Sampled Low numbers of He!iothis spp. were found on lettuce, Lactw.:a sativa Linnaeus,

alfalfa, M(~dicago sativa Linnaeus, field bindweed, Convolvulus sp., pignut, /-loffmonseggia densiflom Bent.h., and devils-claw, Proboscidea parviflora (\oVooL).

The following plants were sampled routinely, i.e., more than three dates at three or mOl'e locations, with whjch no Heliothis spp. larvae were found associatcd: London rocket, Sisymb,.iuTIl irio Linnaeus, little mallow, l\1alrHI parvi{lora Lillnacus, lupine, Lupirws sp., tll1nufLl yello\v sweet-clover, Melilo/,Ils indieLis Linnaeus, desert senna, Ca.'isi(l couesii Gray, slimleaf bursage, Ambrusia conferti{lorfl DC., smallflower guara, Guara pa/'ui{lora Doug!., tree tobacco, Nico/iana g/ow:.a Graham and pecan, C(l})'O illilloe/lsis (Wang).

DISCUSSION

Seasonal activity of I-/efjothis spp. extends over a longer period than does the growing senson of any single species of host plan1. Host planls identified in this survey provide a food source for Heliothis spp. larvae at a lime when collon is unavailable. since squ<lring begins ca. 2 months after spring moth emergence (poneI' and Wat'ion 1980). Jolmson et al. (1975) sUldied the ovipositional response of bollworm lO vurious phenological states of corn, tohacco and soybeans. Flowering slages of all the crops were the p,·eferred phenological sr<lle for oviposition. Extensive studies have <llso been conducted on the ovipositional preferencc of Hdiothi.<: armiJ-tera Hubner. Parsons (1940) detcrmined that Qviposilion \...·as confined to the period of innorescence in 23 species of short-flowering crops. Flowering peaks of major hosts plarlls ident.ified in the sun'cy al'e presented in Fig. I. Estimated dates llrc for desert areas near Tucson, and arc based on 13 yr of observation by McGinnies (1980).

Early season larvae may serve as hosts for the buildul} of p<.lrtlsites which attack Inter generations of He!iothi.<; spp. on summer crops (Tnble :~). /:.'rigeron divergells, an incidental host of H. virl!scens. WllS important in supporting large

392 J. Agl'ic. Entomol. Vol. 2, No. " (1985)

Table 3, Species of parasit.es found on Heliothis spp. in central Arizona during the spring of 1979 and 1980.

Parasite Helio/.his spp. I-lost plant

Dipt-era: Tachinidae

Lespesia archippiuora uirescens, p/lloxiphaga redstem film'ee, daisy neabane, devils-claw

Euc:elaloria sp. phloxiphaga daisy fleabane Chaelogaedia sp, phloxiphagn daisy fleabane Archy/.as marmoralus phlo:riphago daisy fleabane

Hymenoptera: Braconidae

Micf'Oplilis croceipes uirescens, phloxiphaga l'edstem filaree, daisy fleabane

Roj.!os pc/plexus uirescens, zea rcdst.em filaree, Coulter's globemallow

Cardiochiles seminiger p/l!oxljJhaga redstem filaree daisy fleabane

Ichneumonidae: Campoletis sonorensis mrescens, zca redstem filaree,

phloxiphaga daisy fleabane, bird~of-paradise,

devils-claw, garbanzo bean

Hyposoler exiguae ~'irescens, ph/oxiphaga redstem filaree, zea daisy fleabane,

devils-claw, garbanzo bean

Pl'islomerus spina/.o!· virescens,ph!oxiphaga redstem filaree, daisy fleabane

Chalcididae: Spilochalcis sp. L'lreSCens redstem filaree

numbers of N. phloxiphaga larvae; fro1l1 these larvae emerge many parasites common to both bollworm and TBW. /-le!inthis phluxiphaga has never been recorded as a cotton pest; however, it. was reported to attack tomatoes in California (Lange and Michelbacher ] 937),

The true measure of the importance of a host plant in the dynamics of an insect. population is not the number of larvae infest.ing the host, but the number of adults produced per unit area of the host and the abundance of the host plant in the agroecosystem (Stadelbacher 1979). This study can be justly criticized for not quantifying: host plant abundance and emerging moth densities.

Survey data indicate that abundance of Heliothis spp. on desert annuals is difficult to measure accurately as hosts arc widely scattered and attractive to oviposiling moths for relatively short time periods. Populations on wild hosts also seem 1.0 be extremely variable from year to year as is shown by comparison of

Gicer arietinum

Erodium cicutarium

I

Gaesalpinnia gilliesii1----.....;....---.;;---1

Sphaeralcea coulteri

Gossypium hirsutum

» 1 10 20

MARCH

30 •

10 20

APRIL

» 30

• 10

• 20

MAY

30 10 20

JUNE

• 30 10 20

JULY

30 •

10 20 30

AUGUST

Fig. 1. Seasonal sequence of plants found to be important hosts of Heliothis spp.

394 J. Agric. Entomol. Vol. 2. :"Jo. 4 (1985)

1979 and 1980 field collections (Table I). Cage studies are needed to calculate numbers of moths emerging from identified host plants.

Ornamentals and cultivated crops are morc predictable food resources than desert annuals, whose abundance is dependent upon adequate winter rainfall. [11

addition, percent parasitism was found to be lower for Helinthis spp. collected from C. arielinum and C. gilliesi; than from any of the desert annuals ('rable 2). Cultivated plants and ornamentals may provide a large percentage of the adult population of Heliothis spp. that migrate to COlton and create initial infestations. If Heliothis spp. populations increase on yellow bird-oC-paradise and garbanzo bean, as suspected, a control program involving the use of these plants as trap crops with subsequent chemical control might be successful in reducing a significant percentage of the F 1 and P2 generations on cotlOn.

ACK:"OWL8DGM8NTS

We wish t.o thank Dr. Floyd G. Werner, Depnrtmellt of Ent.omology, University of Arizona. for ident.ifying Ihe parasites obtnined in this study, and Dr. Churle!; Mm;on, Universit.y of Arizona Herhariulll, for identification of plnnt specimens.

R8F8REi\CES CITED

Boyer, W. P., J. G. Burleigh, and M. L. Wall. 1977. Larval characLers for sel>afflting bollworm and tobacco budworm, Ann. Entomol. Soc. Am. 70: 5·6.

Brazzel, J. R., L. D. Newsom, J. S. Roussel, C. Lincoln, F. J. Williams, and G. Barnes. 1953. Bollworm and tobacco budworm as coLlon pests in Louisiana and Arkansas. La. Agr. Exp. Sta. Bull. 482: 47 pp.

Crowder. L. A., M. S. Tollefson. and T. r. Watson. 1979. Dosage-mortality studies of synthetic pyrethroids nnd methyl pnrathion on Lhe tobacco budworrn in centl'nl Arizona. ,1. Econ. Entomol. 72: 1-3.

Hardwick, D. F. 1965. The com earwonn complex. Mem. EntmnoL Soc. Can. 40: 247 pp. ,Johnson, M. W., R. E. Stinner. and R. L. Hnbb. 197fl. Ovipositional response of J-1e/jolhis zea

to its major hosts in :-.lortb Carolinn. Environ. Entomol. ,I: 294·297. Lange. W. H.. and A. E. Michelbacher. 1937. Two closely related species of Nelinthis found

in tomato fields of cent rnl California. Cnlif. Dcp. Agr. Bull. 26: 320·325. Lincoln, C. 1972. Seasonal abundance, Pi>. 2·7. III Distribution. Abundance and Control of

Hcliothis spp. in CottOll and Other Host Plllnl~'i. So. Coop. SCI'. Bull. No. 169, 92 PI>. McGinnies, W. G. 1980. lative desert plnnt nowering seasons, Tucson vicinity. Office of

Arid Land Studies. Cniv. Arizona, Tucson. April. 1980. Parsons, r. W. 1940. Investigations on the cotton bollworm, Heliotllis lIrmigem. III.

Relationships between oviposition and nowering curves of food plants. Bull. EnLomol. Res. 31: 1'li-li'7.

Patana, R. 1969. Hearing cOlion insecL~ in the lahoratory, USDA-ARS Prod. Hes. Rpl. No. 108: 6 pp.

Phillips, ,1. 1978. Current reseal'ch is aimed nt speeding up identifying n hollworm/t.obacco bud worm infestation. Ag. Fieldman and ConsultlLllt. Vol. 3,1, No.3. p. 1'1.

Palter. 1'11., lind T. F. Wnlson. 1980. Terminat.ion of dill pause in the tobacco bud\vorm in Arizonn. J. Econ. Entollloi. 73: 847·850.

Snow. J. \V., and ,I. R. Bflli'.zel. 1965. Seasonal host aCLivity of the bollworm lind tobacco budwonn during 1963 in northeast r"'lississippi. r..,liss. J\gr. Exp. Sla. BulL 712: 2,1 pp.

Stadelhacher, E. A. 1979. Gt!rn"ium dissectum: An unreported host of the tobacco budworm and bollworm and its role in their seasonal and long-term population dynamics in the Delta of Mississippi. gll\'iron. Entomol. 8: 1153-1156.

\\'atson. T. F. 1974. Tobacco budworm and bollworm control in weslern cotlon. Proc. West. Cotton Prod. Conf. (Phoenix, :\Z). 38 pp.