Hosts of Plum Curculio, Conotrachelus Nenuphar (Coleoptera: Curculionidae), in Central Georgia

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COMMUNITY AND ECOSYSTEM ECOLOGY Hosts of Plum Curculio, Conotrachelus nenuphar (Coleoptera: Curculionidae), in Central Georgia

1 2 3 3 DAVID JENKINS, TED COTTRELL, DAN HORTON, AMANDA HODGES, AND GREG HODGES

USDAÐARS, Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008

Environ. Entomol. 35(1): 48Ð55 (2006) ABSTRACT Potential host plants for the larvae of plum curculio, Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae), in central GeorgiaÕs peach producing region were surveyed. This fruit-attacking curculionid is reported to have a broad host range, including many plants in the Rosaceae and other families. However, our collections indicated that in this region plum curculio largely is limited to peach (Prunus persica) and plum (P. angustifolia and P. umbellata). Abandoned peach orchards and wild plum thickets are important hosts for the spring generation of plum curculio and are sources of subsequent infestations of managed peach orchards. However, only abandoned peach orchards were available to the summer generation of plum curculio. May haw, Crataegus aestivalis, was also a host, but other species of Crataegus were not used. Although the plum curculio was reported to be a signiÞcant pest of blueberries (Vaccinium spp.) in North Carolina, New Jersey, and Delaware, they were only rarely used as a host in central Georgia. Apple (Malus domestica) and Asian pear (Pyrus pyrifolia), when available, were ovipositional hosts of plum curculio in central Georgia; however, no larvae emerged from these hosts. We report the Þrst records of plum curculio developing in Vaccinium stamineum and Vitis rotundifolia. Our results are compared with a previous survey conducted in the northeastern United States, as well as to data reported in the literature.

KEY WORDS Prunus umbellata, Prunus angustifolia, Vaccinium stamineum, Vitis rotundifolia, peaches

THE PLUM CURCULIO, Conotrachelus nenuphar (Herbst) Ericaceae (Stearns 1931, Mampe and Neunzig 1967, (Coleoptera: Curculionidae), is the most important Polavarapu et al. 2004). Prunus angustifolia Marshall insect pest of peaches in the southeastern United (Chickasaw plum), a thicket-forming species that oc- States (Horton and Ellis 1989). Current calendar- curs frequently on Þeld or woodline edges, is the based pest management options in peach orchards predominant native plum species in central Georgia suppress this pest to subeconomic levels of abun- and is believed to be the primary host for the over- dance; however, regulatory decisions have restricted wintering generation of plum curculio. Quaintance the availability or even eliminated the use of organo- and Jenne (1912) and Maier (1990) reported an array phosphate insecticides that have been the standard of host plant species for plum curculio including apple peach insecticides since the 1950s. These changes (Malus domestica Borkh.), pear (Pyrus communis L.), have prompted reexamination of plum curculioÕs bi- quince (Cydonia oblonga L.), plum (Prunus americana ology, seasonal history, and behavior to develop cost Marshall), peach (Prunus persica L.), nectarine effective and treat-as-needed management options for (Prunus persica variety nectarina L.), and apricot this pest. The ability of bivoltine plum curculio in the (Prunus armeniaca L.). In addition to these hosts, southeastern United States to survive on alternative Wylie (1966) reported the development of plum cur- hosts outside of the peach agrisystem should be a key culio in two nonfruit hosts, plum pockets and plum leaf consideration in any effort to develop less pesticide- curl, both diseases caused by the ascomycete fungus intensive management options. Taphrina communis (Sadeb.) (Taphrinales). Quain- Throughout its habitat, plum curculio uses a broad tance and Jenne (1912) also mentioned that plum range of hosts, including plants in the Rosaceae curculio oviposits in sparkleberry (Vaccinium ar- (Quaintance and Jenne 1912, Maier 1990) and in the boreum Marshall), grape (Vitis spp.), strawberry (Fra- garia spp.), gooseberry, currant (Ribes spp.), black 1 Corresponding author: USDAÐARS, Tropical Agriculture Re- knot fungus, and persimmon (Diospyros virginica L.), search Station, 2200 Pedro Albizu Campos Ave., Suite 201, Mayaguez, but its ability to develop in these hosts is uncertain Puerto Rico 00680Ð5470 (e-mail: [email protected]). because plum curculio will frequently oviposit in un- 2 University of Georgia, Athens, GA 30602. 3 Entomology and Nematology Department IFAS, Gainesville, FL suitable hosts. Hallman and Gould (2004) exposed 22 32611. fruits from 16 families to females of the plum curculio February 2006 JENKINS ET AL.: PLUM CURCULIO HOSTS 49

Table 1. Fruit collected in middle Georgia in 2002, 2003, and chards, public forests/recreational areas, and on the 2004 grounds of the Southeastern Fruit and Tree Nut Lab- oratory in Byron, GA. From March through Septem- Fruit family and species Common name ber in 2002Ð2004, fruits of these plants were collected Rosaceae weekly when available. During the survey, new host Prunus persica L. Peach P. angustifolia Marshall Chickasaw plum plants and sites were added as they were encountered, P. umbellata Elliot Hog plum whereas some were lost to land use (e.g., road wid- Prunus caroliniana Aiton Laurel cherry ening projects) or discarded because of poor fruit Crataegus aestivalis (Walter) May haw production. Depending on the availability of fruit, Crataegus sp. Hawthorns Malus angustifolia (Aiton) Crab-apple between 20 and 150 fruits were randomly selected M. domestica Borkhausen Apple directly from plants and from the ground when Pyrus calleriana Decaisne Bradford pear dropped fruit were available (many fruit abscise when P. pyrifolia (Burman f.) Asian pear infested with plum curculio; Quaintance and Jenne Amelanchier arborea (Michaux f.) Serviceberry Rosa carolina L. Wild rose 1912, Levine and Hall 1977). These fruit were col- Ericaceae lected randomly from each tree if Ͻ10 trees were Vaccinium stamineum L. Deerberry present (most plum thickets) and from at least 10 trees V. corymbosum L. Highbush blueberry in the case of abandoned peach orchards. Fruit were V. elliottii Chapman ElliottÕs blueberry V. arboreum Marshall Sparkleberry examined for the presence of characteristic plum cur- Vitaceae culio oviposition scars (Quaintance and Jenne 1912), Vitis rotundifolia Michaux Muscadine and placed on a wire mesh (3-mm openings) over a Ampelopsis arborea L. Pepper-vine plastic container. The pubescence of peach, P. persica, especially on small, early season fruit, made identiÞ- cation of oviposition scars difÞcult; thus, oviposition in Florida and, although the adults caused feeding scars were not enumerated on this species. Also, the damage to the majority of the fruits, they only ovi- varying stages of decay of dropped fruit did not allow posited in members of the Rosaceae, including apple, us to accurately identify oviposition scars on these M. domestica Borkhausen, peach, P. persica L., plum, fruits. Because it was common to Þnd plum fruits with P. domestica L., and loquat, Eriobotrya japonica Lindl. multiple oviposition scars, in 2004 we recorded the Although their study was not deÞnitive, it showed the number of scars per fruit each week. Feeding damage oligophagous nature of the plum curculio. by adult plum curculio was not reliably identiÞable, so Appreciation for the potential impact of wild host it was not evaluated. The plastic containers were plants on peach pests is not new. Wild plum species, stored in an environmental chamber with a photo- primarily Prunus angustifolia and P. umbellata Elliot, period of 16:8 (L:D) at 25 Ϯ 1ЊC. The containers were have long been regarded as likely host reservoirs for monitored daily for 60 d after fruit collection for the plum curculio, leafhopper species that transmit phony appearance of C. nenuphar larvae, which were placed peach disease (Xylella fastidiosa) (McClure 1980), into a moistened mixture of potting soil and vermic- and brown rot (Monolinia fructicola). In the 1950s, ulite (2:1) in a 950-ml glass jar covered with a glass eradication of wild plum was aggressively pursued to petri dish. Each jar was monitored daily for the emer- reduce insect and disease pressure in cultivated or- gence of adult C. nenuphar. Voucher specimens from chards (D.H., unpublished data). 2002 were placed in the Florida State Collection of The purpose of this study was to survey the prev- Arthropods (FSCA) museum in Gainesville, FL. alence (percent of fruits infested) of plum curculio in Voucher specimens from 2003 and 2004 were retained fruits of various plant species that were fruiting in at the USDA-ARS, SE Fruit and Nut Laboratory in central Georgia at key times during this pestÕs life Byron, GA. cycle, namely when adults of the bivoltine southern To monitor seasonal ßuctuations of C. nenuphar strain of plum curculio emerge from overwintering abundance in 2002, 30 circle traps, 30 TeddersÕ traps, sites in the spring and when the progeny of this spring and 30 cone emergence traps (Tedders and Wood generation emerge from the soil in the summer. We 1994, Mulder et al. 2000, Bloem et al. 2002) were set up assessed ovipositional injury and successful emer- in one abandoned peach orchard and nine plum gence of adults from fruit. We compare our results thickets to capture adults (three of each type of trap with those of a similar study done in the northeastern per site). Circle traps were placed on random trees in United States (Maier 1990). the thicket or orchard, TeddersÕ traps were placed around the thicket, and cone emergence traps were placed randomly on the ground within the thicket Materials and Methods (thickets were closely clumped so cone emergence In 2002, potential hosts plants (any fruiting plants traps were adjacent to tree trunks). In the peach encountered during the survey) were selected at sites orchard, TeddersÕ traps were placed between ran- in Peach, Houston, Taylor, Crawford, and Macon domly selected rows at the border of the orchard, and Counties in central Georgia (Tables 1 and 2). The the cone emergence traps were placed at the base of main criteria for selecting sites was access, so sites three randomly selected trees. These traps were were largely limited to roadsides, abandoned peach checked weekly. The use of these traps was discon- orchards, woods, and Þelds adjacent to peach or- tinued in 2003 and 2004 because of mounting concerns 50 ENVIRONMENTAL ENTOMOLOGY Vol. 35, no. 1

Table 2. Sites where fruit was collected by year

County GPS coordinates Years surveyed Fruit collected Land use descriptor Crawford N 32Њ32.522Ј;W83Њ32.401Ј 2003, 2004 Vaccinium stamineum, Woodland V. arboreum, Ampelopsis arborea, and Crataegus sp. Crawford N 32Њ32.518Ј;W84Њ0.771Ј 2003, 2004 Vitis rotundifolia, Woodland Crawford N 32Њ35.262Ј;W83Њ57.674Ј 2004 Prunus angustifolia Woodland Crawford N 32Њ35.452Ј;W83Њ59.395Ј 2004 Prunus angustifolia Open Þeld Crawford N 32Њ32.991Ј;W83Њ59.441Ј 2004 Vaccinium arboreum Roadside Crawford N 32Њ35.452Ј;W83Њ59.395Ј 2004 Prunus umbellata Woodland Crawford N 32Њ34.613Ј;W83Њ58.548Ј 2004 Prunus angustifolia and Woodland P. umbellata Crawford N 32Њ34.349Ј;W83Њ58.107Ј 2004 Prunus angustifolia Woodland Crawford N 32Њ40.656Ј;W84Њ00.287Ј 2004 Prunus angustifolia Roadside Crawford N 32Њ26.451Ј;W83Њ57.407Ј 2004 Prunus angustifolia Roadside Crawford N 32Њ35.347Ј;W83Њ59.412Ј 2004 Crataegus sp. Woodland Crawford N 32Њ34.825Ј;W83Њ57.014Ј 2004 Prunus angustifolia Roadside Houston N 32Њ32.631Ј;W83Њ34.28Ј 2003 Prunus angustifolia Roadside Houston N 32Њ36.827Ј;W83Њ43.033Ј 2003, 2004 Vaccinium stamineum Woodland and Prunus persica Houston N 32Њ31.567Ј;W83Њ33.581Ј 2003, 2004 Prunus angustifolia Roadside Houston N 32Њ29.754Ј;W83Њ33.348Ј 2003 Crataegus sp. Woodland Houston N 32Њ30.010Ј;W83Њ33.386Ј 2004 Prunus angustifolia Woodland Houston N 32Њ32.594Ј;W83Њ26.429Ј 2003 Prunus angustifolia Roadside Houston N 32Њ30.010Ј;W83Њ33.386Ј 2004 Crataegus sp. Scrub Macon N 32Њ28.718Ј;W83Њ59.265Ј 2003, 2004 Vaccinium stamineum, Dry woodland V. arboreum, and Crataegus sp. Macon N 32Њ30.190Ј;W83Њ51.885Ј 2004 Prunus angustifolia Roadside Macon N 32Њ28.376Ј;W83Њ02.768Ј 2004 Prunus angustifolia Roadside Macon N 32Њ28.350Ј;W83Њ52.273Ј 2004 Prunus angustifolia Roadside County GPS Coordinates Years Surveyed Fruit collected Land use descriptor Macon N 32Њ26.221Ј;W83Њ51.547Ј 2002, 2003, 2004 Prunus angustifolia and Woodlands adjacent to peach orchard Prunus umbellata Peach N 32Њ31.626Ј;W83Њ51.993Ј 2002, 2003, 2004 Prunus angustifolia Open Þeld Peach N 32Њ37.503Ј;W83Њ47.145Ј 2002, 2003, 2004 Prunus angustifolia Roadside Peach N 32Њ36.352Ј;W83Њ47.734Ј 2004 Prunus umbellata Roadside Peach N 32Њ35.495Ј;W83Њ49.827Ј 2004 Prunus angustifolia Adjacent to cotton Þeld Peach N 32Њ35.408Ј;W83Њ50.063Ј 2004 Crataegus sp. Roadside Peach N 32Њ32.202Ј;W83Њ48.525Ј 2002, 2003, 2004 Prunus angustifolia and Woodlands adjacent to peach orchard Prunus umbellata Peach N 32Њ32.002Ј;W83Њ47.957Ј 2003 Vitis rotundifolia Woodlands adjacent to peach orchard Peach N 32Њ32.242Ј;W83Њ48.237Ј 2003 Crataegus sp. Woodlands adjacent to peach orchard County GPS Coordinates Years Surveyed Fruit collected Land use descriptor Peach N 32Њ34.984Ј;W83Њ48.851Ј 2002, 2003, 2004 Prunus angustifolia and Woodland adjacent to railroad P. caroliniana Peach N 32Њ35.462Ј;W83Њ48.736Ј 2002, 2003, 2004 Prunus angustifolia Woodlands adjacent to peach orchard Peach N 32Њ34.022Ј;W83Њ48.982Ј 2004 Prunus persica Abandoned orchard Peach N 32Њ34.155Ј;W83Њ54.237Ј 2004 Prunus angustifolia Open Þeld Peach N 32Њ33.492Ј;W83Њ54.930Ј 2004 Prunus angustifolia Roadside Peach N 32Њ39.227Ј;W83Њ44.270Ј 2002 Crataegus uniﬂora Woodland Peach N 32Њ39.123Ј;W83Њ43.750Ј 2002 Amelanchier arborea Woodland Peach N 32Њ39.531Ј;W83Њ44.354Ј 2004 Vaccinium corymbosum Open Þeld Peach N 32Њ39.183Ј;W83Њ44.020Ј 2004 Prunus persica Abandoned orchard Peach N 32Њ39.426Ј;W83Њ44.023Ј 2004 Vaccinium arboreum Woodland Peach N 32Њ39.747Ј;W83Њ44.023Ј 2004 Vaccinium elliottii Woodland Peach N 32Њ39.152Ј;W83Њ44.481Ј 2004 Malus domestica Open Þeld Peach N 32Њ39.674Ј;W83Њ43.690Ј 2004 Pyrus pyrifolia Orchard Peach N 32Њ39.844Ј;W83Њ43.701Ј 2002, 2003, 2004 Vitis rotundifolia Woodland Peach N 32Њ39.993Ј;W83Њ43.344Ј 2002, 2003, 2004 Prunus angustifolia and Woodland Vaccinium corymbosum Peach N 32Њ39.224Ј;W83Њ42.630Ј 2002, 2003, 2004 Rosa carolina Woodland Peach N 32Њ39.793Ј;W83Њ43.682Ј 2002, 2004 Crataegus aestivalis Orchard Peach N 32Њ40.081Ј;W83Њ43.438Ј 2003, 2004 Malus angustifolia Open Þeld Peach N 32Њ39.222Ј;W83Њ44.032Ј 2003, 2004 Pyrus calleriana Open Þeld Peach N 32Њ39.231Ј;W83Њ44.384Ј 2003, 2004 Ampelopsis arborea Woodland Taylor N 32Њ29.371Ј;W84Њ05.753Ј 2004 Prunus angustifolia Open Þeld Taylor N 32Њ30.994Ј;W84Њ30.091Ј 2004 Prunus angustifolia Roadside that these traps varied in success over the season generation using these traps. To monitor seasonal (Prokopy and Wright 1997, Vincent et al. 1999); dur- abundance of C. nenuphar in 2003 and 2004, all trees ing the 2002 survey, we did not detect the summer (141) in an abandoned peach orchard on the premises February 2006 JENKINS ET AL.: PLUM CURCULIO HOSTS 51

Table 3. Hosts of plum curculio in central Georgia

2002 2003 2004 Totals Percent Percent Percent Percent of fruit of fruit of fruit Percent with Host species No. fruit No. fruit No. fruit No. fruit yielding yielding yielding yielding oviposition collected collected collected collected adult adult plum adult plum adult plum scars weevils curculio curculio curculio Prunus persica 1,287 28.9 1,287 NA 28.9 P. angustifolia 155 20 379 24.8 5358 13.8 5,892 36.4 14.7 P. umbellata 697 0.6 835 6.8 1,532 16.2 4.8 P. caroliniana 724 0 724 0 0 Crataegus uniﬂora 43 0 43 0.4 0 C. sp. 66 0 288 0 354 3.1 0 C. aestivalis 100 7 358 1.4 458 9.1 2.6 Malus domestica 185 0 185 11.4 0 M. angustifolia 50 0 104 0 879 0 1,033 0 0 Pyrus calleriana 131 0 131 0 0 P. pyrifolia 456 0 456 5.7 0 Amelanchier arborea 657 0 657 0 0 Rosa carolina 834 0 834 0 0 Mummy peaches 185 0 185 0 0 Vaccinium corymbosum 723 0 3073 0 3,796 0 0 V. elliottii 118 0 118 0 0 V. stamineum 1,907 0.3 555 0 74 0 2536 0.5 0.2 Vitis rotundifolia 134 0.7 718 0 23 0 875 0.3 0.1 Ampelopsis arborea 366 0 366 0 0

NA, not applicable. of the Southeastern Fruit and Tree Nut Research Lab- Figure 5 gives a general outline of the phenology of oratory in Byron, GA, were jarred (shaking one scaf- fruit collected as it relates to the estimated abundance fold branch of each tree) weekly over a plastic sheet of plum curculio adults throughout the season (based (Ϸ1.4 by 1.4 m), and the number of plum curculio per on estimates made in 2003). tree in the orchard was recorded. Jarring was con- Every thicket of wild plum (P. angustifolia and ducted between 0700 and 0900 hours EST. P. umbellata) surveyed was infested with plum curculio. Distinct crescent-shaped oviposition scars typically attributed to C. nenuphar were not common Results overall, typically ranging from 0 to 36.4% (Table 3); The species of fruits collected, site locations, and however the percentage of wild plums bearing ovi- types of land use at each site are reported in Tables 1 position scars ranged from 0 to 60%, depending on the and 2. Table 3 reports the number of each type of fruit year and week collections were made (Figs. 1Ð4). At collected for each year and the percentage of fruit times, fruit of both species of wild plum bore multiple yielding adult plum curculio, with an overall total for scars (Table 4). Furthermore, at times in the survey, all 3 yr, including the percentage of fruit with distinct every fruit surveyed at some sites was infested; during oviposition scars (number of fruit with at least one the week of 26 May 2004, for instance, 100% of fruit oviposition scar/total number of fruit inspected ϫ surveyed at 13 of 21 sites had ovipositional scars. 100). Because there were often multiple scars per fruit Fruit from only P. persica, P. angustifolia, P. umbel- in wild plum, Table 4 shows the mean number of scars lata, Crataegus aestivalis, Vaccinium stamineum, and per fruit (P. angustifolia and P. umbellata) for the 2004 Vitis rotundifolia yielded adult plum curculio, and of survey and includes the range for the number of scars these, only P. persica and P. angustifolia yielded Ͼ10% per fruit. Figures 1Ð3 show the percentage of wild adult plum curculio adults (Table 3). This is the Þrst plums with oviposition scars along with an estimate of report of C. nenuphar successfully developing in the abundance of plum curculio for each of the 3 yr of V. stamineum, and V. rotundifolia. Adults were reared the study. Figure 4 shows the mean percentage of wild from V. stamineum and V.s rotundifolia in only one plums, by species, with oviposition scars along with season (2002) of the three seasons the survey was the percentage of C. aestivalis and P. pyrifolia with conducted, but many more fruit of V. stamineum were oviposition scars for each week of the survey in 2004. sampled (because of greater availability of fruit) in

Table 4. The mean no. of scars per fruit (P. angustifolia and P. umbellata) by collection date

8 Apr. 16 Apr. 22 Apr. 29 Apr. 5 May 11 May 19 May 25 May Mean no. of scars per fruit Ϯ SE 0.21 Ϯ 0.03 0.69 Ϯ 0.04 0.60 Ϯ 0.05 0.86 Ϯ 0.07 1.44 Ϯ 0.08 1.22 Ϯ 0.08 1.22 Ϯ 0.08 1.41 Ϯ 0.07 Number of fruit collected 223 254 221 241 206 206 193 146 Range of scars per fruit 0Ð3 0Ð5 0Ð4 0Ð5 0Ð8 0Ð6 0Ð5 0Ð5 52 ENVIRONMENTAL ENTOMOLOGY Vol. 35, no. 1

Fig. 1. Percentage of wild plums (P. angustifolia and P. umbellata combined) with oviposition scars characteristic of Fig. 3. Percentage of wild plums (P. angustifolia and P. C. nenuphar superimposed on C. nenuphar abundance umbellata combined) with oviposition scars characteristic of throughout 2002. Bars represent percentage of fruit scarred; C. nenuphar superimposed on C. nenuphar abundance lines represent adults captured. Abundance data were based throughout 2004. Bars represent percentage of fruit scarred; on the number of C. nenuphar captured each week in Ted- lines represent adults per captured. Abundance data were dersÕ traps, cone emergence traps, and circle traps. based on the number of C. nenuphar captured per tree each week by jarring peach trees. 2002 than in subsequent years (Table 3). Although female plum curculio seem to be selective in terms of extremely rare in our surveys, with only one tree fruit in which they choose to oviposit (few if any found throughout the survey. V. rotundifolia and oviposition scars were detected in crabapple, blue- A. arborea are widespread in middle Georgia but, at berries, or hawthorns), a relatively high percentage of least in the case of A. arborea, the fruit is not available Asian pear fruit and cultivated apple inspected had when C. nenuphar are most abundant (Fig. 5). P. caro- distinct oviposition scars (plum curculio females liniana, Rosa carolina, and P. calleriana are widespread were even observed ovipositing on Asian pear), yet in middle Georgia, although none of these yielded no C. nenuphar larvae emerged from collected fruit C. nenuphar. Chickasaw plum matures its fruit early (Table 3). Except for peaches in abandoned orchards, in the growing season. It is available to ovipositing none of the fruit that were used as hosts by larval plum C. nenuphar of the overwintering generation, but its curculio were available to the summer generation of fruiting season is over by the onset of the summer plum curculio (Figs. 1Ð3 and 5). generation of C. nenuphar (Fig. 5). Although hog The various traps used to monitor plum curculio plum is somewhat available to the summer genera- populations in 2002 were effective at detecting the tion of C. nenuphar (Fig. 5), it is a relatively rare migration of the plum curculio in the spring but did plant in middle Georgia. Of the 30 plum thickets sur- not detect the subsequent summer generation (com- veyed in this study, only 4 were reliably identiÞed as pare Fig. 1 to Figs. 2 and 3). pure stands of P. umbellata. This may be an artifact of Crataegus spp. are abundant and easy to Þnd in past efforts to remove wild plums: P. umbellata does central Georgia, but few of these yielded adult or not readily form clonal thickets and may have been larval plum curculio. C. aestivalis, the only Crataegus more effectively removed by these eradication efforts. species to yield adult plum curculio, is probably Hybrids of P. angustifolia and P. umbellata occur, but rare in the area, and the only source of this fruit we they are uncommon and their fruit is typically early, could locate was an orchard on the premises of restricting its availability to the overwintering gener- the USDA Fruit and Tree Nut Laboratory in Byron, ation of C. nenuphar adults. GA. This is also true of P. pyrifolia, both Malus species, and V. corymbosum. Amelanchier arborea was Discussion The genus Conotrachelus is currently restricted to North and South America and includes pests of guava fruit, Psidium guajava L. (Myrtaceae) (attacked by C. psidii Marshall: Bondar 1923, Boscań and Cesares 1980, 1981, Bailez et al. 2003); cupuassu fruit, Theobroma grandiflorum (Willd ex Spreng) (Sterculi- aceae) [attacked by C. humeropictus (Fiedler): DÕAvila Lopes 2000]; nuts and/or shoots of Carya spp. (Cary- aceae) [attacked by C. schoofi (Papp), C. pecanae Buchanan, and C. aratus Germar: Tedders and Payne 1986]; nuts of Chinese chestnut, Castanea mollissima Fig. 2. Percentage of wild plums (P. angustifolia and P. Blume (Fagaceae) (attacked by C. carinifer Casey: umbellata combined) with oviposition scars characteristic of C. nenuphar superimposed on C. nenuphar abundance Payne et al. 1972); acorns of oaks, Quercus spp. (Fa- throughout 2003. Bars represent percentage of fruit scarred; gaceae) (attacked by C. carinifer Casey: Gibson 1964); lines represent adults per captured. Abundance data were fruit of quince, Cydonia oblonga Miller (Rosaceae) based on the number of C. nenuphar captured per tree each (attacked by C. crataegi Walsh: Maier 1990); and week by jarring peach trees. cones/seeds of Pinus spp. (Pinaceae) [attacked by February 2006 JENKINS ET AL.: PLUM CURCULIO HOSTS 53

Fig. 4. Percentage of wild plum (P. angustifolia and P. umbellata), may haw (C. aestivalis), and Asian pear (P. pyrifolia) with oviposition scars characteristic of C. nenuphar in 2004 (error bars ϭϮSD). For P. angustifolia, n ϭ 21 (i.e., 21 separate sites were sampled for each date); for P. umbellata, n ϭ 4; and for C. aestivalis and P. pyrifolia, n ϭ 1.

C. neomexicana (Fall): Bodenham et al. 1976]. The are available to the summer generation of plum cur- geographic distribution and host preferences of the culio in central Georgia, suggesting that they are a genus Conotrachelus suggest that it radiated in the critical alternate host for the bivoltine strain of plum New World, with speciation occurring as groups be- curculio in central Georgia. Commercial peach or- gan to specialize on different hosts. The plum curculio chards in middle Georgia receive insecticide applica- can easily adopt new hosts, because most of its hosts tions that reduce detectable infestation by plum cur- of economic importance are not native to the plum culio. However, abandoned orchards are readily curculioÕs range, e.g., apple, peach, and pear (Quain- infested and are likely an important source of immi- tance and Jenne 1912, Chapman 1938, Maier 1990). grant adults that enter commercial orchards. This ability to use new hosts is also apparent in Cono- Comparison of our results to previous literature trachelus carinifer Casey, whose original hosts proba- suggests regional anomalies in the host preference bly were acorns of Quercus spp. Payne et al. (1972) of C. nenuphar. It is well established that plum cur- found it infesting the kernels of Chinese chestnut culio is a serious pest of apples in the northeastern (Castanea mollissima Blume). The ability to adopt new United States (Chapman 1938, Maier 1990). How- host plants is a key to the success of the genus Cono- ever, searches of apples in middle Georgia revealed trachelus and is an important consideration when de- few oviposition scars, and no adults were reared from veloping holistic strategies of pest management for the fruit, even though Þeld-collected plum curculio bivoltine southern strain of plum curculio. from the region are successfully reared on green The primary hosts of the spring generation of plum thinning apples of many varieties (Amis and Snow curculio in central Georgia appear to be peach, 1985) (Table 3). Apples (crabapples and domestic Chickasaw plum, and hog plum. Indeed, every site varieties) are rare in middle Georgia, and the low where these species were surveyed yielded infested incidence of oviposition scars on apples may reßect fruit, whereas this was not the case for other species this fruitÕs low apparency in the region. In addition, of fruit. Of these, only peaches in abandoned orchards different crabapple cultivars vary in their susceptibil-

Fig. 5. Phenology of selected fruit and adult plum curculio population ßuctuations in a peach orchard in 2003. Fruit phenology is an approximation based on observations of when fruit was available in central Georgia. 54 ENVIRONMENTAL ENTOMOLOGY Vol. 35, no. 1 ity to oviposition by plum curculio (Alm and Hall in middle Georgia peach orchards; however, removal 1986). of native plums and abandoned peach orchards may Hawthorns (Crataegus spp.) are relatively abundant result in elevating these currently minor or nonhosts in middle Georgia, and their fruit is available to both to the status of signiÞcant hosts of plum curculio in generations of plum curculio (Fig. 5). However, we middle Georgia, especially given the genusÕ ability to recorded a very low percentage of fruit with the dis- use novel hosts. tinctive plum curculio oviposition scar, and only fruit of the cultivated may haw, C. aestivalis, yielded adult curculio. The species of Crataegus surveyed by Maier Acknowledgments (1990) also yielded very few plum curculio (0.6% from 16,300 fruit). Our data suggest that most hawthorn We thank B. Stephens and C. Floyd for Þeldwork, the species in our area produce fruit that are not accept- Peach Councils of Georgia and South Carolina for supporting this work, and C. Maier, T. Leskey, R. Mizell, and two anon- able as a reproductive host for plum curculio. Fruits of ymous reviewers for critical evaluations of an early version these species are not very ßeshy and are mostly oc- of this manuscript. cupied with a hard seed, perhaps precluding survival by larval plum curculio. Most surprisingly, plum curculio oviposited only References Cited rarely in Vaccinium species, and adults were only reared from V. stamineum. All are relatively common Alm, S. R., and F. R. Hall. 1986. Crabapple cultivar prefer- in middle Georgia and are available when the Þrst ences of the plum curculio, Conotrachelus nenuphar plum curculio progeny emerge (Fig. 5). These Vac- (Herbst) (Coleoptera: Curculionidae). Fruit Varieties J. 40: 83Ð87. cinium species are all ßeshy enough to serve as suit- Amis, A. A., and J. W. Snow. 1985. Conotrachelus nenuphar, able hosts for C. nenuphar larvae, but in our surveys pp. 227Ð235. In P. Singh and R. F. Moore (eds.), Hand- were not widely used as a host by plum curculio, book of insect rearing. Elsevier, Amsterdam, The Neth- despite the fact that V. corymbosum is reported as a erlands. regular host of plum curculio in both New Jersey and Bailez, O. E., A. M. Viana-Bailez, J.O.G. De Lima, and North Carolina (Beckwith 1943, Mampe and Neunzig D.D.O. Moreira. 2003. Life-history of the guava weevil, 1967, Polavarapu et al. 2004). Conotrachelus psidii Marshall (Coleoptera: Curculion- Although the traps we used to monitor plum cur- idae), under laboratory conditions. Neotrop. Entomol. 32: culio populations are commonly used in plum curculio 203Ð207. Beckwith, C. S. 1943. Insects attacking blueberry fruit. pest management plans (Johnson et al. 2002), we sus- New Jersey Agricultural Experiment Station, New Bruns- pect that their usefulness is restricted to the detec- wick, NJ. tion of the spring migration of plum curculio into Bloem, S., R. F. Mizell, III, and C. W. O’Brien. 2002. Old orchards. It is thought that these traps are only effec- traps for new weevils: new records for curculionids tive at temperatures Ͻ18ЊC, because above this (Coleoptera: Curculionidae), Brentids (Coleoptera: temperature, plum curculio are able to ßy to their Brentidae), and Anthribids (Coleoptera: Anthribidae) hosts and thus avoid many of the traps (Prokopy from Jefferson Co., Florida. Fla. Entomol. 85: 632Ð644. and Wright 1997, Vincent et al. 1999). Further work Bodenham, J., R. E. Stephens, and T. O. Tatcher. 1976. needs to be conducted on monitoring methods for the A cone weevil, Conotrachelus neomexicanus, on pon- derosa pine in Colorado: life history, habitats, and eco- summer generation of the bivoltine strain of plum logical relationships (Coleoptera: Curculionidae). Can. curculio, as well as basic biology. The fact that they Entomol. 108: 693Ð699. were found infesting all plum thickets in our survey Bondar, G. 1923. Gorgulhos das goiabas e araça´s. Conotra- suggests that they can migrate long distances (kilom- chelus psidii Marshall, sp. n. Correio. Agrõć. 1: 325Ð326. eters) or that there are as yet unknown alternate hosts Boscań de Martinez, N., and R. Cesares. 1980. El gorgojo de nearby on which the summer generation can develop la guyaba Conotrachelus psidii Marshall (Coleoptera: in. Curculionidae). I. Evaluaciońdedan˜ os. Agron. Trop. 30: In aggregate, these Þndings suggest that aban- 77Ð83. doned peach orchards and wild plums are the most Boscań de Martinez, N., and R. Cesares. 1981. Distribucioń en el tiempo las fases del gorgojode la guyaba Conotra- important reservoir host for the summer generation chelus psidii Marshall (Coleoptera: Curculionidae) en el of plum curculio in middle Georgia. We suspect that campo. Agron. Trop. 31: 123Ð130. the differences in host use that we have recorded Chapman, P. J. 1938. The plum curculio as an apple pest. between our study and previous studies reßect the New York State Agricultural Experiment Station, Geneva, prevalence of hosts from region to region or possibly NY. differences between the bivoltine and univoltine D’Avila Lopes, C. de M. 2000. Biologia, comportamento strains of plum curculio. Regionally, plum curculio e ßutuaçaõ populacional da broca-do-fruto do cu- exhibits a reduced host range. This may be caused by puaçuzeiro Conotrachelus sp. pro´ ximo humeropictus a number of factors, including reduced choice of hosts (Coleoptera: Curculionidae). Tese de Doutorado, University of Amazonas, Manaus, Brazil. in smaller areas, ßuctuating host densities, and re- Gibson, L. B. 1964. Biology and life history of acorn-infest- gional variations in plum curculio behavior. The low ing weevils of the genus Conotrachelus (Coleoptera: incidence of oviposition by C. nenuphar in these al- Curculionidae). Ann. Entomol. Soc. Am. 57: 522Ð526. ternative hosts suggests that they do not contribute Hallman, G. J., and W. P. Gould. 2004. Evaluation of sub- signiÞcantly to the dynamics of plum curculio as a pest tropical and tropical fruits as potential hosts for the south- February 2006 JENKINS ET AL.: PLUM CURCULIO HOSTS 55

ern strain of plum curculio (Coleoptera: Curculionidae). Payne, J. A., L. S. Jones, and H. Lowman. 1972. Biology and Fla. Entomol. 87: 241Ð243. control of a nut curculio, Conotrachelus carinifer Casey, a Horton, D. L., and H. C. Ellis. 1989. Plum curculio, new pest of chestnuts, pp. 76Ð78. In 63rd annual report of pp. 169Ð170. In S. C. Myers (ed.), Peach production the Northern Nut Growers Association. Iowa State Uni- handbook. Cooperative Extension Service, University of versity, Ames, IA. Georgia, Athens, GA. Polavarapu, S., J. D. Barry, and V. Kyryczenko-Roth. 2004. Johnson, D. T., P. G. Mulder, Jr., B. D. McCraw, B. A. Lewis, Phenology and infestation patterns of plum curculio B. Jervis, B. Carroll, and P. J. McCleod. 2002. Trapping (Coleoptera: Curculionidae) on four highbush blueberry plum curculio Conotrachelus nenuphar (Herbst) (Co- cultivars. J. Econ. Entomol. 97: 1899Ð1905. leoptera: Curculionidae) in the southern United States. Prokopy, R. J., and S. Wright. 1997. How do plum curculios Environ. Entomol. 31: 1259Ð1267. approach host trees and pyramid traps? Fruit Notes. 62: Levine, E., and F. R. Hall. 1977. Effect of feeding and 5Ð8. oviposition on apple and plum fruit abscission. J. Econ. Quaintance, A. L., and E. L. Jenne. 1912. The plum curculio. USDA, Bureau of Entomology Bulletin 103, Washington, Entomol. 70: 603Ð607. DC. Maier, C. T. 1990. Native and exotic rosaceous hosts of ap- Stearns, L. A. 1931. The brood of the plum curculio, Cono- ple, plum, and quince curculio larvae (Coleoptera: Cur- trachelus nenuphar Herbst, in Delaware. J. Econ. culionidae) in the northeastern United States. J. Econ. Entomol. 24: 62Ð66. Entomol. 83: 1326Ð1332. Tedders, W. L., and J. A. Payne. 1986. Biology, life history, Mampe, C. D., and H. H. Neunzig. 1967. The biology, parasit- and control of Conotrachelus schooﬁ (Coleoptera: Cur- ism, and population sampling of the plum curculio on blue- culionidae) on pecans. J. Econ. Entomol. 79: 490Ð496. berry in North Carolina. J. Econ. Entomol. 60: 807Ð812. Vincent, C., G. Chouinard, and S. B. Hill. 1999. Progress in McClure, M. S. 1980. Role of wild host plants in the feed- plum curculio management: a review. Agric. Ecosyst. ing, oviposition, and dispersal of Scaphytopius acutus Environ. 73: 167Ð175. (Homoptera: Cicadellidae), a vector of peach X-disease. Wylie, W. D. 1966. Plum curculio-nonfruit hosts and sur- Environ. Entomol. 9: 283Ð292. vival (Coleoptera: Curculionidae). J. Kansas Entomol. Mulder, P. J., B. D. McGraw, W. Reid, and R. A. Grantham. Soc. 39: 218Ð222. 2000. Monitoring adult weevil populations in pecan and fruit trees in Oklahoma. Oklahoma State Univ. Extension Received for publication 8 September 2005; accepted Facts. 7190: 1Ð8. 17 October 2005.