Rove of the Genus Gravenhorst (Coleoptera: Staphylinidae) Parasitizing the Maggot, radicum (L.) (Diptera: ), in the Northern Central Coast of California Author(s): Shimat V. Joseph, E. Richard Hoebeke and Joseph V. McHugh Source: Proceedings of the Entomological Society of Washington, 117(4):525-528. Published By: Entomological Society of Washington DOI: http://dx.doi.org/10.4289/0013-8797.117.4.525 URL: http://www.bioone.org/doi/full/10.4289/0013-8797.117.4.525

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Rove Beetles of the Genus Aleochara Gravenhorst (Coleoptera: Staphylinidae) Parasitizing the Cabbage Maggot, (L.) (Diptera: Anthomyiidae), in the Northern Central Coast of California DOI: 10.4289/0013-8797.117.4.525

Aleochara bilineata Gyllenhal and that was naturally infested with cabbage Aleochara verna Say (Coleoptera: maggot. An application of insecticidal Staphylinidae: ) are effective soap was administered to manage cab- predators and of the puparia bage aphids seven weeks after planting of economically important anthomyiid the seeds. root samples were flies of cruciferous crops including the collected on consecutive weeks (4, 11 and cabbage maggot, Delia radicum (Linnaeus) 18 April, 2014). Each week, 20 plants (Diptera: Anthomyiidae) (Maus et al. with root systems intact plus associated 1998, Turnock et al. 1995, Klimaszewski were sampled and carefully evalu- 1984). Delia radicum is one of the most ated for the presence of cabbage maggot destructive pests of cruciferous crops puparia. The puparia were labeled and worldwide (Coaker and Finch 1971). In stored in Petri dishes at ;21oC, L:D 16:8 the past decade, it has become a serious photoperiod, ;45% RH, and were ex- of crops in the Salinas amined twice-weekly for the emergence Valley (Monterey County) of the cen- of adult rove beetles and cabbage maggot tral coast of California (Johnsen and flies. Rove beetles reared from puparia Gutierrez 1997, Joseph and Martinez were stored in 95% ethyl alcohol for 2014). Adults of D. radicum move into identification. Aleochara species reared the fields at various stages of plant de- from puparia were determined using cur- velopment and lay eggs at the crown area rent identification keys (Klimaszewski of the plant. The emerging larvae of 1984). Voucher specimens were de- D. radicum feed on the taproot, inhibit- posited in the University of Georgia ing the translocation of nutrients and Collection of (UGCA), Athens, water, which affects the normal growth GA, as well as the collection of the senior and development of plants. author. Aleochara bilineata has been reported Here, we report the occurrence of from most Brassica-producing areas A. bilineata and A. verna in a Brassica worldwide and is an effective biologi- field in the northern central coast of cal control agent against D. radicum California. This represents the first ver- (Hemachandra et al. 2005, 2007; Hummel ified record of A. bilineata in California; et al. 2010). To determine the status of A. verna previously was known to occur Aleochara species in the north central throughout most of the state. In the coast of California, a survey was con- Salinas Valley, Brassica crops such as ductedinanorganicallymanagedbroccoli broccoli (Brassica oleracea var. italica field in Salinas, CA. Seeds of ‘Marathon’ Plenck), cauliflower (B. oleracea L. var. broccoli (Brassica oleracea L.) were botrytis), cabbage (B. oleracea L. var. planted on 2 February, 2014, in a field capitata L.), broccoli raab (B. rapa L. 526 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON subspecies rapa), and Brussels sprouts the pronotum is densely pubescent with (B. oleracea L. var. gemmifera) are long setae and the dense pubescence of the grown in excess of 34,398 ha and are elytra is directed towards the apico-lateral valued at ca. $485 million USD (Crop angles. In contrast, Aleochara suffusa report, Monterey County 2013). The differs by the pronotum being sparsely economic impact of D. radicum on these pubescent and the dense pubescence of crops is considerable. Thus, the de- the elytra is directed posterad. Aleochara tection of these two rove species verna is very similar to A. bilineata but is welcomed news since they add to the differs principally by possessing two pale, known predator and fauna yellowish-brown to rust-colored apico- affecting anthomyiid pests in this region. median elytral spots (Fig. 1). It differs In one surveyed field in Salinas, 11.5%, from A. bimaculata Gravenhorst, another 18.2%, and 32.2% of D. radicum puparia species of the subgenus with elytral spots (collected on 4, 11, and 18 April, 2014, that occurs in California, by its smaller respectively) were parasitized by Aleo- body size (2.0–4.0 mm vs. 4.0–8.0mm chara beetles. Aleochara bilineata con- for A. bimaculata) and by the deeply stituted 83.3%, 88.9%, and 88.9% of the impressed, coarse, setigerous punctures emerged Aleochara specimens on 4, 11, of the pronotum (cf. the pronotum with and 18 April 2014, respectively. The re- slightly impressed, or not, inconspicuous maining specimens of reared Aleochara punctures and thin setae in A. bimaculata). represented the second species, A. verna. Aleochara bilineata is transcontinental All reared specimens of Aleochara in Canada, but ranges south into the belong to the subgenus Coprochara United States to Oregon, Wisconsin, Mulsant and Rey whose diagnostic char- Illinois, New York, Maine, and Massa- acters are elaborated on and illus- chusetts (Klimaszewski 1984). Although trated by Klimaszewski (1984). Species this species was probably accidentally of Coprochara are easily recognized by introduced from Europe, some consider the presence of two longitudinal, par- it to be a Holarctic species (Maus 1998). allel to subparallel rows of punctures on Aleochara verna is a common species the pronotum which are separated by widely distributed throughout North a distinct glabrous area extending down America, and, according to Klimaszewski the pronotal midline (Fig. 1). Members (1984) and Yamamoto and Maruyama of this subgenus also are recognized (2013), probably represents a true by the form of the mesosternum, which Holarctic species that has erroneously bears a longitudinal carina for its entire been regarded as introduced. length (Fig. 3). Aleochara bilineata Females of A. bilineata each lay ca. has unicolorous elytra (Fig. 2). In ad- 700 eggs during their lifespan, usually dition, it can be distinguished by char- near D. radicum puparia in the soil acters of the male aedaegus and female (Colhoun 1953, Fournet et al. 2000). spermatheca — the apex of the median Once eggs hatch, the first instar larvae of lobe of the aedeagus being strongly A. bilineata locate and enter D. radicum produced ventrally, a long bulbous, puparia. Aleochara bilineata larvae de- and fewer number of coils (4–6) of the velop inside D. radicum puparia con- spermatheca. Aleochara suffusa (Casey) suming the pupae and emerging as adults might be confused with A. bilineata, (Royer et al. 1998). Besides being par- but it possesses different pubescence on asitoids, A. bilineata adults are predators the pronotum and elytra. In A. bilineata, of D. radicum as well, with each capable VOLUME 117, NUMBER 4 527

Figs. 1–3. Aleochara (Coprochara). 1, Aleochara verna, dorsal, arrow denotes one of two parallel longitudinal rows of punctures on pronotum, scale bar = 1mm.2,Aleochara bilineata,dorsal,scalebar= 1 mm. 3, Aleochara bilineata, ventral, arrow denotes the complete mesosternal carina, scale bar = 0.5mm. of consuming ca. 23.8 eggs or 2.6 larvae in the California’s central coast Brassica per day (Read 1962). Aleochara verna production areas. These findings war- has a similar life history and relationship rant further investigation to determine with D. radicum (Hummel et al. 2010). the potential utility of these beetles as Until recently, D. radicum has been biological control agents. An assess- managed primarily using organophos- ment of the distribution and seasonality phate such as chlorpyrifos of A. bilineata and A. verna,andan and diazinon in the central coast of Cal- examination of the potential role of these ifornia (Natwick 2009). Because high species in the management of D. radicum concentrations of their residues were de- in organic and conventional Brassica tected in bodies of water (Hunt et al. fields is needed. 2003), the use of in- We thank N. Harkleroad (Agriculture secticides is now stringently regulated and Land-Based Training Association leaving growers with limited options to [ALBA], Salinas, CA) for providing ac- combat D. radicum infestations (CEPA cess to Brassica fields for this project. 2013). In addition, it is likely that this Also, we appreciate the technical assis- widespread use of organophosphate in- tance provided by J. Martinez, C. Martinez, secticides has led to the development of C. Bettiga and J. Zarate in sample collec- resistance in D. radicum populations. tion, and UC IPM for providing funding for Under these circumstances, the occur- this project. rence of Aleochara spp. is noteworthy because these beetles represent additional Literature Cited potential tools for D. radicum control. CEPA (California Environmental Protection In conclusion, this survey documents Agency), Central Coast Regional Water the presence of two species of Aleochara Quality Control Board. 2013. Agricultural or- ectoparasitoids and predators of D. radicum der adopted. http://www.waterboards.ca.gov/ 528 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON

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