Life History of Oriental Beetle and Other Scarabs, and Occurrence of Tiphia vernalis in Ohio Nurseries

The oriental beetle, Anomala orientalis Waterhouse, is a serious pest of nursery crops in northern Ohio and a number of other states because the larvae damage plant roots. In 3 ornamental tree nurseries (field production) in Ohio, the composition of scarab larvae, their life histories, and parasitism rates were examined. Four exotic scarabs, Asiatic garden beetle (Maladera castanea Arrow), European chafer (Rhizotrogus majalis Razoumowsky), Japanese beetle (Popillia japonica Newman), and oriental beetle, were found in this study. The oriental beetle and European chafer were the most common species found. Up to 60% of the oriental beetle population required 2 yrs to complete development, which is much higher than the commonly reported 15% or less in northeastern states. Tiphia vernalis Rohwer, an external parasite of oriental beetle and Japanese beetle larvae, was found in all nurseries surveyed. As much as 31% and 60% of the sampled oriental beetle and Japanese beetle populations, respectively, were parasitized, depending on date and nursery.

Fall Subsurface Insecticide Treatments Control European Chafer Grubs Damaging Field-Grown Nursery Crops

Third instar European chafer (EC), Rhizotrogus majalis (Razoumowsky), were found to be killing field-grown Rhododendrons ‘P.J.M.’ and Eastern hemlocks in two commercial nurseries in northeastern Ohio. Apparently, 1 or 2 grubs per plant were sufficient to severely damage young plants (rhododendrons). Subsurface applications of Dursban TNP were tested as rescue treatments against the grubs in these fields. Three novel single-point subsurface applicators were tested for delivery of Dursban in the rhododendron trial. A subsurface treatment of Dursban TNP was compared to surface applied drench treatments of Dursban TNP and Dylox 80 T & O in the hemlock trial. We found that EC grubs killed young plants of both species by removing most of the fibrous roots and/or girdling the stems. The subsurface treatments of Dursban TNP, significantly reduced (95%) the number of EC grubs compared to untreated hemlocks and rhododendrons when treatments were applied early or late fall, respectively. There were no differences in suppression of grubs among the applicators in the rhododendron trial.

Insecticide Dips for Control of Japanese Beetle and Other Soil-Infesting White Grubs in B&B Nursery Stock

Studies conducted in 1996, 1998 and 1999 show that immersion of root balls in Dursban® (chlorpyrifos) significantly reduces the number of white grubs, particularly Japanese beetle, Popillia japonica Newman, in B&B (ball and burlap) nursery stock. In 1996, the influence of root ball size, soil type, and dip time on the efficacy of Dursban® 50WP, Dursban® 4E, and Oftanol® 2F (isofenphos) for white grub control in dipped B&B nursery stock was evaluated. The grubs found within the root balls were primarily oriental beetle, Exomala orientalis (Waterhouse), European chafer, Rhizotrogus majalis (Razoumowsky), Asiatic garden beetle, Maladera castanea (Arrow), northern masked chafer, Cyclocephala borealis Arrow and Japanese beetle. With one exception, all the insecticide treatments caused similar grub mortality (96–100%) in 61.0 and 81.3 cm (24 and 32 in) root balls, respectively, and in sand or clay soil. There were no significant differences in grub survival due to dip time (1, 2, and 5 min). However, there were consistently fewer live grubs recovered from the root balls dipped 2 or 5 min compared with the number of live grubs recovered from root balls dipped for 1 min. In 1998, trees with 30.5, 45.7 and 61.0 cm (12, 18 and 24 in) root balls were dipped in either 0.453 or 0.906 kg ai/378.5 liter (1 or 2 lbs ai/100 gal) of Dursban® 4E for 2 mins. Both rates of Dursban® provided 100% control of Japanese beetle grubs in all three root ball sizes. Five trees from each treatment were planted one week after dipping and were evaluated for phytotoxicity up to 12 months after dipping. Most of the trees with 30.5 cm (12 in) root balls dipped in Dursban® died. Three of five trees with 45.7 (18 in) root balls dipped in the low rate of Dursban® and all five root balls dipped in the high rate had small leaves. One tree dipped in the low rate and 2 trees dipped in the high rate died 12 months after dipping. All of the trees with 61.0 cm (24 in) root balls dipped in the low rate of Dursban® survived and showed no signs of phytotoxicity. Trees with the same root ball size dipped in the high rate of Dursban® exhibited smaller leaves in 3 of the 5 trees. In 1999, trees with 61.0 cm (24 in) root balls were dipped in either 0.453, 0.226 or 0.113 kg ai/378.5 liter (1, 0.5 or 0.25 lbs ai/100 gal) of Dursban® 4E for 2 mins. All rates of Dursban® provided 100% control of Japanese beetle grubs.

Preventing White Grub Infestation in Container-Grown Nursery Stock

Preplant media incorporation of Talstar 0.2 G (bifenthrin) at 10 ppm (parts per million) or Fireban 1.5 G (tefluthrin) at 15 ppm, based on dry weight of the medium, provided complete control of Japanese beetle (Popillia japonica Newman), oriental beetle [Exomala orientalis (Waterhouse)], and European chafer [Rhizotrogus majalis (Razoumowsky)] in container nursery plants for two growing seasons. Talstar 0.67 F drenched immediately after planting also prevented establishment of these species in containers for two growing seasons. Marathon 1 G (imidacloprid) preplant media incorporated at 6–17.8 g (a.i.)/m3, provided incomplete control, while Marathon 60 W was completely effective when drenched in mid-summer prior to inoculating the pots with eggs. Other granular products mixed into potting media, including 10 ppm of fipronil or Mach 2, or 150 g (a.i.)/m3 of Lorsban or SuSCon Green, provided good control for one season. Several treatments prevented establishment of Japanese but not oriental beetle grubs. Curative drenches were generally ineffective. Registered treatments providing two years of control (Talstar at 10–25 ppm) can be used by growers to prevent white grub larval establishment in containers. Their usage should allow shipment of treated plants throughout the United States and Canada.

STICKY PLASTIC SHEET TRAPS AS SURVEY TOOLS FOR THE EUROPEAN CHAFER (COLEOPTERA: SCARABAEIDAE)

A perforated 4.6 m square sticky plastic sheet placed under the canopy of a tree heavily populated with European chafers, Rhizotrogus majalis (Razoumowsky), consistently captured more beetles than a 15-w blacklight survey trap. The same size sheet, operating with a bird shield under a sparsely populated tree that represented conditions encountered during survey operations, demonstrated detection capability equal to that of the light trap. Bird shields prevented trapping of birds. Lawn injury beneath the sheeting due to heat build-up was not serious. Results suggest that a sticky sheet is an alternative, less expensive, equally effective survey tool for detection of European chafer infestations.