Overwintering, Host-Plant Selection, and Insecticide Susceptibility of Systena frontalis (Coleoptera: Chrysomelidae): A Major Insect Pest of Nursery Production Systems.

Systena frontalis (F.) is a major insect pest of nursery production systems in the Midwest and Northeastern regions of the United States with the adults feeding on plant leaves, which reduces salability. However, there is conflicting information on overwintering, and no information on host-plant selection or insecticide susceptibility of S. frontalis adults. Therefore, we conducted a series of experiments under greenhouse, laboratory, and field conditions from 2015 to 2019. The overwintering experiment was isolated in a greenhouse to assess adult emergence from growing medium of containerized plants collected from a wholesale nursery. We found that S. frontalis overwinters in growing medium based on adults captured on yellow sticky cards and the presence of adults on new plant growth. Host-plant selection experiments were conducted at the wholesale nursery and under laboratory conditions to determine feeding selection based on S. frontalis adult feeding damage on whole plants using a foliar damage ranking scale for different cultivars of Itea virginica L., Hydrangea paniculata Siebold, Weigela florida (Bunge), and Cornus sericea L., plants. We found that S. frontalis adults exhibited no preference for the leaves of the plant species or cultivars tested in the field or laboratory. Insecticide efficacy experiments were conducted under field and laboratory conditions. In the field experiments, the insecticides acetamiprid, dinotefuran, and Isaria fumosorosea (Wize) (Hypocreales: Clavicipitaceae) provided better protection of plants from S. frontalis adult feeding than the untreated check. In the laboratory experiments, the acetamiprid and pyrethrins with canola oil treatments provided the highest percent S. frontalis adult mortality.

Systemic Insecticide Applications: Effects on Citrus Mealybug (Hemiptera: Pseudococcidae) Populations Under Greenhouse Conditions.

The citrus mealybug, Planococcus citri (Risso) (Hemiptera: Pseudococcidae), is a major insect pest of greenhouse-grown horticultural crops. Applications of systemic insecticides as drenches to the growing medium are typically used by greenhouse producers to prevent or suppress citrus mealybug populations. A comprehensive study was conducted that included 11 experimental trials designed to assess the effects of growing medium applications of six systemic insecticides (azadirachtin, dinotefuran, flonicamid, imidacloprid, spirotetramat, and thiamethoxam) in preventing the establishment of and suppressing citrus mealybug populations on different plant species. The experimental trials included four plant species: Solenostemon scutellarioides, Gerbera jamesonii, Begonia × semperflorens-cultorum, and Salvia splendens, with six different cultivars grown in research greenhouses similar to those used in greenhouse production systems. In addition, feeding location (plant stem, leaf top, and leaf bottom) of citrus mealybugs on the various plants was also recorded. Overall, percent citrus mealybug mortality was consistently <50% (n = 255 to 1,598) for any treatment or rate of application; regardless if the systemic insecticides were applied preventatively or curatively. Percent citrus mealybug mortality did reach 78% (n = 36) for thiamethoxam at 8 times the label rate when plants were treated preventatively. Furthermore, none of the treatments prevented development of citrus mealybug F1 individuals to F2 generation egg-laying females on S. scutellarioides or G. jamesonii plants. Citrus mealybugs varied in their spatial distribution on the plant stem, leaf top, and leaf bottom with no noticeable trends. Therefore, based on the results of the study, systemic insecticides are not effective against the citrus mealybug in greenhouse production systems.

Effects of Pesticides on the Survival of Rove Beetle (Coleoptera: Staphylinidae) and Insidious Flower Bug (Hemiptera: Anthocoridae) Adults.

This study determined the direct, indirect, or both effects of pesticides on the rove beetle, Dalotia coriaria (Kraatz) (Coleoptera: Staphylinidae), and the insidious flower bug, Orius insidiosus (Say) (Hemiptera: Anthocoridae). The pesticides evaluated were Capsicum oleoresin extract, garlic oil, and soybean oil; cyantraniliprole; flupyradifurone; GS-omega/kappa-Hxtx-Hv1; Isaria fumosorosea; tolfenpyrad; pyrethrins; and spinosad. One experiment was conducted in a greenhouse with rove beetle adults exposed to growing medium applications of cyantraniliprole. The number of live and dead rove beetle adults was determined after 10 d. Four additional experiments were conducted under laboratory conditions. Rove beetle or insidious flower bug adults were individually placed into Petri dishes with filter paper treated with the pesticides. After 24, 48, 72, and 96 h, the number of live and dead adults of both natural enemies was recorded. GS-omega/kappa-Hxtx-Hv1 (VST-006340LC); tolfenpyrad; Capsicum oleoresin extract, garlic oil, and soybean oil (Captiva); and Isaria fumosorosea were not directly harmful to O. insidiosus (80-100% adult survival). Likewise, the pesticides such as tolfenpyrad, Captiva, and I. fumosoroea were not directly harmful to D. coriaria (80-100% adult survival). D. coriaria was more sensitive to VST-006340LC (40% survival) than O. insidiosus (100% survival), whereas O. insidiosus was more sensitive to flupyradifurone (0% survival) than D. coriaria (80% and 40% survival for both rates tested, respectively). The pesticides pyrethrins, spinosad, flupyradifurone, and combinations of tolfenpyrad and Captiva were directly harmful (<50% adult survival) to both natural enemies. However, none of the pesticides tested affected the ability of O. insidiosus adults to feed on western flower thrips adults.

Direct and Indirect Effects of Pesticides on the Insidious Flower Bug (Hemiptera: Anthocoridae) Under Laboratory Conditions.

Greenhouse producers are interested in integrating natural enemies along with pesticides to suppress western flower thrips, Frankliniella occidentalis (Pergande), populations. The insidious flower bug, Orius insidiosus (Say), is a commercially available natural enemy of western flower thrips. We conducted a series of laboratory experiments to determine the direct and indirect effects of 28 pesticides (insecticides, miticides, and fungicides), 4 pesticide mixtures, and 4 surfactants (36 total treatments plus a water control) on the adult O. insidiosus survival and predation on western flower thrips adults under laboratory conditions. The number of live and dead O. insidiosus adults was recorded after 24, 48, 72, and 96 h. The results of the study indicate that the fungicides (aluminum tris, azoxystrobin, fenhexamid, and kresoxim-methyl), insect growth regulators (azadirachtin, buprofezin, kinoprene, and pyriproxyfen), botanicals (Capsicum oleoresin extract, garlic oil, soybean oil; and rosemary, rosemary oil, peppermint oil, and cottonseed oil), and entomopathogenic fungi (Beauveria bassiana and Metarhizium anisopliae) were minimally directly harmful to adult O. insidiosus, with 80% to 100% adult survival. However, abamectin, spinosad, pyridalyl, chlorfenapyr, tau-fluvalinate, imidacloprid, dinotefuran, acetamiprid, and thiamethoxam directly affected O. insidiosus survival after 96 h (0-60% adult survival). The pesticide mixtures of abamectin + spinosad and chlorfenapyr + dinotefuran reduced adult survival (20% and 0%, respectively, after 48 h). Furthermore, the surfactants were not directly harmful to O. insidiosus adults. All western flower thrips adults were killed by the surviving adult O. insidiosus after 48 h, indicating no indirect effects of the pesticides on predation.