Search

The leafminer, Liriomyza trifolii (Burgess) is a key pest of gerbera daisies (Gerbera jamesonii Bolus), which are among the most preferred cut flowers in the world. While insecticides often fail to control this pest, parasitoids have proven to be effective. To maintain the parasitoids in the system, pesticide applications should be avoided. However, the influx of secondary pests like mites, thrips, whiteflies, and aphids during the growing season necessitates chemical sprays, which are effective in controlling the secondary pests, but are often toxic to the natural enemy and hence disrupt biological control. Since chemicals are not easily avoided in this system, an alternative method to avoid leafminers was sought, using host plant resistance, which can be an important component of integrated pest management (IPM) programs. Sixty gerbera cultivars were evaluated for potential resistance to L. trifolii. A range in susceptibility measured as leaf punctures and developing mines was evident for the first five weeks of a six-week exposure period. Gerberas ‘Jaguar Pink’, ‘Jaguar Rose Deep’, ‘Jaguar Salmon Pastel’, and ‘Revolution Spring Pastel’ were the least damaged, exhibiting less than 20% of the highest damage on at least two observation dates. However, consistent exposure to high numbers of leafminers resulted in similar expression of damage among all cultivars after five weeks. Differences among cultivars in force required to puncture leaves could not be consistently associated with damage due to leafminers

Pesticides commonly used in commercial greenhouse management were evaluated for compatibility with two biological control agents: a leafminer parasitoid (Diglyphus isaea [Walker]), and a predatory mite (Neoseiulus californicus [McGregor]). These natural enemies were exposed to miticides, fungicides, and insecticides targeting leafminers, thrips, and whiteflies, according to label directions in laboratory vial assays, after which mortality at 12, 24, and 48 h was recorded. Greater mortality of predatory mites than leafminer parasitoids was observed overall, illustrating that fewer pesticides were compatible with predatory mites compared with the parasitoid. However, some commonly used pesticides were found to cause high mortality to both the leafminer parasitoid and predatory mites. Twospotted spider mite (Tetranychus urticae Koch) infestations often disrupt leafminer (Liriomyza trifolii [Burgess]) biocontrol programs. Therefore, potentially compatible miticides (bifenazate, hexythiazox, spiromesifen, acequinocyl, etoxazole, and clofentezine) identified in laboratory trials were also evaluated in a greenhouse study and found to be compatible with leafminer biocontrol.

Larra bicolor was introduced to Florida for biological control of mole crickets (Scapteriscus spp.) and has spread to adjacent states. The objectives of this study were to determine the seasonal and diurnal activity of L. bicolor in its expanded range and to compare ornamental plants as nectar sources. Experiments with colored, pan-type traps and sugar solutions to monitor for L. bicolor were unsuccessful and direct observations of wasps feeding on flowers or hunting in turfgrass were used to monitor activity. Seasonal activity of L. bicolor was monitored on four sites in coastal Mississippi from 2006-2008. Wasps are active from June to October and were active later in the season on flowering plants. Diurnal activity on flowering plants was monitored during August and October. Activity began at 0700 h in August and 0900 h in October and continued to near dusk. Populations on flowers were typically male-biased with numbers of females on flowers being greatest in the afternoon (about 1300 h). Sixteen plant taxa representing nine genera and seven families were evaluated in common garden experiments during 2007 and 2008. Of these, wasps only fed on Pentas lanceolata and Spermacoce verticillata. However, pentas, a popular ornamental, may be a more aesthetic and less problematic alternative to S. verticillata, a weed in turfgrass, as a nectar source for L. bicolor in urban landscapes.

The objective of this paper is to identify common species of paper wasps (Polistes spp.) attacking fall armyworm (Noctuidae: Spodoptera frugiperda) larvae and to investigate foraging activity in turfgrass. Three species — Polistes exclamans, P. dorsalis, and P. metricus — were collected while they foraged in bermudagrass turf. Polistes wasps forage in turf for about 10 h a day beginning a few hours after sunrise (0830 h), waning near midday, and increasing again in the late afternoon. Wasps were more abundant in plots infested with fall armyworms although these differences were statistically significant in one of three trials. The benefits of Polistes wasps may be conserved by scheduling insecticide applications in the early evening (0700 h or later) or by using reduced-risk insecticides.