Wayne A. Gardner

Discovery and distribution of Megacopta cribraria (Hemiptera: Heteroptera: Plataspidae) in northeast Georgia

In October 2009, large aggregations of Megacopta cribraria (F.) (Heteroptera: Plataspidae) were discovered on outside, perimeter walls of houses in northeast Georgia, prompting homeowners to contact county Extension agents and pest management professionals to learn more about the insect and to rid the premises of the nuisance. The insect was flying from nearby patches of kudzu ( Pueraria spp .) onto houses, presumably in an attempt to locate overwintering sites. In its native Asia, one of its preferred hosts is kudzu, an invasive, leguminous vine that now grows throughout the southeastern U.S. Before discovery in Georgia, M. cribraria was unknown from the New World. In addition to its emergence as a nuisance pest, M. cribraria has been reported as a pest of numerous legume crops in Asia, including soybean, Glycine max Merrill . As of August 9, 2010, M. cribraria was known from 48 counties in northeast Georgia and 13 counties in northwest South Carolina. In late June and early July 2010, M. cribraria was found on soybeans in 20 of the 48 Georgia counties and five counties in South Carolina.

Survey of entomopathogenic nematodes and fungi endemic to pecan orchards of the Southeastern United States and their virulence to the pecan weevil (Coleoptera: Curculionidae).

Abstract The pecan weevil, Curculio caryae (Horn), is a major pest of pecans in the Southeastern United States. Entomopathogenic nematodes and fungi are potential alternatives to chemical insecticides for C. caryae control. Our objective was to survey pecan orchards in the southeastern United States for entomopathogenic nematodes and fungi and determine the virulence of the new isolates to C. caryae larvae. Soil was collected from 105 sites in 21 orchards in Arkansas, Georgia, Louisiana, and Mississippi. Entomopathogens were isolated by exposing soil to C. caryae and greater wax moth larvae, Galleria mellonella, (L.). We isolated entomopathogenic fungi and nematodes from 16 and 6 of the 21 orchards surveyed, respectively. The entomopathogenic fungi included Beauveria bassiana (Balsamo) Vuillemin and Metarhizium anisopliae (Metschnikoff) Sorokin, and nematodes included Heterorhabditis bacteriophora Poinar, Steinernema carpocapsae (Weiser), Steinernema glaseri (Steiner), and Steinernema rarum (Doucet). This is the first report of Steinernema rarum in the United States. Soil characteristics in orchards were analyzed for pH, organic matter, and nutrients; we detected a negative relationship between fungal occurrence and manganese levels in soil and a positive relationship between M. anisopliae occurrence and calcium or magnesium levels. In laboratory assays, virulence of 15 nematode and 22 fungal isolates to C. caryae larvae was tested in small plastic cups containing soil. Results indicated poor susceptibility of the C. caryae larvae to entomopathogenic nematodes. Several fungal isolates that caused significantly higher mortality in C. caryae larvae than other strains (including a commercial strain of B. bassiana) should be investigated further as potential control agents of C. caryae.

From Asian curiosity to eruptive American pest: Megacopta cribraria (Hemiptera: Plataspidae) and prospects for its biological control

The kudzu bug or bean plataspid, Megacopta cribraria (Fabricius), is native to Asia where it appears to be widely distributed (although the taxonomy is not entirely clear), but is infrequently a pest of legumes. This bug appeared in 2009 in the southeastern United States, where it is closely associated with kudzu, Pueraria montana Lour. [Merr.] variety lobata [Willd.] Maesen & S. Almeida. However, the insect has become a consistent economic pest of soybeans, Glycine max (L.) Merr., and some other leguminous crops in areas where large numbers can build in kudzu, in addition to being a considerable nuisance in urban landscapes where kudzu occurs. The insect has remarkable capacity for movement and has spread rapidly from nine Georgia counties in 2009 to seven states in 2012. Despite being a nuisance in urban areas and a crop pest, high populations of the bug also reduce the biomass of kudzu, which is itself a seriously problematic invasive weed, complicating the status of M. cribraria in its expanded range. Extant predators and a pathogen in the US have been observed attacking kudzu bugs in the laboratory and field, but no parasitism of eggs or nymphs has been observed to date. A single record of parasitism of an adult kudzu bug by a tachinid fly is known from the US, but no other adult parasitism has been observed in the US or elsewhere. Extant enemies may eventually significantly reduce the bug’s populations, but at present native enemies appear to be insufficient for the task, and exotic enemies from the kudzu bug’s native range may offer the best possibility for effective biological control in the US. Based on the available literature, the best option for an importation biological control program appears to be the platygastrid egg parasitoid Paratelenomus saccharalis (Dodd) because of its apparent host specificity, intimate biological linkages with M. cribraria, and wide geographic distribution in the Eastern Hemisphere. Other natural enemies may eventually emerge as good candidates for importation, but at present P. saccharalis appears to be the most promising.

A Review of the Scientific Literature on Fungus Gnats (Diptera: Sciaridae) in the Genus Bradysia2

The majority of the literature concerning fungus gnats in the genus Bradysia (Family Sciaridae) can be divided into two groups, addressing their cytogenetics or their role as economically important pests. Cytological anomalies in sciarids are recognized in (1) chromosome complement, (2) differential chromosome contributions of the sperm and egg, (3) alteration of chromosome complement during embryogenesis, (4) and alteration during gametogenesis. The literature concerning these cytological events is reviewed within the context of the development of the science of cytogenetics and as they relate to the taxonomy and systematics of this group. Although species of Bradysia were recognized as pests of various seedling plants over a century ago, their economic importance in plant and mushroom production was largely overlooked until recently. A review of the scientific literature on the biology and management of the sciarids indicates that members of the genus Bradysia may be especially pestiferous in greenhouse...

Confirmed Distribution and Occurrence of Megacopta cribraria (F.) (Hemiptera: Heteroptera: Plataspidae) in the Southeastern United States

Abstract Megacopta cribraria (F) (Hemiptera: Heteroptera: Plataspidae) was first discovered in North America in 9 counties in northeastern Georgia (USA) in October 2009. By the end of 2012, surveys conducted in Georgia and neighboring states confirmed that the insect had spread into 383 additional counties in the southeastern U.S., including the states of Alabama, Florida, Georgia, Mississippi, North Carolina, South Carolina, Tennessee and Virginia. It was reported from 33 species of plants representing 15 taxonomic families in these surveys, with 17 of those from the family Fabaceae (legumes). Kudzu (Pueraria montana Lour. [Merr.] variety lobata [Willd.] Maesen & S. Almeida) was the most frequently reported host. All life stages of the insect were observed only on kudzu and soybean (Glycine max [L.] Merrill) which, to date, are the only confirmed reproductive host plants of M. cribraria in its expanded North American range.

Parasitism of Phyllophaga hirticula (Coleoptera : Scarabaeidae) by Heterorhabditis heliothidis and Steinernema carpocapsae

Abstract A series of laboratory assays and tests was conducted to determine the route(s) of parasitism of Phyllophaga hirticula larvae by the entomogenous nematodes Steinernema carpocapsae and Heterorhabditis heliothidis as well as the mechanism(s) responsible for the relative resistance of these grubs to nematode parasitism. Scanning electron microscopy (SEM) showed that the spiracles were cribiform in structure with a spiracular plate punctured with aeropyles that were the only openings to the trachae. These openings were too small (6 × 3 μm) for entry by nematodes measuring 25 μm in diameter. Penetration of the cuticle was not observed. Parasitism was higher when nematodes entered through the mouth rather than the anus. Nematodes penetrated the wall of midguts dissected from Galleria mellonella larvae faster than midgut walls dissected from P. hirticula larvae. Histological studies showed the peritrophic membrane to be much denser in P. hirticula than in G. mellonella and, thus, probably acted as a barrier to nematode parasitism. Video tapes of nematode behavior within excised midguts of G. mellonella showed that penetration of the midgut wall was due to random movements of the nematodes within the midgut. Once a hole was created by a nematode, others also escaped through the opening. However, food passing through the alimentary tract may remove a large proportion of the nematodes prior to penetration of the wall.

Discovery of Paratelenomus saccharalis (Dodd) (Hymenoptera: Platygastridae), an Egg Parasitoid of Megacopta cribraria F. (Hemiptera: Plataspidae) in its Expanded North American Range

Megacopta cribraria F. (Hemiptera: Plataspidae), commonly known as the kudzu bug or bean plataspid, was fi rst discovered in the Western Hemisphere in October 2009 (Eger et al. 2010. Insecta Mundi 121:1 11). The plataspid quickly spread from the 9 northeastern Georgia counties in which it was initially confi rmed into 383 additional counties in Alabama, Florida, Georgia, Mississippi, North Carolina, South Carolina, Tennessee, and Virginia by the end of 2012 (Gardner et al. 2013. J. Entomol. Sci. 48:118 127). Subsequent reports show that the insect has now been confi rmed in 4 additional states – Delaware, Kentucky, Louisiana, and Maryland – and the District of Columbia, bringing the total number of confi rmed states to 12 (W.A. Gardner, unpubl. data). Ruberson et al. (2013, Appl. Entomol. Zool. 48:3 13) reported that several existing generalist predators and a single entomogenous pathogen had been recorded as attacking M. cribraria in its expanded range in the southeastern U.S. They also reported a tachinid, Phasia robertsonii (Townsend), parasitizing a single adult M. cribraria in 2012, but no parasitism of eggs or immatures was observed in their 2010 and 2011 surveys in Georgia. Golec and Hu (2013, J. Entomol. Sci. 48: In Press) discovered Strongygaster triangulifer (Loew) (Diptera: Tachnidae) parasitizing individual adults (mean parasitism = 5.14%; n = 214) collected from soybean, Glycine max (L.) Merr.,

Susceptibility of the Two-Spotted Spider Mite, Tetranychus Urticae Koch, to the Fungal Pathogen Hirsutella Thompsonii Fisher

Laboratory bioassays determined the susceptibility of the two-spotted spider mite, Tetranychus urticae Koch, to Hirsutella thompsonii thompsonii Fisher. Direct placement of conidia onto mites which were placed on bean leaf discs floating on distilled water in covered petri dishes yielded a mean mortality of 96.5%. Mortality of mites placed on leaf discs cut from bean plants previously sprayed with a commercial formulation of the bioacaricide (Mycar, Abbott Laboratories, North Chicago, IL) and placed in the covered dishes ranged from ca. 24 to 99%. No significant response to dose of Mycar occurred at the rates tested (1.2-9.6 g/liter). Under greenhouse conditions (22-30@*C; 50-90% RH), the formulated material failed to either sporulate on sprayed foliage or cause mite mortality. Raising humidity levels with intermittent misting of foliage increased sporulation of the fungal inoculum on plant surfaces, but no infections occurred in mites on those plants.

Pathogens for the suppression of the fall armyworm.

The fall armyworm, Spodoptera frugiperda (J. E. Smith), is susceptible to at least 16 species of entomogenous pathogens including viruses, fungi, protozoa, nematodes, and a bacterium. Many of these occur naturally in fall armyworm populations. Some cause natural epizootics. The few attempts to suppress fall armyworm populations on agricultural crops by application of pathogens have had various degrees of success.

Activity of bifenthrin, chlorfenapyr, fipronil, and thiamethoxam against Argentine ants (Hymenoptera: Formicidae).

ABSTRACT Bifenthrin, chlorfenapyr, fipronil, and thiamethoxam were evaluated for activity against the Argentine ant, Linepithema humile (Mayr) (Hymenoptera: Formicidae). Mobility impairment and lethal times were determined after topical treatments. Ants were immobilized most quickly by bifenthrin, followed by chlorfenapyr and thiamethoxam. After 2 h, the number of fipronil-treated ants unable to walk out of test arenas did not differ from control ants. Median lethal time (LT50) after topical treatment was lowest in the bifenthrin treatment, followed by thiamethoxam, chlorfenapyr, and then fipronil. Mortality due to horizontal exposure was evaluated at 10, 20, or 30°C, with topically treated ant corpses serving as donors. There was low to moderate horizontal activity in bifenthrin and chlorfenapyr treatments, with no temperature effect in bifenthrin treatments and a positive temperature effect in chlorfenapyr treatments. Mortality in the fipronil treatments was highest and was positively correlated with temperature. Thiamethoxam treatments did not differ from controls at 10°C, but mortality increased with temperature. To evaluate contact activity, either all of 20% of the ants in a cohort were exposed to insecticide-treated pine needles. In both tests, mortality was highest in fipronil and bifenthrin treatments, followed by thiamethoxam, with lowest mortality in chlorfenapyr treatments. Effectiveness as a barrier was evaluated by providing a choice between bridges treated with insecticide or water. Although bifenthrin did not provide an impenetrable barrier, it was the only treatment having fewer ants than its paired control. Mortality data suggest that lack of recruitment rather than repellency account for this result.