Removing grass clippings reduces bermudagrass mite (Acari: Eriophyidae) infestation during turfgrass regrowth.

Bermudagrass mite (Aceria cynodoniensis Sayed) infestation stunts bermudagrass (Cynodon spp. [Poales: Poaceae]) growth, leading to thinned turf and lower aesthetic and recreational value. Bermudagrass mites cause characteristic symptoms called witch's brooms, including shortened internodes and leaves and the proliferation of tillers. Grass clippings produced by mowing or scalping bermudagrass harbor mites, which abandon the desiccating grass clippings and spread to surrounding turfgrass. Dropped grass clippings can lead to infestation of new turfgrass. Nursery experiments were conducted with potted bermudagrass to determine the effect of removing witch's brooms or grass clippings after scalping on witch's broom densities on the recovering bermudagrass. Additionally, laboratory experiments were conducted to assess the potential for mites to abandon detached witch's brooms and to evaluate mite survival after leaving their hosts. The number of initial witch's brooms and individually removing witch's brooms did not affect subsequent witch's broom densities, suggesting that infested but asymptomatic terminals later developed into witch's brooms. Removing grass clippings after scalping reduced witch's broom densities by over 65% in two trials. Most mites (96%) abandoned witch's brooms within 48 h after detaching witch's brooms, and adult mites survived an average of 5.6 h after removal from the host plant. Removing clippings after scalping may improve bermudagrass mite management and limit damage on the recovering turfgrass. Additionally, clippings resulting from regular mowing or scalping should be disposed of properly because this study demonstrates that mites abandon desiccating host plants and survive sufficiently long to infest surrounding turfgrass.

Bermudagrass mite (Acari: Eriophyidae) infestation worsens in response to increasing nitrogen fertility and decreasing irrigation volume but not mowing height.

Severe bermudagrass mite (Aceria cynodoniensis Sayed) infestation stunts turfgrass growth and reduces the aesthetic and recreational value of managed bermudagrass. Management practices, such as fertilization, mowing, and irrigation, may impact bermudagrass mite infestation and damage, but empirical evidence is lacking. Two 20 wk experiments were conducted with potted bermudagrass in a greenhouse or nursery to evaluate the effect of varying nitrogen rates (0, 24.5, or 49 kg N/ha), mowing heights (1.3, 2.5, 3.8, or 5 cm), and irrigation rates (60%, 100%, or 140% evapotranspiration [ET] rate) on the densities of witch's brooms (i.e., stunted and deformed terminals symptomatic of infestation) and bermudagrass mites. Increasing nitrogen fertility from 0 to 49 kg N/ha increased witch's broom and bermudagrass mite densities by 292% and 339%, respectively. Bermudagrass fertilized with nitrogen maintained higher turf quality than unfertilized grass despite greater mite damage. Decreasing irrigation from 140% to 60% of the ET rate also increased witch's broom densities by 124%. Mowing height did not consistently affect witch's broom or mite densities. Witch's broom and mite densities were positively correlated and followed a general trend with greater densities in April-August and a decline in densities in August-October. These findings suggest that nitrogen fertilization and water stress influence bermudagrass mite damage. Thus, limiting nitrogen fertilization to a level necessary to maintain turfgrass health and quality (0.5 kg N/ha) and minimizing turfgrass water stress can complement current chemical control strategies as part of an integrated pest management program.

Growing media is the major source of damaging population of Systena frontalis (Coleoptera: Chrysomelidae) in ornamental plant nurseries.

Systena frontalis (F.) (Coleoptera: Chrysomelidae) is a serious pest of ornamental shrubs in containerized ornamental plant nurseries in the central and eastern United States. Adult S. frontalis cause numerous shot holes on foliage, rendering ornamental plants unmarketable. Growing media in plant containers is an overwintering site of S. frontalis, but the extent to which adults emerging from the growing media can damage the plants is unclear. Experiments were conducted on panicled hydrangea (Hydrangea paniculata Siebold) in Georgia, North Carolina, and Virginia nurseries in the spring of 2021 and 2022 to answer this question. The treatments were (i) canopy caged, (ii) whole-plant caged, and (iii) noncaged hydrangea plants. In all 3 states, beetle abundance and feeding damage found on caged (whole plant) and noncaged plants were significantly greater than those on plants where only the canopy was caged. In most sites and years, beetle abundance and feeding damage were not significantly different between the noncaged plants and those where the canopy and containers were caged, suggesting that the majority of S. frontalis emerged from the growing media and the majority of damage suffered by the hydrangea plants were caused by beetles emerging from the containers. Because growing media contributed to a significant proportion of the S. frontalis population in a nursery, treatment targeting larvae in the growing media should be a critical component of a holistic management plan against S. frontalis.

Persistence and metabolism of the diamide insecticide cyantraniliprole in tomato plants.

Plant uptake and metabolism of pesticides are complex and dynamic processes, which contribute to the overall toxicity of the pesticides. We investigated the metabolic fate of cyantraniliprole, a new diamide class of insecticide, during various growth stages of tomato. Cyantraniliprole was the major residue in leaves, flowers, and fruits, with the relative metabolite-to-parent ratios maintained at < 10% up to 28 days after treatment (DAT). Mature leaves contained consistently higher residues of cyantraniliprole than young leaves throughout the study. Flowers contained the highest cyantraniliprole residues up to 21 DAT, then gradually decreased. Immature green fruits had the highest cyantraniliprole residues (5.3 ± 0.7 ng/g; 42 DAT), and decreased toward red ripening stages (1.4 ± 0.2 ng/g; 84 DAT). Metabolism of cyantraniliprole primarily occurred in the foliage, where 21 metabolites were tentatively identified. Flowers and fruits contained 14 and four of these metabolites, respectively. Major transformation pathways were characterized by ring closure, followed by N-demethylation, and glycosylation. Additionally, plant metabolism of cyantraniliprole was also associated with several minor phase-I, phase-II, and breakdown metabolites. The occurrence of these metabolites in plants varied as a function of tissue types and their developmental stages. Our study highlights a tissue-specific biotransformation and accumulation of metabolites of cyantraniliprole in tomato.

Can Generalist Predators Control Bemisia tabaci?

The whitefly, Bemisia tabaci, has developed resistance to many insecticides, renewing interest in the biological control of this global pest. Generalist predators might contribute to whitefly suppression if they commonly occur in infested fields and generally complement rather than interfere with specialized natural enemies. Here, we review literature from the last 20 years, across US cropping systems, which considers the impacts of generalist predators on B. tabaci. Laboratory feeding trials and molecular gut content analysis suggest that at least 30 different generalist predator species willingly and/or regularly feed on these whiteflies. Nine of these predators appear to be particularly impactful, and a higher abundance of a few of these predator species has been shown to correlate with greater B. tabaci predation in the field. Predator species often occupy complementary feeding niches, which would be expected to strengthen biocontrol, although intraguild predation is also common and might be disruptive. Overall, our review suggests that a bio-diverse community of generalist predators commonly attacks B. tabaci, with the potential to exert substantial control in the field. The key challenge will be to develop reduced-spray plans so that generalist predators, and other more specialized natural enemies, are abundant enough that their biocontrol potential is realized.

Nitrogen Fertilization of Host Plant Influenced the Nutritional Status and Life History of the Madeira Mealybug (Hemiptera: Pseudococcidae).

Insect herbivores, especially sap-feeders, are sensitive to host-plant nitrogen quantity. However, past studies present contradicting results on sap-feeder life history traits influenced by plant nitrogen supplementation. This study analyzed the bottom-up effects of below-recommended nitrogen fertilization rates (0, 0.021, 0.048, and 0.091 g N/liter) on life history and total protein and lipid contents of a significant pest species, Phenacoccus madeirensis Green (the Madeira mealybug) (Hemiptera: Pseudococcidae). Developmental durations and survivorship from egg to adulthood of male and female mealybugs were similar across nitrogen fertilization levels. Females reared on plants fertilized at 0.021, 0.048, and 0.091 g N/liter produced, respectively, 152, 142, and 67% more eggs than females reared on unfertilized plants. Finite and intrinsic rates of increase and net reproductive rates of females were similar among the nitrogen fertilization levels, whereas the generation times of females from fertilized plants were significantly shorter than those from the unfertilized plants. Lipid contents of adult females and eggs, and average adult female protein content were similar across the nitrogen treatments. Average egg protein content increased with increasing host-plant fertilization rate. These results suggest that the response of the female Madeira mealybug to nitrogen fertilization is complex and may involve trade-offs and nutrient re-allocation.

Natural Enemy Communities and Biological Control of Parthenolecanium spp. (Hemiptera: Coccidae) in the Southeastern United States.

We documented the species composition, seasonal ecology, and impacts of parasitoids and predators of Parthenolecanium corni (Bouché) and P. quercifex (Fitch) (Hemiptera: Coccidae) in the urban landscapes of Georgia, North Carolina, South Carolina, and Virginia, United States. Twenty-one parasitoid morphospecies and 12 predator species were collected through rearing, beat sheet, and sticky card trapping. Coccophagus lycimnia (Walker) (Hymenoptera: Aphelinidae) was the most abundant parasitoid species in South Carolina, North Carolina, and Virginia, whereas Metaphycus sp. 2 (Hymenoptera: Encyrtidae) was the most abundant species in Georgia. Parasitism rates ranged from 59 to 92% in the nymphal population and 27 to 84% in the adult population in South Carolina. Blastothrix sp. 1 (Hymenoptera: Encyrtidae), C. lycimnia, Encyrtus sp. 1 (Hymenoptera: Encyrtidae), Eunotus sp., and Pachyneuron sp. (both Hymenoptera: Pteromalidae) emerged from adult scale insects and significantly reduced the fecundity of parasitized scale insects. Coccophagus lycimnia was the only parasitoid species emerged from nymphs. Hyperaspis signata (Olivier) species group, Chilocorus stigma Say (both Coleoptera: Coccinellidae), and Chrysoperla rufilabris (Burmeister) (Neuroptera: Chrysopidae) were the most abundant predators in South Carolina. The majority of natural enemies (87% of parasitoids and 82% of predators) were active from late March to late August and from late April to late October, respectively.

Life History of Parthenolecanium spp. (Hemiptera: Coccidae) in Urban Landscapes of the Southeastern United States.

This study was conducted to better understand the life history of Parthenolecanium corni (Bouché) and Parthenolecanium quercifex (Fitch) (Hemiptera: Coccidae), and to develop degree-day models for crawler emergence of the two soft scale species in Georgia, North Carolina, South Carolina, and Virginia. Both species were univoltine in the southeastern United States. In South Carolina, eggs hatched from mid-April to early June; second instars began to appear in September and migrated to twigs to overwinter in October; and third instars and adults appeared in mid-March to early April. Each parthenogenetic female produced on average 1,026 ± 52 eggs. Fecundity was positively correlated to the fresh weight, length, width, and height of gravid females. Gross reproductive rate (GRR) was 695.98 ± 79.34 ♀/♀, net reproductive rate (Rº) was 126.36 ± 19.03 ♀/♀, mean generation time (TG) was 52.61 ± 0.05 wk, intrinsic rate of increase (rm) was 0.04 ♀/♀/wk, and finite rate of increase (λ) was 1.04 times per week. Crawlers first occurred across Georgia, North Carolina, South Carolina, and Virginia in 2011-2013 when 524-596 Celsius-degree-days (DDC) had been accumulated with the single sine estimation method, or 411-479 DDC with the simple average method, at the base temperature of 12.8 °C and the start date of 1 January. These regional models accurately predicted the date of crawler emergence within 1 wk of the actual emergence in 2014.

A Comparison of Trap Types for Assessing Diversity of Scarabaeoidea on South Carolina Golf Courses.

A 2-yr survey was conducted on golf courses in South Carolina to 1) document the species richness and seasonal activity of Scarabaeoidea; 2) assess any species compositional differences among three trap types (ultraviolet light, unbaited flight-intercept, and unbaited pitfall); and 3) identify any dominant taxa in each trap type. A total of 74,326 scarabaeoid beetles were captured, of which 77.4% were Aphodiinae (not identified to species). The remaining specimens belong to 104 species in 47 genera and 6 families. The most abundant species were Cyclocephala lurida Bland, Dyscinetus morator (F.), Euetheola humilis (Burmeister), Hybosorus illigeri Reiche, and Maladera castanea (Arrow). In all trap types, >90% of all specimens and taxa were collected between April and August. Ultraviolet light traps collected ∼94% of total specimens consisting of 83 taxa (of which 51 were unique to this trap type), whereas flight-intercept traps captured ∼2% of all specimens representing 53 taxa (18 of which were unique), and pitfall traps captured ∼4% of all specimens representing 15 taxa (no unique species; all species also captured by ultraviolet light traps). Indicator species analysis identified 2-3 and 10-13 taxa that were most frequently collected by flight-intercept and ultraviolet light traps, respectively. Flight-intercept traps complemented ultraviolet light traps by capturing more species of dung and carrion beetles and diurnal phytophagous scarab beetles. Results suggested that a similar survey for domestic or exotic scarabaeoid beetles in turfgrass systems should be conducted between April and August using ultraviolet light and flight-intercept traps at 13-58 sites.

General Biology and Current Management Approaches of Soft Scale Pests (Hemiptera: Coccidae).

We summarize the economic importance, biology, and management of soft scales, focusing on pests of agricultural, horticultural, and silvicultural crops in outdoor production systems and urban landscapes. We also provide summaries on voltinism, crawler emergence timing, and predictive models for crawler emergence to assist in developing soft scale management programs. Phloem-feeding soft scale pests cause direct (e.g., injuries to plant tissues and removal of nutrients) and indirect damage (e.g., reduction in photosynthesis and aesthetic value by honeydew and sooty mold). Variations in life cycle, reproduction, fecundity, and behavior exist among congenerics due to host, environmental, climatic, and geographical variations. Sampling of soft scale pests involves sighting the insects or their damage, and assessing their abundance. Crawlers of most univoltine species emerge in the spring and the summer. Degree-day models and plant phenological indicators help determine the initiation of sampling and treatment against crawlers (the life stage most vulnerable to contact insecticides). The efficacy of cultural management tactics, such as fertilization, pruning, and irrigation, in reducing soft scale abundance is poorly documented. A large number of parasitoids and predators attack soft scale populations in the field; therefore, natural enemy conservation by using selective insecticides is important. Systemic insecticides provide greater flexibility in application method and timing, and have longer residual longevity than contact insecticides. Application timing of contact insecticides that coincides with crawler emergence is most effective in reducing soft scale abundance.

Assessing the integrated pest management practices of southeastern US ornamental nursery operations.

BACKGROUND: The Southern Nursery Integrated Pest Management (SNIPM) working group surveyed ornamental nursery crop growers in the southeastern United States to determine their pest management practices. Respondents answered questions about monitoring practices for insects, diseases and weeds, prevention techniques, intervention decisions, concerns about IPM and educational opportunities. Survey respondents were categorized into three groups based on IPM knowledge and pest management practices adopted. RESULTS: The three groups differed in the use of standardized sampling plans for scouting pests, in monitoring techniques, e.g. sticky cards, phenology and growing degree days, in record-keeping, in the use of spot-spraying and in the number of samples sent to a diagnostic clinic for identification and management recommendation. CONCLUSIONS: Stronger emphasis is needed on deliberate scouting techniques and tools to monitor pest populations to provide earlier pest detection and greater flexibility of management options. Most respondents thought that IPM was effective and beneficial for both the environment and employees, but had concerns about the ability of natural enemies to control insect pests, and about the availability and effectiveness of alternatives to chemical controls. Research and field demonstration is needed for selecting appropriate natural enemies for augmentative biological control. Two groups utilized cooperative extension almost exclusively, which would be an avenue for educating those respondents.

Life history of the mealybug, Maconellicoccus hirsutus (Hemiptera: Pseudococcidae), at constant temperatures.

Important life history parameters of the mealybug, Maconellicoccus hirsutus (Green), were characterized on hibiscus (Hibiscus rosa-sinensis L.) cuttings at six constant temperatures between 15 and 35 degrees C. The development of M. hirsutus was the fastest at 27 degrees C, where the mealybugs completed development in approximately 29 d. The lower (T(min)) and upper (T(max)) developmental thresholds and the optimal developmental temperature (T(opt)) for the development of female mealybugs were estimated as 14.5, 35, and 29 degrees C, respectively. The thermal constant (K), which is the number of temperature-day or degree-day units required for development, of the females was 347 DD. The original distribution range prediction (based on T(min) = 17.5 degrees C and K = 300 DD) indicated that M. hirsutus could complete at least one generation in all of the continental United States. However, results of this study suggested that the distribution range of M. hirsutus may expand northward because of the lower T(min), and the predicted number of generations in a year may be lower because of the higher K required to complete each generation. The average cumulative survival rate of M. hirsutus at 25 and 27 degrees C was 72%, which was significantly higher than 51 and 62% at 20 and 30 degrees C, respectively. M. hirsutus reproduced sexually, with each mated female producing 260-300 eggs between 20 and 27 degrees C but only approximately 100 eggs at 30 degrees C. Female longevity was reduced from 28 d at 20 degrees C to 19-21 d at 25-30 degrees C. At 27 degrees C, the net reproductive rate (R(o)) was estimated at 165 female symbol/female symbol, the intrinsic rate of population increase (r(m)) was 0.119 (female symbol/female symbol/d), the generation time (T(G)) was 43 d, and the doubling time (DT) was 5.8 d. The life table statistics suggested that the currently released biological control agents, which have higher r(m) than M. hirsutus, will be able to complete more generations than the mealybug within the tested temperature range; thus, they are effective against M. hirsutus.

Effect of temperature on the life history of the mealybug Paracoccus marginatus (Hemiptera: Pseudococcidae).

Effect of temperature on the life history of the mealybug Paracoccus marginatus Williams & Granara de Willink (Hemiptera: Pseudococcidae) was investigated in the laboratory. P. marginatus was able to develop and complete its life cycle at 18, 20, 25, and 30 +/- 1 degrees C. At 15, 34, and 35 degrees C, the eggs hatched after 27.5, 5.9, and 5.5 d of incubation, respectively, but further development of the first-instar nymphs was arrested. No eggs hatched at 37 degrees C. The developmental time for egg to adult was the longest at 18 degrees C for both males and females. Approximately 80-90% of the eggs survived between 20 and 30 degrees C. The highest fecundity was at 25 degrees C with each female producing an average of 300 eggs. Adult longevity, and preoviposition and oviposition periods increased with decreasing temperature up to 25 degrees C. The proportion of females was approximately 42% at 25 degrees C and was between 70 and 80% at 18, 20, and 30 degrees C. Adult males and females required 303.0 and 294.1 degree-days (DD), respectively, to complete their development. The estimated minimum temperature thresholds for the adult males and females were 14.5 and 13.9 degrees C, respectively. For adult males, the estimated optimum and maximum temperature thresholds were 28.7 and 31.9 degrees C; and for adult females, they were 28.4 and 32.1 degrees C, respectively. The ability of P. marginatus to develop, survive, and reproduce successfully between 18 and 30 degrees C suggests that it has the capability to develop and establish in areas within this temperature range.