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Twospotted spider mite, Tetranychus urticae Koch (Trombidiformes: Tetranychidae) is a key pest of vegetable crops in the southeastern US. Spider mites can cause significant yield loss in tomato due to reduced photosynthetic capacity and direct feeding damage. Use of acaricides is the primary control method, but acaricide resistance is a serious concern. We sought to characterize efficacy of acaricides registered for use on tomato by conducting 2 field trials in South Carolina in 2015 and 2016. The most effective treatments were abamectin, fenpyroximate, and cyflumetofen. Bifenazate and bifenthrin had lower efficacy than other products, and acaricide resistance was a suspected cause. Therefore, 3 spider mite populations were collected from grower fields in 2017, subjected to concentration-response screening, and compared to a known-susceptible population. Probit analysis revealed that all populations were resistant to bifenthrin at levels that would likely result in field failure. All populations were resistant to abamectin, with the LC50 of 1 population above field rate. Resistance to acequinocyl and spiromesifen also was present in all populations, but LC50 values were well below field rate. Based on our results and known non-target effects of bifenthrin and abamectin on predatory mites, growers should avoid using these products for spider mite management. Poor performance of bifenazate in the efficacy study could not be attributed to resistance, although it is possible that the populations from the efficacy study were resistant and those screened for resistance were not. Many acaricides registered in tomato appear to be effective for mite management in South Carolina.
The red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae), originally is from South America and currently infests over 128 million ha in the US. Its presence has caused significant social, environmental, and economic impacts. Over the decades, chemical insecticides have controlled these pest ants successfully. However, this method is costly and unsustainable because red imported fire ant re-establishes colonies quickly after chemical application. Thus, it is important to develop additional strategies for managing the red imported fire ant in the US. Solenopsis invicta virus 3 is a positive-sense, single-stranded RNA virus specific for S. invicta that offers promise as a classical biological control agent or biopesticide for control of S. invicta. Surveys were conducted to determine the prevalence of Solenopsis invicta virus 3 in alates of S. invicta collected from 5 urban areas (Tallahassee, Pensacola, Jacksonville, Gainesville, and Panama City) and 5 adjacent rural areas (Quincy, Jay, Macclenny, Lake City, and Blountstown) of North Florida, USA, using the reverse transcription polymerase chain reaction technique. The prevalence of Solenopsis invicta virus 3 varied widely from city to city. No statistically significant differences in alate infection rate was found between urban and rural cities sampled. Areas in which no infections of Solenopsis invicta virus 3 were detected may be good candidates for the introduction of this virus as a biological control agent to help manage this pest locally.
Varroa destructor Anderson & Trueman (Parasitiformes: Varroidae) is an ectoparasitic pest of the western honey bee (Apis mellifera L.; Hymenoptera: Apidae) colonies. The ability to study all life stages of the mite in a laboratory setting requires one to rear the mite in vitro. This is a crucial step for the advancement in research studies, and the development of management protocols for Varroa. Current practices require that Varroa be collected from field colonies for use in lab-based studies. Traditional collection techniques for obtaining mites from adult bees include using carbon dioxide or a method in which a combination of powdered sugar and shaking dislodges the mites from a group of adult bees (i.e., a “sugar shake”). Herein, we compared 2 mite collection techniques and measured mortality of the mites after collection using the Varroa maintenance system, a tool for maintaining in vitro populations of Varroa on their host. Our results indicate that mites collected using the sugar shake method lived significantly longer (> 6 d, with 20% mortality at 6 d) than did those collected using carbon dioxide (3.9 d, with 66% mortality at 6 d). Carbon dioxide exposure was detrimental to the recovery of Varroa. These data provide critical information on how to collect Varroa properly for use in in vitro survival studies.
Emmanuel A. Torres-Quezada, Jorge Mancebo Marmolejos, Ambrosio Robles Lara, Willy Maurer, José A. González Cuesta, Sarah M. Medrano Carreño, Lorena Lopez
Torula yeast is the most common bait used by growers and agriculture professionals for trapping of tephritid flies in the Dominican Republic. However, the efficiency of the bait is influenced by weather conditions, aging, and contamination with undesirable microorganisms. Thus, additives such as benzalkonium chloride, a quaternary ammonium compound, have been used together with torula yeast as a bait stabilizer. This study evaluated the effect of the addition of benzalkonium chloride to torula yeast bait, and time of renewal in guava orchards for trapping of Caribbean fruit flies (Anastrepha suspensa Loew; Diptera: Tephritidae). A field study was conducted in 2 consecutive 8-wk periods between Oct 2019 and Feb 2020. Six treatments were evaluated based on the type of bait (torula yeast or torula yeast + benzalkonium chloride) and renewal frequency (weekly, biweekly, or without renewal). Treatments were arranged in a randomized complete block design with 4 replications. Data indicated that torula yeast was attractive to 85.2% and 80.2% more males and females of Caribbean fruit flies compared to torula yeast + benzalkonium chloride, respectively. Similarly, traps without renewal attracted an average of 49.8% more females than traps renewed weekly or biweekly, regardless of the bait type. Analysis of both baits showed a rapid decrease in pH of the torula yeast. The addition of benzalkonium chloride may have affected the microbial activity in the solution, leading to reduced decomposition of torula yeast + benzalkonium chloride and, therefore, reduced captures.
Stink bugs (Hemiptera: Pentatomidae) are economic pests of a variety of fruit crops across the southeastern USA, and damage by stink bugs to peaches is common. The landscape surrounding orchards may influence stink bug distribution and dispersal into this commodity, but such patterns may vary over the growing season. Accordingly, stink bug control should be targeted seasonally towards habitats that effectively reduce or prevent damage to peach. In this study, we used pheromone-baited traps to characterize distribution patterns of 2 stink bug species, Euschistus servus (Say) and Euschistus tristigmus (Say) (both Hemiptera: Pentatomidae), in peach orchards and surrounding habitat over 2 seasons at 3 sites in central Georgia, USA. In addition, we used Spatial Analysis by Distance Indices to identify significant aggregations of each species over the duration of the growing seasons. Adults captured in traps differed by species, and distribution patterns varied by habitat and wk sampled. Euschistus servus was commonly found in peaches, whereas E. tristigmus was not. Regardless of orchard or yr, adult E. servus tended to avoid woodland habitat, whereas E. tristigmus tended to prefer this habitat type. Both species increased later in the season in peach orchards with significant spatial aggregations of each detected at all orchards. However, the wk in which aggregations were detected varied by orchard and yr. Across all orchards, E. servus adults clustered mainly in peach trees adjacent to pecan, as well as pine, fallow, and kudzu habitat. Adult E. tristigmus aggregated primarily in woodland, pine, and pecan habitat. Seasonal distribution patterns of E. servus and E. tristigmus suggest that control measures may need to be implemented on a fine spatial scale across peach and non-crop habitats.
Scarab beetles (Coleoptera: Scarabaeidae) are one of the most limiting pests of avocado in Antioquia Department, Colombia. The establishment of management strategies to control these beetles has been difficult because the species causing damage to avocado fruit and young leaves have not been identified. Selected commercial avocado fields were surveyed at different times of d for scarab beetle adults affecting small fruit and young leaves, as well as other plant structures such as flowers, tender buds, stems, and mature leaves. Additionally, ultraviolet light traps were placed at each field to quantify the species captured. After direct scouting of avocado trees, the only scarab beetle species detected causing damage to fruit and young leaves at all sampling sites was Astaena pygidialis Kirsch (Coleoptera: Melolonthinae). Adults were observed chewing the green skin of small fruit causing striations on the fruit and skeletonization of young leaves by chewing the leaf tissue between veins on the upper surface. Other species observed include Anomala cincta Say (Coleoptera: Rutelinae), Charioderma xylina Blanchard, and Strigoderma sp. (all Coleoptera: Rutelinae) associated with flowers, Isonychus sp. (Coleoptera: Melolonthinae) with flower buds, Cyclocephala fulgurata Burmeister (Coleoptera: Dynastinae) with tender buds, stems and flowers, and Astaena valida Burmeister and Plectris pavida (Burmeister) (both Coleoptera: Melolonthinae) with mature leaves. The species detected through scouting also were captured with light traps. The dominant species captured with light traps was Phyllophaga obsoleta (Blanchard) (Coleoptera: Melolonthinae), which was not observed causing damage to avocado fruit or young leaves. Correct identification of the species is the key to establish adequate sampling and management strategies for these scarab beetles in avocado crops.
In North America, monitoring for Agriotes spp. click beetles typically has been done using Vernon beetle traps baited with bubble cap sex pheromone lures. This trap and lure are no longer produced commercially and a new trap, the Vernon pitfall trap, and lure design are used now for both invasive Agriotes and native pest species. Herein we compare the 2 trapping methods for Agriotes sputator (L.) (Coleoptera: Elateridae), and provide a calibration factor between them to allow comparison of survey results using the different methods. When deployed for the entire swarming season, Vernon pitfall traps fitted with the new capsule lures collect 0.7× as many A. sputator as Vernon beetle traps fitted with the bubble cap lures, and Vernon beetle traps fitted with capsule lures collect 0.5× as many beetles as Vernon beetle traps fitted with bubble cap lures. Unlike bubble cap lures, however, capsule-style lures need to be primed (maintained at room temperature for 3 wk) before deployment in the field, or else their initial attractiveness will be limited and trap catches will not be representative of populations present at the time. In addition, results from field studies indicate that these capsule lures deplete over the swarming season, and depending on the trapping objective (e.g., mass trapping) may need to be replaced after 5 to 6 wk of deployment. Increasing the lure load to 2× or 4× the regular 40 µL geranyl butanoate, or the capsule container size from 1.0 to 2.5 mL, did not significantly increase the number of A. sputator collected.
Surveys of arthropods associated with hops at the University of Florida's Gulf Coast Research and Education Center, Wimauma, Florida, USA, from 2016 to 2020 reveal that spider mites are the primary pest of the crop. Lepidoptera and lace bugs also were observed causing occasional damage to the crop. Whiteflies and thrips have been observed on the crop in low numbers. The tall (5.5 m) canopy of the hops trellis creates a challenge to applying insecticides with adequate coverage. Sampling data indicate that spider mite densities tend to be higher in the upper canopy than at ground level. Efforts to control spider mites with releases of the commercially available predator Phytoseiulus persimilis showed promise. Naturally occurring spider mite predators observed on hops at Gulf Coast Research and Education Center include Stethorus sp., Neoseiulus sp., Orius sp., and trash bugs.
The twin flagged jumping spider, Anasaitis canosa (Walckenaer) (Araneae: Salticidae) is a common ant-predating spider whose diet has been quantified previously only in the laboratory. We investigated the diet of this spider species in the field, as well as approximated its abundance in the observation area. During 30 d of observation, A. canosa occurred in a density of 2.43 ± 1.35 spiders per m2 where 32 attacks were observed on a variety of invertebrate prey. These results parallel previous observations of spiders having greater success killing ant workers opposed to other invertebrates in addition to providing evidence that these spiders likely are not dietary specialists on ant prey.
This study confirmed that some glues used for trapping insects may inhibit mycosis; therefore, care should be taken to select “mycosis-friendly” glues when selecting sticky traps for monitoring entomopathogen infection levels in target pest populations. The results also showed that, rather than attempting to extract small, delicate insects from the glue for further incubation, the entire sticky trap simply can be incubated for the purpose of evaluating mycosis levels.
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