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During 2017 and 2018, gardeners at 36 locations across 21 Georgia counties volunteered to be part of the Georgia Pollinator Census project. The goals of the project were to generate a snapshot of pollinator population data while educating gardeners about the importance of pollinators and other beneficial insects and assisting schools with science, technology, engineering, art, and math programming. Effective insect identification training and on-going support were crucial parts of this citizen science project. Insect counting was conducted in September and October on an aster species and another plant species chosen by the participants. Twenty-eight plant taxa were chosen by participants to be frequently visited by pollinators. Analysis of the data indicates a higher number of sightings of bumble bees, Bombus spp. Latrelle (Hymenoptera: Apidae); honey bees, Apis mellifera L. (Hymenoptera: Apidae), and wasps (Hymenoptera: Vespidae) in rural areas and a higher number of sightings of carpenter bees, Xylocopa spp. Latrelle (Hymenoptera: Apidae); flies (Diptera); and “other insects” (e.g., those that did not fall into any of the other seven categories) in urban areas. We also saw an increase in entomological interest among the participants as well as an increase in insect knowledge. This pilot project was used to refine criteria for a larger state-wide census.
The citrus mealybug Planococcus citri (Risso) (Hemiptera: Pseudococcidae) is a major insect pest of greenhouse-grown horticultural crops. The citrus mealybug causes direct damage by feeding on plant leaves, stems, flowers, and fruits, which can lead to substantial economic losses. Consequently, insecticides are used to suppress citrus mealybug populations in greenhouse production systems. However, application factors may influence the efficacy of insecticides in suppressing citrus mealybug populations. Therefore, experiments were conducted under greenhouse conditions to determine the effect of spray volume and application frequency on insecticide efficacy against the citrus mealybug feeding on coleus, Solenostemon scutellarioides (L.) Codd, plants. Four spray volumes (15, 25, 50, and 75 mL), 2 application frequencies (1 or 2 applications), and 3 insecticides (acetamiprid [TriStar®], flonicamid [Aria®], and cyfluthrin [Decathlon®]), each with a different mode of action, were tested. Based on mean percent citrus mealybug mortality, acetamiprid was more effective against citrus mealybugs than flonicamid or cyfluthrin. In the spray volume experiments, acetamiprid applied at 75 mL to each plant resulted in a mean percent citrus mealybug mortality of over 70%. In contrast, flonicamid and cyfluthrin resulted in less than 50% mean citrus mealybug mortality across all experiments. In the application frequency experiments, two spray applications did not result in a significantly higher mean citrus mealybug mortality than one spray application. Our study emphasizes the importance of spray volume and application frequency when using insecticides to suppress citrus mealybug populations.
Tannins are a large group of polyphenolic compounds and natural protective substances for plant survival. The differentially expressed genes (DEGs) of Micromelalopha troglodyta (Graeser) under tannin stress were studied by Solexa sequencing technology. A total of 51,797,038–54,991,822 and 51,674,478–52,307,172 clean reads were obtained from the tannin treatment (TT) library and the control (CK) library transcriptomes, respectively, and assembled into 21,236 nonredundant consensus sequences. The expression of 1,627 unigenes in the TT library was remarkably different from that of the CK library; 885 genes were upregulated, and 742 genes were downregulated (P ≤ 0.001). The expression of 18 DEGs was detected by real-time fluorescent quantitative PCR, and the trend of gene expression was consistent with that of transcriptome data. In the biological process category, the DEGs were primarily related to cellular processes, metabolic processes, and single-organism processes. In the molecular function category, the DEGs were mainly involved in binding and catalytic activity, and in the cellular component category, the DEGs were mainly related to the cell, cell part, and organelle. Pathway enrichment analysis indicated that drug metabolism-cytochrome P450 and glutathione metabolism may be associated with detoxification-related processes under tannin stress, and glutathione S-transferases and other detoxification enzyme genes play an important role in detoxifying tannins in M. troglodyta larvae. This study also provides important resources for further study of the genes related to pesticide targets and metabolic processes in M. troglodyta.
The subterranean termite Reticulitermes chinensis Snyder is an important pest in China. We determined the inhibition of six selected insecticides to acetylcholinesterase (AChE) extracted from R. chinensis. Our results yielded half maximal inhibitory concentrations (I50) for each of the insecticides to be 3.49 × 10–3 M for methomyl, 3.87 × 10–2 M for phoxim, 2.18 × 10–3 M for triazophos, 1.89 × 10–3 M for profenosos, 1.10 × 10–3 M for malathion, and 4.39 × 10–2 M for omethoate. Furthermore, the inhibitory activity of AChE by the six insecticides was increased with the increase of insecticide concentration from 3.3 × 10–7 to 5 × 10–3 M. These results provide a theoretical basis for the management of R. chinensis.
Previous research has indicated that electrostatic radiation may induce biological and physiologic changes in plants and aphids. This study was conducted to determine effects of long-term exposure of electrostatic radiation on biology and feeding behavior of Sitobion avenae (F.). To imitate the natural electrostatic radiation stress, both wheat seeds and S. avenae nymphs (produced within 12 h) were exposed to an electrostatic radiation of 4 kV/cm for 20 min and 5 kV/cm intensity for 40 min, respectively. Controls received no treatment (0 kV/cm). Then, the mean relative growth rate (MRGR) and feeding behavior of the 5th-, 10th-, 15th-, 20th-, 27th-, 33rd-, and 39th-generation aphids were examined, respectively. Data showed that electrostatic radiation exposure within a certain period of time can promote weight increases of S. avenae, but long-term exposure of electrostatic radiation had an adverse effect on the weight gain of aphids. The comparison of the two treatment intensities showed that electrostatic radiation at the intensity of 4 kV/cm for 20 min had a significant influence on the probing behavior of S. avenae. This study initially evaluated the effect of electrostatic radiation on S. avenae from the aspect of nutrient feeding behavior, which further verifies the biological characteristics of electrostatic radiation.
Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) has been phylogenetically divided into several putative species based on nucleotide sequence of mitochondrial cytochrome oxidase 1 (mtCOI). To confirm the putative species among B. tabaci populations in Iran, insects were collected from different regions and plant hosts in Khuzestan province of southwestern Iran, and their mtCOI sequences were determined. DNA polymorphism and phylogenetic analysis of the 10 mtCOI sequences obtained showed four haplotypes among the specimens from Khuzestan province that were identified as the putative species MEAM1-subcladeB. Moreover, specimens previously collected from Iran were found to be members of the MEAM1-subcladeB2. Twelve variable sites were detected throughout the Iran-originated mtCOI sequences contributing to their position on the phylogenetic tree. This is the first study reporting the putative species MEAM1-subcladeB from southwestern Iran.
Ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) inoculate species specific symbiotic fungi into the sapwood of their hosts. Some fungi are innocuous, but others are pathogenic and can kill plants in a short time. The main objectives of this study were to identify ambrosia beetle species found in wholesale and retail nurseries and an apple orchard in western Kentucky and monitor population abundance and phenology of the more common invasive ambrosia beetles. Baker traps baited with ultra-high or standard release ethanol were deployed in late February or March and removed in either fall (2016 and 2017) or August (2018). Sixteen ambrosia beetle species were captured, and eight of them were invasive. The invasive species Cnestus mutilatus (Blandford), Xylosandrus crassiusculus (Motschulsky), Xylosandrus germanus (Blandford), and Xyleborinus saxesenii (Ratzeburg) were the most common and abundant species. The highest counts of these invasive species were recorded from April to May. In addition, we are reporting 13 bark beetle species captured in this study; among them, Phloeotribus dentrifrons (Blackman) and Thysanoes fimbricornis LeConte are reported for the first time for Kentucky, whereas Scolytus multistriatus (Marsham) was the only invasive bark beetle collected.
Rhinotermitidae (Isoptera) is an economically important termite family globally. The family is not monophyletic, and the relationships among some of its taxa remain confusing. The taxonomic status of some subfamilies is likely questionable because of various morphological characters of the soldiers and imagoes. Twenty species in 10 genera, representing all six subfamilies of Rhinotermitidae were studied herein. Morphological phylogenetic trees based on 65 characters and molecular phylogenetic trees based on mitochondrial COII and 16SrRNA genes were reconstructed. The sequence composition and genetic distance were analyzed. Based on these results, Rhinotermitidae is polyphyletic. In the morphological trees, the family was divided into five clades. Heterotermitinae and Coptotermitinae were grouped into the most apical one of them and constituted the sister group to Termitidae in the Bayesian inference (BI) tree. In the combined molecular tree, Rhinotermitidae was divided into three clades. The position of the clade composing Heterotermitinae and Coptotermitinae was the same as in the morphological BI tree. The nucleotide sequence analyses also showed that the genetic distances between Heterotermitinae or Coptotermitinae with Termitidae might be closer than those between Heterotermitinae or Coptotermitinae with other subfamilies in Rhinotermitidae. It is postulated that the relationship of Heterotermitinae and Coptotermitinae with other subfamilies of Rhinotermitidae is not as close as that indicated in the current taxonomic system. They might be the real representative of the intermediate lineage from lower to higher termites. These findings further suggest that Heterotermitinae and Coptotermitinae should be separated from Rhinotermitidae and be upgraded as a whole to family rank.
This study determined the effects of nitrogen (N) and potassium (K) plant fertilizers on the survival and development of fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), on ‘TifEagle’ bermudagrass [Cynodon dactylon (L) Pers. x C. transvaalensis Burtt-Davy]. The treatments were various ratios of N:K: (1) 0:0, (2) 1:0, (3) 2:1, (4) 1:1, (5) 0:1, and (6) 1:2, where 1 = 113.4 g N or K per 92.3 m2. Treatments were applied from May to October in 2018 and 2019 at biweekly intervals via foliar spraying. Neonates of S. frugiperda were introduced to treated plants under laboratory conditions. In 2018, survival was significantly lower in the 0:1, 1:2, 1:0, and 0:0 treatments than in the 2:1 and 1:1 treatments at 10 d and 24 d postintroduction; whereas, in 2019, survival was significantly lower in the 0:0 treatment than in the other treatments at 10 d and 24 d postintroduction. Development of S. frugiperda larvae was significantly faster in the 2:1 treatment than in the 1:1 treatment in both years. Our data indicate that N favors and K discourages the growth and development of S. frugiperda larvae on bermudagrass.
We described the overlap of arthropod communities between agricultural lands and adjacent wetlands using transect sampling, to determine if these juxtapositions might be influencing abundances of beneficial arthropods in agricultural lands. We further assessed experimentally whether these beneficial arthropods migrating from wetlands may potentially enhance crop productivity. Large numbers of predaceous carabid beetles and spiders moved from the wetlands into the agricultural lands; both of these groups can be important to biological control of crop pests. However, our exclusion experiments did not detect significant impacts of these predators on herbivorous insects or on crop productivity. Numerous studies have established that natural habitats adjacent to crop lands serve as refuge to beneficial arthropod communities and enhance overall biodiversity. Wetlands adjacent to agricultural lands appear to serve the same function. Our study suggests that wetlands may provide the ecosystem service of enhancing numbers of arthropods beneficial to agriculture, a service not established previously, and a factor that may motivate farmers to conserve wetlands that they own.
Thanasimus substriatus (Gebler) (Coleoptera: Cleridae) is an important predator of bark beetles (Scolytidae) and has been used in China for the biological control of the larch bark beetle, Ips subelongatus Motschulsky, and the spruce bark beetle, Ips typographus L. In this study, the number, external morphology, and distribution of antennal sensilla of T. substriatus were determined using scanning electron microscopy. The capitate antennae of both sexes consist of the scape, pedicel, and 9 flagellomeres. Two types of sensilla chaetica (SC1 and SC2), 2 types of sensilla trichodea (ST1 and ST2), 3 types of sensilla basiconica (SB1, SB2, SB3), and Böhm's bristles (BB) were identified according to the morphology and fine structure of each type of sensilla in both sexes. No differences in shape, structure, sensilla distribution, and typology were observed between the sexes. The density of sensilla was greater on the last 3 than on the first 8 segments. SC1 and SC2 occurred on all antennal segments in both sexes. SB1 were located only on the last 5 segments of the antennae. SB2 and SB3 were found only on the last 3 segments of the antennae and were absent on the first 8 segments in both sexes. ST1 and ST2 were absent from the scape and pedicel. BB only occurred on the scape and pedicel. The distal antennal sensilla of T. substriatus had notably more sensilla than proximal ones in type and number, indicating this is the main area to detect environmental stimuli for feeding or oviposition.
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