Arthropod abundance and diversity in street trees of south Texas, USA

In urban areas, street trees provide a variety of ecological services, including biodiversity conservation. In this study we examined arthropod diversity on native and non-native street trees sampled during the fall of 2010 and spring of 2011 in McAllen, Texas, one of the most rapidly growing urban areas in the country. Eighty-eight street trees were sampled by removing arthropods from the lower canopy foliage using a hand held vacuum. Arthropods were collected into nylon bags, identified to order, and counted by morphospecies. Overall, street trees supported a significant and diverse population of arthropods: a total of 1,971 arthropods were collected, from which 12 different orders and 102 different morphospecies were identified. We found arthropod abundance was higher on street trees native to the Lower Rio Grande Valley compared to non-native trees, especially for beetles, wasps, bees, ants, and spiders. This difference was particularly striking in spring when trees were flushed with new growth. The significant deficiency of arthropods on non-native trees is indicative of their relatively low value for maintaining entomological fauna. Local land managers who aim to include biodiversity conservation in their efforts thus should enhance the urban forest through the conservation of existing native remnant trees and promoting the use of native tree species in landscaping

Host range of Tetramesa romana Walker (Hymenoptera: Eurytomidae), a potential biological control of giant reed, Arundo donax L. in North America

The eurytomid wasp, Tetramesa romana Walker was evaluated as a potential biological control agent of the invasive reed grass, Arundo donax in North America. No-choice tests and timed behavioral studies were used to determine the fundamental host range of two genotypes of the wasp collected from Granada, Spain and Perpignan, France. Thirty-five species, including two genotypes of A. donax and seven ecotypes of Phragmites australis, along with closely related grasses, economic grasses and habitat associates were tested. Complete development of both T. romana genotypes was restricted to A. donax and Arundo formosana. The mean number of offspring produced from individual females was significantly greater on the A. donax genotype from Laredo, TX (12.8 ± 3.2) as compared to the genotype from San Juan, TX (3.9 ± 1.0) and A. formosana (0.8 ± 0.4). In behavioral studies, ovipositor probing was observed on 15 of the 35 species but development only occurred on A. donax and A. formosana. Based on our results, the wasp T. romana appears to be specific to the genus Arundo and is unlikely to harm native or cultivated plants in the Americas

Agricultural and Environmental Weeds of South Texas and their Management

The Lower Rio Grande Valley (LRGV) in south Texas is one of the most productive agricultural regions in southern United States. With subtropical climate and highly fertile soils, this region provides a year-round growing condition for crops. Along with citrus, major crops grown in the region are sorghum cotton and corn in the summer and vegetables in winter. Thus, a fallow period of 3-6 months between successive crops is common in the re-gion. Growers in this region report weeds as their number one economic and agronomic problem affecting crop yield and quality and increasing the cost of production and weeds account for the largest annual loss agricultural produce. In addition to the agronomic weeds, South Texas also has invasive non-native plants which result in eco-nomic or environmental consequences. Traditionally, land managers and farmers have depended on chemical and cultural (mowing/cultivation) methods for weed management. These methods are costly, labor intensive and might potentially pose environmental problems. With additional challenges posed by herbicide resistance in weeds and changing weather patterns, weed management is an important consideration for the growers in this region. Under-standing the weed ecology and biology should be part of developing and maintaining an effective weed manage-ment strategy for the LRGV. Here we present a review on the most economically and agronomically important weeds and their management options in the LRGV region

Walking Velocity and Estimated Distance of the Armored Scale Crawler Rhizaspidiotus donacis, a Biological Control Agent for Arundo donax

Arundo scale, Rhizaspidiotus donacis (Leonardi) (Hemiptera: Diaspididae), is an armored scale biological control agent established on the invasive weed, Arundo donax L. (Poaceae; Arundinoideae) at several locations along the Rio Grande in Texas (Goolsby et. al. 2009, Moran and Goolsby 2010, Goolsby et al. 2011, Villarreal et al. 2016). The arundo scale is having significant impact on the target weed in areas where it established (Goolsby and Moran 2019), and no non-target plant use was observed (Goolsby et al. 2020). Armored scale crawlers usually live for less than a day and settle within 1 m of their sessile mother (Beardsley and Gonzalez 1975). Their low level of dispersion led to biological studies of the arundo scale in quarantine before release to quantify aspects of its biology that influenced dispersal. We measured walking velocity, estimated the potential distance a crawler could travel during a 12-hour period, and variations of the attributes for crawlers that emerged over time from different geographical accessions. The information was used to prioritize populations for release at field sites or nearby rearing facility. Three accessions of R. donacis crawlers from France, Italy, and Greece were evaluated (Table 1). Crawlers of each accession were isolated as individuals in gelatin capsules on Monday, Wednesday, and Friday mornings and kept for observation in the laboratory at 23°C and 50% relative humidity. Crawlers in gelatin capsules were observed with the aid of a dissecting microscope (Leica MZ-16). Distances walked were measured using a stage micrometer during 10-second periods. Arundo scale crawlers walked at an average velocity of 0.47 mm per second, which is similar to measurements of crawlers of black scale, Saisettia olea Bern., walking on wax paper at 0.38 mm per second (Quayle 1911). The estimated distance walked by black scale crawlers in 12 hours was 9.1 m, which is similar to arundo scale that ranged from 14.4 to 20.7 m (Table 1). Arundo scale crawlers from different European accessions showed significant differences in mean velocity walked and potential estimated maximum distance during 3 and 12 hours and for days during the week they emerged. Differences might reflect the nutrition of the plant host. All accessions were harvested from A. donax stands with high population levels of R. donacis, so rhizomes and ramets might have been significantly depleted of nutrient reserves which influenced the vigor of crawlers. As expected, crawlers collected on Mondays had the least vigor because some might have been as old as 3 days. Arundo scale crawlers seemed to be capable of traveling as far as 20 m which is the maximum height of an A. donax stem. Although we did not estimate distance for more than 12 hours, the period of time represents the typical life span of an arundo scale crawler (Beardsley and Gonzalez 1975). Dispersal of arundo scale is limited to movement of the crawlers over short distances and displacement of infested rhizomes during flood events. Considering the limited dispersal ability of R. donacis, additional rearing and release might be needed to achieve maximum benefit from this key agent where the weed is invasive and especially over the 350 river miles of the Rio Grande along the Texas-Mexico border

Automatic Camera Trap Classification Using Wildlife-Specific Deep Learning in Nilgai Management

Camera traps provide a low-cost approach to collect data and monitor wildlife across large scales but hand-labeling images at a rate that outpaces accumulation is difficult. Deep learning, a subdiscipline of machine learning and computer science, has been shown to address the issue of automatically classifying camera trap images with a high degree of accuracy. This technique, however, may be less accessible to ecologists, to small scale conservation projects, and has serious limitations. In this study, a simple deep learning model was trained using a dataset of 120,000 images to identify the presence of nilgai Boselaphus tragocamelus, a regionally specific non-native game animal, in camera trap images with an overall accuracy of 97%. A second model was trained to identify 20 groups of animals and 1 group of images without any animals present, labeled as “none”, with an accuracy of 89%. Lastly, the multigroup model was tested on images collected of similar species but in the southwestern United States and resulted in significantly lower precision and recall for each group. This study highlights the potential of deep learning for automating camera trap image processing workflows, provides a brief overview of image-based deep learning, and discusses the often-understated limitations and methodological considerations in the context of wildlife conservation and species monitoring

Development of a remotely activated field sprayer and evaluation of temperature and aeration on the longevity of Steinernema riobrave entomopathogenic nematodes for treatment of cattle fever tick-infested nilgai

A remotely activated field sprayer was developed for application of the entomopathogenic nematode, Steinerne-ma riobrave (Cabanillas, Poinar, and Raulston) for eradication of the southern cattle fever tick, Rhipicephalus microplus (Canestrini) infesting free-ranging nilgai (Boselaphus tragocamelus) in South Texas. The battery pow-ered sprayer is activated by sonic sensors that detect movement of nilgai through fence crossings. An onboard computer operates the sprayer pump and aerator that oxygenates the solution of nematodes. Several types of aeria-tion, agitation, and cooling were tested to prolong the viability of the nematodes in water. Continuous aeration extended the longevity of S. riobrave to more than two weeks as compared to cooling or intermittent agitation. The potential use of nematodes pathogenic to R. microplus dispensed by the remotely activated sprayer to infested nil-gai, and potentially white-tailed deer (Odocoileus virginianus), as part of integrated cattle fever tick eradication efforts is discussed

Development and testing of artificial membranes for rearing of Rhipicephalus microplus, the Southern Cattle Fever Tick

The southern cattle fever tick, Rhipicephalus microplus, is a livestock pest worldwide in tropical and subtropical climates, including South Texas, and can vector Babesia spp., the causal agents of bovine babesiosis. Artificial rearing methods for R. microplus are needed, especially for rearing specialist tick parasitoids that are under evaluation for classical biological control. In this study, we tested the efficiency of artificial feeding of R. microplus larvae, nymphs, and adults on a siliconized substrate (goldbeater’s membrane, lens paper, or Hemotek), or on nonsiliconized goldbeater’s membrane or Hemotek. Other variables tested were a warm water bath, incubator, positioning blood above or below ticks, using various attractants to stimulate attachment to membrane, incubating with or without 5% CO2, changing static blood once a day versus peristaltic pumping of blood, and using heparinized versus defibrinated blood. Peristaltic pumping of blood across the membrane inside the incubator significantly increased larval attachment. We found that up to 25% percent of these life stages would attach to the siliconized goldbeater’s membrane and feed, although none molted or completed their entire life cycle. A red color observable in the “fed” ticks’ legs seemed to indicate that bovine hemoglobin had penetrated the gut and entered the hemolymph of the ticks. We were successful rearing unfed nymphs to the engorged stage, which is the pre-requisite for rearing Ixoidiphagus tick parasitoids. Suggestions for future experimentation for rearing R. microplus on artificial membranes are discussed

Biological Control of Giant Reed (Arundo donax): Economic Aspects

Arundo donax is a large, invasive weed consuming large quantities of water in the riparian area of the Texas Rio Grande Basin. With water availability a concern to the area, the USDA-ARS is investigating biological control agents to increase available water, creating a benefit to both the region’s economy and society in general.Arundo donax, Giant Reed, Water, Economics, Invasive, Environmental Economics and Policy, Resource /Energy Economics and Policy,

Biotic and abiotic factors influencing infestation levels of the arundo leafminer, Lasioptera donacis, in its native range in Mediterranean Europe

Lasioptera donacis is a biological control agent of Arundo donax, which is an invasive weed in the riparian hab-itats of the Rio Grande Basin of Texas and Northern Mexico. Field research was conducted in the native range of L. donacis in Mediterranean Europe to evaluate the biotic and abiotic factors that influence its local infestation levels. Lasioptera donacis feeding damage was documented on 40.4 and 67.8 % of dead and decaying leaf sheaths respectively across all sites. Lasioptera donacis was active in all locations including highly disturbed sites, but showed a slight preference for sites near running freshwater sources and lower infestation levels adjacent to salt water sources. The environmental preferences of L. donacis in Europe are similar to conditions in the Rio Grande Basin and Southwestern U.S. where A. donax is invasive

Horticultural technique for rearing and redistribution of the sessile biological control agent, Rhizaspidiotus donacis on its host plant, Arundo donax

Arundo donax, giant reed is an invasive weed in the riparian habitats of the Rio Grande Basin. A biological control program using specialist insects from the native range in Mediterranean Europe, including the arundo scale, Rhi-zaspidiotus donacis has been implemented. The arundo scale is a sessile insect that spends most of its life cycle affixed to its host plant, thus creating challenges for its rearing and redistribution to field sites. A horticultural technique was developed which allowed for rearing of the scale on small, potted A. donax microplants, which could later be transplanted to field sites. Female scale reach maturity on the microplants and produce mobile crawler scale, which move to adjacent uninfested A. donax plants. Arundo scale were established at 48 sites on the Rio Grande using microplants. This horticultural technique allows for movement of the arundo scale at any stage of its life cycle to field sites to conduct biological control programs for A. donax where it is invasive