Honey bees (Apis mellifera) may serve as bioindicators of habitat quality for themselves and also other insect pollinators because we can observe, decode, map, and analyze the information encoded in the waggle dance communication behavior, which allows us to know where and when bees are collecting high quality forage. Previously we measured honey bee foraging dynamics for two years (2018-2019) by waggle dance decoding at three geographically distanced sites in Virginia (Blacksburg, Winchester, Suffolk), consisting of different dominant landcover types. Here we use those data on where and when honey bees were finding profitable resources throughout the season to predict the success of a non-Apis bee in these same landscapes. Alfalfa leafcutting bees (Megachile rotundata) are managed, polylectic, solitary, cavity-nesting bees that are widely naturalized in North America. We selected M. rotundata as a model organism to validate the honey bee foraging data because they share some characteristics with other cavity nesting wild bees, but they are a tractable study system because they are commercially reared and can be purchased for study. At each of the three sites, we installed 15 nest box stations, each stocked with nesting materials and 160 M. rotundata cocoons, at varying distances and directions from the original honey bee hive locations. Most importantly, nest box stations were distributed across a range of honey bee foraging propensities, calculated as the mean foraging probability determined from our honey bee waggle dance decoding data, within a 300m buffer around each nest box. We hypothesized that honey bee foraging probability would positively correlate with M. rotundata cocoon production and survival. For two years (2021-2022) from May-August, we monitored the nest boxes and also collected data on the relative abundance of floral resources at each of the 15 stations per site. At the end of each season, we collected nesting materials and counted both M. rotundata along with incidental (i.e., non-M. rotundata) wild bee cocoons. M. rotundata cocoon productivity varied by location (log-likelihood ratio test: χ2 = 311.0, df = 2, p < 0.001), with Winchester as the most productive location (mean cocoon count (95% CI): 26.2 (23.7 to 28.9)), followed by Blacksburg (20.4 (18.2 to 22.9)), and Suffolk (4.4 (3.5 to 5.5)). The abundance of clover, both red and white, had a significant positive effect on ALCB productivity (log-likelihood ratio test: χ2 = 778.36, < 0.001). On the other hand, the number of ALCB cocoons decreased significantly with the count of Trypoxylon wasp cocoons present in the nest boxes (log-likelihood ratio test: χ2 = 54.37, < 0.001). Most importantly, we found that there was an overall negative relationship between honey bee foraging probability and alfalfa leafcutting bee cocoon productivity ((log-likelihood ratio test: χ2 = 55.42, < 0.001), where areas of higher honey bee foraging probability were associated with lower levels of alfalfa leafcutting bee productivity. This surprising result is in the opposite direction to our original hypothesis that preferred honey bee foraging areas in the landscape, as indicated by decoded waggle dance data, would be positively correlated with alfalfa leafcutting bee productivity. These data demonstrate that while honey bees may indeed act as bioindicators to other insect pollinators, this indication will likely be species and context specific and may even specify the opposite direction. / Master of Science in Life Sciences / Recent challenges facing the beekeeping industry have laid bare the fragility of honey bee pollination services, highlighted the role of other bee pollinators, and sparked widespread concern over the effect of declining bee populations on food security and continued ecosystem function and services. Both honey bees and wild bees face similar challenges including pesticides, parasites, pests, and poor nutrition from a lack of flowers in the landscape. Therefore, it is critical that we develop methods to evaluate the landscape's ability to feed bees in order to help them and other pollinators continue providing essential pollination services. There are many ways to measure the quality of a landscape for pollinators, but honey bees offer a unique opportunity to do the work for us: honey bees communicate the location of where they find food to their nestmates through a behavior called the waggle dance. Waggle dances can be observed and the dance language decoded so that we can determine the location of high-quality food sources. Previously, we used honey bee waggle dance data to map where bees are collecting food in three geographically distinct sites (Blacksburg, Winchester, and Suffolk, Virginia). These data allow us to understand where, when, and on what flowers the honey bees were feeding. The goal of this project was to investigate the relationship between honey bee foraging and non-honey bee success across the same three landscapes to determine if honey bees can be used as bioindicators of habitat quality for other bees. We chose Alfalfa leafcutting bees (Megachile rotundata) as a model organism because they are solitary, cavity-nesting bees, like the majority of wild bees. However, as managed pollinators, Alfalfa leafcutting bees (ALCBs) can be purchased commercially and retained in nesting boxes to allow us to gather productivity and survival data, which we can then compare to what the dancing honey bees previously told us about where and when they can collect good food. We hypothesized that areas of the landscape that honey bees had indicated where higher quality would correlate to better ALCB cocoon production and survival. We placed wooden nest boxes, 15 per site, stocked with ALCBs across the same landscapes for which honey bee data had been collected in the previous years and measured their productivity in terms of cocoons produced at each site. ALCB productivity varied by location, with Winchester as the most productive location (mean ALCB count (95% CI): 26.2 (23.7 to 28.9)), followed by Blacksburg (20.4 (18.2 to 22.9)), and Suffolk (4.4 (3.5 to 5.5)). The abundance of clover, both red and white, had a significant positive effect on ALCB productivity (log-likelihood ratio test: χ2 = 778.36, < 0.001). On the other hand, the number of ALCB cocoons decreased significantly with the count of a non ALCB nest box resident, Trypoxylon wasp cocoons, present in the nest box (log-likelihood ratio test: χ2 = 54.37, < 0.001). Surprisingly, we found that there was an overall negative relationship between honey bee foraging probability and alfalfa leafcutting bee cocoon production (log-likelihood ratio test: χ2 = 55.42, < 0.001). In this study, across three different field sites with varying landscapes in Virginia, areas of higher honey bee foraging probability were associated with lower levels of alfalfa leafcutting bee productivity.

The alfalfa harvest in Ecuador constitutes one of the most important activities, especially as a primary product for animal feeding. The crop is widely distributed in the mountain region of the country. It is important to have studies on the production systems, which facilitate a real and compete vision of those characteristics that interact among them in the agricultural production. With this knowledge it will be possible to look for the most adequate solutions to the conditions of the area where alfalfa is produced. The objectives of the study reported herein were: 1. To make an agricultural, social and economical diagnosis in the community of El Troje, San Luis Parish, Riobamba Canton, Province of Chimborazo. 2. To identify the production system used by the farmers to harvest alfalfa in El Troje community.

Resistant (65-410 and 65-393) and susceptible (breeders Lahontan) alfalfa seedlings were infected with the Northern root-knot nematode, Meloidogyne hapla. Infected roots were fixed, stained, and embedded in plastic for ultrastructural investigations. Sections of plastic embedded tissue, cut at 0.5-1.5 microns for light microscopy investigations, were stained with various histochemical stains to determine the chemical composition of the nematode-altered tissues. In the susceptible cultivar, giant cells were formed by enlargement of nematode-stimulated cells without cell wall lysis. The giant cells became multinucleate by karyonkinesis without cytokinesis. Proplastids in the giant cells became structurally altered to form tubular complexes. The resistant plants usually responded to the nematodes by a hypersensitivity reaction followed by extensive wall buildup in cells surrounding the infection sites. Nematodes often remained in the necrotic tissues.

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The alfalfa weevil, Hypera postica (Gyllenhal) (Coleoptera: Curculionidae), remains a serious pest in Virginia despite being under complete biological control in the northeastern U.S. In 1996, a survey of 187 alfalfa fields in Virginia was initiated to determine the current pest status of alfalfa weevil and incidence of natural enemies. Fields located in the Piedmont region of the state had significantly higher alfalfa weevil pressure than those in the Shenandoah Valley and southwestern region. The dominant natural enemy of alfalfa weevil larvae was the parasitoid, Bathyplectes anurus (Thomson). Larval parasitization was lower in the Piedmont compared with the other regions. The entomopathogenic fungus, Zoophthora phytonomi, also killed weevil larvae in all regions. A more intensive ecological investigation of alfalfa weevil population dynamics and mortality was initiated in 1997 to determine why H. postica remains a pest in Virginia, particularly in the Piedmont region. Nine alfalfa weevil populations from three geographic locations were sampled and measured over a period of two years. Results showed that warmer winter temperatures in the Piedmont region contributed to a higher rate of alfalfa weevil oviposition compared with the Shenandoah Valley and southwestern mountains. Parasitization of adult weevils by Microctonus aethiopoides (Loan) was low in all regions of Virginia relative to rates reported in the northeastern U.S. This also contributes to relatively high alfalfa weevil fecundity in Virginia because a greater percentage of adults reproduce. Phenological asynchrony between M. aethiopoides and the alfalfa weevil may explain the low parasitism. The 1st generation of M. aethiopoides adults did not emerge until most of the overwintering alfalfa weevil adults had reproduced and died. A majority of alfalfa weevil eggs were laid before January at all locations in Virginia. Approximately half of the egg population survived to contribute to spring larval infestations. In the northern U.S., very few alfalfa weevil eggs survive the winter, and larval populations result primarily from spring-laid eggs. Mortality of larvae was high in Virginia and comparable to that reported in other states. Bathyplectes anurus was well-synchronized with alfalfa weevil and killed a high percentage of larvae. / Ph. D.

Previous research on grazing behavior has shown that ruminants will select a mixed diet. The use of adjacent monocultures is an essential tool for determining dietary preference of forages. Much of the work to date has been conducted with white clover (Trifolium repens L.) and perennial ryegrass (Lolium perenne L.). Partial preference for white clover over ryegrass has been reported consistently and partial preference for legumes is thought to occur regardless of the legume and grass species being evaluated. Two forage species, tall fescue (Festuca arundinacea Schreb. or Lolium arundinaceum (Schreb.) S.J. Darbyshire) and alfalfa (Medicago sativa subsp. sativa L.), which had not been evaluated together previously as adjacent monocultures were grazed by beef steers in the present set of experiments. Steers exhibited a partial preference for alfalfa of 61 to 65% when given a choice of grazing alfalfa or tall fescue as adjacent monocultures, regardless of the ground area proportion of the two forages offered. Steers grazing tall fescue monocultures spent more time ruminating (P = 0.02) and tended to graze less time (P = 0.06) than steers in adjacent monoculture treatments. Time spent idling, number of prehensions and mastications, and bite rate were similar (P > 0.05) among treatments. Steers grazing tall fescue monocultures spent less time standing, more time lying, were less active and took fewer steps (P ≤ 0.05) than steers in adjacent monoculture treatments. Grazing behavior was examined when alfalfa had not been in the previous diet of the steers. Cattle without previous experience grazing alfalfa spent 78% of the time grazing alfalfa, whereas after having experience grazing it they spent a lower (P = 0.04) proportion of their time grazing alfalfa (72%). Overall proportion of the day spent grazing both forages was lower (P = 0.0001) when alfalfa was novel (40%), compared to when steers were experienced grazing both forages (46%). Proportion of the day spent idling was greater (P < 0.0001) when alfalfa was novel (35%), compared to when both forages were familiar to the steers (26%). Previous research has reported that ruminants exhibit a diurnal pattern of preference by decreasing the proportion of white clover consumed from morning to late afternoon while increasing the proportion of perennial ryegrass in the diet. This is thought to be a strategy to increase fiber intake before nightfall or as a response to higher carbohydrate levels in grass in the afternoon. In the present study, proportion of grazing time in alfalfa was higher (P = 0.02) in the afternoon (76.8 %) than in the morning (72.1 %). While fiber concentration was higher in the tall fescue, carbohydrate concentrations were similar. Steers were not attempting to increase fiber intake in the afternoon in the present study. Dry matter intake of steers grazing adjacent monocultures of alfalfa and tall fescue was estimated with n-alkanes. Diet composition was estimated using n-alkanes and long chain alcohols (LCOH) in several different combinations. The use of LCOH added additional characterization of the forages, but diet composition estimates were not different (P ≥ 0.22) than when estimated using four different n-alkanes. Laboratory analysis costs may be reduced if n-alkanes alone can adequately characterize the forages being consumed, depending on the forage species in question. Meteorological conditions impacted DMI with intake being less in hotter conditions. Steers had similar partial preferences for alfalfa over tall fescue (P = 0.13, 79% and 70% alfalfa in yr 1 and 2, respectively) even though total DMI differed between years (P = 0.002, 9.4 kg d-1 and 4.5 kg d-1 in yr 1 and 2, respectively). Lower DMI in yr 2 was attributed to hotter air temperatures. When animals are consuming two different forages as adjacent monocultures such as in the current experiments, it is important to determine the proportion of each forage in the diet before calculating DMI using odd chain n-alkanes of the forage along with a dose even chained n-alkane. Dry matter intake can be overestimated if the proportion of the forages consumed is not estimated and accounted for in the equation. This would apply to other studies utilizing mixed swards or any diet containing multiple components that differ in concentration of the n-alkane being used for DMI estimation. Analysis of n-alkane concentration should be performed on each item in the diet and the proportion of each item in the diet estimated so that the right value can be used in the calculation. Differences in marker concentrations between years also indicate the importance of analyzing those concentrations in the feed or forage at the time of fecal collection and not using values reported from previous research. / Ph. D.