Role of substrate moisture, relative humidity and temperature on survival and foraging behavior of Formosan subterranean termites

The Formosan subterranean termite is an important structural pest in the southern United States, especially Louisiana. Baiting systems and spot treatment with non-repellent delayed action termiticides are among the most eco-friendly control approaches. However, to achieve a desired success from these approaches requires a sophisticated knowledge of foraging behavior and food transfer system of these social insects. Moisture and temperature play a vital role in influencing the foraging behavior of these desiccation prone insects. A series of laboratory experiments were conducted to understand the subtleties of foraging behavior of Coptotermes formosanus Shiraki in relation to moisture, relative humidity and temperature. Foraging behavior, food consumption and distribution pattern were studied in a suitably designed sand moisture gradient arena. Results showed that C. formosanus can adapt to a wide range of sand moisture levels but not in dry and saturated sand. Next, termites were studied to determine how combinations of various food moisture and temperature levels impact their foraging behavior. C. formosanus was unable to maintain sustained feeding when the wood moisture was lower than the fiber saturation point (~ 25% wt/wt). In the absence of moist soil, C. formosanus always preferred the highest moisture wood with the optimum feeding and survival obtained at 28°C. Relative humidity and temperature mainly determine the water loss from an organism. Soldiers and workers of C. formosanus, which are extremely prone to desiccation, were exposed to various temperature and relative humidity conditions to determine their survival. Even the near saturated relative humidity (~99%) level was not sufficient to keep them from desiccating, indicating that a continuous supply of moisture either from moist substrate or food is required for their normal survival. Likewise, impact of food source disturbance on termites’ escape behavior was studied with wet versus dry sand conditions in the periphery of the food source, and its implications for termite baiting is discussed. Finally, exploratory tunneling behavior was examined in different substrates in different moisture and temperature situations. With the same moisture level, sand was found to be the preferred substrate for aggregation and tunnel construction to sandy loam and loam

Survival Rate, Food Consumption, and Tunneling of the Formosan Subterranean Termite (Isoptera: Rhinotermitidae) Feeding on Bt and non-Bt Maize

Although several termite species were reported to be susceptible to some Bacillus thuringiensis (Bt) subspecies, no research has been conduced to evaluate the possible non-target effect of genetically modified (GM) Bt crops on termites. In this study, plant tissues of three commercial planted Bt maize (YieldGard* Corn Borer, Genuity* VT Triple PROTM and Genuity* SmartStaxTM) and two non-Bt maize hybrids were provided to Formosan subterranean termite, Coptotermes formosanus, as food. Five food sources including wood blocks and filter paper treated with maize leaf extract as well as leaves, stalks, and roots of maize were tested in the laboratory. The experiment was maintained for two weeks and the survival rate of termites, food consumption, and tunneling behavior were recorded. The results revealed no significant differences in survival rate, food consumption and length of tunnels between termites feeding on Bt and non-Bt maize planting materials, indicating that Bt proteins expressed in the three Bt maize products did not negatively affect C. formosanus. However, compared to wood block and filter paper treatments, termites feeding on maize tissues showed different consumption pattern and tunneling behavior. Our study also suggests that maize stalk is a good candidate for termite bait matrices

Digestibility of Sunflower Hulls Treated with Sodium, Ammonium, and Potassium Hydroxides

In vitro dry matter digestibility (IVDMD) of sunflower hulls (SFH) treated with sodium hydroxide (NaOH), ammonium hydroxide (NH4OH), and potassium hydroxide (KOH) at increasing levels were studied. Tested concentrations of each alkali as percent dry matter (DM) on SFH were 1.63, 2.45, 3.26, and 4. 08. In vitro dry matter digestibility of sunflower hulls increased with higher concentrations of NaOH and KOH. Percent IVDMD for control (un-treated SFH) was 18.0. Percent IVDMD for SFH treated at 1.63, 2.45, 3.26, and 4.08% of DM were: 18.9, 21.4, 22.2, and 22.9 for NaOH; 18.3, 18.0, 18.3, and 18.5 for NH4OH; and 18.9, 20.2, 21.0, and 22.5 for KOH. Twenty wethers averaging 41 kg were utilized in a switch-back design experiment to evaluate the in vivo digestibility of alkali treated SFH. Diets contained 0% SFH (positive control), 25% of DM as untreated SFH (negative control), or 25% of DM as SFH treated with 2.45% NaOH, 2.45% KOH, or 3.42% NH4OH. Other ration components were alfalfa meal, corn, soybean meal, dicalcium phosphate, trace mineralized salt, and vitamins. All rations were made isonitrogenous at 14.6% crude protein and pelleted. Feed and water consumptions were highest with diets containing alkali treated SFH, especially NaOH and KOH treated SFH. Digestibilities of acid detergent fiber and neutral detergent fiber (%) for the respective diets were: positive control, 42.6 and 58.2; untreated SFH, 30.2 and 42.9; NaOH treated SFH, 34.3 and 44.0; NH4OH treated SFH, 26.2 and 35.3; and KOH treated SFH, 37.4 and 42.0

SIP-428, a SIR2 Deacetylase Enzyme and Its Role in Biotic Stress Signaling Pathway

SABP2 (Salicylic Acid Binding Protein 2) plays a vital role in the salicylic acid signaling pathway of plants both regarding basal resistance and systemic acquired resistance against pathogen infection. SIP-428 (SABP2 Interacting Protein-428) is a Silent information regulator 2 (SIR2) like deacetylase enzyme that physically interacts with SABP2 in a yeast two-hybrid interaction and confirmed independently by a GST pull-down assay. We demonstrated that SIP- 428 is an NAD+ dependent SIR2 deacetylase enzyme. Transgenic tobacco plants silenced in SIP- 428 expression via RNAi showed enhanced basal resistance to microbial pathogens. Moreover, these SIP-428-silenced lines also exhibited a robust induction of systemic acquired resistance. In contrast, the transgenic tobacco lines overexpressing SIP-428 showed compromised basal resistance and failed to induce systemic acquired resistance. These results indicate that SIP-428 is likely a negative regulator of SA-mediated plant immunity. Experiments using a SABP2 inhibitor showed that SIP-428 likely functions upstream of SABP2 in the salicylic acid signaling pathway. It also indicates that SABP2 is dependent on SIP-428 for its role in the SA signaling pathway. Subcellular localization studies using confocal microscopy and subcellular fractionation showed that SIP-428 localized in the mitochondria. These results clearly show a role for SIP-428 in plant immunity

Evaluation of Naked Barley Landraces for Agro-morphological Traits

Naked barley (Hordeum vulgare var. nudum L.) is a traditional, culturally important, climate-resilient winter cereal crop of Nepal. Evaluation of the naked barely genotypes for yield and disease is fundamental for their efficient utilization in plant breeding schemes and effective conservation programs. Therefore, to identify high yielding and yellow rust resistant landraces of naked barley for hilly and mountainous agro-ecosystem, twenty naked barley landraces collected from different locations of Nepal, were evaluated in randomized complete block design (RCBD) with three replications during winter season of 2016 and 2017 at Khumaltar, Lalitpur, Nepal. Combined analysis of variances revealed that NGRC04902 (3.46 t/ha), NGRC00886 (3.28 t/ha), NGRC02309 (3.21 t/ha) and NGRC06026 (3.10 t/ha) were the high yielding landraces and statistically at par with the released variety 'Solu Uwa' (3.15 t/ha). The landraces namely NGRC00837 (ACI Value: 1.86) was found resistant to yellow rust diseases. Landraces NGRC06034 (131.7 days) and NGRC02363 (130.8 days) were found early maturing and NGRC02306 (94.36 cm) was found dwarf landraces among tested genotypes. These landraces having higher yield and better resistance to yellow rust need to be deployed to farmers' field to diversify the varietal options and used in resistant breeding program to improve the productivity of naked barley for Nepalese farmers

An Improved IOC-ω Technique: Part V - Ionization Potentials & Heats of Formation of Some Organic Molecules

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