Effect of feeding stimulants on the insecticidal properties of Pieris brassicae granulovirus (PbGV) against Pieris brassicae

Feeding stimulants (phagostimulants) increase the food uptake by the host insect larvae and thereby play a vital role in enhancing overall activity of insect viruses formulated as biopesticides. A local strain of granulovirus of Pieris brassicae (PbGV), a serious pest of cole crops worldwide, has shown potential as a biopesticide against this pest and with slight increase in its efficacy can be used successfully as a promising biocontrol agent in integrated pest management (IPM) programs of the pest. The addition of phagostimulants may enhance the efficacy but so far no specific phagostimulant for PbGV has been reported. In the present studies, some reported phagostimulants for insect viruses were tested for their impact on food utilization by host larvae and efficacy of the virus. The specified concentration of virus isolate was mixed with phagostimulants and laboratory studies were conducted to uncover their effect on consumption index (CI) and larval mortality. The studies revealed that phagostimulants, viz. boric acid and crude sugar, when mixed with PbGV, showed highest CI and larval mortality. Consumption index of 1.34, 1.49 and 1.43 mg/mg/day and corresponding larval mortality of 32.9%, 45.8% and 34.2% were recorded with the addition of 0.5% and 1% boric acid and 2% crude sugar, respectively, in PbGV. The leaf extracts of cabbage, cauliflower and broccoli at both the concentrations (1% and 2%) also enhanced the CI but were comparatively less effective than the boric acid and crude sugar. Field evaluation of PbGV alone and in combination with phagostimulants carried out at two geographically isolated locations, viz. Palampur (subtropical) and Sangla (temperate) on three cole crops (cabbage, cauliflower and broccoli) showed that boric acid was the most promising candidate for enhancing the PbGV efficacy under field conditions, followed by crude sugar.     

First report of dry rot of potato caused by Fusarium proliferatum in India

Journal of Plant Diseases and Protection - Potato stands first as a non-cereal food crop for global consumption purposes. During the year 2019–20, dry rot disease symptoms were observed on...     

Glycolytic oscillations and limits on robust efficiency

Both engineering and evolution are constrained by trade-offs between efficiency and robustness, but theory that formalizes this fact is limited. For a simple two-state model of glycolysis, we explicitly derive analytic equations for hard trade-offs between robustness and efficiency with oscillations as an inevitable side effect. The model describes how the trade-offs arise from individual parameters, including the interplay of feedback control with autocatalysis of network products necessary to power and catalyze intermediate reactions. We then use control theory to prove that the essential features of these hard trade-off "laws" are universal and fundamental, in that they depend minimally on the details of this system and generalize to the robust efficiency of any autocatalytic network. The theory also suggests worst-case conditions that are consistent with initial experiments.     

Ultrastructure of potato tubers infected with potato virus X

The ultrastructure of Katahdin tubers infected with potato virus X (PVX) is compared with PVX-free tubers by electron microscopy. Electron-dense globules surrounding the inner periphery of the tonoplast were observed in PVX-infected tubers, while PVX-free tubers did not show such bodies. Other organelles were comparable in PVX-infected and PVX-free tubers     

Quality of potato tubers as affected by freezing: I. texture,ascorbic acid and enzymatic discoloration

The effect of freezing on the turgor, ascorbic acid content and enzymatic discoloration of Katahdin and Atlantic potatoes was studied. Tubers were exposed to a temperature of ?20°C for 24 hrs. then thawed for 1 hr. at 20°C before analysis. Frozen tubers were then compared with unfrozen controls. Both varieties lost turgor following freezing and exuded a sticky liquid with increased thawing time. At the end of 3 hrs. thawing, a sponge-like texture was observed in both varieties. In both varieties freezing resulted in a significant reduction (p<.01) in ascorbic acid and phenolic content (p<.01). Enzymatic discoloration was also significantly reduced (p<.01) in both varieties.     

Effects of Latency Periods and Injection Doses with Carp Pituitary Extract on Spawning Performance and Egg Quality of Asian Catfish,Clarias batrachus (Linn.)

ABSTRACT

An experiment was conducted to evaluate the spawning performance and egg quality of Clarias batrachus at variable latency periods (11, 14, 17, 20, and 23 h) and doses of carp pituitary extract (10, 20, 30, 40, and 50 mg/kg). The fish could not be stripped at 11 h latency with 10 or 20 mg carp pituitary extract (CPE). The highest quantity of eggs was obtained at 14 to 23 h latency with 30–40 mg CPE or 50 mg CPE with 14 to 17 h latency, which did not vary significantly (P < 0.05) at a water temperature of 27°C–28.5°C. The eggs did not fertilize and hatch when stripped at 11-h latency period. Over 80% of total eggs stripped from females injected with 30 and 40–50 mg CPE per kg body weight, and stripped at 14 to 23 h and 14- to 17-h latency, respectively, were fertilized. However, the highest (P < 0.05) number of larvae was obtained from females injected with 40 mg CPE and stripped at 14 or 17 h latency periods. Therefore, this CPE dose and 17 h latency period combination was regarded as the best for obtaining the highest number of larvae during induced spawning of C. batrachus.