The use of neutron tomography for the structural analysis of corn kernels

Neutron tomography was studied as a technique for non-destructively analyzing the internal structure of dried corn kernels. The study had two goals: first, to determine if the analysis could identify well-known anatomical features of the kernels; and second, to determine if it could distinguish between different types and treatments of kernels. Specifically, kernels which were infected vs. uninfected with the aflatoxin-producing fungus Aspergillus flavus were analyzed. Two different varieties of corn were used: VA35 (susceptible to A. flavus infection) and GT-MAS:gk (resistant). It was found that many anatomical features of the kernels could be identified using neutron tomography, including the scutellum, endosperm, aleurone, pericarp, pedicel, coleorhizae, radical, plumule, and coleoptile. Furthermore, differences were detected between susceptible kernels that had been inoculated and those that had not. Infected kernels were found to have lower neutron attenuation in the scutellum and embryo regions, possibly caused by lower hydrogen concentrations due to fungal degradation. No systematic structural differences were detected between resistant inoculated and resistant uninoculated kernels, as expected. This study indicated that neutron tomography could be a useful technique for the structural analysis of corn, and possibly other grains or small biological objects.     

‘On-farm’ seed priming with zinc sulphate solution—A cost-effective way to increase the maize yields of resource-poor farmers

The effect of adding zinc sulphate (ZnSO₄) to maize (Zea mays L.) growing on calcareous, Zn deficient soils in the North West Frontier Province of Pakistan was assessed in vitro, on-station and in on-farm trials. The zinc sulphate was added either as a powder to the soil or by soaking seeds for 16 h in dilute solutions prior to sowing. For the first time in maize, we separated the benefits of priming simply with water from those provided by added zinc.     

Successful Treatment for Subinvolution of Placental Sites in the Bitch with Low Oral Doses of Progestagen

Subinvolution of placental sites (SIPS) is the major cause of persistent sanguineous vaginal discharge after parturition in the bitch. Spontaneous remission is common but may take several months, and hence, medical therapy to end the discharge is often requested. In this retrospective study, we evaluated the effect of treatment for SIPS with low oral doses of a progestagen. Nine bitches with SIPS, but otherwise clinically healthy, were found in the computer database of the Department of Clinical Sciences of Companion Animals. Seven of these bitches were treated with low oral doses of a progestagen (megestrol acetate, 0.1 mg/kg body weight (bw) once daily for the 1st week, then 0.05 mg/kg bw once daily for the 2nd week). The other two bitches were untreated. Treatment results were evaluated by a telephone questionnaire. Progestagen treatment was successful in all of the treated dogs; sanguineous vaginal discharge stopped within the treatment period. One of the two untreated dogs remained symptomatic until the next oestrus, approximately 120 days after parturition, and the other remained symptomatic until 6 weeks before the start of the next pro‐oestrus, 270 days after parturition. No side effects of the progestagen treatment were observed. Subsequent gestations, parturitions and puerperal periods of 5 mated bitches were uneventful. One bitch did not become pregnant after mating. In conclusion, the results of this study indicate that oral administration of low doses of progestagen for 2 weeks is effective in stopping persistent sanguineous vaginal discharge in bitches with SIPS, with neither side effects nor reduced subsequent fertility.     

Immunohistochemistry Diagnosis of an Ovarian Dysgerminoma in One Bitch

An ovarian enlargement (diameter, 8 cm) was identified and surgically excised from a 5-year-old female dog. Microscopic examination of the multinodular neoplasm revealed sheets of polygonal neoplastic cells with large nuclei, frequent mitosis, necrosis and haemorrhage. Immunohistochemically, the neoplastic cells were positive for vimentin and alkaline phosphatase but were negative for CD3, CD79a, cytokeratin, alpha-fetoprotein, inhibin-α and S-100. The histopathological diagnosis of the mass was unilateral ovarian dysgerminoma.     

Effect of hCG Treatment on the Oestrous and Ovulation Responses to FSH in Prepubertal Gilts

To ensure sufficient numbers of pregnant females, particularly at hotter times of the year, hormonal induction of gilt oestrus may be necessary. However, the gilt oestrus and ovulation responses to gonadotrophin treatment have often proven unpredictable. The objective of this study was to examine possible reasons for this unpredictability. Prepubertal gilts (approximately 150 days of age, n = 63) were assigned to one of three treatments: injection of 300 IU hCG (n = 15); pre-treatment with 100 mg FSH in polyvinylpyrrolidinone administered as 2 × 50 mg injections 24 h apart, followed by 600 IU eCG at 24 h after the second FSH injection (n = 23); or FSH pre-treatment as above followed by 300 IU hCG at 24 h after the second FSH injection (n = 25). To facilitate oestrus detection, gilts were exposed to a mature boar for 15 min daily for 7 days. Blood samples were obtained on the day of eCG or hCG injection and again 10 days later and gilt ovulation responses determined based on elevated progesterone concentrations. The oestrus responses by 7 days were 6.7%, 17.5% and 64.0% for gilts treated with hCG, FSH + eCG and FSH + hCG, respectively (p < 0.001). The oestrous gilt receiving hCG alone and one oestrous FSH + hCG gilt did not ovulate, all other oestrous gilts ovulated. A further two anoestrous FSH + eCG-treated gilts ovulated. These data suggest that FSH pre-treatment facilitated the development of ovarian follicles to the point where they became responsive to hCG, but had little effect on the response to eCG.     

Diapause disruption with tebufenozide for early-instar control of the spruce budworm, Choristoneura fumiferana

In North America, the eastern spruce budworm, Choristoneura fumiferana Clem., is an important coniferous pest against which tebufenozide has proven effective as a control product. By acting as an ecdysone agonist, tebufenozide can induce precocious moulting in late (fifth-sixth) instars but can also be carried over to the next generation owing to its persistence on foliage. The authors conducted laboratory experiments on first-instar larvae treated with tebufenozide dissolved in acetone. Larvae exposed to doses equal to or above 0.1 microg cm(-2) displayed precocious moulting in the second instar after hibernaculum spinning, which effectively disrupted diapause. Larger doses induced moulting in first instars. Evidence is provided that this dose-response difference is related to whether or not an effective dose of tebufenozide is ingested by the first instar prior to the peak of moulting hormone (20-hydroxyecdysone) in first instars. Doses ineffective to kill first instars are carried over to the second instar, where they induce a precocious moult. This type of response to tebufenozide is dependent on the presence of a moulting machinery (the EcR-USP receptor complex) that is ready for ecdysone transduction. Interestingly, ecdysone levels are low in second instars, as measured by a radioimmunoassay, which suggests that diapause in spruce budworm is maintained by a suppression of ecdysone production. Thus, diapause disruption by tebufenozide may well provide an alternative control strategy for this important pest.     

Cotton whitefly (Bemisia tabaci) resistance to organophosphate and pyrethroid insecticides in Pakistan

Resistance to three organophosphate and four pyrethroid insecticides was monitored from 1992 to 2000 in field populations of adult whiteflies, Bemisia tabaci, from Pakistan using a leaf-dip method. There was generally a very high resistance to dimethoate and deltamethrin, and a moderate resistance to monocrotophos during 1992 to 1996. From 1997 to 2000, resistance to these insecticides dropped to low levels because of less reliance on them for whitefly control, and introduction of new chemistries with novel modes of action that had no cross-resistance to conventional insecticides. Concurrently, whitefly resistance to acephate, fenpropathrin, lambda-cyhalothrin and bifenthrin mostly remained low. An insecticide resistance management strategy is recommended that particularly emphasizes the rotation of still-effective insecticides from different chemical classes along with the use of novel chemicals and other tactics of integrated pest management.