Laboratory studies on the efficacy of nuclear polyhedrosis virus againstHeliothis armigera (Hbn.) on some cotton cultivars

Mortality ofHeliothis armigera (Hbn.) larvae due to nuclear polyhedrosis virus (NPV) was significantly higher onGossypium barbadense (cv. DCH 32) than onG. birsutum (cv. LRA 5166) andG. arboreum (cv. K 10). A positive correlation existed between leaf area consumed and NPV mortality of the larvae. Among the three dosages of NPV tested, 2.16×10⁸ polyhedral occlusion bodies (POB)/ml as ultra low volume application caused the maximum larval mortality. Probit analysis of time mortality responses showed that the LT₅₀ was lower onG. barbadense than on other two species tested.     

Spatial variability of surface peat properties and carbon emissions in a tropical peatland oil palm monoculture during a dry season

The expansion of oil palm monocultures into globally important Southeast Asian tropical peatlands has caused severe environmental damage. Despite much of the current focus of environmental impacts being directed at industrial scale plantations, over half of oil palm land-use cover in Southeast Asia is from smallholder plantations. We differentiated a first generation smallholder oil palm monoculture into 8 different sampling zones, and further divided the 8 sampling zones into oil palm root influenced (Proximal) and reduced root influence (Distal) areas, to assess how peat properties regulate in situ carbon dioxide (CO₂) and methane (CH₄) fluxes. We found that all the physico-chemical properties and nutrient concentrations except sulphur varied significantly among sampling zones. All physico-chemical properties except electrical conductivity, and all nutrient content except nitrogen and potassium varied significantly between Proximal and Distal areas. Mean CO₂ fluxes (ranged between 382 and 1191 mg m⁻² h⁻¹) varied significantly among sampling zones, and between Proximal and Distal areas, with notably high emissions in Dead Wood and Path zones, and consistently higher emissions in Proximal areas compared to Distal areas within almost all the zones. CH₄ fluxes (ranged between −32 and 243 µg m⁻² h⁻¹) did not significantly vary between Proximal and Distal areas, however significantly varied amongst sampling zones. CH₄ flux was notably high in Canal Edge and Understorey Ferns zones, and negative in Dead Wood zone. The results demonstrate the high heterogeneity of peat properties within oil palm monoculture, strengthening the need for intensive sampling to characterize a land use in the tropical peatlands.     

Probing the chiroptical response of a single molecule

Chirally sensitive measurement techniques have generally been restricted to bulk samples. Here, we report the observation of fluorescence-detected circular dichroism (FDCD) from single (bridgedtriarylamine) helicene molecules by using an excitation wavelength (457 nanometers) in the vicinity of an electronic transition that shows circular dichroism in bulk samples. The distributions of dissymmetry (g) parameters by analysis of signals from pure M- and P-type diastereomers are almost perfect mirror images of one another, each spanning a range of both positive and negative values. In addition, we observe a well-defined structure in the histogram of dissymmetry parameters suggestive of specific molecular orientations at the polymer interface. These single-molecule results highlight strong intrinsic circular dichroism responses that can be obscured by cancellation effects in ensemble measurements of a randomly oriented bulk sample.     

Genetics of resistance to Sesamia inferens infestation and its correlation with yield in maize

Sesamia inferens (Walker) causes 25.7–78.9% losses in maize production in South and South‐East Asia. The genetic basis of host plant resistance is the prerequisite for resistance breeding. Twenty‐four populations derived from S. inferens resistant × susceptible inbreds were used to study the genetic regulation of resistance to S. inferens in maize, to determine the importance of genetic effects through generation mean analysis (GMA) and to understand correlation between resistance and yield. Resistant and susceptible inbreds differed significantly in leaf and stem injury ratings (LSIR), a measure of host plant resistance. Mean LSIR range among resistant and susceptible parents was 2.15–2.55 and 7.83–8.22, respectively. The broad‐sense heritability ranged from 0.40 to 0.71, and the mean number of effective factors ranged from 1.9 to 2.6. The resistance against S. inferens was largely governed by additive × additive (i), followed by dominance (d) and additive (a) gene effects. Significant negative correlation (?0.27 to ?0.96) was observed between LSIR and yield. The findings suggest reciprocal recurrent selection for development of new inbreds with resistance followed by their involvement in hybrid development to exploit additive and non‐additive gene effects/variance.     

Nutrient and trace element concentrations influence greenhouse gas emissions from Malaysian tropical peatlands

Tropical peatlands are unique and globally important ecosystems for carbon storage that are generally considered nutrient poor. However, different nutrient and trace element concentrations in these complex ecosystems and their interactions with carbon emissions are largely unknown. The objective of this research was to explore the concentrations of macro‐ and micronutrients and othertrace elements in surface peats, and their relationship with greenhouse gas emissions in North Selangor peatlands subjected to different land use. All nutrient and trace element concentrations except chromium exhibited significant differences between sites. Most macronutrients and some micronutrients showed significant differences between seasons, typically with a reduction over time from wet to dry seasons, possibly due to leaching. CO₂ emissions were positively related to organic matter content and manganese concentrations and negatively correlated with selenium. CH₄ emissions were positively correlated with organic matter content, manganese, copper, barium, cobalt and aluminium, and negatively correlated with molybdenum, selenium, lithium and vanadium. This research has detected loss of essential nutrients over time, aiding to increase nutrient limitation in tropical peatlands due to drainage. The observed significant correlation between trace elements and greenhouse gas emissions strengthens the importance of including trace element analyses in understanding the biogeochemical functions of these understudied peatlands.     

Constituents of Cassia auriculata.

The isolation and spectral data of di-(2-ethyl) hexyl phthalate (1) from Cassia auriculata leaves are reported.     

Improving RNA interference in the southern green stink bug,Nezara viridula

Journal of Pest Science - The southern green stink bug, Nezara viridula, is a worldwide pest of many important crops. RNA from N. viridula nymphs and adults was sequenced and assembled into a...