Cryptic diversity and habitat partitioning in an economically important aphid species complex.

Cardamom Bushy Dwarf Virus (CBDV) is an aphid-borne nanovirus which infects large cardamom, Amomum subulatum (Zingiberaceae family), in the Himalayan foothills of Northeast India, Nepal and Bhutan. Two aphid species have been reported to transmit CBDV, including Pentalonia nigronervosa and Micromyzus kalimpongensis (also described as Pentalonia kalimpongensis). However, P. nigronervosa was recently split into two species which exhibit different host plant affiliations. Whilst P. nigronervosa primarily feeds on banana plants, Pentaloniacaladii (previously considered a 'form' of P. nigronervosa) typically feeds on plants belonging to the Araceae, Heliconiaceae and Zingiberaceae families. This raises the possibility that CBDV vectors that were originally described as P. nigronervosa correspond to P. caladii. Accurate identification of vector species is important for understanding disease dynamics and for implementing management strategies. However, closely related species can be difficult to distinguish based on morphological characteristics. In this study, we used molecular markers (two mitochondrial loci and one nuclear locus) and Bayesian phylogenetic analyses to identify aphid specimens collected from 148 CBDV infected plants at a range of locations and elevations throughout Sikkim and the Darjeeling district of West Bengal (Northeast India). Our results revealed the presence of a diversity of lineages, comprising up to six distinct species in at least two related genera. These included the three species mentioned above, an unidentified Pentalonia species and two lineages belonging to an unknown genus. Surprisingly, P. caladii was only detected on a single infected plant, indicating that this species may not play an important role in CBDV transmission dynamics. Distinct elevation distributions were observed for the different species, demonstrating that the community composition of aphids which feed on large cardamom plants changes across an elevation gradient. This has implications for understanding how competent vector species could influence spatial and temporal transmission patterns of CBDV.

Purification of elastase-like chymotrypsin from cardamom shoot and Capsule borer [corrected].

An elastase-like chymotrypsin was purified by aprotinin-agarose affinity chromatography from the midgut extract of cardamom shoot and capsule borer, Conogethes punctiferalis. The purified enzyme had a Vmax of 687.6 +/- 22.1 nmole pNA released/min/mg protein, Km of 0.168 +/- 0.012 mM with SAAPLpNA as substrate and gave a single band on SDS-PAGE with a molecular mass of 72.1 kDa. Casein zymogram revealed one clear zone of proteolytic activity, which corresponded to the band obtained with SDS-PAGE indicating that this could be a single-polypeptide enzyme.

Midgut proteases of the cardamom shoot and capsule borer Conogethes punctiferalis (Lepidoptera: Pyralidae) and their interaction with aprotinin.

Protease inhibitors cause mortality in a range of insects, and transgenic plants expressing protease inhibitors have been protected against pest attack, particularly internal feeders that are not amenable to control by conventional means. A study of luminal proteases in Conogethes punctiferalis Guenée was performed to identify potential targets for proteinaceous biopesticides, such as protease inhibitors. The midgut protease profile of the gut lumen from C. punctiferalis was studied to determine the conditions for optimal protein hydrolysis. Optimum conditions for peptidase activity were found to be in 50 mm Tris-HCl, pH 10 containing 20 mm CaCl2; incubation for 30 min at 40 degrees C. Four synthetic substrates, i.e. benzoyl-arg-p-nitroanilide, benzoyl-tyr-p-nitroanilide, succinyl-ala-ala-pro-leu-p-nitroanilide (SAAPLpNA) and leu-p-nitroanilide were hydrolysed by C. punctiferalis gut proteases in Tris-HCl buffer pH 10. Trypsin and elastase-like chymotrypsin were the prominent digestive proteases, and age-related modulation of midgut proteases existed for trypsin, chymotrypsin, elastase-like chymotrypsin and leucine aminopeptidase. Serine protease inhibitors such as aprotinin, soybean trypsin inhibitor and phenylmethanesulfonyl fluoride inhibited peptidase activity. Some metal ions such as Ca(2+), Mg(2+), Pb(2+) and Co(2+) enhanced BApNA-ase activity whereas others like Mn(2+), Zn(2+), Cu(2+), Fe(2+) and Hg(2+) were inhibitory at 6 mm concentration. Trypsin and elastase-like chymotrypsin were significantly inhibited by 94% and 29%, respectively, by aprotinin (150 nm) under in vitro conditions. A possible incorporation of protease inhibitors into transgenic plants is discussed.

Efficacy of neem products and insecticides for the control of shoot fly Formosina flavipes Mall. of Cardamom (Elettaria Cardamomum Maton.).

Experiments were conducted at Zonal Agricultural Research Station, Mudigere, India, for two years with an objective to study the population fluctuation, seasonal incidence and evaluation of neem products and insecticides for their efficacy against cardamom shoot fly. During the study period, it was noticed that shoot fly population the increased during the dry months (March, May and October) but was low from June to September months. The population exhibited a negative correlation with rainfall, minimum temperature and maximum relative humidity and positive correlations with maximum temperature and sunshine h. Among the six insecticides tested, phorate, phorate with neem cake and neem cake alone were found superior over other treatments. The present study clearly indicated that application of neem cake helps not only in reduction of shoot fly incidence but also enhances the production of side suckers compared to other treatments.