V. V. Ramamurthy

Biology of the mealybug, Phenacoccus solenopsis on cotton in the laboratory.

Abstract Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) has been the current topic of research for insect taxonomists and applied entomologists in India due to its invasiveness, rapid spread, morphological and biological variations and the need for establishing an effective control strategy. The biology of the mealybug P. solenopsis was studied on cotton under laboratory conditions between August and October of 2009 with mean temperature and relative humidity of 23.3–30.2°C and 40.5–92.5% RH, respectively, in central India. Neonate crawlers that emerged from a field population were collected and constituted the study population. The developmental period from immature crawler to adult stage was greater for males (18.7 ± 0.9 days) compared to females (13.2 ± 1.8 days), probably due to the additional molt to the pupal stage in males. Survival of second instars was lower (45.5%) than first and third instars (71.4%). Females showed dynamic patterns of fecundity with the number of crawlers produced per female ranging between 128 and 812, with a mean of 344 ± 82. The reproductive period lasted 30.2 ± 8.2 days. Parthenogenesis with ovoviviparity (96.5%) was dominant over the oviparous (3.5%) mode of reproduction. Adult females lived 42.4 ± 5.7 days. Males accounted for less than 5% of the population, and lived 1.5 ± 0.1 days. The life history parameters of P. solenopsis adult females are discussed relative to the appearance of symptoms on the cotton crop, and the importance of making management interventions during the effective reproductive period of the insect.

Molecular Identification and Phylogeny of Bactrocera Species (Diptera: Tephritidae)

ABSTRACT Fruit flies that belong to the genus Bactrocera (Diptera: Tephritidae) are major invasive pests of agricultural crops in Asia and Australia. Increased transboundary movement of agricultural produce has resulted in the chance introduction of many invasive species that include Bactrocera mainly as immature stages. Therefore quick and accurate species diagnosis is important at the port of entry, where morphological identification has a limited role, as it requires the presence of adult specimens and the availability of a specialist. Unfortunately when only immature stages are present, a lacunae in their taxonomy impedes accurate species diagnosis. At this juncture, molecular species diagnostics based on COX-I have become handy, because diagnosis is not limited by developmental stages. Yet another method of quick and accurate species diagnosis for Bactrocera spp. is based on the development of species-specific markers. This study evaluated the utility of COX-I for the quick and accurate species diagnosis of eggs, larvae, pupae and adults of B. zonata Saunders, B. tau Walker, and B. dorsalis Hendel. Furthermore the utility of species-specific markers in differentiating B. zonata (500bp) and B. tau (220bp) was shown. Phylogenetic relationships among five subgenera, viz., Austrodacus, Bactrocera, Daculus, Notodacus and Zeugodacus have been resolved employing the 5′ region of COX-I (1490-2198); where COX-I sequences for B. dorsalis Hendel, B. tau Walker, B. correcta Bezzi and B. zonata Saunders from India were compared with other NCBI-GenBank accessions. Phylogenetic analysis employing Maximum Parsimony (MP) and Bayesian phylogenetic approach (BP) showed that the subgenus Bactrocera is monophyletic.

Distribution of Bemisia tabaci genetic groups in India.

ABSTRACT The whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a phloem-feeding, economically important pest of crops worldwide. In addition to direct damage, it also vectors a number of plant viruses belonging to the family Geminiviridae. Its populations differ biologically with respect to insecticide resistance, virus transmission and host range. Therefore, understanding genetic variation among populations is important for management. We sequenced 850 bp of the mitochondrial COI (mtCOI) gene from B. tabaci populations surveyed across India. BLAST analysis of the mtCOI sequences generated in this study with sequences from the mtCOI dataset showed the presence of one invasive group, MEAM1, and eight other groups of B. tabaci in India. mtCOI sequence analyses showed the presence of Asia I, Asia I-India, Asia II-1, Asia II-5, Asia II-7, Asia II-8, and Asia II-11 genetic groups. We also found China-3 in a field in Birbhum district, West Bengal, India, suggesting a role of anthropogenic activities in the distribution of B. tabaci. Interestingly, more than one genetic group was found coexisting in the same field.

Development of Species-Specific Markers and Molecular Differences in mtDNA of Thrips palmi Karny and Scirtothrips dorsalis Hood (Thripidae: Thysanoptera), Vectors of Tospoviruses (Bunyaviridae) in India

ABSTRACT: Nearly 6000 species of thrips have been described and only 12 species are reported to be vectors of tospoviruses (Bunyaviridae) globally In this regard, Thrips palmi and Scirtothrips dorsalis are two important vectors of Watermelon Bud Necrosis Virus (WBNV) and Peanut Yellow Spot Virus (PYSV) to watermelon and groundnut respectively in India. Accurate and timely identification of thrips vectors in the early developmental stages is important for understanding the epidemiology of tospoviruses, their management and also in quarantine. Morphological identification of thrips often has been a stumbling block in the absence of trained personnel. Using the tools of molecular biology, morphological identification is further strengthened by developing species-specific markers, which can differentiate the above two species of thrips based on the PCR amplicon size. Molecular studies can elucidate the occurrence of biotypes or cryptic species, if any. In this study, we examined genetic differences in COI among 21 populations of T. palmi collected from Karnataka, India, along with the sequences from other countries which were acquired from GenBank. The phylogenetic analysis showed that there are two major groups: one is clearly associated with Indian population of T. palmi and the second is associated with the remaining countries (Japan, Thailand, Dominican Republic, China, and U.K.). Our studies clearly refute the general belief that T. palmi is a single cosmopolitan and polyphagous species. On the contrary, by the standards of genetic and ecological differentiation in other species groups, the recognition of geographically associated and distinct T. palmi subspecies may be considered, similar to what has been observed in T. tabaci. Such similar results have been observed for S. dorsalis, where Indian and Chinese population of S. dorsalis form separate groups.

Biology of Bactrocera (Zeugodacus) tau (Walker) (Diptera: Tephritidae)

The biology of the fruit fly Bactrocera tau, an important horticultural pest, was studied under laboratory conditions at 25°C and 60–70% relative humidity on Cucurbita maxima. The duration of mating averaged 408.03 ± 235.93 min. After mating, the female fly had a preoviposition period of 11.7 ± 4.49 days. The oviposition rate was 9.9 ± 8.50 eggs and fecundity was 464.6 ± 67.98 eggs/female. Eggs were elliptical, smooth and shiny white, turning darker as hatching approached, and measured 1.30 ± 0.07 mm × 0.24 ± 0.04 mm. The chorion has polygonal microsculpturing and is species‐specific with polygonal walls. The egg period lasts for 1.3 ± 0.41 days. The duration of the larval period is 1.2 ± 0.42, 1.7 ± 0.48 and 4.0 ± 0.94 days for first, second and third instars, respectively. Pupation occurs in the sand or soil and pupal periods are 7.0 ± 0.47 days. The life cycle from egg to adult was completed in 14.2 ± 1.69 days; the longevity of mated females and males was 130.33 ± 14.18 and 104.66 ± 31.21 days, respectively. At least two to three generations were observed from June 2008 to June 2009.

Cardioprotective effect of vincristine on isoproterenol-induced myocardial necrosis in rats

This study investigated the protective effect of vincristine (VCR) on isoproterenol (ISO)-induced cardiac necrosis (CN) in rats. Animals (n=7 in each group) were pretreated with vincristine (25µg/kg) intraperitoneal (i.p.) daily in 5-day cycles with 2 days pause between cycles using a 5-day-on, 2-day-off schedule for two weeks and then intoxicated with isoproterenol (100mg/kg, s.c., for 2 consecutive days). ISO-induced myocardial damage was indicated by changes in electrocardiographic (ECG) patterns, increased activities of marker enzymes such as creatine kinase-MB, serum glutamate pyruvate transaminase and lactate dehydrogenase and the levels of troponin-T in the serum. The levels of lipid peroxide products, (thiobarbituric acid reactive substances (TBARS) and lipid hydroperoxides (HP)) were increased with a parallel decrease in the activities of antioxidants (superoxide dismutase, catalase, glutathione peroxidase and reduced glutathione) in ISO-induced rats. Furthermore, ISO-induced rats showed increase in the activities of membrane bound enzymes such as Ca(2+)-ATPase and Mg(2+)-ATPase with a decreased activity of Na(+)/K(+)-ATPase. Triphenyl tetrazolium chloride (TTC) staining of the heart section showed increased area of necrosis in ISO-induced rats. Pretreatment with VCR (25µg/kg) eliminated all ISO-induced biochemical and histopathological changes, and decreased the myocardial necrosis to a greater extent. Transmission electron microscopic findings on the structure of the heart mitochondria confirmed the protective effects of VCR. Present study provides first scientific report on protective effect of vincristine against ISO-induced cardiac damage in rats.

Mouthparts and stylet penetration of the lac insect Kerria lacca (Kerr) (Hemiptera:Tachardiidae)

Hitherto less known aspects on mouthpart morphology and penetration mechanism of the lac insect Kerria lacca have been explored. Unique details of the mouthparts, i.e. morphology of labium and stylets and salivary sheath have been brought out. The gross morphology of the mouthparts though resembled other plant sucking homopterans; a two-segmented labium with symmetrically distributed six pairs of contact-chemoreceptors on its surface was distinct; the mandibular stylets had serrations on its extreme apical region, while the maxillary stylets had their external surface smooth with parallel longitudinal grooves on their inner surface. Formation of flanges, salivary sheath and penetration pathway observed along with probing and penetration of the stylets intracellularly up to the phloem cells, as illustrated herein, are the addition to the existing knowledge on the structural details of the mouthparts and the feeding behavior thereupon.

DNA Barcoding and Elucidation of Cryptic Diversity in Thrips (Thysanoptera)

Abstract Accurate and timely identification of invasive insect pests underpins most biological endeavors ranging from biodiversity estimation to insect pest management. In this regard, identification of thrips, an invasive insect pest is important and challenging due to their complex life cycles, parthenogenetic mode of reproduction, sex and color morphs. In the recent years, DNA barcoding employing 5′ region of the mitochondrial Cytochrome Oxidase I (CO-I) gene has become a popular tool for species identification. In this study, we employed CO-I gene sequences for discriminating 151 species of thrips for the first time. Analyses of the intraspecific and intrageneric distances of the CO-I sequences ranged from 0.0 to 7.91% and 8.65% to 31.15% respectively. This study has revealed the existence of cryptic species in Thrips hawaiiensis (Morgan) (Thysanoptera: Thripidae) and Scirtothrips perseae Nakahara (Thysanoptera: Thripidae) for the first time, along with previously reported cryptic species such as Thrips palmi Karny (Thysanoptera: Thripidae), T. tabaci Lindeman, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), Scirtothrips dorsalis Hood. We are proposing, the feasibility of hosting an independent integrated taxonomy library for thrips and indicate that it can serve as an effective system for species identification, this approach could potentially play a key role in formulating effective insect pest management strategies.

Weevils of the genus Lepropus Schoenherr from the Oriental Region (Coleoptera: Curculionidae: Entiminae)

Abstract All the thirty-six species of the entimine genus Lepropus Schoenherr of the family Curculionidae (Coleoptera) known from the Oriental Region are reviewed. The taxonomic characters used and the economic importance of the group are discussed. Eight new species, namely, christopheri, janakiramani, mysorensis, siamensis, sublateralis, swarajae, thompsoni and venkataramani are described. Five species, chinensis, cinereus, lateralis, scintillans and submarginalis are redescribed. The descriptions of many already described species are supplemented with characters of elytral vestiture and genitalia. An annotated checklist and a key to the Oriental species are given.

A Bemisia tabaci midgut protein interacts with begomoviruses and plays a role in virus transmission.

Begomoviruses are a major group of plant viruses, transmitted exclusively by Bemisia tabaci (Gennadius) in a persistent circulative non‐propagative manner. The information regarding molecular and cellular basis underlying Begomovirus – whitefly interaction is very scarce. Evidences have suggested that the insect gut possesses some crucial protein receptors that allow specific entry of virus into the insect haemolymph. We have performed yeast two hybrid gut cDNA expression library screening against coat protein of Tomato leaf curl New Delhi virus (ToLCV) and Cotton leaf curl Rajasthan virus (CLCuV) as bait. Midgut protein (MGP) was the common protein found interacting with both ToLCV and CLCuV. MGP was localized in whole mount B. tabaci as well as in dissected guts through confocal microscopy. Pull down and dot blot assays confirmed in vitro interaction between ToLCV/CLCuV coat protein and MGP. Immunolocalization analysis also showed colocalization of ToLCV/CLCuV particles and MGP within insects gut. Finally, anti‐MGP antibody fed B. tabaci, exhibited 70% reduction in ToLCV transmission, suggesting a supportive role for MGP in virus transmission.