Badal Bhattacharyya

Bioecology and management of giant African snail, Achatina fulica (Bowdich).

Giant African snail ( Achatina fulica Bowdich) belongs to the Phylum-Mollusca and Class- Gastropoda. It is known for its destructive nature on cultivated crops wherever it occurs and is one of the worlds largest and most damaging land snail pests. The pest is an East African origin, has spread in recent times by travel and trade to many countries. They now widely distributed and no longer limited to their region of origin due to several factors viz., high reproductive capacity, voracious feeding habit, inadequate quarantine management and human aided dispersal. A. fulica can cause serious economic damage on different crops and extensive rasping (scrapping), defoliation, slime trials, or ribbon like excrement is signs of infestation. In recent times, severe outbreak of this pest has been noticed due to some desirable agricultural and gardening practices like minimum tillage practices and straw retention techniques which help in survival of snails and make seedlings more susceptible to damage. This review paper aims to enlighten on taxonomy, distribution, extent of damage, morphology, biology, ecology, homing behaviour, seasonal incidence, nature of damage, host plants of A. fulica and its ecofriendly management strategies.

Faunal Composition of Scarab Beetles and Their Hosts in Assam

Field investigations were conducted in the Instructional cum Research Farm and Horticultural Orchard of Assam Agricultural University, Jorhat, to monitor the population of foliage-feeding scarab beetles on eight different host plants during 2010–2012. The highest numbers of beetles were collected from sthal-padma (Hibiscus mutabilis) (1579 numbers) followed by agar (Aquilaria malaccensis) (1526 numbers) and guava (Psidium guajava) (1348 numbers). The lowest number was found on jute (Corchorus sp.) (370 numbers). The host plants, viz., rose (Rosa chinensis), ber (Ziziphus jujuba), Silikha (Terminalia chebula), and Soalu (Litsaea polyantha) recorded 1143, 1143, 1065, and 930 beetles, respectively. The present investigation also revealed 13 numbers of new host plants of scarab beetles, viz., devil tree (Alstonia scholaris), albizia (Albizia odoratissima), dalchini (Cinnamomum zeylanicum), cocoa (Theobroma cacao), indigo (Indigofera zollingeriana), mango (Mangifera indica), Assam lemon (Citrus lemon), green gram (Vigna radiata), jamun (Syzygium cumini), rain tree (Samanea saman), mast tree (Polyalthia longifolia), jackfruit (Artocarpus heterophyllus), and drumstick (Moringa oleifera). Through scouting 20 species of scarab beetles were recorded, of which, Sophrops iridipennis, Anomala perplexa, Anomala dussumieri, and Adoretus renardi are new records from Assam.

Management of termite in preserved setts of sugarcane (Saccharum officinarum) with microbes

An investigation was carried out during 2010–11 and 2011–12 using five microbes and an insecticidal check against termite in preserved setts of sugarcane (Saccharum officinarum L.) in Assam. Among the microbials, the setts treated with Metarhizium anisopliae @ 1012 spore litre−1 recorded lowest infestation of termite (21.25 and 19.06% and 22.62 and 23.59% as numbers and portions of setts attacked) with germination percentage of 67.86 and 67.81 during 2010–11 and 2011–12, respectively. The insecticidal check i.e. chlorpyriphos 20 EC @ 2 ml litre−1 recorded least mean number (15.16 and 14.84%) and portion of setts (14.81 and 16.10%) infestation by termite coupled with a marked increase in per cent germination (78.02 and 76.82%). Experimental results further indicated very high level of infestation of termite in untreated control, which led to the poor germination of setts.

Life cycle of the southern cattle tick, Rhipicephalus ( Boophilus ) microplus Canestrini 1888 (Acari: Ixodidae) under laboratory conditions

Abstract The southern cattle tick, Rhipicephalus (Boophilus) microplus is one of the most important tick species affecting bovine wealth worldwide. Three uninterrupted generations of this species were observed under laboratory conditions (28±3 °C and 80±5% R.H.) using rabbit hosts. The average life cycle was determined as 65±8 days. Adult feeding period averaged 7..1±1.24 days. Pre-oviposition and oviposition periods averaged 4.1±1.3 days and 8.6±0.85 days, respectively. Pre-hatching periods averaged 21.03±2.99 days. Larval free-living and feeding to moulting periods averaged 3.5±0.75 days and 7.9±0.69 days, respectively. Nymphal feeding to moulting periods averaged 10.9±1.38 days. Weights of unfed and fed females averaged 1.26±0.29 mg and 120.32±45.6 mg, respectively and produced egg masses with average weights of 29.5±9.03 mg. Number of eggs per female averaged 1455.3±434.5 eggs with peak oviposition on the 3rd day. Average hatching rate was 83.5±2.94%, and the reproduction efficiency index averaged at 12.79±2.85. The conversion efficiency index averaged at 0.26±0.05 and the reproduction fitness index averaged at 10.68±2.4. Tick recovery rate averaged at 4.7%. A strong linear relationship was found between weights of engorged females and weights of egg masses (r = 0.83) and also between weights of engorged females and number of eggs laid (r = 0.82). This work aims to describe temporal and quantitative biological facts of R. (B.) microplus life cycles. Few studies have discussed R. (B.) microplus biology in quantitative terms, and these data can be useful in designing control plans or in epidemiological studies under laboratory conditions.

Nutritional Composition of Five Soil-Dwelling Scarab Beetles (Coleoptera: Scarabaeidae) of Assam, India

Abstract Proximate and elemental compositions of five soil-dwelling scarabs, Lepidiota mansueta Burmeister, Lepidiota albistigma Burmeister, Xylotrupes gideon (Linnaeus), Catharsius molossus (Linnaeus), and Sophrops iridipennis (Brenske), were assessed. Nutrient content varied widely, and the ranges of proximate contents were as follows: moisture (2.04–2.55%), crude protein (68.54–79.33%), crude fat (4.00–5.50%), crude fibre (5.16–8.28%), total mineral (0.80–4.98%), and carbohydrate (5.28–11.84%). Caloric content was greater in L. mansueta (379.29 kcal) compared to the other four species. The caloric contents of X. gideon (375.54 kcal) and C. molossus (375.19 kcal) were at par but significantly higher than those of L. albistigma (371.04 kcal) and S. iridipennis (361.55 kcal). Sodium content ranged 23.16–35.91 mg/100 g; potassium 14.20–44.33 mg/100 g; calcium 23.33–33.37 mg/100 g; iron 1.41–37.05 mg/100 g; copper 2.01–16.13 mg/100 g; zinc 2.38–15.86 mg/100 g; and manganese 1.09–19.66 mg/100 g. The phenol, flavonoid, and antioxidant activities of L. mansueta and L. albistigma were 4.00 and 6.42 mg catechol equivalent/g, 1.59 and 3.71 mg quercetin equivalent/g, 22.60, and 28.20%(DPPH activity), respectively. Tannin content was higher in L. albistigma (13.30 mg/g) than in L. mansueta (3.24 mg/g). Based on our study, these scarab species can be explored as food supplements and nutraceutical resources in ensuring food security.

Antenna morphology and sensilla microstructure of the male and female scarab beetle, Lepidiota mansueta Burmeister (Coleoptera: Scarabaeidae)

Abstract Studies on Lepidiota mansueta Burmeister were conducted to describe and compare the external morphology of the antenna and its sensilla of male and females. Distinct variations were observed in antennal segments between the sexes with males possessing longer scape, pedicel, flagellum and lamellar club segments. Variation was also seen in the antennal sensilla, with males possessing three different types of sensilla while the females possessed seven types of sensilla. Sensilla trichodea (TRS), sensilla placodea (PLAS) type I and sensilla placodea (PLAS) type II were common in both sexes while sensilla chaetica (CHS), sensilla auricilica (AUS) type I, sensilla auricilica (AUS) type II and sensilla auricilica (AUS) type III were found only in females.

Field evaluation of some insecticides against white grub, Lepidiota mansueta B. (Coleoptera: Scarabaeidae), on potato (Solanum tuberosum) in Assam (India)

Field studies were conducted to evaluate the efficacy of six insecticides against white grub, Lepidiota mansueta, in potato in 2012 and 2013 at Majuli river island in Assam (India). All the insecticide treatments significantly reduced tuber damage as against untreated control. Of the insecticides tested, fipronil 5 SC @ 150 g a.i.ha−1 showed low tuber damage on weight basis (5.24 and 4.57%) and was at par with fipronil 5 SC @ 100 g a.i.ha−1 (5.91 and 5.09%), chlorpyriphos 20 EC @ 400 g a.i. ha−1 (5.55 and 6.2%) and quinalphos 25 EC @ 400 g a.i.ha−1 (6.14 and 6.72%). On number basis, fipronil 5 SC @ 150 g a.i.ha−1 showed lowest tuber damage (4.2%), followed by chlorpyriphos 20 EC @ 400 g a.i.ha−1 (5.25%) and quinalphos 25 EC @ 400 g a.i.ha−1 (5.66%). All insecticide treatments were at par in tuber yield, except emamectin benzoate 5% SG @ 12.5 g a.i.ha−1. Highest cost benefit ratio was observed in chlorpyriphos 20 EC @ 400 g a.i.ha−1 treatment (2.50 and 2.62), followed by quinalphos 25 EC @ 400 g a.i.ha−1 (2.23 and 1.85). Chlorpyriphos 20 EC @ 400 g a.i.ha−1 and quinalphos 25 EC @ 400 g a.i.ha−1 seem better alternatives than fipronil to reduce infestation of L. mansueta in potato.