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Behavioural studies of mango leaf webber, Orthaga exvinacea were carried out both in the laboratory and field conditions, majorly focusing on neaonate larva, mating, oviposition and intra specific competition. The feeding behaviour of O. exvinacea was found to be gregarious i.e., a group of larvae coalesce together and scrape the chlorophyll content of young leaves. However, the later instars start feeding voraciously by making webs joining the adjacent leaves along with the shoots. The female moths laid eggs individually or in groups (8-14 eggs/cluster) on the lower surface of leaves near the midrib, while eggs were occasionally laid on the upper surface of the leaves during the early hours of photophase. Under field conditions, a series of observations revealed that the eggs were commonly laid in well-established older webs. During scotophase, several behavioural transitions in both male and female moths were observed while studying the mating behavior under laboratory conditions. Larval migration among the brood members of O. exvinacea was also noticed during the study. [ABSTRACT FROM AUTHOR]

The present study investigated the ovipositional preference of okra shoot and fruit borer, Earias vittella (Fabricius) (Order: Lepidoptera; Family: Noctuidae) in relation to host plant biochemical traits independently and also through combining with host plant morphological traits in different wild and cultivated Abelmoschus species. Correlation studies revealed a significant positive relationship between the number of eggs laid by E. vittella to total protein (P, r = 0.17) and a significant negative relationship with total phenols (TP, r = -0.57), total flavonoids (TF, r = -0.38), total sugar (TS, r = -0.57) and total reducing sugars (TRS, r = -0.64). Path co-efficient analysis revealed that total phenols, flavonoids, and total reducing sugars appear to be particularly important, as they, directly and indirectly, affect is. vittella egg-laying choice. Multiple step-wise regression analyses of the number of eggs laid by E. vittella on different Abelmoschus species with host plant biochemical traits together explained the variability in the egg laying to the tune of 54% (R2 = 0.54; Y=26.71-0.30Tp+0.32TF-1.39TS-4.41TRS+8.29p; R2=0.54; VIF=2.19). Further, combining the significant biochemical traits (TRS and P) with significant morphological traits (FL: fruit length, FW: fruit width, T: trichomes) based on r/SE explained the variability in the number of eggs laid by E. vittella to the tune of 78%; Y=7.15+1.35FL-3.64FW+0.05T-2.00TRS+1.66p; R^O.78; VIF^.56. [ABSTRACT FROM AUTHOR]

Insect pollination services play a major role in onion, Allium cepa L. due to the prevalence of protandry. A study was conducted at the experimental fields of ICAR - Indian Institute of Horticultural Research, Bengaluru, Karnataka, India (13.13 oN; 77.49 oE) to understand the foraging behaviour of major insect pollinators associated with onion crop (cv. Arka Kalyan). Continuous surveillance revealed that onion took 70 - 75 days for flower bud initiation and 90 - 95 days for maximum flower opening. A single bulb produced 4.00 ± 1.05 flowering stalks which produced umbel inflorescence that consisted of numerous individual flowers called florets. The mean number of florets in an umbel (449.30 ± 29.47) and the duration of each floret (5.60 ± 0.52 days) were worked out. In general, each floret produced 6.00 -7.00 anthers (Mean ± SE: 6.10 ± 0.32) with a mean number of 1581 pollen grains per anther. A total of 1735 and 1852 individual pollinators were observed visiting the onion during 2020 and 2021, respectively. The floral visitor's data from transect sampling revealed their abundance as: Apis florea > Trigona iridipennis > Apis dorsata > Apis cerana > Ischiodon scutellaris > Eristalis obliquus for two consecutive years. Of all floral visitors, A. florea had recorded highest visits (26.92 %), while Eristalis obliquus recorded the least foraging visits (7.38 %). The observations on foraging behaviour revealed that major foraging activity was carried out by A. cerana, as it spent maximum amount of time on inflorescence (3.30 ± 0.82 umbel / min) followed by A. dorsata (2.50 ± 0.71 umbel / min) and the least with T. iridipennis (1.40 ± 0.52 umbel / min). However, time spent / umbel was maximum with T. iridipennis (45.80 ± 4.41 sec / umbel) and the least was found with A. cerana (16.10 ± 1.85 sec / umbel). [ABSTRACT FROM AUTHOR]

Pulse beetle (Callosobruchus chinensis) is a significant pest in tropical climates that affects stored legumes. Our objective was to study the repellent effect of the selected aromatic plant volatiles, namely Azadirachta indica (neem), Mentha spicata (spear mint), Cymbopogon flexuosus (lemongrass), Ocimum basilicum (sweet basil) and Manihot esculenta (tapioca) to pulse beetle, C. chinensis. Both single-, dual- and multiple-choice olfactometer assays to investigate the way C. chinensis reacts behaviourally to headspace volatiles revealed a significant repellent response to lemongrass and sweet basil headspace volatiles. Gas chromatography-mass spectrometry analysis revealed the presence of 42 and 50 volatile organic compounds in lemongrass and sweet basil respectively. Further, electrophysiological studies involving gas chromatography-electroantennographic detection (EAD)-revealed eight EAD active compounds each in lemongrass (4 nonanone, linalool, citronellal, β -citral, citral, β -elemene, cis-muurola-4(15), 5-diene and β -dihydroagarofuran) and sweet basil (linalool, estragole, 2-methyl-1-decanol, α-guaiene, allo aromadendrene, germacrene D, δ-guaiene and taucadinol). Of these, when the behavioural studies were performed on synthetic EAD active compounds, C. chinensis showed significant repulsion behaviour to monoterpenes, namely citronellal and linalool, indicating the potential of these compounds for the management of C. chinensis. [ABSTRACT FROM AUTHOR]

Insect pests that attack plants generally exhibit a strong preference for specific phenological stages of their host plants for feeding and oviposition. In this study, we examined the influence of different phenological stages volatiles of okra (Ablemoschus esculentus), namely pre-flowering, flowering and fruiting, on the behaviour of the notorious pest, spotted bollworm (Earias vittella Fabricius). To understand the olfactory response of E. vittella, we utilized a Y-tube olfactometer, gas chromatography electroantennographic detection (GC-EAD) and gas chromatography-mass spectroscopy (GC-MS) techniques. Among the three host plant phenological stages, the volatile cues from the fruiting stage were significantly attractive to E. vittella. The specific chemical cues responsible for this attraction were identified using GC-EAD/GC-MS. The electrophysiological studies revealed a total of 14 chemical cues that elicited a clear antennal response in the gravid female moths of E. vittella. Further, detailed olfactometer bioassays with synthetic compounds revealed that four compounds elicited a significant attraction in gravid female moths and one elicited significant repulsion response. The study provides valuable insights into the host plant preference of E. vittella and identifies the underlying potent attractive chemicals for its future management strategies. [ABSTRACT FROM AUTHOR]

Red banded mango caterpillar (RBMC) Deonolis sublimbalis Snellen is a monophagous pest in the tropical regions of South and South East Asia. Behavioural studies on this were carried out both in the field and laboratory conditions during 2016-17, focusing on neonate larva, pupal emergence time, mating and oviposition. Field observations revealed that the eclosion time of neonate larva would be during early hours between 2.00 to 06.00 am, and the larvae preferably attack pea to lemon sized fruits, particularly towards the beak portion (chalazal portion). The larval feeding was majorly nocturnal, photosensitive and gregarious. Larvae were also found to be active during the early hours of photophase and found to migrate among the fruits. Under laboratory conditions, the peak adult emergence was during the 15th standard week (active fruiting season). However, moth emergence was also noticed during the off-season (June to January) in the absence of host. Series of behavioural transitions were noticed while studying the mating behaviour. Gravid females were significantly (p < 0.0001 and p < 0.03) attracted to volatiles of lemon size mango fruits in olfactometer bioassays. [ABSTRACT FROM AUTHOR]