Watermelon, Citrullus lanatus is one of the most widely grown fruit crops in all parts of India. The cotton aphid, Aphis gossypii Glover was found to be the most destructive pest of watermelon in the early stage of crop growth. The aphid secretion of honeydew and development of sooty mould prevent the photosynthetic activity of leaves causing 45-75 % of seedling mortality. In this context, a field experiment was conducted to evaluate certain biorational pesticide against A. gossypii in watermelon. It was found that a significantly lowernumber of A. gossypii population (4.39 aphid/leaf) was recorded with the treatment of Azadirachta indica oil @ 3% followed by Beauveria bassiana (1x108 cfu spores @ 8 g /L) (6.01 aphid/leaf) and spinosad 45% SC @ 0.3mL/L (9.16 aphid/leaf), respectively resulting 92.89%, 90.27% and 85.17% reduction of A. gossypii population. Similarly, with the same trend the highest fruit yield (25.50 t ha-1) was recorded in the treatment of A. indica followed B. bassiana (24.43 t ha-1), spinosad (23.53 t ha-1) and lowest in the untreated check (16.30 t ha-1). The increase in fruit yield (56.44%) was recorded in the treatment of A. indica followed B. bassiana, (49.87%) and spinosad (44.17%). A maximum incremental benefit cost ratio of 1:2.84 was recorded in the treatment of A. indica followed by B. bassiana (1:2.74) and spinosad (1:2.68). From these findings it may be recommended that three rounds of application of A. indica oil @ 3% or B. bassiana (1x108cfu spores @8g /L) or spinosad 45% SC@ 0.3 mL/L at 15 days interval for the management of A. gossypii in watermelon

A field experiment was conducted to evaluate the efficacy of certain selective insecticides against the serpentine leaf miner Liriomyza trifolii (Burgess) in water melon Citrullus lanatus (Thunb.) Matsum and Nakai. The hybrid F1 (Melody) was sown in protray and 13 days old seedlings were transplanted in the main field. Significant less live mines (1.48/leaf) was observed with chlorantraniliprole 18.5%SC @0.6 ml/l. This was followed by flubendiamide 39.35%SC @0.6 ml/l (2.09/leaf) and indoxacarb 14.5%SC @0.65ml/l (3.05/leaf). Leaf damage/plot was 2.72, 3.48 and 4.03%, with chlorantraniliprole, flubendiamideand indoxacarb, respectively. Significantly maximum yield of fruits (25.5 t/ha) was obtained withchlorantraniliprole given as three sprays at 15 days interval. Thus, chlorantraniliprole 18.5%SC @0.6ml/l can be recommended against L. trifolii in water melon.

Two spotted spider mite Tetranychus urticae Koch is an economically serious pest posing threat to major vegetable crops. Roving survey in and around Coimbatore region revealed that farmers do not target mites with acaricides instead they use higher dose of insecticides at frequent intervals which results in development of resistance. The bioassay results revealed that fenpropathrin (2.07 to 6.86-folds) and fenazaquin (2.74 to 7.13-folds) exhibit higher susceptibility, whereas diafenthiuron (5.35 to 12.25-folds) revealed a low to moderate level of resistance. The propargite (43.80 to 60.63-folds) and chlorfenapyr (61.01 to 75.10-folds) exhibited high resistance, followed by spiromesifen (222.28 to 300.26-folds) and buprofezin (382.60 to 417.87-folds), with extremely high level of resistance. The higher specific activity of GST (4.54-folds), MFO (10.06-folds) and CarE (15.06-folds) in Puthupalayam population suggested the role of biochemical resistance. A significant positive correlation was observed between diafenthiuron and CarE activity (r = 0.981*), fenpropathrin and MFO activity (r = 0.964*).

Background: Two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) is a destructive, polyphagous and cosmopolitan pest infesting a wide range of vegetables. Farmers frequently use acaricides in the vegetable ecosystem for mite management leading to increased probability for the development of resistance against acaricides in mite species. Literature about resistance in T. urticae to novel acaricides is scanty from this region. Hence, this study was aimed to evaluate the magnitude of acaricide resistance in T. urticae populations on vegetable crops from Southern districts of Tamil Nadu against seven acaricides. The role of detoxification enzymes in conferring bio-chemical resistance in the mite species was also studied. Methods: The laboratory experiments were conducted at completely randomized design (CRD) during 2019-2021 in central instrumentation laboratory, Department of Agricultural Entomology, Agricultural College and Research Institute, Tamil Nadu Agricultural University, Madurai. The level of resistance in T. urticae populations to fenazaquin, propargite, spiromesifen, buprofezin, fenpropathrin, diafenthiuron and chlorfenapyr was evaluated following the leaf dip bioassay technique. The activity of the detoxifying enzymes viz., Glutathione S Transferase (GST), Mixed Function Oxidase (MFO) and Carboxylesterase (CarE) were estimated. Result: Fenazaquin was highly toxic to T. urticae, which recorded a low level of resistance (2.00 to 8.62-fold). T. urticae exhibited a low to moderate level of resistance to fenpropathrin (1.86 to 37.28-fold), moderate to a high level of resistance to diafenthiuron (15.81 to 50.53-fold), high level of resistance to propargite (45.16 to 65.10-fold) and chlorfenapyr (54.67 to 100.14-fold) and extremely high level of resistance to spiromesifen (193.04 to 452.61-fold) and buprofezin (377.97 to 514.44-fold). Among all the test populations, the highly resistant DAmRg population exhibited the highest specific activity of the detoxifying enzymes, viz., GST (26.98 nmoles ml-1 min-1 mg of protein-1), MFO (5.07 nmoles ml-1 min-1 mg of protein-1) and CarE (827.90 nmoles ml-1 min-1 mg of protein-1). The CarE activity was found to be positively correlated with highly resistant acaricide, propargite (r = 0.995) and MFO activity with buprofezin having an extremely high level of resistance (r = 0.997). This preliminary knowledge would be instrumental in framing the acaricide resistant management (ARM) strategies.

Hexane extracts of certain botanicals were evaluated in the laboratory for their oral, contact, fumigant toxicity and repellent activity at 5% concentration against rice weevil Sitophilus oryzae L. at the Natural Pesticide Laboratory, Department of Agricultural Entomology, Agricultural College and Research Institute, Madurai, Tamil Nadu during 2019-2021. The results revealed that all the botanicals were effective. Considering the contact toxicity, 5% hexane extract of Mentha spicata 5% (80.00%) performed better at 72 hr after treatment. M. spicata and Vitex negundo 5% hexane extract exhibited maximum oral toxicity (90.00%). Fumigant effect was maximum in V. negundo (73.33%), M. spicata, Ocimum sanctum and Tagetes erecta flower extracts (70.00%). Ocimum sanctum (70.56%) and M. spicata (67.22%) exhibited maximum repellency. Thus, M. spicata at 5% was the most effective as contact, oral, fumigant toxicant and repellent against S. oryzae in stored maize.

The present investigation was carried out to estimate the efficacy of different elicitors on rice leaf folder, Cnaphalocrocis medinalis (Guenee) and coccinellid predators under field conditions at Puthuthamaraipatty village and AC&RI, Madurai. Among the different elicitors tested, Methyl salicylate @ 10 mM conc. recorded the lowest per cent leaf damage of 3.38 and 4.16 in field trial I and field trial II respectively. The per cent reduction of leaf damage over untreated check in field trial I was 74.37 and 75.08 in field trial II, followed by salicylic acid @ 10 mM conc. with 68.12 and 68.79 in field trial I and field trial II. Methyl salicylate @ 10 mM conc. attracted more population of coccinellids, 0.99/sweep and 1.15/sweep in field trial I and field trial II, respectively, followed by salicylic acid @ 10 mM conc. which recorded the mean coccinellid population of 0.83/sweep in field trial I and 0.93/sweep in field trial II.

Field experiment was carried out to evaluate the efficacy of certain new acaricide molecules against citrus leaf mite Panonychus citri McGregor at the Agricultural College and Research Institute, Madurai during December to March 2019. Among these, fenpyroximate 5EC @1.0 ml/ l led to 85.9% reduction of mites, closely followed by spiromesifen 22.9SC @0.75 ml/ l (83.2 % reduction) and propargite 57EC @ 2.0 ml/ l (79.4% reduction). These treatments also gave higher fruit yield (14.7 t/ ha, 13.9 t/ha, 11.6 t/ha) and increased cost benefit ratio (1:2.8, 1:2.6, 1:2.2), respectively.

Fall armyworm (FAW), Spodoptera frugiperda (J.E.Smith) is one of the most important pests of maize, suddenly appeared in India 2018 and other cereal crops.The colloidal chitosan was synthesized in the laboratory, from the waste of sea food and studied for its bio efficacy by leaf dip bioassay on FAW.The antifeedant effect was assessed on first instar larva at concentration of one, three, five and seven per cent under no choice condition.The one and 7 per cent colloidal chitosan showed 40.51 per cent and 85.38 per cent antifeedant effect over untreated check respectively.The leaf weight loss was observed at one and 7 per cent colloidal chitosan exhibited 24.95 and 11.05 per cent respectively.The per cent reduction in leaf consumption on weight basis was 66.68 per cent when fed with 7 per cent colloidal chitosan treated leaf.Among different concentration used 7 per cent colloidal chitosan showed higher antifeedant effect against first instar larva of FAW.

Cyanogenic glycosides are nitrogen containing secondary metabolites which offer plant defense mechanism against herbivores while recently various insects have developed ability to detoxify, sequester and synthesize these cyanogenic compounds. Dhurrin was the first identified and isolated CNGs from young leaves of sorghum, Sorghum vulgare. The presence of CNGs were confirmed in few species of Chilopods, Diplopods, Heteropterans, Coleopterans and Lepidopterans. Linamarin and Lotaustralin were the major CNGs distributed in Lepidopterans. They have developed an ability to de novo synthesize CNGs and detoxify them with the help of β-cyanoalanine synthase and rhodonase. This may be due to the course of insect evolution or the genes responsible for the synthesis of CNGs may get transferred from plants to insects. In future, the responsive genes in these arthropods should be silenced and expansion of transgenic cyanogenic plants may encouraged to ensure plant defense mechanism.

The present study evaluates the effect of host plant resistance by antixenosis (trichomes) in 40 brinjal entries to the two spotted spider mite Tetranychus urticae Koch, an important pest of brinjal. The maximum trichome density was observed (719.15/ 0.5cm2 leaf area) with the variety Namakkal local and minimum (276.82/ 0.5cm2 leaf area) was with Tiruppur local. Stellate type of trichomes were observed on all the entries, with maximum length on the upper surface of the leaves being 200.18 μm on Namakkal local, and on lower surface of leaves (269.36 μm) on Chinthapalli local-2. Manapparai local measured 247.40 μm long on midrib and 206.84 μm on veins. The correlation coefficients between the trichome density, length and T. urticae incidence revealed a significant negative correlation. Arka Nidhi was found to be resistant (2.07/cm2 leaf area) with low trichome density (427.50 μm).

The present study was conducted to evaluate the insecticidal property of Ocimum basilicum (L.) against cigarette beetle, Lasioderma serricorne (Fab.). The bioactive compounds from the leaves were extracted using Soxhlet apparatus with methanol. Five different concentrations viz., 1%, 2%, 3%, 4%, 5% were used against adult beetles of L. serricorne. In contact toxicity, highest mean mortality was effected by 5% methanol extract (66.67%), followed by 4% methanol extract (58.33%), 3% methanol extract (52.22%), 2% methanol extract (47.22%) and 1% methanol extract (43.33%). In repellency test, 5% methanol extract produced highest mean repellency (86.88%) (Class V) followed by 4% methanol extract (80.00%) (Class V), 3% methanol extract (73.75%) (Class IV), 2% methanol extract (68.13%) (Class IV) and 1% methanol extract (64.38%) (Class IV).

In the present study, botanicals (11 nos.) were extracted using ethyl acetate solvent (mid-polar) and evaluated for their fumigant toxicity and repellent activity at 5% concentration against rice weevil, Sitophilus oryzae L. in comparison with Acorus calamus.The results revealed that all the botanicals were effective against Sitophilus oryzae compared to untreated control. Mentha spicata 5% ethyl acetate extract exhibited 83.33% fumigant toxicity after 72 hours of treatment with maximum repellency rate of 76.11%. Ocimum sanctum displayed 80.00% fumigant toxicity with the repellency rate of 76.11% and grouped under Class IV. Vitex negundo 5% treatment caused 83.33% fumigant toxicity, and it was statistically on par with the M. spicata and the repellency rate was 72.78 against S. oryzae. Curcuma longa caused effective repellency rate of 75.56% and was grouped under Class IV. Hence, it is concluded that 5% ethyl acetate extract of M. spicata, V. negundo and O.sanctum were toxic against S. oryzae in stored maize.

Morphological and biochemical features of host plants have an impact on survival, feeding, distribution, reproduction and behavior of many phytophagous insects. Chemical communication is most common between the insects and their host plants. The survival and the behaviour of many of the phytophagous insects depends on their host plants. Sex and aggregation pheromones play a major role in their intra-specific communication among the insect species. The behaviour and physiology of insects including pheromonal communication optimizes the mating and reproduction is by the host plant phytochemicals. Host plants aids insects by producing cues to find mating partners, and insects have also developed some tactics to optimize mating for better reproduction using these host plant chemicals. In general, the phytophagous insect pests are a major constraint in the production of agricultural, horticultural crops and plantation too. As many broad-spectrum chemicals are restricted as a result of indiscriminate application, a need to develop better alternative control method with long term sustainability is the need of hour in the management system. Development of pheromone-based lures can be of greater importance in control along with the use of host plant chemicals to enhance or synergize sex attraction of insects. Knowledge on insect behaviour in response to the combinations of their host plant chemicals and their pheromonal communications is important in research and for production of sexual and host plant attractants as a new approach to biologically manage the phytophagous insect pests.

The study of form and structure of an insect at a microscopic level is known as insect micro-morphology. This review emphasizes some of the spectacular micro-structures present in insects namely gyroid photonic crystals in butterflies and weevils, brochosomes in leaf hoppers, neck region of dragonflies, labium of rove beetles, hypochaeta in forewings of fairyflies, hydrophobic structures in springtails, stridulatory organs in crickets, tymbal organs in cicadas, anti-reflective coatings in glass wing butterfly, facet lenses in robber fly, ocelli in halictid bees, reaction chamber in bombardier beetles and the keel of stick insects. The gyroid photonic crystals are essential for the reflection of colour in certain butterflies and weevils. The brochosomes secreted by the malphigian tubules of leaf hoppers covers their integument which acts as a protective covering. The further studies on the destruction of brochosomal layer would be helpful to maximize the parasitization and insecticidal efficiency. The knowledge on the similar other micro-structures might be worthy for species identification.

The field investigation was carried out to evaluate the acaricidal property of certain plant oils against citrus leaf mite, P. citri at Madurai Agricultural College and Research Institute during Kharif 2018. Among the plant oils evaluated, neem oil (6.3 No./ leaf, 76.6% reduction), citrus peel oil (7.0 No./ leaf, 74.0% reduction) and citronella oil (7.3 No./ leaf, 72.9% reduction) were proved to be superior with the least mite population and the highest per cent reduction over untreated check coupled with higher fruit yield (9.6, 7.7, 6.9 t/ha) and increased cost benefit ratio (1:3, 1:2.4, 1:2.1), respectively over untreated check.

Solitary bees are excellent ecosystem servants for efficient pollination in angiosperms. The present study on these was carried out at the Agricultural College and Research Institute, Madurai campus through surveys carried out in various zones. Species diversity, richness, evenness and floral preference were explored for the variations in the zones. The results revealed that the variation is depending upon the nature of the locations included in these agroclimatic zones. The foraging activity of sonicating native bees was predominant on the plants belonging to the in families like Fabaceae, Pedaliaceae, Bignoniaceae, Asteraceae followed by Verbenaceae, Solanaceae, Malvaceae and Cucurbitaceae. Comparatively less preference could be observed on Apocynaceae, Punicaceae and Polygonaceae as regards cultivated and uncultivated crops. Mostly the bees preferred floral colour like purple and yellow followed by white for both nectar as well as pollen collection, whereas the least preference was for pink.

Citrus red mite (P. citri) is one of the key pests of citrus and distributed all over the world where citrus is cultivated predominantly. Nymphs and adults sucks the nutrients from the leaf and fruits by means of their long stylets. The feeding produces tiny grey or silvery spots on leaves and fruits known as stippling. Damage to leaves inhibits photosynthesis, increases transpiration which may lead to necrosis. Severe infestations can lead to premature leaf fall, discoloration of fruits, dieback symptom and decreased plant vigour (Kranz, 1977). Citrus is commercially grown in the southern regions of Tamil Nadu.

Ceratina binghami Cockerell is an efficient pollinator of cultivated and uncultivated crops. They construct the linear nest for their young ones in pruned sticks, hollow stems and dead wood. The present investigation was carried out at Agricultural College and Research Institute, Madurai, during 2018-2019. Nests (29 nos.) were collected for this study from six different host plants viz., Crotons, Codiaeum sp., Yellow bell, Tecoma sp., Peacock flower, Caesalpinia pulcherrima, Copper pod tree, Peltophorum pterocarpum and Rose. The nests were linear and partitioned with chewed straw. Among these, the most preferred host was Peltophorum pterocarpum. Diameter of the nest entrance, length and width of the nests were recorded as 0.36±0.06 cm, 11.59± 4.35 cm and 0.36±0.06 cm, respectively. Duration of each and every stage of immatures was recorded. Younger ones were located at the nest entrance and the older progeny was placed in the inner side of the nest. Some brood cells were empty between the cells and adult were found at the nest entrance, to guard the immatures from predators and parasitoides.

The investigation on screening forty one germplasm collections of okra for their reaction against two spotted spider mite Tetranychus urticae (Koch) by damage grading index and mean mite population/cm2 expressed a diverse reaction among the tested entries. The results revealed that the entry viz., IC 117238 which recorded mean mite population of 35.6 /cm2 leaf area was found to be highly susceptible to TSSM with the damage rating of four (0-4 Scale). The seven highly resistant okra germplasm collections (IC 128092, IC 128095, EC 305743, EC 306737, IC 031850, IC 105742 and IC 117235) which recorded the minimum mite population ranging between 13 and 15.67/cm2 leaf area were categorized under the grade zero and could be exploited in developing a resistant source against two spotted spider mite Tetranychus urticae.