Efficacy of Citrullus colocynthis seed extract on Earias vittella, Fabricius, (Lepidoptera: Noctuidae): environment sustainable approach

Earias vittellaFabricius, 1794 (Noctuidae: Lepidoptera) is deliberated to be one of the most destructive pests of cotton and okra vegetation in the world including Asia. The pest has established resistance to various synthetic insecticides. The use of bio-pesticide is one of the unconventional approaches to develop a vigorous ecosystem without harming non- target pests and beneficial natural insect fauna. In the present study, the toxicity levels of Citrullus colocynthis seed extract have been evaluated against the populations of E. vittellaunder standardized laboratory conditions. The toxic effects of C. colocynthis on development periods, protein contents and esterase activity of the life stages of E. vittella were also evaluated. The toxicity levels of methanol, ethanol, hexane, water and profenofos were evaluated on the 1st instar larvae of E. vittella. LC30 and LC80 concentrations exhibited the effectiveness of methanol-based C. colocynthis seed extract against 1st instar larvae of E. vitella. The enhanced larval and pupal periods were revealed in treated samples during the comparison with untreated samples. The intrinsic rate of increase, net reproductive rate in the LC30 and LC80 concentrations exposed larvae remained less than the control treatment. Fecundity, the esterase activity and protein contents were declined in LC30 and LC80 treated samples as compared to the control. The present findings suggest that C. colosynthis extracts based botanical insecticides are beneficial, ecosystem sustainable and can be integrated with insect management programs from environment safety perspective.

Morphological and Biochemical Responses Associated With Resistance to Earias Vittella Fab. (Lepidoptera: Noctuidae) In Okra Varieties

Response of morphological and biochemical traits against okra shoot and fruit borer in different okra varieties were studied. Among the fifteen okra varieties under test Kashi Satdhari was the most superior variety as it showed lowest (2.60) per cent shoot damage followed by D-1-87-5 (3.62%) and Pusa A-4 (4.24%). On the contrary, in Pusa Sawani highest level of shoot infestation (16.23%) followed by SB-2 (13.74%) as against Kashi Pragati (check) 10.08 per cent were recorded. Further, okra variety Kashi Satdhari (7.87%) showed lowest fruit infestation and was considered as least susceptible variety which was at par with NO-136 (8.77%), D-1-87-5 (9.12%) and Kashi Leela (9.38%). Amongst all the okra varieties evaluated for their susceptibility to fruit infestation, Pusa Sawani and VRO-03 showed relatively higher fruit infestation i.e. 35.17 and 33.41 per cent, respectively and registered as the most inferior varieties against (26.12%) Kashi Pragati (check). The correlation study between fruit infestation and morphological factors implied that primary branching and trichome length adversely affect the borer infestation. Further, phenol and phosphorus availability in host plant also showed negative effect on shoot and fruit borer infestation. Bangladesh J. Bot. 50(4): 1059-1066, 2021 (December)

A study of life cycle of vegetable pests in Ranchi

The study is done to investigate the different pests found in the vegetables in Ranchi. The pests who damage these vegetables are Plutella xylostella (cauliflower pest), Earias vittella (Okra Pest), Etiella zinckenella (pea pod borer) and Thysanoplusia orichalcea (coriander leaf pest). The pests’ life cycle was studied in detail by culturing the insect in the laboratory. Pest problem is one of the major constarints for getting good yield in the agricultural crops. India also suffers a huge loss in crop yield due to pests and diseases each year. The study of life cycle of the pests show that the insects undergo metamorphosis and the larval stage is the damaging phase of the life cycle. The use of pesticides to kill the pests causes environmental pollution which has become an increasing problem.

INSECTICIDAL AND INHIBITORY POTENTIAL OF TWO CHITIN SYNTHESIS INHIBITORS, BUPROFEZIN AND LUFENURON ON OKRA SHOOT AND FRUIT BORER, EARIAS VITTELLA

In this laboratory study, insecticidal and inhibitory potential of two chitin synthesis inhibitors (CSIs) viz. Buprofezin and Lufenuron were evaluated against okra shoot and fruit borer (OSFB). CSIs were applied on three days old larvae through different bioassay methods like topical or direct, okra-dip or indirect and combined (topical + leaf-dip). Data were collected on larval mortality, weight reduction and deformations of larvae and adults. Results showed that larval mortality and weight reduction were clearly dose, application methods and time dependent. In case of both CSIs, the highest mortality was found @ 1.0 ml/L that was followed by 0.75 ml and 0.50 ml/L respectively. Likewise, the highest body weight reduction was also found from 1.0 ml/L. In both cases, the concentration 0.5 ml/L was found less effective. In case of application methods, combined bioassay method was found superior than that of rest of the two methods. Moreover, a significant percentage of deformed larvae and adults were developed when 3 days old larvae were treated with either Buprofezin or Lufenuron @ 1.0 ml/L through combined bioassay method. The concentration 0.5 ml/L had very less efficacy on the development of deformed larvae or adults. Therefore, based on the laboratory findings Buprofezin and Lufenuron may be the potential component in IPM programmed, rather than their individual application, for controlling okra shoot and fruit borer as well as production of safe okra.