Tufail Ahmad

Effect of Indian mustard on feeding, larval survival and development of Plutella xylostella at constant temperatures

Feeding behavior of Plutella xylostella under optional to non‐optional conditions was studied at 10°C, 15°C, 20°C, and 25°C on Indian mustard, Brassica juncea. The study reveals that the variety Pusa Bahar was significantly less preferred by the larvae as compared with Pusa Bold and Varuna under optional to non‐optional conditions. Larvae of P. xylostella consumed more food at 25°C than 20°C, 15°C and 10°C. Larval survival was found to be highest on cabbage (control) as compared with Indian mustard and was found to vary with host plants and temperature. The larval survival decreased to 11.29% on Pusa Bahar at 10°C. Increasing the temperature from 10°C to 20°C, larval mortality resulted more on Varuna than Pusa Bahar and Pusa Bold. Developmental period was prolonged on Pusa Bold at 10°C while it was shortest on cabbage at 25°C. A total of 536.47 degree days were required to complete the development by immature stages on Varuna at 25°C and 421.64 degree days on cabbage.

Microbial Insecticides: Food Security and Human Health

Sustainable agricultural systems must be adopted to increase the food and fiber production keeping in view of human health and increase in population; the number of undernourished has increased to almost 20% (The state of food insecurity in the world economic crises – impacts and lessons learned. In Food and Agriculture Organization of the United Nations, Rome). Insect pests have been causing serious damage in the fields and stored grains and their products. Interventions is required to limit the losses, therefore, synthetic insecticides have played a significant role in their management for more than 60 years. Indiscriminate use of insecticides have left undesirable residues in the environment, which are toxic to human beings and non target organisms as well as insects have developed resistance against them and resurgence of pests that lead to find a suitable, sustainable and efficient method of management. Microorganisms: bacteria, viruses, fungi and protozoa form the most abundant and diverse groups, which offer a vast resource for exploitation to use in the management program. Bacillus thuringiensis is a gram positive, occurs in soil and ubiquitous in distribution. It produces parasporal crystalline body which contains one or more cry proteins that can be toxic to a number of insects. cry proteins are encoded by cry genes and 200 of them are identified. Similarly, a number of insect pests are also vulnerable to viral diseases. Nuclear Polyhedrosis and Granulosis Viruses are commonly used against the Lepidoptera. They are highly species specific and safer to human beings. Fungi, often act as important natural control agents that limit the insect population. Promising results are obtained by Beauveria bassiana and Metarhizium anisopliae against many insect pests. B. bassiana grows naturally in soil throughout the world and causes white muscardine disease. Therefore, intensive work is required to improve the efficacy of microbial insecticides through molecular biology and genetic engineering to enhance their role in the insect management for better food security.

Characterization of four Brassica crops for development of diamondback moth Plutella xylostella (L.) (Lepidoptera: Yponomeutidae)

Development of Plutella xylostella was studied on cauliflower, cabbage, broccoli and radish in protected field condition under nylon net cage for two consecutive years. Result revealed that P. xylostella preferred to lay maximum eggs on cauliflower followed by cabbage, broccoli and radish. Fecundity was more at beginning but declined gradually with advancing of female age. The highest unhatched eggs were recorded on radish and minimum on cauliflower. Larval mortality was least when P. xylostella reared on cauliflower and maximum on radish. Mortality survival ratio for immature stages was highest on radish and lowest on cauliflower. The immature stages of P. xylostella were over within 27.45 days on cauliflower and 30.62 days on radish. Thermal constants significantly differed among the host plants during both the years of study. Maximum degree-days 66.66 and 125.00 was required for development of P. xylostella on cauliflower and minimum 37.03 and 58.82 on radish during both the cropping seasons, respectively. However, P. xylostella required maximum degree days to complete the development of immature stages on broccoli 473.03 and 394.95 degree-days in both cropping years.