Toxic effects of neem-based insecticides on Pieris brassicae (Linn.)

The effect of different cole crops was studied on biological parameters of Pieris brassicae (L.) in the laboratory at 28 °C, 65% RH, and 12L:12D photoperiod. The results indicated that host plants significantly affected the life history, i.e. survival of developmental stages, oviposition period, and sex ratio of P. brassicae. Comparative study on different host plant revealed that P. brassicae required a maximum of 40 days to complete generation on cabbage, cauliflower, and broccoli. The survivorship and expectation of life declined gradually with the advancement of age; the life expectancy of newly deposited eggs was 23.96 days while it was 8.12 days at the time of adult emergence on cabbage. However, the fluctuations of mortality parameter were seen on all the cole crops. On cabbage, 100% hatching of eggs with low larval mortality were noticed. The highest net reproductive rate (R0) occurred on cauliflower, i.e. 27.1 followed by cabbage 24.89, females per female per generation. Intrinsic rate of increase (rm), was found to be highest (0.09558954) on cauliflower followed by broccoli and cabbage, 0.078886 and 0.077551 females per female per day, respectively. The smallest rm (0.059469 females per female per day) occurred on radish which shows that P. brassicae did not perform well on radish. In addition, P. brassicae may double in 7.2 days on cauliflower, 8.7 days on broccoli, and 8.9 days on cabbage. The sex ratio was computed as 1.5:1, female:male, respectively on cabbage.

Effect of different cole crops on the biological parameters of Pieris brassicae (L.) (Lepidoptera: Pieridae) under laboratory conditions

Effects of different brassicaceous host plants on the fitness of Pieris brassicae (L.)

Horticultural crops undergo various physiological and biochemical changes that lead to undesirable physiological disorders, decay and subsequent economic losses during storage. Quality degradation of horticultural crops is mainly caused by postharvest pathogens such as Botrytis cinerea and Penicillium spp., etc. The application of synthetic fungicides remains the most effective method to control postharvest pathogens. However, their use is becoming increasingly restricted internationally due to health concerns and consumers’ requests for safe and natural alternatives. This has led researchers to investigate natural flora as one of the alternatives to be used in crop protection and preservation. Various medicinal plant parts have different phytochemicals and antioxidants that can be used in crop protection and preservation. Extracts from plants such as Ruta chalepensis, Eucalyptus globulus, etc., have proven to be effective in controlling postharvest pathogens of horticultural crops and increased their shelf life when used as a substitute for synthetic chemicals. Furthermore, extracts from neem and other medicinal plants contain a predominant and insecticidal active ingredient. The application of medicinal plant extracts could be a useful alternative to synthetic chemicals in the postharvest protection and preservation of horticultural crops. This review paper details the application of medicinal plant extracts for postharvest protection and preservation of horticultural crops.

https://www.mdpi.com/2071-1050/13/11/5897/pdf

Potentials of Medicinal Plant Extracts as an Alternative to Synthetic Chemicals in Postharvest Protection and Preservation of Horticultural Crops: A Review

Myzus persicae Sulzer, 1776 (Sternorrhyncha: Aphididae) is an insect pest of several crops. Chemical control against pests causing harmful effects, so it is necessary to find alternative methods. In this context, insecticidal activity of water and hydroethanol extracts of neem leaves was investigated against the aphid M. persicae through biological performance and feeding behavior assessment. Water and hydroethanol extracts of neem leaves are prepared by soaking ground leaves in water or 10% ethanol overnight. Both water and hydroethanol extracts of neem leaves at 1, 5 and 10% in artificial diet significantly reduced (p < 0.05) the survival of nymphs, leading to more than 95% mortality. Both extracts at 0.1% significantly reduced (p < 0.05) the survival rate and fecundity of M. persicae adults. The feeding behavior of aphids was studied with a dual-choice assay and using the electrical penetration graph (EPG) technique. Dual-choice assays revealed the aphid rejection of the water extract at 10% and the hydroethanol extract at 1 and 5% concentrations. EPG monitoring showed enhanced duration of probing and ingestion on artificial diet containing the water extract at 10%. On plants sprayed with water extract at 10%, EPG monitoring showed reduced duration of probing, delayed phloem access, and reduced salivation and ingestion phases. Our results showed that neem leaves-based preparations are insecticidal agents and effective to control M. persicae.

	 

	Key words: Neem leaves extracts, Myzus persicae, survival, feeding behavior.

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Evaluation of neem leaves-based preparations as insecticidal agents against the green peach aphid, Myzus persicae (Sternorrhyncha: Aphididae)

In the present study, aqueous extract of eight plants, namely Azadirachta indica A. Juss, Melia azedarach Linn., Lantana camara L. Moldenke., Cannabis sativa Linn., Nerium indicum Mill., Eucalyptus sp., Ricinus communis Linn. and Solanum nigrum Linn. were tested for antifeedant and toxic effects against Pieris brassicae (Linn.). The ethanol extract of four potential plants were further tested for their biological activity against the test insects. Aqueous extract of A. indica and M. azedarach repelled maximum number of larvae protected 94.0 per cent and 89.2 per cent cabbage foliage, respectively. Aqueous extract of M. azedarach, N. indicum and A. indica showed higher mortality of larvae (19.6, 19.6 and 18.5%, respectively) while R. communis was the least toxic resulting in 8.9 per cent larval mortality. In case of ethanol extract, seed extract of M. azedarach protected 58.3 per cent cabbage foliage while Eucalyptus sp. protected minimum cabbage foliage. The maximum protection to the cabbage foliage was provided at 5 per cent of M. azedarach (88.3%) and A. indica (82.5%). Ethanol extract of A. indica exhibited statistically higher larval mortality of 50.0 per cent and N. indicum the lowest mortality of 3.2 per cent. In general, antifeedant and larval mortality was dose dependent.

/pdf/biological-activity-of-some-plant-extracts-against-pieris-ksaheo4v4u.pdf

Rakesh Gupta

Papers

Biological activity of some plant extracts against Pieris brassicae (Linn.)

Effect of Plant Extracts on Fecundity of Spodoptera litura