With the aim of selecting potential botanical insecticides, seven plant extracts (Daphne mucronata (Family: Thymelaeaceae), Tagetes minuta (Asteraceae), Calotropis procera (Apocynaceae), Boenninghausenia albiflora (Rutaceae), Eucalyptus sideroxylon (Myrtaceae), Cinnamomum camphora (Lauraceae) and Isodon rugosus (Lamiaceae)) were screened for their toxic effects against four important agricultural pest insects, each representing a separate insect order; pea aphids of Acyrthosiphon pisum (Hemiptera), fruit flies of Drosophila melanogaster (Diptera), red flour beetles of Tribolium castaneum (Coleoptera), and armyworms of Spodoptera exigua (Lepidoptera). Aphids were the most susceptible insect with 100% mortality observed after 24 h for all the plant extracts tested. Further bioassays with lower concentrations of the plant extracts against aphids, revealed the extracts from I. rugosus (LC50 36 ppm and LC90 102 ppm) and D. mucronata (LC50 126 ppm and LC90 198 ppm) to be the most toxic to aphids. These most active plant extracts were further fractionated into different solvent fractions on polarity basis and their insecticidal activity evaluated. While all the fractions showed considerable mortality in aphids, the most active was the butanol fraction from I. rugosus with an LC50 of 18 ppm and LC90 of 48 ppm. Considering that high mortality was observed in aphids within 24 h of exposure to a very low concentration of the butanol fraction from I. rugosus, we believe this could be exploited and further developed as a potential plant-based insecticide against sucking insect pests, such as aphids. 相似文献
Journal of Plant Diseases and Protection - Potato virus Y (PVY) is a destructive plant virus causing important damage in different crops, particularly in potato. PVY is transmitted in a... 相似文献
The pollen beetle Brassicogethes aeneus is a serious pest of oilseed rape (Brassica napus) in Europe. Management of this pest has grown difficult due to B. aeneus’s development of resistance to pyrethroid insecticides, as well as the pressure to establish control strategies that minimise the impact on nontarget organisms. RNA interference represents a nucleotide sequence-based, and thus potentially species-specific, approach to agricultural pest control. The present study examined the efficacy of targeting the coatomer gene coatomer subunit alpha (αCOP), via both microinjection and dietary exposure to exogenous complementary dsRNA, on αCOP-silencing and subsequent mortality in B. aeneus. Beetles injected with dsRNA targeting αCOP (at 0.14 µg/mg) showed 88% and 100% mortality at 6 and 10 days post-injection, respectively; where by the same time after dietary exposure, 43%–89% mortality was observed in the 3 µg dsRNA/µL treatment, though the effect was concentration-dependent. Thus, the effect was significant for both delivery routes. In working towards RNA-based management of B. aeneus, future studies should include αCOP as a target of interest.