Laboratory Evaluation of Local Plant Extracts and an Organophosphate Insecticide against Seabuckthorn Psyllid

Psyllids or jumping plant lice are small phloem feeding insects having piercing and sucking mouth parts. The psyllids have been reported to vector phytoplasma diseases in horticultural plants. For instance, Cacopsylla pyri L. , C. pyricola (Foerster) and C. pyrisuga (Foerster) are considered as important vectors of pear decline caused by phytoplasma [1-3] and C. picta (Foerster) as a vector of apple proliferation phytoplasma [4-6]. A psyllid, Cacopsylla sp. (Hemiptera: Psyllidae) infests seabuckthorn (Hippophae rhamnoides L.) growing naturally in high altitude regions of north west Himalayas [7]. While feeding, the nymphs and adults of this psyllid insert their mandibular and maxillary stylets into the young succulent leaves, inject saliva and then absorb the liquid food. Excess water with dissolved sugars is subsequently excreted as tiny white droplets of honeydew on to the leaves and stems. Copious honeydew secretions by colonies of this psyllid lead to sooty fungal growth. Consequently, the affected leaves and stems get blackened. The uncontrolled infestations often lead to poor plant vigour and reduced berry production. Seabuckthorn is a very useful plant whose bark, berries, leaves and seeds possess many compounds like aminoacids, carbohydrates, carotenes, flavonoids, minerals, vitamins and volatile oils that are of paramount importance in pharmaceutical, nutraceutical and cosmetic industries [8-12]. The antioxidant properties of the flavonols of seabuckthorn berries such as isorhamnetin, kaempferol, myricetin, quercetin, rutin [13], tocopherols, tocotrienols [14, 15] and carotenoids [16, 17] have been experimentally established [18]. Also, seabuckthorn seeds are rich in carotenoids, fatty acids, flavonoids, kaempferol, organic acids, phytosterols, phenolic compounds, proanthocyanidins, sugar, triacylglycerol, vitamin C and vitamin E [19-21]. Various other extracts of this plant also exhibit marked antioxidant activity [22-27]. The nitrogen fixing ability coupled with wealth of nutrients contained in various parts of seabuckthorn make its cultivation potentially useful in improving the nutritional status of poor degraded soils and economic status of tribal farmers [28]. However, despite immense industrial utility, this plant somehow remained grossly unexploited in its natural habitat in north west Himalayan region. Even berries from the self perpetuating seabuckthorn stands growing on approximately 12000ha in these high altitude areas [29] are virtually wasted. Therefore, in the beginning vast natural seabuckthorn stands can be transformed into managed orchards. Afterwards, its scientific cultivation can be vigorously promoted. However, one of the major stumbling blocks in this endeavor is the psyllid infestation noted in Abstract Botanical extracts namely aqueous leaves extracts of Artemisia brevifolia (7.5%) and Eupatorium adenophorum (7.5%), aqueous drupes extract of Melia azedarach (7.5%); and malathion 50EC (0.025%) were evaluated for their efficacy against psyllid, Cacopsylla sp. (Hemiptera: Psyllidae) infesting seabuckthorn (Hippophae sp.) in Lahaul valley of Himachal Pradesh. Malathion 50EC (0.025%) caused up to 97.33 and 100 per cent psyllid mortality after 24 and 48h of its application, respectively. The psyllid mortality caused by leaves extracts of A. brevifolia (7.5%), E. adenophorum (7.5%) and drupes extract of M. azedarach (7.5%) was 60.27, 57.87, 60.27 and 75.73, 81.33, 81.60 per cent at 24 and 48h after application, respectively during 2011. The corresponding psyllid mortality during 2012 was 57.07, 57.33, 54.67 per cent at 24h and 80.80, 81.33, 73.07 per cent at 48h after application, respectively.