Prediction of Whitefly Population and Infestation Based on Multitrophic Analysis between Competitor Pest,Plant Traits and Natural Enemy

Interaction among arthropods(insect-acarine)was investigated at all trophic levels in agro-ecosystem and affects the population dynamic and diversification of arthropod pests and intensity of natural enemy(parasitism)as well as stimulates the plant chemical defence.In the present study of two cropping periods,nutrient concentration and early infestation of plant-sucking pests are known to trigger different degrees of interactions(plant’s parameters)which potentially alert abundance and diversity of the insect pests.Clearer interaction and magnitude of impact could be assessed(multivariate analysis of variance(MANOVA)and redundancy analysis(RDA))and observed between arthropods(insect-acarine)community and plants’parameters from the strongest to the lowest effects.The two factors could have affected the community of insect-pests with various degrees of pressure effect and interaction that occurred naturally,thus leading to the predictable abundance of insect-acarine populations under eggplant leaves in response to plant physical characteristics(e.g.,size of leaves,number of leaves and plant height)and biochemical constituents(flavonoid,phenolic,peroxidase andβ-1,3-glucanase).Based on multivariate analyses of multitrophic interaction,MANOVA and RDA have the potential to elucidate the complex interaction among plant performance,abundance of pests and activity chemical defence compounds.Both analyses interpreted similar interactions of measured parameters in different ways.Whitefly population in this study was predictable by aphids,thrips and total phenolic contents in eggplant.Eggplant has capable defence systems against insect-acarine pests after stimulation(pre-infestation).In relation to IPM strategy,early stages of plant growth are known as susceptible periods for pests attack but the plant becomes more tolerant during the fruiting stage.

Potato aphid Macrosiphum euphorbiae performance is determined by aphid genotype and not mycorrhizal fungi or water availability

Intra- and interspecific variation in plant and insect traits can alter the strength and direction of insect-plant interactions, with outcomes modified by soil biotic and abiotic conditions. We used the potato aphid （Macrosiphum euphorbiae Thomas） feeding on cultivated Solanum tuberosum and wild Solanurn berthaulti to study the impact of water availability and plant mutualistic arbuscular mycorrhizal （AM） fungi on aphid performance and susceptibility to a parasitoid wasp （Aphidius ervi Haliday）. Plants were grown under glass with live or sterile AM fungal spores and supplied with sufficient or reduced water supply. Plants were infested with 1 of 3 genotypes ofM. euphorbiae or maintained as aphidfree controls; aphid abundance was scored after 1 week, after which aphid susceptibility to A. ervi was assayed explanta. Solarium tuberosum accumulated c. 20% more dry mass than S. berthaultii, and root mass of S. berthaultii was smallest under reduced water supply in the presence of AM fungi. Aphid abundance was lowest on S. berthaultii and highest for genotype ＂2＂ aphids; genotype ＂1＂ aphid density was particularly reduced on S. berthaultii. Aphid genotype ＂1＂ exhibited low susceptibility to parasitism and was attacked less frequently than the other two more susceptible aphid genotypes. Neither AM fungi nor water availability affected insect performance. Our study suggests a fitness trade-offin M. euphorbiae between parasitism resistance and aphid performance on poor quality Solarium hosts that warrants further exploration, and indicates the importance of accounting for genotype identity in determining the outcome of multitrophic interactions.

Trichoderma harzianum enhances tomato indirect defense against aphids

Many fungal root symbionts of the genus Trichoderma are well-known for their beneficial effects on agronomic performance and protection against plant pathogens; moreover, they may enhance protection from insect pests, by triggering plant resistance mechanisms. Defense barriers against insects are induced by the activation of metabolic pathways involved in the production of defense-related plant compounds, either directly active against herbivore insects, or exerting an indirect effect, by increasing the attrac- tion of herbivore natural enemies. In a model system composed of the tomato plant, the aphid Macrosiphum euphorbiae and the parasitoid Aphidius ervi, plant metabolic changes induced by Trichoderma harzianum and their effects on higher trophic levels have been assessed. T. harzianum T22 treatments induce a primed state that upon aphid attacks leads to an increased attraction of aphid parasitoids, mediated by the enhanced produc- tion of volatile organic compounds （VOCs） that are known to induce Aphidius ervi flight. Transcriptome sequencing of T22-treated plants infested by aphids showed a remarkable upregulation of genes involved in terpenoids biosynthesis and salicylic acid pathway, which are consistent with the observed flight response ofA. ervi and the VOC bouquet profile underlying this behavioral response.