Arbuscular mycorrhizal fungi (AMF) are one of the environment-friendly organisms that increase soil fertility. Hence, AMF affect the herbivorous insect community by indirectly modifying host plant nutrient uptake, growth and defense, also known as priming. Here in the current study, we investigated under greenhouse conditions the effect of inoculation of tomato seedlings with four species of AMF (Funneliformis mosseae, Rhizophagus intraradices, Rhizophagus irregularis and Glomus iranicus) on tomato plant growth parameters, plant defense enzymes, total phenol content, and the life table parameters of whiteflies, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), that are important phloem-feeding pest insects. The results indicated that the growth parameters of tomato plants (including plant height, stem diameter, number of leaves, root volume, leaf surface area and weight root and aerial organs) were greater and larger in the mycorrhizal plants compared to the non-mycorrhizal plants. Twenty days after exposing the plant to B. tabaci the largest amounts of defense enzymes comprising of peroxidase, phenylalanine ammonia lyase, polyphenol oxidase and total phenol contents were measured in the mycorrhizal plants compared to non-mycorrhizal plants. Furthermore, the life table parameters of the whitefly pest insects (net reproduction rate, R0; intrinsic rate of natural increase in insect population, r; finite rate of population increase, λ; and the mean generation time, T) were decreased in the mycorrhizal plants compared to the non-mycorrhizal plants. Altogether, we believe that our plant-based results obtained here under greenhouse conditions are indications that AMF colonization enhanced tomato resistance to B. tabaci by improving plant growth parameters and increasing defense enzymes.
Aphids are one of the most important economic pests and vectors of viral diseases in crops. Brevicoryne brassicae L., one of the most serious aphid pests in Brassicaceae, if not controlled, often reaches very high densities. The present study compared the systemic effects of ethanolic, methanolic and aqueous Melia azedarach L., Peganum harmala L., Calendula officinalis L. and Otostegia persica Boissier extracts with two systemic pesticides, acetamiprid and pirimicarb (at the maximum label-recommended rate). Population growth percentages of B. brassicae through leaf spraying under greenhouse conditions were assessed. The chemicals were sprayed on one of the leaves in greenhouse condition. The results indicated that all the plant extracts have systemic effects at different levels. Among different extracts, O. persica ethanolic extract, P. harmala methanolic extract and M. azedarach aqueous extract resulted in a reduction of the B. brassicae population.
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