Rhizoctonia solani is a phytopathogenic fungus affecting a wide range of plants hosts including the sunflower causing various diseases such as damping-off. Current management approaches of this pathogen are inadequate. Aim of this study was to assess the potential of eco-friendly control methods, the indigenous biocontrol fungus Trichoderma harzianum and ZnO nanoparticles for controlling of the sunflower damping-off pathogen, R. solani. The biocontrol agent T. harzianum showed a high antagonism effect on R. solani growth. Additionally, growth of R. solani was significantly (p = 0.01) reduced gradually by presence of various concentrations of the ZnO NPs indicating to concentration-dependent toxicity effect. However, a similar impact was also observed on growth of T. harzianum. On the other hand, the percentage of seed germination and stem length of sunflower (Coban cv.) did not affect significantly by ZnO NPs. Conversely, the root lengths were significantly decreased. In the horticultural canopy trial, the best reduction to the sunflower damping-off incidence percentage was achieved by treatment of sunflower seedlings growing in compost inoculated with T. harzianum and R. solani 68.75% comparing to 100% in the control. In contrast, a significant reduction in severity percentage of damping-off symptoms was accomplished in most of the treatments. The best suppression was achieved in treatments of spraying the seedlings with ZnO NPs (15 mg/ml) in two days prior of planting that was 50% in compression with 97.50% in control. These findings can justify the application of the local biocontrol agent T. harzianum alone or in integration with ZnO NPs to be included with current management approaches of sunflower damping-off, which could lead to a diminution in the utilizing of fungicides.

1 Whiteflies are major pests of many crops worldwide. Trialeurodes vaporariorum was introduced into the U.K. approximately 160 years ago. In the present study, we aimed to understand their genetic diversity and population structure and thus their invasion history. 2 Mitochondrial CO1 sequencing showed that T. vaporariorum had a low level of variation. Microsatellite analysis showed a high diversity and indicated the presence 2, 6 and 10 clusters, which were, to a limited extent, linked to locations but not to host plants. The primary symbiont Portiera aleyrodidarum was detected in both sexes of T. vaporariorum, whereas only one secondary symbiont Arsenophonus sp. was detected in almost all females but not males. 3 The population structure suggested that glasshouse agroecosystems restricted gene flow between glasshouse whitefly populations and that the movement of glasshouse whitefly was linked to human-assisted spread. 4 Taken together, the results of the present study suggest multiple but limited numbers of introductions of T. vaporariorum, mainly from countries nearest to U.K.

Whiteflies (Hemiptera: Aleyrodidae) are major pests of many crops worldwide. Bemisia tabaci is a cryptic species complex composed of more than 39 putative species. Understanding which putative species of B. tabaci are predominant in an area is vital for effective pest management since they may vary considerably with respect to insecticide resistance, host plant range and virus transmission. Here, for the first time, the genetic diversity, the symbiont diversity and population structure of B. tabaci in Iraq were studied. Fourteen populations were analysed using mitochondrial cytochrome C oxidase subunit 1 (mtCO1) sequencing and microsatellite genotyping. Symbiotic bacteria were identified using 16S rRNA and 23S rRNA sequencing. MtCO1 sequencing detected two putative species of B. tabaci. The predominant putative species in Iraq was Middle East‐Asia Minor (MEAM) 1 subcladeB2. In addition, one individual was MEAM1‐subcladeB. The second putative species was a single individual of MEAM2. The microsatellite data indicated low genetic diversity, with no biologically informative clustering. All MEAM1 individuals harboured one primary symbiont, Portiera aleyrodidarum, and most (96%) have two secondary symbionts: Hamiltonella sp. and Rickettsia sp. This study has identified the genetic diversity and population structure of B. tabaci in Iraq. Further investigation is needed to update the pest status of B. tabaci in this region. The current data, combined with investigations into the capacity of the various putative species to transmit plant viruses, especially tomato yellow leaf curl virus, will aid pest management and horticultural production.

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