Predation of Florida red scale Chrysomphalus aonidum (L.) by the metallic blue ladybeetle Curinus coeruleus (Mulsant)

Florida red scale, Chrysomphalus aonidum (L.) is a species of armored scales, which attacks citrus crops. Biological control, particularly ladybeetles, are critical for its management in citrus production systems. We evaluated predation of C. aonidum by adult and larvae (3rd–4th instar) of the metallic blue ladybeetle, Curinus coeruleus. C. coeruleus were tested against C. aonidum in three separate treatments on Valencia orange leaves in Petri-dish arenas (1) individuals with armor intact, (2) individuals with armor removed, and (3) mix of individuals with armor intact or removed, to determine if armor inflicts distraction to predator consumption of scale and impact. Within 24 h of exposure to C. aonidum, adult beetle consumption rate averaged 64–68% in the two treatments containing all or half of the individuals with armor, compared to 100% in the treatment with armor removed. The consumption rate in the former two treatments increased to 83–89% within 72 h. Larval consumption of C. aonidum with armor intact was 25% at 24 h and 41% at 72 h, compared to 92–100% in the treatment with armor removed. The adults resulting from the larvae developed on C. aonidum with the armor intact or between the diets of armor intact or removed consumed more scales without armor than with armor. Significant consumption of C. aonidum by adults and larvae of C. coeruleus indicates that it is an efficient predator of this pest species. These novel findings suggest that this predator could be useful for suppressing C. aonidum populations in citrus production systems, particularly in habitats where both species are established such as Florida.

Genomic and transcriptomic analyses of Citrus sinensis varieties provide insights into Valencia orange fruit mastication trait formation

Valencia orange (Citrus sinensis Osbeck) (VO) is a type of late-ripening sweet orange whose ripening occurs 4 to 5 months later than that of the mid-ripening common sweet orange (CO). Notably, the mastication trait of VO fruit is inferior to that of CO fruit. To date, how inferior pulp mastication trait forms in VO has not been determined. In this study, 13 VO varieties and 12 CO varieties were subjected to whole-genome resequencing. A total of 2.98 million SNPs were identified from 25 varieties, and a SNP molecular marker was developed to distinguish VO and CO. Moreover, 144 and 141 genes identified by selective sweep analysis were selected during VO and CO evolution, respectively. Based on gene functional enrichment analysis, most of the selected VO genes were related to the stress response and lignin biosynthesis. Simultaneously, we comparatively analyzed the transcriptome profiles of peel and pulp tissues among three VO varieties and three CO varieties, and the results demonstrated differences in lignin biosynthesis between VO and CO fruits. Furthermore, coexpression network analysis was performed to identify hub genes of lignin-related and variety-specific networks, which included CsERF74, CsNAC25, CsHSFB3, CsSPL4/13, etc. Overall, this study provides important insights into the mastication trait formation of Valencia orange fruit.

Different Host Plants Distinctly Influence the Feeding Ability of the Brown Citrus Aphid Toxoptera citricida

Piercing–sucking insects are important crop pests, and an understanding of their feeding behavior and population development plays a crucial role in studying insect population dynamics and crop resistance. In our study, we examined the probing behavior of the brown citrus aphid, Toxoptera citricida, using electropenetrography and assessed its population development after 8 days on seven host plants: Yuzu, Citrus junos Sieb. ex Tanaka; Rough Lemon, C. jambhiri Lush.; ‘Luofu’ kumquat, Fortunella margarita Swingle; ‘Olinda’ valencia orange, C. sinensis (L.) Osbeck; ‘Yanxiwanlu’ Ponkan, C. reticulata Blanco; ‘Rohde Red’ valencia orange, C. sinensis; and ‘Eureka’ lemon, C. limon (L.) Osbeck. The results demonstrated that probing by the brown citrus aphid differed significantly according to the target hosts. Toxoptera citricida produced significantly more pathway activities on Eureka than on Rough Lemon and Yuzu. Toxoptera citricida spent more time from the first probe to first salivation into phloem sieve elements on Eureka compared to Yuzu. In addition, the total duration of ingestion from sieve cells of each aphid in the phloem-feeding phase was shortest on Eureka, and this was significantly shorter than that on Yuzu, Rough Lemon, Luofu, and Olinda. The population number of T. citricida on Eureka after 8 days was significantly lower than that on the other hosts. Overall, Eureka was found to have obvious resistance to T. citricida, whereas Yuzu and Rough Lemon were susceptible host plants. These results provide a theoretical basis for exploring aphid-resistant fruit tree resources using resistant varieties.

Antioxidative Potential and Phytochemical Content of Detox Water

Detox water is a fusion of different fruits immersed in water. It has been shown to possess many health benefits including toxin removal, increased immune function, weight loss and hydration. The following research aimed to extend previous investigation into the beneficial properties of detox water by determining the antioxidant potential and phytochemical content of water infused with a combination of Valencia orange (Citrus sinensis) and Fuji apple (Malus domestica) in different ratios. The three trails studied were 25:75 (T1), 50:50 (T2) and 75:25 (T3) Apple: Orange ratios. The antioxidant activity, total phenolic content (TPC) and total flavonoid content (TFC) were assayed using the 1, 1-diphenyl-2-picrylhydrazyl- DPPH assay, the Folin Ciocalteu assay and the aluminum chloride colorimetric assay respectively. The assays were carried out on water samples taken at 0.5, 1,2,4,6 and 8 hours after infusion, and on the fruit residue. Vitamin C concentration of the water and fruit residue were determined by titration against potassium iodide at the eight- hour of infusion. The antioxidant, TPC and TFC values of water samples increased with infusion time. At the eight-hour, the antioxidant potential of the water samples ranged from 74.45% (T1) - 68.16% (T3). The TPC, TFC and Vitamin C values for all three trails were found to be significantly different (p<0.05), with TPC values of 189.01 µg GAE/ml sample (T1), 172.10 µg GAE/ml sample (T2) and 144.82 µg GAE/ml sample (T3); TFC values were 32.11 µg QE/ml sample (T1), 25.24 µg QE/ml sample (T2) and 17.62 µg QE/ml sample (T3). Vitamin C values were 237.76 µg vitamin C/ml sample (T1), 161.44 µg vitamin C/ml sample (T2) and 114.48 µg vitamin C/ml sample (T3). The fruit residues possessed very low antioxidant potential and phytochemical content. The study has proven that detox water possesses beneficial properties due to its high phytochemical content.

Extraction Method Affects Contents of Flavonoids and Carotenoids in Huanglongbing-Affected “Valencia” Orange Juice

A previous study using healthy “Valencia” orange fruit found that juicing extraction methods dramatically changed the orange juice (OJ) flavor and phytochemical profiles. The present study was conducted to confirm whether the same changes occur when Huanglongbing (HLB)-affected oranges were used. HLB has extensively spread to most OJ processing regions around the world, substantially deteriorating fruit and juice flavor quality and altering the phytochemical profiles. In this study, the effect of two major juice extractor types, a shear force extractor (SFE) and a reamer extractor (RE), on the juice quality and physiochemical profile was assessed using HLB-affected orange fruit. Juice extracted via SFE resulted in a lower yield with lower peel oil and higher pellet (peel tissue particles) content compared to juice obtained via RE. The SFE juice also had higher levels of hesperidin and other flavonoid glycosides, mainly due to plentiful peel tissue particles. The SFE juice was also abundant in carotenoids due to a large amount of flavedo particles in the juice. On the other hand, polymethoxylated flavones occurred at higher concentrations in the RE juice, and this may be due to the higher peel oil content in this juice. The SFE juice was rich in flavonoid glycosides and carotenoids, which are associated with potential antioxidant properties; however, the extra portion of the phytonutrients mostly existed in the pellets and possibly had low bioavailability. The results obtained from the HLB-affected oranges are in agreement with the previous observations of healthy oranges.

Huanglongbing and Foliar Spray Programs Affect the Chemical Profile of “Valencia” Orange Peel Oil

Florida orange trees have been affected by huanglongbing (HLB) for more than a decade. To alleviate disease-caused tree decline, maintain fruit productivity, and reduce disease transmission, enhanced foliar spray programs combining vector control and nutritional supplementation have been applied to healthy and diseased trees. The aim of this research was to discover if the various foliar sprays affect fruit peel oil chemical components. In this study, “Valencia” orange trees, with or without HLB (HLB±), were treated with the grower standard program (control, C) or one of four proprietary enhanced foliar spray programs (N1, N2, N3, and N4) over 16 months. Compared with HLB−, HLB+ samples had lower concentrations of typical peel oil components, including valencene, octanal, and decanal, and were abundant in oxidative/dehydrogenated terpenes, such as carvone and limonene oxide. However, limonene, the dominant component, was not affected by any treatment. Control and three out of four enhanced foliar spray programs, N2, N3, and N4, had very little influence on the chemical profiles of both HLB− and HLB+ samples, while N1 treatment greatly altered the chemical profile of HLB+ samples, resulting in peel oil similar to that of HLB− samples.

Deep learning framework for leaf damage identification

Foliar disease is common problem in plants; it appears as an abnormal change in the plant’s characteristics, such as the presence of lesions and discolorations, among others. These problems may be related to plant growth, which causes a decrease in crop production, impacting the agricultural economy. The causes of leaf damage can be variable, such as bacteria, viruses, nutritional deficiencies, or even consequences of climate change. Motivated to find a solution for this problem, we aim that using image processing and machine learning algorithms (MLA), these symptomatic characteristics of the leaf can be used to classify diseases. Then, contributions of this research are (i) the use of image processing methods in the feature extraction (characteristics), and (ii) the combination of assembled algorithms with deep learning to classify foliar features of Valencia orange (Citrus Sinensis) tree leaves. Combining these two classification approaches, we get optimal rates in binary datasets and highly competitive percentages in multiclass sets. This, using a database of images of three types of foliar damage of local plants. Result of combination of these two classification strategies is an exceptional reliable alternative for leaf damage identification of orange and other citrus plants.