Several studies have suggested reasons why galls have conspicuous colours, but none of the ideas have been confirmed. However, what if the vibrant colours of some galls are explained simply by the effect of light exposure? This may lead to anthocyanin accumulation, functioning as a defence mechanism against the effects of high light. We studied the globoid galls induced by Cecidomyiidae (Diptera) on Qualea parviflora (Vochysiaceae), relating anthocyanin accumulation and chlorophyll fluorescence parameters to light incidence in abaxial and adaxial galls. We also tested if the anthocyanin accumulation patterns apply to another Cecidomyiidae‐induced gall morphotype (intralaminar) within the same plant. Adaxial galls are exposed to higher incident light, with more anthocyanin accumulation and therefore red coloration. In galls from angled leaves, the greater the angle of the leaf, the higher the difference between anthocyanins on the sun and shade sides of galls. Photosynthetic pigment concentrations did not differ between abaxial and adaxial galls. However, we found higher (Fm′ − F′)/Fm′ and Fv/Fm in the abaxial galls. Conversely, NPQ and Rfd were higher in adaxial galls. Finally, the pattern of anthocyanin accumulation was not found in the intralaminar gall. Anthocyanin accumulation in galls functions as a photoprotective strategy, maintaining tissue vitality in regions exposed to high light conditions. However, this mechanism may vary even among galls within the same host, indicating idiosyncrasy when it comes to coloration in galls. To date, this is the first study to demonstrate quantitatively why the galls of a specific species may be coloured: the variation in light regimes creates differential anthocyanin accumulation, influencing coloration.
Hydropower constructions cause severe disturbances to biodiversity. Arboreal plants die after flooding; however, they expose their emerged branches (also called paliteiros) as a new habitat for animals and plants. Nothing is known about how paliteiros influence the presence of aquatic birds. This study verified which species of birds use the paliteiros, what are their behaviors and probably consequences to ecological processes. In November 2018, we sampled 5 km of paliteiros recording perched birds and their behaviors in the Três Marias dam, a 1040 km2 flooded area in southeastern Brazil. In total, 5.4% of paliteiros were used by 14 bird species. The Neotropic Cormorant Nannopterum brasilianus (Gmelin, 1789) was the most frequent species. Birds mainly preened feathers; they also rested (with no apparent activity), defecated, hunted, fed, vocalized and drank water. Attention must be focused to some behaviors such as resting and defecation, which may influence long-term ecological processes (e.g., incorporating additional organic matter and changing aquatic community) in the dam.
In a general way, galling insects can induce only one gall morphotype on the host plant species. However, some taxa of galling insects such as Eriococcidae can induce sexually dimorphic galls on the same host. In the present study, Lopesia mataybae (Diptera: Cecidomyiidae) induced two gall morphotypes on the leaflets of Matayba guianensis (Sapindaceae), a rare evidence of sexual dimorphism in galls induced by Cecidomyiidae. We investigated the adult emergence of galling insects and the morphological, histological, and histochemical attributes of the gall morphotypes. Both gall morphotypes showed the galling insect in the larval or pupal stage, and the insect adult emergence from different morphotypes was sexually distinct. Galls occupied by females (Globoid) were significantly larger (average height = 4.67 mm. S = 0.43/average width = 4.59 mm. S = 0.70) than galls occupied by males (cylindrical) (average height = 2.95 mm. S = 0.46/average width = 2.34 mm. S = 0.45). Both gall types were composed of elongated cells in the inner cortex and rounded cells in the outer cortex of the vessel-like structure. The globoid galls showed 42 cell layers (14 of them cylindrical, S = 3.86; 28 rounded, S = 5.89) and cylindrical galls showed 29 layers. There were no differences between morphotypes in the histochemical compounds detected. We have shown here significant morphological and histological differences between male and female galls possibly due to the different nutritional requirements of Lopesia mataybae sexes. Therefore, the expression of sexual dimorphism in gall morphotypes may be associated with developmental pathway differentiation between the sexes of L. mataybae.
The developmental processes of galls are better known when induced on vegetative organs, while they have hardly ever been described for reproductive ones. Herein, galls induced by Allorhogas uberlandiensis (Hymenoptera) on ovules of Miconia chamissois (Melastomataceae) were analyzed in terms of morphological, anatomical, histochemical and cytological characteristics. Galls are induced on the ovules before fertilization, acting as a physiological seed. Therefore, the ovary grows and develops into a fruit-like gall. The ovule-galls are on average 20 times larger than the seeds, and fruit-like gall volume is on average 5.4 times larger than that of mature fruits. These are related to cell hypertrophy and tissue hyperplasia in the host organ. There is a typical nutritive tissue formation in the ovule-gall with lipid, protein and pectin storage, as well as a storage tissue close to the epidermis. This nutritive tissue shows a smooth endoplasmic reticulum, multivesicular bodies and mitochondria-rich cells. After gall induction, all the ovules degenerate and ovary and hypanthium hypertrophy to form the fruit-like gall. The fruit-like galls form a physical barrier blocking the anthesis, preventing fertilization and keeping only ovule-galls. Our study shows that the A. uberlandensis galling insect may reduce the reproductive success of Miconia chamissois, thus acting as a biological control agent for this host plant population.
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