Pesticide impacts on insect pollinators: Current knowledge and future research challenges.

With the need to intensify agriculture to meet growing food demand, there has been significant rise in pesticide use to protect crops, but at different rates in different world regions. In 2016, the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) global assessment on pollinators, pollination and food production identified pesticides as one of the major drivers of pollinator decline. This assessment highlighted that studies on the effects of pesticides on pollinating insects have been limited to only a few species, primarily from developed countries. Given the worldwide variation in the scale of intensive agricultural practices, pesticide application intensities are likely to vary regionally and consequently the associated risks for insect pollinators. We provide the first long-term, global analysis of inter-regional trends in the use of different classes of pesticide between 1995 and 2020 (FAOSTAT) and a review of literature since the IPBES pollination assessment (2016). All three pesticide classes use rates varied greatly with some countries seeing increased use by 3000 to 4000 % between 1995 and 2020, while for most countries, growth roughly doubled. We present forecast models to predict regional trends of different pesticides up to 2030. Use of all three pesticide classes is to increase in Africa and South America. Herbicide use is to increase in North America and Central Asia. Fungicide use is to increase across all Asian regions. In each of the respective regions, we also examined the number of studies since 2016 in relation to pesticide use trends over the past twenty-five years. Additionally, we present a comprehensive update on the status of knowledge on pesticide impacts on different pollinating insects from literature published during 2016-2022. Finally, we outline several research challenges and knowledge gaps with respect to pesticides and highlight some regional and international conservation efforts and initiatives that address pesticide reduction and/or elimination.

Agricultural policies against invasive species generate contrasting outcomes for climate change mitigation and biodiversity conservation.

Direct consequences of biological invasions on biodiversity and the environment have been largely documented. Yet collateral indirect effects mediated by changes in agri-environmental policies aimed at combating invasions remain little explored. Here we assessed the effects of recent changes in water management in rice farming, which are aimed at buffering the impact of the invasive apple snail (Pomacea maculata, Lamarck) on greenhouse gas emissions and diversity of waterbird communities. We used observational data from a 2-year field monitoring (2015-2016) performed at the Ebro Delta regional scale. We found that drying rice fields reduced methane emission rates by 82% (2015) and 51% (2016), thereby reflecting the contribution of rice farming to climate change. However, there was a marked reduction (75% in 2015 and 57% in 2016) in waterbird diversity in dry fields compared with flooded fields, thus suggesting that post-invasion policies might hinder biodiversity conservation. Our results highlight the need for accounting for potential collateral effects during the policy decision-making process to design efficient agricultural management plans that lessen undesirable agri-environmental outcomes.

Bottom-up effects of woodland eutrophication: Interacting limiting nutrients determine herbivory frequency in northwestern Patagonia.

Nutrient enrichment disrupts plant-animal interactions and ecosystem functioning globally. In woodland systems, the mechanisms of bottom-up turnover on plant-herbivore interactions remain understudied. Here, we performed a full-factorial field experiment to evaluate the interactive effects of nutrient addition (nitrogen, phosphorus, and/or potassium) on the assemblage of foliar herbivores and the interaction frequency with Berberis microphylla, a dominant shrub species in Patagonian woodlands. Additionally, we assessed whether these effects could be mediated by changes in vegetative traits and microhabitat characteristics (i.e., canopy cover) that may ultimately influence the foraging behavior of herbivores. The addition of nitrogen reduced the herbivory frequency by 41%, yet this effect was diluted in the presence of potassium. We found no effects of phosphorus addition. Our results suggest that the impact of multiple nutrient additions (N and K) on herbivory patterns could be mediated by changes in two important foliar traits, leaf size and leaf density. This study shows how multiple nutrient addition can change the magnitude of antagonistic plant-animal interactions in woodlands. Since herbivory by arthropods has a relevant role in net primary productivity, our results highlight the importance of buffering human-driven woodland eutrophication to maintain important ecological functions (e.g., herbivory) associated with antagonistic plant-animal interactions and avoiding ecosystem dysfunction.

Impact of Invasive Bees on Plant-Pollinator Interactions and Reproductive Success of Plant Species in Mixed Nothofagus antarctica Forests.

Invasive social bees can alter plant-pollinator interactions with detrimental effects on both partners. However, most studies have focused on one invasive bee species, while the interactions among two or more species remain poorly understood. Also, many study sites had a history of invasive bees, being hard to find sites with historical low abundances. In Patagonia, Bombus ruderatus (F.) invasion begun in 1993 and B. terrestris (L.) in 2006. Though honey bees (Apis mellifera L.) introduction started in 1859, their density is still low in some parts. By experimentally increasing honey bee densities, we evaluated the effect of honey bees and bumblebees floral visitation on native pollinator floral visitation, pollen deposition, and reproductive success of three plant species in mixed Nothofagus antarctica forests of northern Patagonia: Oxalis valdiviensis, Mutisia spinosa and Cirsium vulgare. Our results show that exotic bees became the main floral visitors. No negative association was found between invasive bee and native pollinator visitation rates, but there was evidence of potential competition between honey bees and bumblebees. Floral neighborhood diversity played an important role in pollinator behavior. Conspecific pollen deposition was high for all species, while deposition of heterospecific pollen was very high in M. spinosa and C. vulgare. Not as expected, honey bees visitation rate had a negative effect on heterospecific pollen deposition in C. vulgare. For O. valdiviensis, exotic visitation rates increased conspecific pollen deposition, which was positively related to reproductive success. Although exotic bees became main floral visitors, their contribution to reproductive success was only clear for one species.

Insect Pollination, More than Plant Nutrition, Determines Yield Quantity and Quality in Apple and Pear.

Agricultural yield is the result of multiple factors and ecological processes (e.g., pollination, fertilization, pest control). Understanding how the different factors interact is fundamental to designing management practices aimed to increase these yields, which are environmental friendly and sustainable over time. In this study, we focus on insect pollination and plant nutrition status, since they are two key factors that influence crop yield. The study was carried out in Northwest Patagonia Argentina, which is an area of intensive production of pears and apples of global importance, during the harvest seasons 2018 and 2019. The plant nutrition was estimated from leaf chlorophyll content. Biotic pollination benefits were evaluated by comparing fruit quantity (fruit to flower ratio) and quality (weight, size, and sugar concentration) from approximately 25 flowers exposed to pollinators and 25 flowers excluded to them per tree (a total of 160 apple trees and 130 pear trees). In addition, we estimated the visitation rate of pollinators to flowers and related it to fruit quality in apple. Despite different floral characteristics, we found in both crops a positive effect of insect pollination in both the quantity and the quality of the fruits. Interestingly, the nutrition of the trees, although variable, did not affect either the quantity or the quality of the fruits. Despite the weak effect of nutrition, we found no interaction between pollination and plant nutrition (i.e., additive effects). These results highlight the importance of agricultural practices that promote pollinators on farms.

Data on litter quality of host grass plants with and without fungal endophytes.

Certain Pooideae species form persistent symbiosis with fungal endophytes of Epichloë genus. Although endophytes are known to impact the ecology and evolution of host species, their effects on parameters related with quality of plant biomass has been elusive. This article provides information about parameters related with the quality of plant litter biomass of two important grass species (Schedonorus phoenix and Schedonorus pratensis) affected by the symbiosis with fungal endophytes (Epichloë coenophiala and Epichloë uncinata, respectively). Four population origins of S. phoenix and one of S. pratensis were included. Mineral, biochemical and structural parameters were obtained from three samples per factors combination [species (and population origin)×endophyte]. This data can be potentially used in other studies which, by means of 'data reanalyzing' or meta-analysis, attempt to find generalizations about endophyte effects on host plant litter biomass. The present data is associated with the research article "Role of foliar fungal endophytes on litter decomposition among species and population origins" (Gundel et al., In preparation) [1].

Prospective assessment of pituitary size and shape on MR imaging after suppressive hormonal therapy in central precocious puberty.

OBJECTIVE: The diagnostic significance of an enlarged pituitary gland regarding both shape and size parameters on MR imaging has previously been demonstrated in children with central precocious puberty. This study was designed to assess changes in these parameters following successful suppressive therapy of central precocious puberty with the gonadotropin-releasing hormone (GnRH) analogue. MATERIALS AND METHODS: Twelve girls (mean age 7.3 years) with central precocious puberty were prospectively enrolled in our study protocol. Sagittal and coronal MR images of the pituitary region were obtained in all patients before treatment and after at least 6 months of GnRH analogue therapy (mean 18.0 months). Parameters measured included pituitary gland height, length, width, sagittal cross-sectional area, and volume. RESULTS: All patients had excellent clinical response to treatment with arrest of secondary sexual development, normalization of serum estradiol levels, and complete obliteration of the LH response to diagnostic GnRH stimulation. No significant change occurred in any pituitary size or shape parameter following GnRH analogue therapy. CONCLUSION: Favorable clinical response to GnRH analogue therapy in central precocious puberty is not accompanied by significant a change in pituitary gland size and shape.

Mutations of the ACTH receptor gene in a new family with isolated glucocorticoid deficiency.

Isolated glucocorticoid deficiency (IGD) is an autosomal recessive disorder characterized by primary adrenocortical insufficiency, without mineralocorticoid deficiency. Mutations of the ACTH receptor gene have been reported in several families with IGD. We have amplified and directly sequenced the entire intronless ACTH receptor gene in a new family with IGD. The proband was found to be compound heterozygote for two different point mutations, one in each allele: (a) a substitution (360C>G) which changed neutral serine at position 120 in the apolar third transmembrane domain of the receptor to a positively charged arginine (S120R), probably disrupting the ligand-binding site; and (b) a substitution (761A>G) changing tyrosine at position 254 to cysteine (Y254C) in the third extracellular loop of the receptor protein, that also likely disrupts its structure and interferes with ligand binding. Each of the two mutations in the proband has previously been described in a different family, S120R in compound heterozygosity with a stop codon (R201X) and Y254C in homozygote form. Thus, in the absence of in vitro functional studies, our findings confirm the pathogenetic role of the S120R and Y254C mutants in the development of resistance to ACTH.

Renal structural-functional relationships in early diabetes mellitus.

To define the earliest renal morphological changes in patients with type I diabetes, we studied renal function and morphometric analysis of renal biopsies in 59 patients with diabetes for 5-12 years and normal blood pressure, normal creatinine clearance (CCr), and negative dipstick urinary protein. Arteriolar hyalinization and intimal fibrous thickening were noted in 43%. Glomerular basement membrane thickness and fractional mesangial volume were increased in 51% and 56%, respectively. The pre-pubertal and post-pubertal years of diabetes were associated with similar degrees of renal structural changes, but during the pre-pubertal years normal urinary albumin excretion (UAE) was seen. Principal factor analysis of morphometric structural parameters yielded four clusters of variables: "glomerular size" correlated with patient age, CCr, and UAE; "peripheral capillary decrease" correlated with glycosylated hemoglobin, diastolic blood pressure, glomerular filtration rate, and UAE; "mesangial increase" correlated with UAE; and "interstitial scarring" correlated with diastolic blood pressure. This study provides unique documentation of renal structural abnormalities which precede clinically evident renal functional abnormalities and documents that these early structural abnormalities are present in the pre-pubertal years of diabetes as well as postpuberty, and are associated with each other in constellations that correspond to postulated mechanisms in diabetic nephropathy.

Sleep apnea in patients receiving growth hormone.

Among 145 patients treated with recombinant human growth hormone (GH), four developed sleep apnea (two obstructive, two mixed) associated with tonsillar and adenoidal hypertrophy in three. These four patients had no local risk factors predisposing to upper airway obstruction (i.e., frequent pharyngitis or sinusitis). Clinical and/or polysomnographic features of sleep apnea improved following cessation of GH therapy in one patient, and following tonsillectomy and adenoidectomy in all patients. The present observations indicate that, albeit rarely, obstructive and/or central sleep apnea may occur in children treated with GH. Polysomnography should be considered if symptoms of snoring, interrupted sleep, daytime somnolence-particularly if associated with tonsillar hypertrophy-appear in children during GH therapy.

Factors predicting cerebral edema in young children with diabetic ketoacidosis and new onset type I diabetes.

We have attempted to identify any characteristics which could be used to predict the development of cerebral edema in four children under 5 years of age with new onset insulin-dependent diabetes mellitus and diabetic ketoacidosis. We retrospectively analysed and compared the concentration of serum sodium (corrected for serum glucose value) and effective serum osmolality of these 4 children with values of 10 age-matched controls with new onset insulin-dependent diabetes mellitus who did not develop cerebral edema during treatment of diabetic ketoacidosis. The initial serum sodium values of the two groups were not statistically different. Patients who developed cerebral edema had lower initial serum glucose values and effective serum osmolality. During treatment, patients who developed cerebral edema had consistently lower mean serum sodium and osmolality than controls at each 4-h interval after the first 4 h of therapy. Serum sodium and osmolality declined progressively after the initiation of therapy in cerebral edema patients, while remaining stable in controls. These data suggest that children who develop cerebral edema during treatment for diabetic ketoacidosis initially may have a relatively normal serum osmolality and subsequently develop progressive hyponatremia and/or a trend of declining serum sodium before developing cerebral edema.

Absence of molecular defect in the type II 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) gene in premature pubarche children and hirsute female patients with moderately decreased adrenal 3 beta-HSD activity.

To date the molecular basis and hormonal criteria for inherited mild late-onset 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) deficiency congenital adrenal hyperplasia (CAH) have not been defined. We have thus investigated the presence or absence of mutation in the type II 3 beta-HSD gene encoding adrenal/gonadal 3 beta-HSD in each of five premature pubarche children and hirsute female patients manifesting moderately decreased adrenal 3 beta-HSD activity. ACTH-stimulated hormonal levels in all patients compared with mean levels in pubertal stage-matched normal subjects were between 2.5 and 6.5 SD for 17-hydroxypregnenolone levels, and between 2.5 and 7 SD for dehydroepiandrosterone levels in all except one patient. 17-Hydroxypregnenolone to cortisol ratios were between 2.5 and 4.3 SD, and dehydroepiandrosterone to androstenedione ratios were between 3 and 8.6 SD. The type II 3 beta-HSD gene regions of a putative promoter, exons I, II, III, and IV, and exon-intron boundaries in all subjects were amplified by polymerase chain reaction and then sequenced. All patients had normal sequences of the type II 3 beta-HSD gene in both alleles. Three female patients heterozygotic for severe 3 beta-HSD deficiency CAH with one allele mutation of the gene demonstrated normal ACTH-stimulated hormone profiles. These data indicate that moderately decreased adrenal 3 beta-HSD activity resulting in modestly increased delta 5 precursor steroid levels and delta 5 to delta 4 steroid ratios in premature pubarche and hirsute patients is not caused by a mutation in the type II 3 beta-HSD gene.(ABSTRACT TRUNCATED AT 250 WORDS)

MR imaging diagnosis of central precocious puberty: importance of changes in the shape and size of the pituitary gland.

OBJECTIVE: Central precocious puberty occurs as a result of premature pituitary stimulation and increased secretion of gonadotropins. The aims of this study were to analyze MR imaging findings in the pituitary glands of children with central precocious puberty compared with matched control subjects, to define MR imaging-derived variables useful in the diagnosis of central precocious puberty, and to correlate MR imaging-derived variables with the hormonal profile and other imaging and clinical findings. MATERIALS AND METHODS: Twenty-six children with central precocious puberty (two boys and 24 girls) were divided into two subgroups according to MR imaging findings: idiopathic (21 patients) and nonidiopathic (five patients: three hypothalamic hamartomas, one pineal tumor, one empty sella syndrome). The control group consisted of 17 normal age- and sex-matched children (two boys, 15 girls). Analyzed parameters included pituitary height, length, width, midsagittal cross-sectional area, calculated volume, and shape. The shape was assessed by a pituitary grading system and two other shape indexes (length-to-height and length-to-width ratios). Pituitary grade was defined by the concavity of the upper pituitary surface (grade 1 = marked concavity, grade 2 = mild concavity, grade 3 = flat, grade 4 = mild convexity, grade 5 = marked convexity). RESULTS: Pituitary grade showed a highly significant difference among groups (p < .001). Area, height, and length-to-height ratio were significantly different (p < .05), whereas length, width, length-to-width ratio, and volume were not. There was no significant difference in any of the variables compared between idiopathic and nonidiopathic groups. When selected variables (pituitary grade, area, height, length) in the central precocious puberty group were stratified by bone age and findings on pelvic sonograms, patients with advanced bone age had a significantly higher pituitary grade (p < .01) and had a tendency toward a greater pituitary length. Pituitary size and shape correlated with the hormonal profile. CONCLUSION: Change in pituitary grade is the most helpful variable for the diagnosis of central precocious puberty in a prepubertal child. A high pituitary grade (4 or above) is highly predictive of central precocious puberty, with the highest specificity and positive predictive value, but with low sensitivity. The use of combinations of high pituitary grade with two other positive findings (height and area greater than 1 SD from the respective means in the control group) improves the sensitivity, specificity, and predictive value of MR imaging in the diagnosis of central precocious puberty.

Hypothalamic-pituitary-gonadal axis function in pubertal male and female siblings with glucocorticoid-treated nonsalt-wasting 3 beta-hydroxysteroid dehydrogenase deficiency congenital adrenal hyperplasia.

We report pubertal maturation and dynamic studies of gonadotropin and gonadal hormone secretion in long term glucocorticoid-treated siblings with nonsalt-wasting classic adrenal and gonadal 3 beta-hydroxysteroid dehydrogenase (3 beta HSD) deficiency. The 18-yr-old female siblings spontaneously developed thelarche and menarche at 10 and 12 yr, respectively, and manifested irregular menses, hirsutism, and polycystic ovaries at 17 yr. The 16-yr-old male sibling spontaneously developed secondary sex characteristics at age 11 yr and exhibited Tanner IV-V pubic hair, a 6.5 x 3.0-cm surgically repaired penis, and enlarged nonnodular testes. Overnight (2200-0700 h) plasma gonadotropin (every 20 min) and gonadal steroid levels (every 2 h) under ACTH adrenal suppression revealed the following. In the male sibling, there were overall normal Tanner V male LH (3-21 mIU/mL) and FSH (1.2-13 mIU/mL) levels, normal peak frequency and amplitude of LH (70 +/- 62 min and 15 +/- 3 mIU/mL, respectively) and FSH (65 +/- 28 min and 13 +/- 3 mIU/mL), and low normal Tanner V testosterone (T) levels (11.4-17.9 nmol/L). In the female sibling, there were normal follicular phase range LH (10-28 mIU/mL) and FSH (5.1-17.2 mIU/mL) levels, normal peak frequency and amplitude of LH (96 +/- 17 min and 22 +/- 4.5 mIU/mL, respectively) and FSH (62 +/- 27 min, 13 +/- 4 mIU/mL), and early follicular phase estradiol (E2) levels (100-170 pmol/L). The LH-releasing hormone-stimulated LH response was in the normal adult range in the male and normal for the early follicular phase in the female. In contrast, ACTH and adrenal delta 5-steroid responses to CRH administration were elevated in each sibling. Gonadal suppression via Norlutin administration (30 mg/day for 3 days) after prolonged adrenal suppression by dexamethasone resulted in suppression of dehydroepiandrosterone (DHEA) and E2 in the female and DHEA and T in the male. Gonadal stimulation via hCG administration (5000 IU/day for 3 days, im) during continuous adrenal suppression resulted in a low E2 response in the female (200 pmol/L; control, 295-660 pmol/L) and a low T response in the male (15.3 nmol/L; control, 17-39 nmol/L), whereas delta 5-17-hydroxypregnenolone and DHEA levels rose 2- to 4.7-fold in each sibling. In conclusion, despite partial gonadal 3 beta HSD deficiency, the dynamics of gonadotropin and gonadal hormone secretion in these siblings indicate the absence of increased LH secretion, in contrast to the markedly increased ACTH secretion resulting from adrenal 3 beta HSD deficiency.(ABSTRACT TRUNCATED AT 400 WORDS)

The pattern of gonadotropin and estradiol secretion in exaggerated thelarche.

PURPOSE: To assess the dynamics of the pituitary-ovarian axis in exaggerated thelarche, defined as premature thelarche associated with signs of systemic estrogen effects (advanced bone age and/or growth acceleration) without progression to complete puberty. SUBJECTS AND METHODS: Seven girls (age < 2.5 years) with exaggerated thelarche, 6 girls with inactive pituitary-ovarian axis (premature adrenarche) and 21 girls with activated axis (central precocious puberty) had serum FSH, LH and E2 measured serially before and 1 to 24 h after gonadotropin-releasing hormone agonist (GnRHa) administration (leuprolide, 20 micrograms/kg sc), used as a test of combined pituitary-ovarian stimulation. RESULTS: Although girls in the exaggerated thelarche and adrenarche group had similar [mean (SEM)] baseline FSH [3.2 (0.9) vs 1.4 (0.3) IU/l], LH [0.36 (0.1) vs 0.27 (0.02) IU/l] and E2 [20 (1.2) vs 21 (2) pmol/l] concentrations, and similar peak post-GnRHa LH concentrations [5.5 (1.1) vs 2.4 (0.5) IU/l], girls with exaggerated thelarche achieved higher peak FSH [41 (9) vs 14 (3) IU/l, p < 0.01] and E2 [243 (40) vs 37 (6) pmol/l, p < 0.001] concentrations after GnRHa. In comparison to patients with exaggerated thelarche, girls with precocious puberty had higher (p < 0.01-0.001) baseline LH [3.6 (0.8) IU/l], baseline E2 [69(11) pmol/l], GnRHa-stimulated peak LH [68 (17) IU/l] and peak E2 [648 (58) pmol/l] concentrations, but similar FSH parameters. CONCLUSIONS: Girls with exaggerated thelarche exhibit substantial E2 secretory potential that can be demonstrated by GnRHa stimulation, is predominantly FSH-driven, and probably accounts for the manifestations of estrogen effect seen in these girls.

The relationship between luteinizing hormone and estradiol secretion in female precocious puberty: evaluation by sensitive gonadotropin assays and the leuprolide stimulation test.

We used the GnRH agonist (GnRHa) stimulation test (20 micrograms/kg leuprolide sc, followed by 24-h serial sampling) to investigate the relationship between gonadotropin and estradiol (E2) secretion in the early phase of female central precocious puberty (CPP). Girls with CPP and moderately increased (early pubertal) peak E2 concentrations after GnRHa stimulation (136 +/- 11 pmol/L; range, 92-176; group B; n = 7) were compared to girls with CPP and higher (midpubertal) peak E2 responses to GnRHa (mean +/- SE, 590 +/- 63 pmol/L; range, 235-1189; group C; n = 19) and to a group of subjects with no breast development and a prepubertal hypothalamic-pituitary-gonadal axis (peak E2 response to GnRHa, 39 +/- 7 pM/L; range, 18-62; group A; n = 6). Compared to group A subjects, patients in group B had similar (P > 0.2) peak GnRHa-stimulated LH concentrations (B, 4.8 +/- 1 IU/L; A, 2.3 +/- 0.5 IU/L) and peak nocturnal LH (B, 0.81 +/- 0.2; A, 0.25 +/- 0 IU/L), but higher peak GnRHa-stimulated FSH concentrations (B, 26 +/- 7; A, 11 +/- 2 IU/L; P < 0.05) and mean nocturnal FSH (B, 4.2 +/- 1; A, 1.1 +/- 0.3 IU/L; P < 0.05) concentrations. Compared to group B, group C patients had higher (P < 0.001) GnRHa-stimulated peak LH (67 +/- 19 IU/L) and higher (P < 0.05) peak nocturnal LH (9.7 +/- 2.9 IU/L) concentrations, but similar GnRHa-stimulated peak FSH (27 +/- 3 IU/L) and mean nocturnal FSH (3.8 +/- 0.5 IU/L) levels. Group C patients with a ratio of peak GnRHa-stimulated LH to FSH concentrations below or above 1, respectively, had similar peak E2 responses to GnRHa (516 +/- 80 vs. 644 +/- 92 pM/L; P > 0.1). Stepwise regression analysis indicated that the peak LH response to GnRHa (r = 0.76; P < 0.001), but none of the FSH secretory parameters (P > 0.10), affected the E2 response to GnRHa. These data suggest that girls with CPP in the early phase of activation of the hypothalamic-pituitary-gonadal axis are capable of clinically relevant E2 production, which may occur in the face of low LH secretion and low LH/FSH ratios and cannot be explained solely on the basis of increased FSH secretion. Thus, endocrine or paracrine factors other than gonadotropins may be important in amplifying E2 secretion in the early phase of CPP.