Assessment of chlorinated pesticide exposure to white-rumped vulture Gyps bengalensis in India.

Populations of the critically endangered white-rumped vulture (WRV) Gyps bengalensis have declined drastically due to the use of diclofenac for veterinary purposes in Indian subcontinent. Thirty-two dead WRVs collected from three states, namely Gujarat, Assam and Tamil Nadu in India between 2011 and 2014 were investigated to understand the role of diclofenac in the death, and the results were published. Furthermore, since organochlorine pesticides have been linked to long-term impact on populations in many species of birds across the globe, available tissues of 21 WRVs were tested also for six organochlorine pesticides (DDT, HCH, endosulfan, heptachlor, dieldrin and dicofol) and chlorpyrifos. All vultures were found to have had one or more detectable levels of pesticides in their tissues except one. Similarly, all the pesticides included in the study were detected in at least one of the vultures analysed. DDT (95.2%) was the most frequently detected pesticide followed by HCH (90.5%), and DDT (73.6%) contributed the most to the total pesticide load. Total pesticide load ranged between below detection limit (BDL) and 8753.4 ng/g. High levels of total pesticide load recorded in gut contents showed recent exposure to these legacy pesticides even long after their ban. However, it is perceived that studied pesticides' exposure to birds and their presence in the environment is in decreasing trend in India. Although, varying levels of pesticides were detected, all of which were below the levels reported to be toxic, and also reported earlier in the same species in India. Recorded levels may not create a problem to vultures unlike diclofenac; nevertheless, as continued exposure to the pesticides studied may lead to sub lethal effects in birds, it is prudent to monitor these pesticides along with new generation pesticides and NSAIDs in the critically endangered white-rumped vulture in India, towards its conservation.

Nimesulide poisoning in white-rumped vulture Gyps bengalensis in Gujarat, India.

Population of white-rumped vulture has not recovered in India to a desired level even after diclofenac was banned in 2006. During 2019, there were two known separate incidents of white-rumped vulture mortality involving four white-rumped vultures in Gujarat. After post-mortem examinations, tissues of all four vultures were received for toxicological investigation at the National Centre for Avian Ecotoxicology, SACON. Tissues were screened for a set of toxic pesticides, and none of them was at detectable level. Subsequently, the tissues were analysed for thirteen NSAIDs and paracetamol. Of all the drugs tested, only nimesulide was detected in all the tissues (17-1395 ng/g) indicative of exposure. Visceral gout was also observed in all the four vultures during post-mortem. Residues of nimesulide in tissues with symptoms of gout indicated that the vultures died due to nimesulide poisoning. Although, other than diclofenac, many NSAIDs are suspected to be toxic to white-rumped vultures, only nimesulide is reported in the recent past with clear symptom of gout in wild dead white-rumped vultures similar to diclofenac. Since, nimesulide appears to act similar to diclofenac in exerting toxic effects, if veterinary use of nimesulide continues, white-rumped vulture are bound to suffer. Hence, it is recommended that nimesulide should be banned by the government to conserve white-rumped vulture in the Indian subcontinent. Further, an effective system is recommended to be put in place to collect the tissues of dead vultures for toxicological investigations and eventual conservation of the critically endangered species.

Variation in Polycyclic Aromatic Hydrocarbon Contamination Between Native and Introduced Species of Fishes of Pallikaranai Wetland, Chennai, Tamil Nadu, India.

The impacts of invasive fish species on recipient communities are mostly considered a threat to the biodiversity of freshwater systems. A characteristic of introduced species turning invasive is their higher tolerance to environmental stressors. To understand if non-native fishes in Pallikaranai wetland, Tamil Nadu, India, are more tolerant to anthropogenic pressures in the Wetland, we assessed the variation in Polycyclic Aromatic Hydrocarbon contamination between introduced and native fish species. Mean levels of Naphthalene, fluorene, phenanthrene, anthracene, pyrene, and total PAH in samples of introduced species were higher than native species, while High Molecular weight PAH and carcinogenic PAH4 were higher in native fish species. The data was also analysed to assess if co-variates (organs, seasons, and sex) affected PAH accumulation patterns in non-native species. It was observed that only organs, sex, and year contributed significantly.

Pyriproxyfen induced impairment of reproductive endocrine homeostasis and gonadal histopathology in zebrafish (Danio rerio) by altered expression of hypothalamus-pituitary-gonadal (HPG) axis genes.

Pyriproxyfen (PPF), a broad-spectrum insecticide known to cause reproductive and endocrine disruption in invertebrates, while the data is scarce in aquatic vertebrates. The goal of this study is to investigate the impact of PPF on reproductive endocrine system of male and female zebrafish along hypothalamus-pituitary-gonadal (HPG) axis. In brain, PPF caused significant alteration in the transcripts of erα, lhß, and cyp19b genes in male and fshß, lhß, and cyp19b genes in female zebrafish. The downstream genes of steroidogenic pathway like, star, 3ßhsd, 17ßhsd, and cyp19a expression were significantly altered in gonad of both sexes. Subsequent changes in circulatory steroid hormone levels lead to imbalance in hormone homeostasis as revealed from estradiol/testosterone (E2/T) ratio. Further, the vitellogenin transcript level was enhanced in hepatic tissues and their blood plasma content was increased in male (16.21%) and declined in female (21.69%). PPF also induced histopathological changes in gonads such as, reduction of mature spermatocytes in male and vitellogenic oocytes in female zebrafish. The altered E2/T ratio and gonadal histopathology were supported by the altered transcript levels of HPG axis genes. Overall, these findings provide new insights of PPF in zebrafish reproductive system and highlights for further investigations on its potential risks in aquatic environment.

Incidences of mortality of Indian peafowl Pavo cristatus due to pesticide poisoning in India and accumulation pattern of chlorinated pesticides in tissues of the same species collected from Ahmedabad and Coimbatore.

Incidences of mortality of Indian peafowl Pavo cristatus, the national bird (Schedule I Indian Wild Life Protection Act 1972), are rampant in India. Between January 2011 and March 2017, around 550 peafowl in 35 incidences were reported dead across the country. Due to the non-availability of fresh carcases, poisoning could not be confirmed. Birds which died due to kite string injuries in Ahmedabad (15) and accidents in Coimbatore (5) were tested for residues of chlorinated pesticides, namely hexachlorocyclohexane (HCH), dichloro-diphenyl-trichloroethane (DDT), endosulfan, heptachlor, dicofol, dieldrin and cholipyrifos. The liver, kidney and muscle were the tissues considered to document pesticide load. Total load ranged from BDL to 388.2 ng/g. DDT (95%) and HCH (80%) were detected more frequently. DDT (40%) and endosulfan (26%) contributed maximum to the total pesticide load followed by HCH (21%). Pesticide accumulation pattern among the organs was in the order of liver (123.9 ng/g) > kidney (91.9 ng/g) > muscle (19.5 ng/g) with significant difference (p < 0.05). Peafowl from Ahmedabad had significantly (p < 0.05) higher level of total pesticide (149.0 ng/g) than birds from Coimbatore (47.8 ng/g). Although varying levels of chlorinated pesticide were detected, they were below reported toxic limits. Nevertheless, persistence of chlorinated pesticides and poisoning due to modern pesticides across the entire distribution range of Peafowl in India is a cause for concern.

Residues of Diclofenac in Tissues of Vultures in India: A Post-ban Scenario.

Populations of three resident Gyps species (Indian white-backed vulture Gyps bengalensis, Indian vulture Gyps indicus, and Slender-billed vulture Gyps tenuirostris) in India have decreased by more than 90% since mid 1990s, and they continue to decline. Experimental studies showed the mortality of vultures to be due to renal failure caused by diclofenac, a nonsteroidal anti-inflammatory drug. India, Pakistan, and Nepal banned the veterinary usage of diclofenac in 2006 to prevent further decline in vulture population. This study was performed to know the current status of the impact of diclofenac on vultures in India. Between 2011 and 2014, 44 vultures comprising two species, namely Indian white-backed vulture (32) and Himalayan griffon Gyps himalayensis (12) were collected dead from Gujarat, Assam, and Tamil Nadu on an opportunistic basis. Kidney and liver tissues and gut content were analysed for diclofenac. Of the 32 dead white-backed vultures analysed, 68.75% of them had diclofenac ranging from 62.28 to 272.20 ng/g. Fourteen white-backed vultures had diclofenac in kidney in toxic range (70-908 ng/g). Of 12 Himalayan griffon studied, 75% of them had diclofenac in the range of 139.69 to 411.73 ng/g. Himalayan griffon had significantly higher levels of diclofenac in tissues than Indian white-backed vultures. It is possible that 14 of 29 white-backed vultures and 9 of 12 Himalayan griffon included in this study died due to diclofenac poisoning. Studies have indicated that diclofenac can continue to kill vultures even after its ban in India for veterinary use.