Evaluation of Insect Growth Regulators (IGRs) as biological pesticides for control of Aedes aegypti mosquitoes.

BACKGROUND OBJECTIVES: Insect growth regulators (IGRs) are biological hormone analogue or mimics used as pesticides to inhibit the growth of larva during their molting and skin shedding. This study aimed to test the effect of IGRs on the eggs hatching and post-hatching inhibition of Aedes mosquitoes and understanding its effect in the mosquito breeding habitats for reduction in adult emergence. METHODS: Experiments on the evaluation of three insect growth regulators (IGRs) for the control of different stages of Aedes aegypti was carried out during 2020-21. Each experiment consisted of four treatments viz., Pyriproxyfen, Novaluron, and Larvicol at 1.0 ppm and distilled water as a control. All experiments were carried out in completely randomized design (CRD) except eggs which were carried out in factorial design each with three replications. RESULTS: All tested IGRs performed better in affecting eggs, larval and pupal stages of Ae. aegypti. Highest eggs hatching inhibition (80%) of fresh eggs occurred in Pyriproxyfen followed by Novaluron (66%) and lowest in Larvicol (62%). Eggs hatch inhibition of embryonated eggs was lower than fresh eggs. Pyriproxyfen caused 69%, Novaluron 59% and Larvicol 39% eggs hatch inhibition of embryonated eggs. Both Pyriproxyfen and Novaluron performed better in causing 98-100% larval mortality followed by Larvicol (39%). Larval development to pupal stage was completely prevented by both Pyriproxyfen and Novaluron. Although Larvicol resulted in lowest eggs hatch and larval inhibition but prevented pupae to emerge as adults. Results further showed 70-89% mortality of 3rd instar larvae of Ae. aegypti when exposed to Pyriproxyfen and Novaluron solutions after 30 days storage at lab. temperature (27±2°C), RH 70±5. INTERPRETATION CONCLUSION: None of the IGRs was more effective at the pupal stage but showed carry-on activity of growth inhibition and mortality of the successive stages of development when used against eggs stages. Therefore, we recommend early application of IGRs at mosquito habitats during the beginning and onset of the season when very early stages of mosquitoes are available in the field.

Unique case of abdominal aortic aneurysm causing obstructive jaundice and duodenal obstruction.

Obstruction of the duodenum by an abdominal aortic aneurysm (AAA) (aortoduodenal syndrome) has rarely been reported. It presents with symptoms of upper gastrointestinal (GI) tract obstruction. Obstructive jaundice caused by an AAA is also extremely rare and requires high clinical suspicion. We present a unique case with informed consent of an elderly gentleman who presented with both rare presentations over a course of few months. After extensive literature search, we have found case reports of patients showing either of the two unusual presentations, but none were found to show them together.

Retroperitoneal Fibrosis as a Cause of Chylous Ascites.

Retroperitoneal fibrosis is a rare condition characterized by chronic inflammation and marked fibrosis of the retroperitoneal tissue, often leading to entrapment of abdominal organs. We report a 69-year-old white man who presented with a 5-week history of gradual onset of progressive abdominal distension. He had no history or risk factors for an underlying liver condition. Ascites and a retroperitoneal mass encasing the major abdominal vessels were revealed on imaging. Biopsies of the mass confirmed the presence of retroperitoneal fibrosis, and the ascitic fluid was milky, consistent with chylous ascites. We discuss this rare presentation and the challenges of treatment for chylous ascites caused by RPF, including the role for supportive treatment.