Toxicity of Turmeric Extracts to the Termite Reticulitermes flavipes (Blattodea: Rhinotermitidae)

Turmeric shortens lifespan in houseflies

Climate change poses a significant threat to food security and global public health with the increasing likelihood of insect pest outbreaks. Alternative ways to control insect populations, preferably using environmental-friendly compounds, are needed. Turmeric has been suggested as a natural insecticide with toxicity properties in some insect groups. However, empirical evidence of the effects of turmeric - and their interaction with other ecological factors such as diet - on insect survival has been limited. Here, we tested the effects of turmeric and its interactions with diets differing in protein source in the common housefly, Musca domestica. We found that turmeric shortened lifespan independent of diet and sex. Females in turmeric diets were heavier at death, which was likely driven by a combination of relatively lower rates of body mass loss during their lifetime and a higher percentage of water content at death. Each sex responded differently to the protein source in the diet, and the magnitude of the difference in lifespan between sexes were greatest in diets in which protein source was hydrolysed yeast; individuals from both sexes lived longest in sucrose-milk diets and shortest in diets with hydrolysed yeast. There was no evidence of an interaction between turmeric and diet, suggesting that the toxicity effects are independent of protein source in the diet. Given the seemingly opposing effects of turmeric in insects and mammals being uncovered in the literature, our findings provide further evidence in support of turmeric as a potential natural insecticide.

Synergistic effects of botanical curcumin-induced programmed cell death on the management of Spodoptera litura Fabricius with avermectin

Chemical pesticides and adjuvants have caused many negative effects. Botanical compounds provide solutions for the development of environment friendly pesticides and the management of increasing pest resistance. Curcumin, a natural polyphenol, showed synergistic effects on avermectin upon the destructive agricultural pest, Spodoptera litura. However, the botanical synergist and its relevant mechanisms remain unclear. In the article, curcumin significantly enhanced the growth inhibition and midgut structural damage of avermectin on the larvae of S. litura, and the synergistic effects were confirmed with pot experiments. There were only a few influences on the gene expression of avermectin targets, while apoptotic and autophagic related genes and proteins were accumulated in the avermectin/curcumin mixed regent (0.013/0.0013 μg/mL) treated group. Moreover, the potential mechanism was explored with an in vitro model, insect Spodoptera frugiperda Sf9 cell line. Morphology observation featured the damage on cells and Hoechst33258 staining revealed the fragments of DNA after treating with the avermectin/curcumin mixed regent (10/1 μg/mL). Dansylcadaverine and LysoTracker staining, as well as the gene expressions, supposed that curcumin exhibited autophagy inducing effects and the mixed regent possessed a higher ability to induce apoptosis and autophagy. All these results suggested that the synergistic effects of curcumin on the pest management of avermectin potentially mainly derived from the enhancement of programed cell death. It provides new sights for the application of natural compounds in integrated pest management and enriches examples of synergistic mechanisms.

Effects of White Mulberry (Morus alba) Heartwood Extract Against Reticulitermes flavipes (Blattodea: Rhinotermitidae)

Heartwood extract from white mulberry (Morus alba L.) (Rosales: Moraceae) were investigated for antitermitic activity against Reticulitermes flavipes (Kollar) (Blattodea: Rhinotermitidae) in laboratory experiments. An ethanol:toluene (2:1) solvent system was used to remove extract from heartwood shavings. A concentration-dependent feeding response and mortality were observed for termites exposed to a concentration series range of 1.25 to 10 mg/ml of extract based on their dry weight. Results showed that maximum termite mortality occurred at 10 mg/ml. Based on the concentration series data, LC50 was calculated at 1.71 mg/ml. In filter paper feeding and repellency assays, extract significantly decreased the total number of gut protozoa compared with untreated and solvent controls. After feeding on filter paper treated at 10 mg/ml for 2 wk, protozoan populations were reduced by >55%. In choice and no-choice tests with mulberry heartwood, greater wood loss from termite feeding was found on solvent extracted blocks compared with nonextracted. Complete (100%) mortality was observed after feeding on nonextracted blocks compared with extracted blocks. Heartwood extract from white mulberry imparted resistance to vacuum pressure treated, nondurable southern pine and cottonwood. At every concentration tested, 100% mortality was observed after feeding on extract-treated southern pine or cottonwood. GC-MS analysis of extract showed high levels of the phenol compound, resorcinol. Results indicated that heartwood extract from white mulberry have antitermitic properties and might be potentially valuable in the development of environmentally benign termiticides.

Chemical Constituents of Coreopsis lanceolata Stems and Their Antitermitic Activity Against the Subterranean Termite Coptotermes curvignathus

Coreopsis lanceolata is an Asteraceous plant known to contain semiochemicals active against nematodes and leukemic agents. The objective of the study was to discover termite resistant constituents from C. lanceolata stems. Five compounds were isolated from C. lanceolata stems. These compounds were identified as 5-phenyl-2-(1-propynyl)-thiophene (1), 1-phenylhepta-1,3,5-tryne (2), β-sitosterol (3), succinic acid (4), and protocatechuic acid (5), respectively; they were confirmed by spectroscopic analysis. Their antitermitic effects were evaluated with the no-choice feeding test against Coptotermes curvignathus. Of the isolates, 5-phenyl-2-(1-propynyl)-thiophene (1) and 1-phenylhepta-1,3,5-tryne (2) showed strong potent antitermitic activity. Our findings suggested that compounds 1 and 2 isolated from C. lanceolata stems appears to be the active ingredients.