Breakdown of Azadirachtin A in a Tropical Soil Amended with Neem Leaves and Animal Manures

A field investigation was conducted to assess the breakdown of azadirachtin A in a tropical coastal savanna soil amended with neem leaves （NL） combined with poultry manure （PM） or cow dung （CD） using gas chromatography. Samples in polythene bags 15 cm long and 4.8 cm in diameter were randomly placed to a depth of 14 cm in the soil, and azadirachtin A concentration was assessed on days 0, 14, 28, 42, 56, 70, and 84. Azadirachtin A degradation in the soil followed first-order reaction kinetics with different half-lives obtained for varying combinations of the amendments. Higher neem amendment levels of 100 g gave shorter half-lives of azadirachtin A than the lower levels of 50 g. Within the 50 g NL group the additions of the poultry manure and the cow dung gave significantly shorter （P 〈0.05） half-lives of azadirachtin A than the sole neem amendment, whereas in the 100 g NL group only additions of 10 g CD and 10 g PM were significantly less （P 〈 0.05） than the sole neem amendment. Different changes resulting from the kind and quantity of animal manure added were observed in the half-lives of azadirachtin A. The 100 g NL group had significantly higher （P 〈0.05） moisture content, which, coupled with the likely differeaces in microbial biomass, could be the major factor responsible for variations in the half-llfe of the compound. Therefore, the quantity of the neem leaves applied and the addition of animal manure affected the breakdown of azadirachtin A in the soil amended with neem leaves.

Taste Adaptation of Helicoverpa armigera Larvae to Azadirachtin and Its Physiological Mechanism

Dual-choice behavioral assays and electrophysiological tip-recording technique were used to investigate the taste adaptation of different diet-experienced frith instar larvae of Helicoverpa armigera to azadirachtin. The behavior test showed that the larvae reared with normal artificial diets were highly deterred by aza- dirachtin. However, the larvae reared with the artificial diets containing low concentration of azadirachtin showed insensitivity to asadirachtin. The electrophysiological tests showed that there was a changed responsiveness in the deterrent neuron responding to asadirachtin in the lateral sensilla styloconica of different diet-experienced larvae. It indicated that there was a taste adaptation to azadiraehtin in different diet-experienced larvae of H. armigera and this taste adaptation was correlated with desensitization of related taste neurons.

A comprehensive review of azadirachtin: physicochemical properties, bioactivities, production, and biosynthesis

Azadirachtin,a complex tetratriterpenoid limonin with potent insecticidal properties,is the most widely used biological pesticide worldwide.Its versatile pharmacological applications include the inhibition of tumor growth and anti-malarial,anti-bacterial,and anti-inflammatory properties.Azadirachtin plays a pivotal role in pest control and novel drug development.The primary source of azadirachtin is the neem tree(Azadirachta indica A.Juss),with an azadirachtin content ranging from 0.3%to 0.5%.Despite the market demand for botanical pesticides reaching approximately 100,000 tons per year,the annual neem production in China is only 1.14 tons.Although azadirachtin can be obtained through plant extraction or chemical synthesis,the quantity obtained does not meet the market demand in China.The sluggish pace of azadirachtin biosynthesis results from the limited availability of genetic information and the complexity of the synthetic pathway.Recent advancements in azadirachtin biosynthesis hold promise as an efficient collection method.In this study,we explored the physicochemical properties,biological activities,mechanisms of action,and acquisition methods of azadirachtin.We also delved into recent progress in azadirachtin biosynthesis and assessed potential future usage challenges.This study aims to establish a theoretical foundation for the scientific application and efficient synthesis of azadirachtin,offering valuable reference information to the industry.

Variation in seed morphometric characters, oil content and azadirachtin content of seeds, in vitro shoot cultures and callus cultures among different populations of Azadirachta indica

We studied seed morphometric characters, oil content and azadirachtin content in a medicinally important and insect repellent tree species Azadirachta indica A.Juss. Ten populations were selected from two central Indian states of Madhya Pradesh and Chhattisgarh and twenty candidate plus trees were selected from each population based on tree attributes. Azadirachtin content was estimated in seeds, in vitro shoots and callus cultures through HPLC. Significant variation（p ／ 0.05） was observed in seed morphometric characters, oil content and azadirachtin content among the ten populations. Maximum value for 100 seed weight was obtained in seeds of Raigarh（30.51 g） which was on par with seeds of Bargi（28.37 g）and Chhatarpur（26.36 g）. The ratio of highest kernel to seed was also obtained in seeds of Raigarh（60.11%）.Kernels from Chhatarpur population recorded the highest oil content（24.20%）, which was equal to that in Sihore（23.75%） and Katni（21.75%）. We recorded highly significant variation in azadirachtin content in seed samples,in vitro shoot samples and callus cultures. Maximum azadirachtin was present in the seeds of Gwalior（0.882%）which was on par with azadirachtin content in seeds of Chhatarpur, Katni, Sihore, Shahdol and Chhindwara.Maximum azadirachtin in the in vitro shoots was present in the cultures of Gwalior（0.218%） which was statistically on par with Sihore（0.176%）. Similarly, in callus cultures of nodal segments maximum azadirachtin was recorded in the Gwalior population（0.033%） which was statistically on par with Sihore（0.028%）. The trees of Gwalior and Sihore populations can be produced in large numbers through vegetative propagation to obtain seeds with higher azadirachtin content.

STUDIES ON THE SYNTHESIS OF THE SPIROKETAL FRAGMENT OF AZADIRACHTIN(Ⅰ)

The stereoselective synthesis of substituted [2,2,1]-bicyclo- heptan-2-one 12,a supposed intermediate to the spiroketal fragment of azadi- rachtin was described.When 12 was treated with mCPBA in CH_2Cl_2 in the pres- ence of excess amount of solid sodium bicarbonate,only 13 was obtained.The spiroketal intermediate 20 was converted from 9 through 5 steps by an alterna- tive route.

Integrated Control of Tetranychus cinnabarinus by Five Kinds of Pesticides Combined with Neoseiulus cucumeris

To find the method for the integrated control of Tetranychus cinnabarinus （carmine spider mite） and delay its resistance to pesticides, the joint actions of each of five commonly pesticides （abamectin, azadirachtin, matrine, pyrethrins and imidacloprid）, and Neoseiulus cucumeris （Oudemans）, the natural enemy of cotton red spider mite, were studied. N. cucumeris was released after application of pesticides for seven days （for 0,3% azadirachtin EC） or six days （for other pesticides）. The results showed that the combined action of 1.8% abamectin EW （1：8 000） and N. cucumeris had the best control efficacy of 96.63% at 20 days after N. cucumeris releasing. The control efficacies of N. cucumeds and 0.3% azadirachtin EC （1：250） were 59.7% and 90.1% after one day and 20 days, respectively, after N. cucumeris releasing. The control efficacy of N. cucumeris and 0.5% matrine AS （1：2 000） was 82.65% at 20 days after N. cucumeris releasing. The results provide options for sustainable control of T. cinnabarinus and for the delay of pesticides resistance.

The bio-interactions between plants,insecticides and fertilizers:an innovative approach for the research of xenobiotic substances

In this experiment carried out on Caribbean chili pepper plants(Capsicum chinensis),the bio-insecticide azadirachtin in combination with an NPK fertilizer proved to have a greater lethal impact on the larvae of Aedes albopictus than each substance on its own.This synergistic effect is noticeably important when both inputs are sprayed directly on the leaves of the plant(foliar application).While the plants treated with azadirachtin or NPK alone cause a 33.6%and 36.4%mortal-ity respectively of the Ae.albopictus larvae,the combination of the two inputs induces a 74.4%mortality on the mosquito larvae.To account for this synergistic effect phenomenon inside the plant,the azadirachtin+NPK combination most likely interacts with the capsaicinoid compounds naturally produced by the plant.Not only does this study carried out on azadirachtin reveal major results but the methodology itself offers a most interesting approach on how to boost the agricultural inputs within the plants.As a matter of fact,this research axis demands developing since the control of pests harmful to men has been dramatically lacking insecticide molecules acting on new targets over the past three decades.

印楝素对小菜蛾敏感种群和抗性种群的拒食活性

用叶片浸渍法测定了印楝素(Azadirachtin)对小菜蛾抗性及敏感种群拒食活性。实验结果表明,印楝素对田间抗性及敏感小菜蛾种群均具有较好的拒食作用,且拒食活性随其的浓度的增加而显著增强;相对于抗性种群,印楝素对小菜蛾敏感种群表现了更强的拒食活性,其抗性种群拒食中浓度AFC50(1.2591 mg/L)是敏感种群AFC50(0.2567 mg/L)的4.91倍。

Effects of neem-based insecticides on beet armyworm （Lepidoptera： Noctuidae）

Three commercial neem [Azadirachta indica A. Juss (Meliaceae)]-basedinsecticides, Agroneem, Ecozin, and Neemix, and a non-commercial neem leaf powder, were evaluatedfor oviposition deterrence, antifeedant effect on larvae, and toxicity to eggs and larvae of thebeet armyworm, Spodoptera exigua (Huebner) (Lepidoptera: Noctuidae), on cotton leaves in thelaboratory. Oviposition deterrence in no-choice, and two- and five-choice assays, was observed forthe neem-based insecticide treatments when compared with a non-treated control. Neem-basedinsecticides also deterred feeding by beet armyworm larvae. Direct contact with neem-basedinsecticides decreased the survival of beet army-worm eggs. Survival of beet armyworm larvae fed for7 days on leaves treated with neem-based insecticides was reduced to 27, 33, 60, and 61% for neemleaf powder, Ecozin, Agroneem, and Neemix, respectively. Possibilities for adoption of neem-basedinsecticides in commercial cotton for beet armyworm control are discussed.

Behavioral predictability in a lynx spider is interactively influenced by mean behavior, prey density,and an insecticide

Behavioral predictability,i.e.,short-term intra-individual variability under relatively constant environmental conditions,has only recently begun to gain attention.It is unknown,however,whether predictability of individuals with distinct mean behavior changes differently as a response to ecological factors such as resource availability.Moreover,the response might be affected by anthropogenic contaminants that are ubiquitous in the environment and that can affect animals' variability in behavior.Here,we investigated the relationship between mean predatory activity and predictability in predatory activity along a prey density gradient in the lynx spider Oxyopes lineatipes.We further examined how this relationship is influenced by insecticides,azadirachtin,and a plant extract from Embelia ribes.We found that all studied variables affected the predictability.In the control and Embelia treatments,that did not differ significantly,the predictability decreased with increasing prey density in a mean behavior-specific way.Individuals with low mean predatory activity were relatively less predictable than were those with high activity from low to moderate prey densities but more predictable at high prey densities.Azadirachtin altered this pattern and the individuals with low predatory activity were less predictable than were those with high predatory activity along the whole gradient of prey density.Our results show that predictability can change along an environmental gradient depending on a mean behavior.The relative predictability of the individuals with distinct mean behavior can depend on the value of the environmental gradient. In addition,this relationship can be affected by anthropogenic contaminants such as pesticides.

Cell Suspension Culture of Neem Tree

The establishment of suspension culture system for neem (Azadirachta indica A. Juss) cells and the suspension culture condition was studied. It shows that the neem cell suspension culture system was best in B5 liquid medium, 2.0~4.0mg/L NAA with direct spill method. Based on the integrated analysis of cell biomass, Azadirachtin content and productivity, the optimum culture conditions were B5 liquid medium, 2.0-4.0 mg/L NAA, 3% sucrose at 25 ℃. The optimum rotating speed of the shaker and broth content d...