Insect herbivores and pathogens of Alnus species in Uganda

Published documentation of insect pests and pathogens associated with Alnus species in Africa is very scarce. We surveyed damaging insects and pathogens, and arthropod natural enemies on Alnus acuminata and A. nepalensis in Kabale and Mbale districts, Uganda between March 1999 and August 2000 in order to identify the range and relative abundance of arthropods and pathogens associated with the Alnus species. Frequently encountered damaging insects on the Alnus species included Apis mellifera, Apion globulipenne, a Systates sp. (Coleoptera: Curculionidae), Phymateus viridipes, a Lobotrachelus sp. (Coleoptera: Curculionidae), Coloborrtics corticina and some Chrysomelidae. Some species such as Aphis fabae, Parastictococcus multispinosus and a Cacopsylla sp. (Homoptera: Psyllidae) were observed feeding on other agroforestry tree species and/or crops although they generally occurred at low population intensities. Spiders and parasitic Hymenoptera were the most common natural enemies. Diseases were more severe in nurseries than in the field. Damping-off caused by Fusarium oxysporum, Septoria brown leaf spot and stem canker were the most serious diseases of Alnus. The array of damaging insects and pathogens indicates a potential danger to the cultivation of Alnus species in Uganda as adoption of the species for agroforestry continues to expand in the country. In view of the increasing demand for Alnus species for agroforestry in Uganda, regular pest monitoring and appropriate control strategies are necessary.This revised version was published online in November 2005 with corrections to the Cover Date.     

气候变化对包头地区农作物病虫害发生发展的影响

气候变暖对农作物病虫害的影响是巨大的,直接导致大部分病虫害的发生、流行、越冬、危害规律产生变化。在包头地区,年平均气温逐步升高,这样的变化更加有利于蝗虫、马铃薯晚疫病等病虫害的发生、发展,使其为害、流行趋势加重,给综合防治工作带来困难,应引起重视。     

我国食用昆虫资源及其开发利用的途径与前景

针对我国动物蛋白严重不足的现状,本文指出昆虫是重要的动物蛋白质资源,并综述了昆虫的营养价值及可食用昆虫的种类,进而提出我国开发利用昆虫蛋白需采取先进的科学加工工艺等三种途径和广阔的应用前景。     

昆虫作为可食用资源的相关研究

昆虫是地球上最大的生物类群,是人类可开发利用的重要的可再生资源。世界许多国家都有食用昆虫的习俗,因此,研究昆虫是否能作为一类适合人类食用的资源具有重要意义。研究表明,食用昆虫益处多,同时也比较安全。     

Impacts of insect herbivores on rare plant populations

Population-level impacts of insect herbivory on rare and endangered plants are poorly understood, being frequently suggested but seldom quantified. We compiled 37 studies from the primary literature encompassing 35 rare plant species and at least 63 insect herbivore species, and assessed patterns in the effects of insect herbivores on rare plant populations and vital rates. Only three studies directly quantified effects of insect herbivory on population size or growth rate, with the vast majority instead extrapolating from vital rates to population size. Few studies (eight) studied herbivory experimentally, and feeding guilds other than seed predators have been relatively neglected. Estimates of population-level impacts vary extremely widely, but for many rare plants insect herbivores cause major reductions in survivorship or fecundity or can even drive local extinctions. Four studies documented positive (plant-) density dependence in insect attack, suggesting that herbivores may have a stabilizing influence on plant populations and thus may play a role in regulating rare plant population size. Most reported herbivores of rare plants are oligophagous or polyphagous, but monophagous herbivores of rare plants do exist, and there was no detectable difference in impact among specialization classes. Attack on rare plants by escaped biocontrol agents can sometimes have significant population-level effects, but such cases appear uncommon. Because insect herbivory can strongly suppress rare plant populations or vital rates, we need to know much more about what ecological and evolutionary factors determine the population-level impacts of insect herbivores. We suggest several ways in which the results of such research could inform conservation practices for rare plant species – for example, the possibility of different management regimes for plants under attack by monophagous, oligophagous, and polyphagous herbivores.     

Canopy vs. understory: Does tree diversity affect bee and wasp communities and their natural enemies across forest strata?

Bees and wasps provide important ecosystem services such as pollination and biocontrol in crop-dominated landscapes, but surprisingly little information is available on hymenopteran communities in temperate forest ecosystems. Species richness and abundance of bees and wasps can be hypothesised to increase with plant diversity, structural complexity, and availability of food and nesting resources. By experimentally exposing standardised nesting sites, we examined abundance and species richness of cavity-nesting bees (pollinators), wasps (predators) and their associated parasitoids across a tree diversity gradient in a temperate deciduous forest habitat. In addition, spatial distribution of individuals and species across forest strata (canopy vs. understory) was tested. Abundance and species richness was high for predatory wasps, but generally low for pollinators. Species-rich forest stands supported increased abundance, but not species richness, of pollinators and predatory wasps, and also increased abundance and species richness of natural enemies. In addition, the forests showed a distinct spatial stratification in that abundance of bees, wasps and parasitoids as well as parasitism rates were higher in the canopy than understory. We conclude that particularly the canopy in temperate forest stands can serve as an important habitat for predatory wasp species and natural enemies, but not bee pollinators. Enhanced tree diversity was related to increased hymenopteran abundance, which is likely to be linked to an increase in nesting and food resources in mixed forest stands.     

Development of a bioacoustic sensor for the early detection of Red Palm Weevil (Rhynchophorus ferrugineus Olivier)

The Red Palm Weevil (Rhynchophorus ferrugineus Olivier) is one of the worst pests for palms, since it can completely destroy the plant. Its early detection is very difficult and when the action of the pest is discovered, normally it is too late for recovering the plant. Bioacoustic sensors provide a good alternative for early detection of this pest because larvae activity is audible while they excavate tunnels to feed. This work describes the different stages for the development of an original electronic device based on acoustic sensors for early detection of Red Palm Weevil larvae in the interior of palms. This device is based on characteristic frequencies possibly related to their feeding activity. The performed tests have demonstrated that is possible to detect two week old larvae activity studying the sound intensity around 2250 Hz in palms infested only with 5 individuals under controlled environmental conditions. The activity of other insects artificially situated in the interior of palms did not affect the response of the device, possibly because they produce different frequencies (in the range 5–7 kHz). Future work will be aimed at assessing the infestation levels.     

我国谷子害虫种类初步调查

通过对我国谷田不同生育期害虫的详细调查,初步明确了当前为害我国谷子的害虫有8个目30科58种。同时对各产区主要害虫种类及发生情况进行了总结,并对各产区主要虫害的防治对策进行了阐述。     

三江平原环形湿地昆虫种类多样性与季节动态

以三江平原典型环形湿地为研究对象,在小叶章群落、沼柳小叶章群落、漂茷苔草群落、塔头毛苔草群落,采用黄盘诱集法和扫网法定期对湿地昆虫群落进行采集,研究了该区内的昆虫生物多样性及其季节性变化特征.共采集昆虫标本25945号,其中双翅目和同翅目数量最多,其次为膜翅目、缨翅目、弹尾目、鞘翅目、半翅目、直翅目等.各个植物群落昆虫种群的数量,Shannon-Wiener指数、Pielou指数受季节性影响显著.6月下旬湿地昆虫数量最多,但是Shannon-Wiener指数,Pielou指数最低.Shannon-Wiener指数在塔头苔草群落最高,在小叶章植物群落最低.