Establishment and spread of Gyranusoidea tebygi noyes and Anagyrus mangicola noyes (hymenoptera: encyrtidae), two biological control agents released against the mango mealybug Rastrococcus invadens williams (homoptera: pseudococcidae) in Africa

Two specific endophagous parasitoids Gyranusoidea tebygi and Anagyrus mangicola, of Indian origin, were mass‐reared at the International Institute of Tropical Agriculture in Cotonou and released against the mango mealybug Rastrococcus invadens, in collaboration with national biological control programmes. G. tebygi was released in the following countries: Benin, Gabon, Ghana, Nigeria, Sierra Leone and Zaire. In Togo, it had been released earlier and studied during another project. This parasitoid is now established in all areas infested by the mango mealybug. In addition, it established itself without previous release in Congo and Côte d'Ivoire. A. mangicola has been released in Benin, Gabon and Sierra Leone since 1991, and by mid‐1993 was recovered from a few sites. It seems locally established in southern Benin.     

Adult dispersal of Ostrinia nubilalis Hübner (Lepidoptera: Crambidae) and its implications for resistance management in Bt-maize

Abstract:  Dispersal of European corn borer, Ostrinia nubilalis Hübner was examined by release and recapture of the dye marked adults and by capture of the feral adults in and around the large 50 ha center pivot irrigated fields of Bacillus thuringiensis (Bt) maize. Pheromone and black light traps were used to catch the adults. In 1999, 15 094 marked males and 7993 marked females were released, and in 2001, 13 942 marked males and 9977 marked females were released. In 1999, maximum mean recapture beyond the release point was 1.95 and 1.67% for males and females, but in 2001, the recapture rate was 9.97 and 4.37% for males and females. Few males (3.8%) and females (2.07%) were recaptured in neighbourhood maize fields. An exponential decay function explained recapture of marked adults across the dispersal distance. More than 90% of marked adults were recaptured within 300 m of the release point. Large numbers of feral adults were captured throughout the study fields. Feral adult dispersal could be fitted to a linear model. Virgin females (20% marked and 8% feral) were captured throughout the study fields. The recapture of marked insects suggests that the dispersal was limited. However, capture of feral adults throughout Bt-maize fields indicate that the actual dispersal may be more extensive than indicated by recapture of marked adults. Potential refuge sources for the feral adults were 587–1387 m from the edge of the study fields. It is not clear if the dispersal recorded in this study is extensive enough to support the current resistance management strategy for corn borers. There appears to be some dispersal of corn borers from the non-transgenic 'refuge' fields into the transgenic fields that allows some genetic mixing of the two populations.     

Health status of Pomatoschistus microps populations in relation to pollution and natural stressors: implications for ecological risk assessment

Effects induced on wild populations by recurrent environmental contamination may difficult the ecological risk assessment of punctual pollution events such as oil spills. Here, the issue was addressed by comparing the health status of Pomatoschistus microps populations from four NW Iberian estuaries, using an integrated chemical–biological monitoring. Despite high seasonal variability, the parameters measured discriminated estuaries with different contamination levels and associated biological effects with chemical and abiotic stress. The decreased health status of fish from polluted sites strengthens the need of considering pollution-induced background effects and seasonal variability when assessing impacts and risks of oil and other chemical spills.     

Within‐plant distribution of Phorodon humuli (Hemiptera: Aphididae) and natural enemies on hops with implications for sampling and management

A field trial was performed on a hop yard throughout 2006, 2007 and 2008 in order to analyze the within‐plant distribution of Phorodon humuli (Schrank) and its natural enemies. The aphid population was higher on the leaves of the middle section of the main stem. Specifically, the population was significantly higher at 2 and 3.25 m than at 6 m during the three years. Natural enemies consisted of aphidophagous predators of which Coccinella septempunctata was recorded in the highest number. Its number was greater where the aphid population was higher, with a significantly higher number of eggs, larvae and adults at 2 and 3.25 m than at 6 m. Lacewing eggs were also frequently observed, with a significantly higher population where the number of aphids was higher. The number of winged aphids was higher at 3.25 m than at 2 m within a plant. Understanding hop aphid distribution within the hop canopy is important in developing sampling programs, in evaluating injury and helps the development of sustainable management practices.     

A survey of mealybugs and their natural enemies in horticultural crops in North Island,New Zealand,with implications for biological control

More than 1300 mealybugs and their natural enemies were collected from six crops (apples, pears, nashi, citrus, persimmon and grapes) at 91 sites. Pseudococcus longispinus and P. calceolariae were the commonest species in all crops, except in pipfruit in Hawkes Bay, inhabited almost exclusively by P. affinis. These three species accounted for more than 99% of all mealybugs collected. Mealybugs were attacked by 14 species of natural enemy, only two of which had been deliberately introduced to New Zealand. Six species of Encyrtidae were reared. Anagyrus fusciventris was recorded from New Zealand for the first time. Parectromoides varipes was newly identified as a primary parasitoid of mealybugs, and males of this species and Gyranusoidea advena, previously unknown, were found. Both species, together with Tetracnemoidea sydneyensis, T. peregrina and T. brevicornis, and Coccophagus gurneyi (Aphelinidae) and two species of Ophelosia (Pteromalidae) were widespread throughout the surveyed regions. Common predators included Cryptolaemus montrouzieri (Col: Coccinellidae), Cryptoscenea australiensis (Neuroptera: Coniopterygidae) and Diadiplosis koebelei (Dipt: Cecidomyiidae). Hyperparasitoids were extremely rare. Five species of ants were recorded tending mealybugs, but none is known to be disruptive to mealybug natural enemies. The implications of these data for biological control of mealybug pests in horticultural crops is discussed, and it is concluded that Pseudaphycus maculipennis (Hym: Encyrtidae) should be introduced against P. affinis. No other importations are recommended. The activity of existing species should be encouraged in future integrated pest management (IPM) programmes, by, for example, distributing A. fusciventris around the country, and commercializing the mass rearing and release of C. montrouzieri.     

Influence of meteorological factors on the quantitative following relationship between Empoasca onukii Matsuda (Hemiptera: Cicadellidae) and its natural enemies in tea plantations

Our aim was to study the close relationship between the number of Empoasca onukii and its natural enemies in tea plantations to provide a scientific basis for the control of E. onukii. The relationship between the number of E. onukii and its main natural enemies in tea plantations in Hefei, China, were compared by gray relational analysis, and then the relationships between seven meteorological factors and the populations of E. onukii were analyzed by the method of path analysis. The results showed that among the top six natural enemies most closely related to the population of E. onukii, two natural enemies were the same in the three years of study and four natural enemies were the same in any two years of the study, and that the natural enemy species closely related to the population of E. onukii varied greatly among years. The direct effect of monthly average relative humidity was the greatest effect in 2020 and the direct effect of monthly average temperature was the greatest effect in 2021, with both being negative in terms of their effect on the population size of E. onukii. The direct effect of the number of days of rainfall was the greatest effect in both 2021 and 2022, and the indirect effect of monthly sunshine hours through rainfall days was the greatest effect on the population of E. onukii. The highest temperatures in early and mid-August 2022 were higher than in previous years, which had an impact on the growth and development of subsequent E. onukii.     

Multilevel grouped regression for analyzing self-reported health in relation to environmental factors: the model and its application

A method for modeling the relationship of polychotomous health ratings with predictors such as area characteristics, the distance to a source of environmental contamination, or exposure to environmental pollutants is presented. The model combines elements of grouped regression and multilevel analysis. The statistical model describes the entire response distribution as a function of the predictors so that any measure that summarizes this distribution can be calculated from the model. With the model, polychotomous health ratings can be used, and there is no need for a priori dichotomizing such variables which would lead to loss of information. It is described how, according to the model, various measures describing the response distribution are related to the exposure, and the confidence and tolerance intervals for these relationships are presented. Specific attention is given to the incorporation of random factors in the model. The application that here serves as an example, concerns annoyance from transportation noise. Exposure-response relationships obtained with the described method of modeling are presented for aircraft, road traffic, and railway noise.     

The impact of aphicide drenches on Micromus tasmaniae (Walker) (Neuroptera: Hemerobiidae) and the implications for pest control in lettuce crops

Abstract  The recent arrival of lettuce aphid ( Nasonovia ribis-nigri (Mosley) ) in Australia has resulted in a pesticide-based protection program based upon seedling drenches of imidacloprid being promoted by many advisory agencies and accepted by growers as the only option available. This has caused concern about potential for incompatibility with existing integrated pest management programs for other pests in lettuce. Two neonicotinoid insecticides, imidacloprid (Confidor 200SC) and thiamethoxam (Actara), were applied to lettuce seedlings by drenching. A model aphid ( Macrosiphum euphorbiae (Thomas) ), used because N. ribis-nigri was not present in mainland Australia at that time, was periodically released onto the seedlings over 10 weeks. The effects of imidacloprid and thiamethoxam on larvae of predatory brown lacewings ( Micromus tasmaniae (Walker) ) which fed on the aphids were measured over 10 weeks by bioassay. Imidacloprid applied at a rate of 11 mL active ingredient (ai) per 1000 seedlings and thiamethoxam applied at 0.5 g ai per 1000 seedlings were highly toxic to M. tasmaniae that consumed aphids from the seedlings for up to 4 weeks after application. A 1/10 rate of imidacloprid (1.1 mL ai per 1000 seedlings) caused moderate toxicity for 3 weeks, and was then harmless to M. tasmaniae . Thiamethoxam and the high rate of imidacloprid caused almost complete mortality of aphids for about 6 weeks after application, and the low rate of imidacloprid displayed similarly high activity for about 3 weeks.     

The influence of host plant genotype on variation in population densities of the gorse thrips,Sericothrips staphylinus (Thysanoptera: Thripidae), and its consideration in relation to release strategies

Large variations in population densities of Sericothrips staphylinus were observed between gorse bushes at a field site in an earlier Tasmanian study. A replicated potted plant experiment was conducted to assess whether genetic variation between gorse bushes could affect densities of S. staphylinus. There were significant differences in the number of S. staphylinus recovered from the individual bushes sampled within sites and individual bushes across all sites. This provides evidence that genetic variation between gorse bushes is at least partly responsible for the observed variability in field populations. The result validates the current release strategy used for the field establishment of S. staphylinus in south-eastern Australia. This strategy involves making multiple small releases (ca. 250 adults per bush per site) instead of a small number of large releases (ca. 1000 per bush per site), thereby reducing variation in numbers due to genetic affects. Genetic variation between individual plants of the same species and associated effects on herbivore densities should be considered when devising release strategies for biological control agents.     

Insect natural enemies of coffee green scales [Hemiptera: Coccidae] in Kenya and their potential for biological control ofCoccus celatus andC. viridis in Papua New Guinea

Coffee green scales,Coccus celatus De Lotto andC. viridis (Green), are major pests of coffee in Papua New Guinea (PNG). Surveys for insect natural enemies of coffee green scales were conducted in Kenya to find species suitable for introduction to PNG. Natural enemy communities in Kenya were found to be diverse, particularly those located in the central highlands where 3 primary parasitoids,Metaphycus stanleyi Compere,M. baruensis Noyes andDiversinervus stramineus Compere (Encyrtidae), were dominant onC. celatus andC. alpinus De Lotto. It is suggested that these 3 parasitoids may be potential biological control agents forC. celatus. Several insect predators were found associated withC. celatus in the central highlands but most were only common in ant-free scale populations. An aphelinid primary parasitoid,Coccophagus rusti Compere, was the only natural enemy ofC. viridis located. This species, however, could be of potential as a biological control agent, especially in view of its previous use in biological control against soft scales.      

我国入侵植物多样性的区域分异及其影响因素——以74个地区数据为基础

以我国74个地理单位282种外来入侵植物的分布和环境数据为基础,应用除趋势对应分析、典范对应分析和回归分析方法,探讨了我国境内入侵植物区系组成、地理分布格局及其影响因素。主要结果如下:(1)我国74个地区共有282种外来入侵种,出现频率相对较高的外来入侵种是小飞蓬(Conyza canadensis)、刺苋(Amaranthus spinosus)、一年蓬(Erigeron annuus)、空心莲子草(Alternathera philoxeroides)、土荆芥(Chenopodium ambrosioides)、圆叶牵牛(Pharbitis purpurea)、曼陀罗(Datura stramonium)、皱果苋(Amaranthus viridis)、裂叶牵牛(Pharbitis nil)、反枝苋(Amaranthus retroflexus)、三叶鬼针草(Bidens pilosa)、凤眼莲(Eichhornia crassipes)等;(2)菊科(Compositae,67,种数)、禾本科(Gramineae,32)、豆科(Leguminosae,29)、苋科(Amaranthaceae,23)、旋花科(Convolvulaceae,13)是我国境内含入侵种最丰富的5个科,共计有164种,占我国入侵植物总数的58.16%;(3)我国外来入侵植物主要源自于热带美洲、北美洲、欧洲、地中海-西亚和中亚、非洲和南亚;(4)外来入侵植物多样性在我国的区域分异明显,热带-南亚热带、中(北)亚热带和温带三大区域的入侵种组成有较大差异:马缨丹(Lantana camara)、含羞草(Mimosapudica)、胜红蓟(Ageratum conyzoides)、刺苋、小飞蓬、飞扬草(Euphorbia hirta)、五爪金龙(Ipomoea cairica)、空心莲子草、三叶鬼针草和金腰箭(Synedrella nodiflora)是热带-南亚热带区域中出现频率最高的前10种入侵植物;中亚热带和北亚热带区域出现频率最高的入侵种分别是一年蓬、小飞蓬、刺苋、土荆芥、北美独行菜(Lepidium virginicum)、美洲商陆(Phytolacca americana)、牛筋草(Eleusine indica)、紫茉莉(Mirabilis jalapa)、空心莲子草和三叶鬼针草;温带区域出现频率最高的是反枝苋、小飞蓬、圆叶牵牛、一年蓬、野西瓜苗(Hibiscus trionum)、杂配藜(Chenopodium hybridum)、苦苣菜(Sonchus oleraceus)、野燕麦(Avena fatua)、曼陀罗和皱果苋;(5)年降雨量、年均温度、年极端低温、无霜期和年均积温是影响我国外来入侵种空间分布格局的主要气象因素,年极端高温和年日照时数的影响相对较小;人口密度和交通密度对入侵种的地理分布也均有很大的影响;(6)随着年均温度、无霜期、人口密度、交通密度、年极端低温、年均降雨量和年积温的增加,外来入侵植物的种数呈线性增加,随着纬度的增加,种数则呈线性递减,种数与这8个环境因素间的关系达到极显著的水平;(7)不同地理来源的外来入侵种在我国的分布主要受纬度、年降雨量、年均无霜期、年均温度、交通密度、年极端低温和年均积温的影响。由于外来入侵种在我国分布呈现明显的区域分化,因此,应用建立具有区域特点的外来植物入侵风险评估系统。     

First record of a specialist folivore of Chromolaena odorata (Asteraceae) in Togo,and indices of its range expansion in Nigeria: implications for biological control

Pareuchaetes pseudoinsulata is reported for the first time in Togo and widespread in south-western Nigeria, albeit in low densities and difficult to detect. Country-wide surveys are warranted in both countries, with the intention of renewing efforts in the biological control of Chromolaena odorata in western Africa, where the socio-ecological impact of the weed is significant.     

Biology of Platycephala planifrons (Diptera: Chloropidae) and its potential effectiveness as biological control agent for invasive Phragmites australis in North America

Phragmites australis is a cosmopolitan clonal grass valued for its support of diversity-rich communities in its native range and feared for its devastating effects on native diversity where the species is introduced. Lack of successful control in North America resulted in the initiation of a biological control program. We used a combination of field surveys and common garden experiments in Europe to study life history and ecology of a chloropid fly, Platycephala planifrons, to assess its potential as a biological control agent. The fly is widely distributed (in non-flooded sites) throughout Eurasia but attack rates are generally low (mean 5–10%; max. 29%). Adults emerge in late June and may live for several months. Females lay eggs at the base of Ph. australis shoots. First instar larvae of this stem-feeding fly overwinter in dormant below-ground shoots of Ph. australis and rapidly complete development in early spring. Larval feeding destroys the growing meristem of the shoot causing premature wilting and 60–70% reductions in shoot biomass production. Early season attack and considerable impact suggest that Pl. planifrons could be a potent biocontrol agent, if it can escape suppression by natural enemies in the introduced range. However, the generally low attack rates in its native range and its dependence on dry sites appear to make the species a “second-choice” candidate for potential release in North America.     

The taxonomic status of Larinus cynarae F. and Larinus latus Herbst (coleoptera: Curculionidae), and its implications for the biological control of Onopordum (asteraceae: Cardueae) in Australia

Analyses were made of the allozyme frequencies of sympatric populations of the capitulum weevils L. latus Herbst and Larinus cyarae F. in Greece. It was found that the two taxa are genetically isolated and that they can therefore be considered as separate species. This complemented ecological data showing separation of the L. latus and L. cynarae populations by their choice of Onopordum illyricum L. and Cynara cardunculus, respectively, as hosts. Onopordum spp. are serious weed problems in Australia while Cynara contains several crop plants. L. latus is a potential biological control agent of Onopordum spp., but its use had been compromised by the uncertainty of the taxonomic distinctness from L. cynarae, biotypes of which are pests of artichoke Cynara scolymus L. Clarification of its taxonomic status lifts these reservations and clears the way for the introduction of L. latus into Australia for the biological control of Onopordum thistles.     

Contact networks in a wild Tasmanian devil (Sarcophilus harrisii) population: using social network analysis to reveal seasonal variability in social behaviour and its implications for transmission of devil facial tumour disease

The structure of the contact network between individuals has a profound effect on the transmission of infectious disease. Using a novel technology – proximity sensing radio collars – we described the contact network in a population of Tasmanian devils. This largest surviving marsupial carnivore is threatened by a novel infectious cancer. All devils were connected in a single giant component, which would permit disease to spread throughout the network from any single infected individual. Unlike the contact networks for many human diseases, the degree distribution was not highly aggregated. Nevertheless, the empirically derived networks differed from random networks. Contact networks differed between the mating and non-mating seasons, with more extended male–female associations in the mating season and a greater frequency of female–female associations outside the mating season. Our results suggest that there is limited potential to control the disease by targeting highly connected age or sex classes.