Dipteran predators of Simuliid blackflies: a worldwide review

Haematophagous female blackflies (Diptera: Simuliidae) are serious biting pests and obligate vectors of vertebrate pathogens, namely filarial Dirofilaria, Mansonella, Onchocerca and protozoal Leucocytozoon. Immature stages of Simuliidae inhabit lotic waterways, the sessile larvae filter-feeding and often forming a large proportion of the benthic biomass, usually aggregated in well-oxygenated sections of streams, rivers, waterfalls and spillways. Simuliid control practices depend on larvicidal chemicals, biological products (bacteria, nematodes) and environmental modification. The potential use of predators for biological control of Simuliidae has not been exploited. Predators of Simuliidae include examples of at least 12 families of Diptera and other predaceous arthropods (Crustacea and insects: Coleoptera, Odonata, Plecoptera, Trichoptera), invertebrates (notably Turbellaria), as well as browsing fish. Diptera impacting upon simuliid populations comprise mainly Chironomidae, Empididae and Muscidae, although several other families (Asilidae, Dolichopodidae, Phoridae, Drosophilidae, Scathophagidae) play a significant role as predators. Details of predator and prey species and life stages are presented, by zoogeographical region, including the prevalence of cannibalism among Simuliidae.     

Essential oil composition in leaves of carrot varieties and preference of specialist and generalist sucking insect herbivores

• 1 The carrot psyllid Trioza apicalis and Lygus rugulipennis can cause serious damage to cultivated carrots, especially at the seedling stage. The essential oil composition in leaves of several carrot varieties was studied in relation to oviposition acceptance by sucking insect herbivores that have different feeding strategies. Of the insect species studied, T. apicalis is a carrot specialist, T. anthrisci is an Apiaceae specialist, and L. rugulipennis is a generalist.
• 2 The oil composition differed significantly between leaves from different carrot varieties (Flakkeer 2, Nantura, Parano, Napoli, Panther, Splendid, Nantes 3 Express).
• 3 There were no differences in the mean numbers of eggs laid by T. apicalis or T. anthrisci on different varieties, but L. rugulipennis laid fewer eggs on the Panther variety than on Nantes 3 Express.
• 4 There was a negative linear correlation between limonene concentration and number of eggs laid by T. apicalis, confirming that limonene is a repellent to the carrot psyllid. Results suggest that only particular compounds influence the preference of the carrot psyllid, and these compounds may not be the main components in the essential oil of carrots.
• 5 A positive correlation was found between myrcene concentration and number of eggs laid by T. anthrisci. Essential oil composition did not explain egg‐laying preference of L. rugulipennis.
• 6 The results indicate that essential oil composition of carrot varieties affects host preference of Apiaceae specialists more than that of generalists.

     

The effect of anoxic treatment on the larvae of six species of dermestids (Coleoptera)

Abstract: Based on surveys of species of museum pest insects commonly found in Finland, Norway, Denmark and Sweden, six species were selected for a study of the effect of exposure to anoxic treatment on the larval stage. An oxygen level of 0.3% (the rest, nitrogen) was applied and lethal exposure times were determined. Anthrenus museorum L. was the most susceptible species (LT₉₉ = 32.2 h), while Attagenus woodroffei Halst. & Green and Attagenus smirnovi Zhantiev (LT₉₉ = 88.1 h) were the most tolerant species. The LT₉₉ value of At. woodroffei was not calculated, as only 50% of the larvae were killed by the treatment. The results indicate that large intraspecific variation is present in these two Attagenus species. Larvae of Anthrenus verbasci (L.) (LT₉₉ = 43.9 h), Reesa vespulae (Milliron) (LT₉₉ = 53.6 h), and Trogoderma angustum (Solier) (LT₉₉ = 57.2 h) showed intermediate tolerance.     

Selection responses and quantitative-genetic analysis of preadult performance on two host plants in the bean weevil, Acanthoscelides obtectus

The infectivity and biocontrol potential of entomopathogenic nematodes against two common urban tree leaf beetles (Altica quercetorum and Agelastica alni) pupating in the soil were examined under laboratory and semi‐field conditions. In the laboratory experiments, pre‐pupae and pupae of both insect species were shown to be highly susceptible to nematode infection when challenged in soil pre‐treated with the parasites’ infective juveniles. In general, Heterorhabditis megidis was more effective than Steinernema feltiae. However, significant differences were observed between individual isolates within the latter species. Nematodes developed and reproduced in cadavers of both insect species. A semi‐field experiment studying the biocontrol potential of selected nematode strains, conducted under the canopy of urban trees, confirmed the preliminary laboratory findings and revealed that H. megidis could eliminate most of the insects pupating in the soil, when applied at a relatively low dose of 10⁵ IJs m^?2. The potential of entomopathogenic nematodes as environmentally safe, effective, and economically viable agents for the biological control of tree leaf beetles in urban green areas is discussed.     

Biological control: lessons from a study of California red scale

A 20-year study of suppression of California red scale, a world-wide pest of citrus, by the parasitoid Aphytis melinus has established that the interaction is dynamically stable and that the mechanisms leading to control and stability operate at a local scale: spatial processes are not important. Key features appear to be an invulnerable class in the pest and rapid development of the parasitoid compared with the pest, as well as the fact that the parasitoid is an in situ specialist on the pest. Although another parasitoid species and two predator species are also present, they play at most a negligible role in pest control. These features—long-term persistence, suppression by a single natural enemy, an invulnerable stage in the pest and rapid development in the natural enemy—appear to be common in other coccid pest systems. By contrast, in temporary crops where the pest and enemy populations are open (i.e., sustained over the long run mainly by immigration) and non-persistent locally, as is frequently found in aphid pests, we expect that multiple generalist enemies are required for control and, of course, that spatial processes are important. There are very few well-studied examples of such systems, but these support our expectations. In these cases, it also appears that neither rapid enemy development nor an invulnerable pest stage is important for successful control.     

PROSPECTS FOR THE CLASSICAL BIOLOGICAL CONTROL OF MAJOR INSECT PESTS AND WEEDS IN SOUTHERN CHINA

Abstract  This paper deals with the prospects for the classical biological control of major insect pests and weeds in southern China. One hundred and seventy-four species of insect pests in southern China are nominated and their broad distribution and origin or possibly origin in other countries are discussed. An attempt is made to draw together information relevant to where a search might be made for natural enemies if an arthropod pest is being considered as the target for classical biological control. The success of classical biological control of the six insect pests and five weeds elsewhere in the world has been indicated. It is recommended to take urgent measures to strengthen and expand projects in classical biological control in China.     

应用“海燕”超轻型飞机防治森林害虫的效果及经济效益的评估

本文研究报道了“海燕”超轻型飞机同其它防治法防治森林害虫的防治教果、每公顷平均防治成本及投入产出比。结果表明,“海燕”超轻型飞机治虫具防治投入低、防治效果稳定良好等优点,有较高的防治实用价值,经济效益显著,是一种合理,经济、有效同时易被基层单位接受的防治手段。     

Wading bird use of established and newly created reactor cooling reservoirs at the Savannah River Site,near Aiken,South Carolina,USA

We compared wading bird use of a newly created 405-ha reactor cooling reservoir (L-Lake) at the Savannah River Site, near Aiken, South Carolina, with that of two similar > 25-year-old reservoirs (1130-ha Par Pond and 87-ha Pond B) at the same site. L-Lake was constructed in 1984–1985 and filled in late 1985. Approximately 25% of the shoreline of L-Lake was planted with lacustrine vegetation in early 1987 in an attempt to speed the establishment of a self-sustaining balanced biological community (BBC) at the reservoir. Even so, during the course of our studies, L-Lake had considerably less wetland vegetation, especially floating-leaved species such as yellow nelumbo (Nelumbo lutea), than did either of the two older reservoirs.Sixty-three surveys of the avian communities using the three reservoirs were conducted between fall of 1987 and summer of 1989. These surveys indicated that (1) at least seven species of wading birds (order: Ciconiiformes) used L-Lake, (2) wading bird density was higher at L-Lake than at the other two reservoirs, (3) wading birds represented a higher proportion of the total avian community at L-Lake than at the other two, older reservoirs, and (4) wading birds at L-Lake used planted portions of the shoreline more than unplanted portions. We suggest that the inter-reservoir differences we observed represent a trophic upsurge (sensu O'Brien, 1990) resulting from the increased availability of fishes at L-Lake compared with the two older reservoirs.Work was performed at the University of Georgia's Savannah River Ecology Laboratory, Aiken, South Carolina 29802.     

Uscana lariophaga, egg parasitoid of bruchid beetle storage pests of cowpea in West Africa: the effect of temperature and humidity

The stored-product bruchid pests,Callosobruchus maculatus (Fabricius) andBruchidius atrolineatus (Pic) cause considerable production losses in cowpea in West Africa.Uscana lariophage Steffan parasitizes the eggs of the bruchids both in the field and in storage. As chemical control of bruchids in traditional granaries is not appropriate for poor farmers, enhancement of the efficacy of the parasitoid by environmental manipulation has been investigated. The effect of temperature on the capacity ofU. lariophaga to parasitize eggs has been studied at eleven constant and three fluctuating temperatures within the range 10 to 45°C. Longevity of the female wasp decreased with increasing temperature. The rate of development increased linearly at temperatures from 17.5 to 35°C, but decreased from 35 to 40°C. Mortality of the developing wasp remained below 20% from 20 to 37.5°C, but outside this range, mortality reached 100% at 15 at 42.5°C. Most parasitization occurred at temperatures of 25 and 30°C. Sex ratio (percentage females) increased with temperature in the high temperature range. The intrinsic rate of increase (r_m) forU. lariophaga was highest in the temperature range from 30 to 37.5°C and was higher than that ofC. maculatus at all temperatures. While the r_m value ofC. maculatus did not vary much at temperatures from 25 to 35°C, the r_m value of the wasp doubled. Relative humidity did not effect longevity, egg-laying capacity, mortality, development time and sex ratio of the wasps withC. maculatus as host. However, withB. atrolineatus as the host, development time and mortality increased at lower relative humidity levels. The results indicate that temperature is the major regulating factor on the parasitoid. As the type of storage structure and its location (sun or shade) affects the temperature inside the store, ways are being investigated of manipulating the storage environment through temperature regulation to increase the impact of the parasitoid.     

Analysis of importations for biological control of insect pests and weeds in New Zealand

Importations of biological control agents for insect pests and weeds in New Zealand are summarized and factors contributing to the relative success of the programmes are examined. The establishment rate of 30.9% is similar to that achieved worldwide, but is significantly lower than the rate achieved in the island habitat of Hawaii. The pioneering role of New Zealand in biological control is shown by the high proportion of programmes first attempted in this country. Although this novelty has not reduced the establishment rate, introductions against endemic species have not succeeded. Size of release was not a dominant feature in the establishment of agents. Complete or substantial success is recorded for 17 of the 70 target pests, with a relatively high success rate in forestry programmes. Examples of the influence of climate matching and competitive exclusion are also discussed. Changing practices and attitudes to the introduction of biological control agents are documented to show the increasing emphasis on specialists. No adverse effects of introductions are reported. The challenge to practitioners and regulators is to develop systems to evaluate conflicts of interest and develop workable mechanisms to determine which biological control agents are suitable for release.