Ecology of the entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae in temperate agroecosystems: Potential for conservation biological control

Greenhouses, plants and mites introduction to acari methods and techniques spider mites false spider mites tarsonemid mites eriophyoid mites acarid mites.

Mites of Greenhouses: Identification, Biology and Control

The currently recognized robust support for the monophyly of the Lepidoptera (and the superorder Amphiesmenoptera comprising Lepidoptera + Trichoptera) is outlined, and the phylogeny of the principal lineages within the order is reviewed succinctly. The state of the taxonomic inventory of Lepidoptera is discussed separately for ‘micro-moths’, ‘macro-moths’ and butterflies, three assemblages on which work has followed historically somewhat different paths. While currently there are about 160,000 described species of Lepidoptera, the total number of extant species is estimated to be around half a million. On average, just over one thousand new species of Lepidoptera have been described annually in recent years. Allowing for the new synonyms simultaneously established, the net increase in species numbers still exceeds 800/year. Most of the additions are foreseeable in the micro-moth grade, but even for butterflies ca 100 species are added annually. Examples of particularly interesting new high-rank taxa that have been described (or whose significance has become realized) since the middle of the 20th century include the non-glossatan lineages represented by Agathiphaga and Heterobathmia and the heteroneuran families Andesianidae, Palaephatidae, Hedylidae and Micronoctuidae. Some thoughts on how present and future systematic lepidopterology might be prioritised are presented.

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Lepidoptera phylogeny and systematics: the state of inventorying moth and butterfly diversity

Moths have evolved highly successful mating systems, relying on species-specific mixtures of sex pheromone components for long-distance mate communication. Acyl-CoA desaturases are key enzymes in the biosynthesis of these compounds and to a large extent they account for the great diversity of pheromone structures in Lepidoptera. A novel desaturase gene subfamily that displays Δ11 catalytic activities has been highlighted to account for most of the unique pheromone signatures of the taxonomically advanced ditrysian species. To assess the mechanisms driving pheromone evolution, information is needed about the signalling machinery of primitive moths. The currant shoot borer, Lampronia capitella, is the sole reported primitive non-ditrysian moth known to use unsaturated fatty-acid derivatives as sex-pheromone. By combining biochemical and molecular approaches we elucidated the biosynthesis paths of its main pheromone component, the (Z,Z)-9,11-tetradecadien-1-ol and bring new insights into the time point of the recruitment of the key Δ11-desaturase gene subfamily in moth pheromone biosynthesis. The reconstructed evolutionary tree of desaturases evidenced two ditrysian-specific lineages (the Δ11 and Δ9 (18C>16C)) to have orthologs in the primitive moth L. capitella despite being absent in Diptera and other insect genomes. Four acyl-CoA desaturase cDNAs were isolated from the pheromone gland, three of which are related to Δ9-desaturases whereas the fourth cDNA clusters with Δ11-desaturases. We demonstrated that this transcript (Lca-KPVQ) exclusively accounts for both steps of desaturation involved in pheromone biosynthesis. This enzyme possesses a Z11-desaturase activity that allows transforming the palmitate precursor (C16:0) into (Z)-11-hexadecenoic acid and the (Z)-9-tetradecenoic acid into the conjugated intermediate (Z,Z)-9,11-tetradecadienoic acid. The involvement of a single Z11-desaturase in pheromone biosynthesis of a non-ditrysian moth species, supports that the duplication event leading to the origin of the Lepidoptera-specific Δ11-desaturase gene subfamily took place before radiation of ditrysian moths and their divergence from other heteroneuran lineages. Our findings uncover that this novel class of enzymes affords complex combinations of unique unsaturated fatty acyl-moieties of variable chain-lengths, regio- and stereo-specificities since early in moth history and contributes a notable innovation in the early evolution of moth-pheromones.

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Key biosynthetic gene subfamily recruited for pheromone production prior to the extensive radiation of Lepidoptera.

Invasive species pose a serious threat to native plant communities and are an important contributor to loss of biodiversity. In the case of Phalaris arundinacea, L. (Poaceae), reed canary grass, a cool-season, long-lived perennial plant native to Eurasia and North America, nonnative agronomically important genotypes were introduced to North America for numerous uses such as forage and soil stabilization. Following repeated introductions, reed canary grass became an aggressive invader that takes over natural wet prairies, stream-banks and wetlands. Reed canary grass can outcompete native plant species, resulting in monospecific stands with concomitant loss of plant and insect diversity and ultimately to alteration in ecosystem function. Abiotic factors such as disturbance, changes in hydrological regime, and particularly nutrient runoff to wetlands can enhance reed canary grass establishment and vegetative spread. In addition, the species' capacity for early season growth, rapid vegetative spread, high ste...

Reed Canary Grass (Phalaris arundinacea) as a Biological Model in the Study of Plant Invasions

For phytophagous insect species in regions with a variable climate, there is an inherent risk in having all progeny in one peak following the winter, during the critical period of adult development, emergence, and reproduction (Walbauer, 1978; Goulson, 1993). Temperate zone insects have developed a great diversity of phenological strategies to enhance survival under conditions of frequent annual variation in environmental conditions. One such strategy is polymodal emergence. According to published records, polymodal emergence has been observed in only three insect orders: Hymenoptera, Diptera, and Lepidoptera (Biron et al., 2002). One such species, the cabbage root fly, Delia radicum (L.) (Diptera: Anthomyiidae), has been studied intensively. The postdiapause bimodal emergence pattern of D. radicum adults was first noted by Finch & Collier (1983) who later defined the two phenotypes as follows: after diapause, the adult flies of the early emerging phenotype emerge in less than 20 days at 19 ± 1 ° C (320 ° d 4 ) while adults of the late emerging phenotype emerge after more than 30 days at 19 ± 1 ° C (320 ° d 4 + 280 ° d 7 ) (Collier et al., 1989a,b). At first it was assumed that diapause was necessary for the expression of the polymodal emergence, but this phenological strategy has been found in both diapausing and non-diapausing D. radicum pupae (Biron et al., 1998). The turnip root fly, Delia floralis (Fallén) (Diptera: Anthomyiidae), occurs sympatrically with D. radicum in northern parts of the holarctic region. The two species have a similar biology and host range, but D. floralis is mostly confined to sandy soils (Jørgensen, 1957, 1976). They also differ phenologically and in the number of generations per year: D. floralis generally has a single generation (but see Jørgensen, 1976) while D. radicum in most areas has more than one generation, with adults of the first generation emerging earlier than those of D. floralis . In the current study our main objective was to investigate, under controlled conditions, the patterns of emergence for two diapausing field populations of D. floralis from Sweden and Finland. Secondly, we investigated whether early and late emerging phenotypes are expressed in pupae in continuous development without diapause. Thirdly, we segregated and reared early and late emerging phenotypes without diapause from both the Swedish and the Finnish populations to assess changes in phenotype frequency over two generations.

Expression of a bimodal emergence pattern in diapausing and non‐diapausing Delia floralis: a phenological survival strategy

Under an artificial light:dark cycle, females of Lampronia capitella were observed calling, with extended terminal abdominal segments, during the first 2 hr of the photoperiod. Extracts of terminal abdominal segments from females elicited large electroantennographic responses from male antennae. Gas chromatography with electroantennographicDetection revealed three active peaks. Based on comparison of retention times and mass spectra of synthetic standards, these compounds were identified as (Z,Z)-9,11-tetradecadienol and the corresponding acetate and aldehyde. The electroantennographic activity of the four geometric isomers of all three compounds was investigated, and the respective (Z,Z)-isomer was found to be the most active in all cases. Aldehydes generally elicited larger antennal responses than alcohols, whereas acetates were the least active compounds. A subtractive trapping assay in the field, based on a 13:26:100 μg mixture of (Z,Z)-9,11-tetradecadienal, (Z,Z)-9,11-tetradecadienyl acetate, and (Z,Z)-9,11-tetradecadienol confirmed that all three compounds are pheromone components. Subtraction of (Z,Z)-9,11-tetradec- adienol from the blend completely eliminated its attractiveness, whereas the other two-component blends showed reduced activity. This is the first pheromone identification from the monotrysian superfamily Incurvarioidea, confirming that the common pheromones among ditrysian moths (long-chain fatty acidDerivatives comprising alcohols, acetates, and aldehydes with one or more double bonds) is not an autapomorphy of Ditrysia, but a synapomorphy of the more advanced heteroneuran lineages.

Identification of the Sex Pheromone of the Currant Shoot Borer Lampronia capitella

The effects of mulching with organic materials on yield and damage by brassica root maggots (Delia floralis and D. radicum) in cauliflower, were studied in field experiments for 3 years. Mulching with grass‐clippings consistently resulted in increased yield and reduced damage by root maggots, as measured by wilting symptoms and root damage. During one of these years, the effects of mulching with grass‐clippings on root fly population dynamics was also studied. Mulching did not reduce egg‐laying but resulted in increased egg‐predation. The number of D. floralis pupae per plant was not reduced by mulching, probably because of higher larval mortality owing to competition in unmulched plots. Mulching decreased the rate of parasitization by Aleochara bilineata (Staphylinidae), resulting in a higher number of healthy pupae per plant in grass‐mulched plots, and these healthy pupae were heavier. All these effects were most pronounced when the mulch material completely covered the ground, even close to th...

Mulching with grass-clippings in cauliflower: effects on yield and brassica root flies (Delia spp.).

Lygus spp. (tarnished plant bugs) are generalist herbivores and occur as pests on a wide range of crops. In the development of conservation biological control strategies for Lygus spp. in Sweden, more information is needed on the impact of different natural enemies. In this study, we determined the occurrence and the degree of parasitism on adults and nymphs of the most common Lygus species in alfalfa, barley, red clover and oilseed rape in Uppsala in Central Sweden and in Umea in Northern Sweden. Nymphs and adults of Lygus spp. were collected by sweep netting for estimation of their parasitism level (by dissection) and identification of parasitoid species (from reared Lygus specimens). The dominant Lygus species in both locations was L. rugulipennis (75–99%). Parasitism by Phasia obesa (Tachnidae) on overwintering Lygus adults was recorded in almost every field sampled at both locations. The parasitism level was low at overwintering sites but increased in arable fields during summer. Lygus nymph...

A survey of Lygus parasitoids in Sweden.

Variation in damage levels on certain black currant, Ribes nigrum L., genotypes, caused by the black currant leaf midge, Dasineura tetensi (Rubs.) (Diptera: Cecidomyiidae), has been observed in northern Sweden. I investigated whether this variation is due to variation in virulence among midges. From a field population of midges, I successfully selected for virulence and avirulence, respectively, on the resistant black currant genotype cultivar ‘Storklas’ (called resistant genotype). The performance of avirulent and virulent midge larvae on two black currant genotypes were studied in experiments where first or second instar larvae were artificially transferred. There were no differences in larval survival and developmental rate between the two midge types when transferred to the susceptible currant genotype ‘7801–31’ (called susceptible genotype). Larvae of the virulent strain established galls and developed on ‘Storklas’ but development was initially slower there than on the susceptible currant genotype. Larvae of the avirulent strain suffered high mortality or remained in first instar on that same currant genotype when transferred alone, but developed readily if transferred together with virulent larvae. Larvae transferred in second instar to host plants susceptible to the larvae resumed feeding and developed further to maturity. Second instar larvae were also able to establish new galls even though these galls were not as well developed as those caused by first instar larvae. Black currant plantations in northern Sweden were surveyed and local midge populations were found to be composed of either avirulent, virulent or a mixture of both midge types. Virulent midges were not restricted to plantations where resistant currant genotypes were grown. I conclude that, at least, two biotypes of the midge exist, and that those two are distinguished by the ability to gall and survive on ‘Storklas’.

Sven Hellqvist

Papers

Expression of a bimodal emergence pattern in diapausing and non‐diapausing Delia floralis: a phenological survival strategy

Identification of the Sex Pheromone of the Currant Shoot Borer Lampronia capitella

Mulching with grass-clippings in cauliflower: effects on yield and brassica root flies (Delia spp.).

A survey of Lygus parasitoids in Sweden.

Biotypes of Dasineura tetensi, differing in ability to gall and develop on black currant genotypes