Do root-emitted volatile organic compounds attract wireworms?

in Communications in Agricultural and Applied Biological Sciences (in press)

Wireworms are the soil dwelling larvae of click beetles (Coleoptera: Elateridae). Their importance as crop pests increases since the efficient chemical means to control them cannot be considered anymore ... [more ▼]

Wireworms are the soil dwelling larvae of click beetles (Coleoptera: Elateridae). Their importance as crop pests increases since the efficient chemical means to control them cannot be considered anymore. Therefore, many integrated pest management strategies have been investigated in the past few years. Most of them rely on the understanding of the ecology of the click beetles during their whole life cycle. We focus our work on the chemical ecology of wireworms, more precisely on the root-emitted volatile organic compounds (VOCs) that might intervene in the food-searching process of the larvae by helping them to find a suitable host-plant or by acting as key factors in the belowground defence mechanism of the plant. Here, we present our first results of dual-choice orientation tests in olfactometric pipes. Wireworms (Agriotes sordidus Illiger) were submitted individually to a variety of olfactory baits ranging from entire barley roots (Hordeum vulgare L. var. Quench) to isolated VOCs identified as part of the emitting profile. The latter was described thanks to HS-SPME samplings and GC-MS analysis, for roots grown in the exact same conditions as for the olfactometric experimentations with entire roots. Most of the experimentations gave significant results. When confronted to volatiles emitted by entire roots, wireworms significantly orientated towards the bait (χ²-goodness-of-fit test, χ²=8, P-value=0.005). This result allowed us to follow up with the same device and to progressively vary the nature of the baits. Our protocol should be used for other plant-wireworm species combinations. Our results should be taken into account in varietal selection, in crop rotation, or in trapping systems aiming at the reduction of the populations of wireworms. [less ▲]

Depths and type of substrate influence the ability of Nasonia vitripennis Walker (Hymenoptera: Pteromalidae) to encounter host

in Journal of Insect Science [=JIS] (in press)

The foraging behaviour of a parasitoid insect species includes the host’s habitat and subsequent location of the host. Habitats-substrate, substrate moisture and light levels can affect the host location ... [more ▼]

The foraging behaviour of a parasitoid insect species includes the host’s habitat and subsequent location of the host. Habitats-substrate, substrate moisture and light levels can affect the host location made by different species of parasitoids. However, the depth at which parasitoids concentrate their search effort is an another important ecological characteristic and play an important role on the host location. Here, we have investigated the ability of a pupal parasitoid, Nasonia vitripennis Walker, to penetrate and kill fly pupae located at different depth of the substrate. Three different types of substrate were tested: loam soil, compost and vermiculite substrate. In both loam soil and compost, all of the parasitism activity was restricted to pupae placed directly on the surface. Parasitism activity in vermiculite showed that the average number of pupae parasitized was decreased with depth. These results suggest that fly pupae situated deeper in the substrate are less subjected to parasitism by N. vitripennis. [less ▲]

Diversity of forensic rove beetles (Coleoptera, Staphylinidae) associated with decaying pig carcass in a forest biotope

in Journal of Forensic Sciences (2013)

Most forensic studies are focused on Diptera pattern colonization while neglecting Coleoptera succession. So far, little information is available on the postmortem colonization by beetles and the ... [more ▼]

Most forensic studies are focused on Diptera pattern colonization while neglecting Coleoptera succession. So far, little information is available on the postmortem colonization by beetles and the decomposition process they initiate under temperate biogeoclimatic countries. These beetles have however been referred to as being part of the entomofaunal colonization of a dead body. Forensic entomologists need increased databases detailing the distribution, ecology and phenology of necrophagous insects, including staphylinids (Coleoptera, Staphylinidae). While pig carcasses are commonly used in forensic entomology studies to surrogate human decomposition and to investigate the entomofaunal succession, very few works have been conducted in Europe on large carcasses. Our work reports the monitoring of the presence of adult rove beetles (Coleoptera, Staphylinidae) on decaying pig carcasses in a forest biotope during four seasons (spring, summer, fall and winter). A total of 23 genera comprising 60 species of rove beetles were collected from pig carcasses. [less ▲]

Electrophysiological and behavioural responses of Thanatophilus sinuatus F. (Coleoptera: Silphidae) to selected cadaveric volatile organic compounds

in Journal of Forensic Sciences (2013)

Soon after death, carcasses release volatile chemicals that attract carrion insects including Silphidae. Nevertheless, it is not known which chemical cues are involved in the attractiveness of the carcass ... [more ▼]

Soon after death, carcasses release volatile chemicals that attract carrion insects including Silphidae. Nevertheless, it is not known which chemical cues are involved in the attractiveness of the carcass. So far, little information is available on the chemical ecology of carrion beetles, particularly concerning the subfamily of Silphinae. The biological role of selected cadaveric volatile organic compounds including: dimethyldisulfide (DMDS), butan-1-ol, n-butanoic acid, indole, phenol, p-cresol, putrescine, and cadaverine on the silphine species, Thanatophilus sinuatus Fabricius, was investigated by using both electrophysiological and behavioural techniques. Among the tested cadaveric compounds, butan-1-ol and DMDS elicited the strongest EAG from both T. sinuatus male and female antennae. In a two-arm olfactometer, males and females were significantly attracted to dimethyldisulfide (DMDS) for both tested doses, whereas only males were attracted to p-cresol at 100 ng. Putrescine was repellent to males at the dose of 1 µg [less ▲]

Substrate Marking by an Invasive Ladybeetle: Seasonal Changes in Hydrocarbon Composition and Behavioral Responses

in PLoS ONE (2013), 8(4),

The multicolored Asian ladybeetle, Harmonia axyridis (Pallas), aggregates inside dwellings during the winter to survive the cold. Recent published reports have highlighted that overwintering individuals ... [more ▼]

The multicolored Asian ladybeetle, Harmonia axyridis (Pallas), aggregates inside dwellings during the winter to survive the cold. Recent published reports have highlighted that overwintering individuals use hydrocarbon markings deposited on surfaces by conspecifics to orient toward aggregation sites. In the current study, monthly GC-MS analyses revealed seasonal modifications in the chemical profile of substrate markings deposited by moving individuals. The markings of overwintering ladybeetles contained larger proportions of heptacosadiene, nonacosadiene, hentriacontadienes, and methyl-nonacosanes, along with a lower proportion of heptacosene and nonacosene. This finding suggests the importance of the unsaturated and/or branched hydrocarbons in the H. axyridis aggregation process. Subsequently, we conducted behavioral assays to test whether (1) there is seasonal variation in the behavioral response of H. axyridis individuals toward substrate markings deposited by conspecifics in the same physiological state and (2) the observed behavioral modification is due to a change in ladybeetle sensitivity and/or a change in the chemical composition of the substrate marking. The results indicate that overwintering individuals exhibit a stronger ‘‘following’’ response toward conspecific substrate markings. This behavior is linked to both the physiological state of ladybeetles and the specific chemical profile of the marking biomolecules deposited under overwintering conditions. [less ▲]

Consumption of Immature Stages of Colorado Potato Beetle by Chrysoperla Carnea (Neuroptera: Chrysopidae) Larvae in the Laboratory

in American Journal of Potato Research (2013), 90(1), 51-57

The Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), has been an important defoliator of potatoes for 150 years. Although the use of insecticides allowed drastic reductions of CPB ... [more ▼]

The Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), has been an important defoliator of potatoes for 150 years. Although the use of insecticides allowed drastic reductions of CPB populations, resistance development against active substances has been observed. In this context, biological control using predatory larvae of the lacewing may represent a good alternative. CPB egg and larval consumption rates have been evaluated for all Chrysoperla carnea (Stephens) instars for 24 h. While first and second C. carnea instars only consumed eggs (1.3 and 1.8), first (1.5 and 2.4) and second (0.6 and 0.8) CPB instars, third instar of lacewing consumed all CPB immature stages: 6.8 CPB eggs, 8.5 first, 4 s, 0.5 third and 0.1 fourth CPB instars. This third instar killed 4-fold more CPB larvae than other larval stages. Handling time for third instar lacewing has been evaluated at 52 min on first instar CPB, 102 min on second instar and 164 min on third instar. Our laboratory assays highlight a potential for lacewing larvae to control CPB immature stages with a greater efficiency on young CPB larval stages. Fields assays are however needed to confirm efficiency of this CPB natural enemy under field conditions. [less ▲]

Wireworms’ Management: An Overview of the Existing Methods, with Particular Regards to Agriotes spp. (Coleoptera: Elateridae)

in Insects (2013), 4(1), 117-152

Wireworms (Coleoptera: Elateridae) are important soil dwelling pests worldwide causing yield losses in many crops. The progressive restrictions in the matter of efficient synthetic chemicals for health ... [more ▼]

Wireworms (Coleoptera: Elateridae) are important soil dwelling pests worldwide causing yield losses in many crops. The progressive restrictions in the matter of efficient synthetic chemicals for health and environmental care brought out the need for alternative management techniques. This paper summarizes the main potential tools that have been studied up to now and that could be applied together in integrated pest management systems and suggests guidelines for future research. [less ▲]

Influence de la plante hôte sur les stades de développement de Borocera cajani (Lepidoptera: Lasiocampidae)

in Entomologie Faunistique = Faunistic Entomology (2013), 66

Borocera cajani Vinson (Lepidoptera: Lasiocampidae) is a silk moth endemic to Madagascar that is currently used to produce silk textiles. This silk moth is polyphagous and colonizes forests situated in ... [more ▼]

Borocera cajani Vinson (Lepidoptera: Lasiocampidae) is a silk moth endemic to Madagascar that is currently used to produce silk textiles. This silk moth is polyphagous and colonizes forests situated in the central highlands, mainly constituted by Tapia trees (Uapaca bojeri). Two host plants are commonly used by the caterpillar of this moth species: Tapia and Voafotsy (Aphloia theiformis). In this work we have evaluated parameters of different stage (survival rate, development duration, weight and size, fecundity…) of B. cajani on both host plants. We have observed a 30% higher survival rate on U. bojeri. Larval and pupae duration were shorter on U. bojeri (64,8 ± 1,5 days) than on A. theiformis (87,4 ± 2,0 days). Cocoons were bigger when obtained from larvae fed on U. bojeri. This plant is therefore better for the development of B. cajani and should be used in intensive rearing of this silk moth. [less ▲]

Comparative analyses of salivary proteins from three aphid species

in Insect Molecular Biology (2013), Accepted pending revision

Silkworm moths inventory in their natural tapia forest habitat (Madagascar): diversity, population dynamics and host plants

in African Entomology (2013), 21(1), 137-150

Endemic silk moths (Lepidoptera: Lasiocampidae) in Madagascar have been collected and exploited for centuries by local populations either for food or as a source of silk cocoons from which textiles are ... [more ▼]

Endemic silk moths (Lepidoptera: Lasiocampidae) in Madagascar have been collected and exploited for centuries by local populations either for food or as a source of silk cocoons from which textiles are made. Moth natural forest habitat has also been degraded, leading to a drastic decrease in silk moth populations. However, very few scientific reports highlighted these observations well known by the local people.We have inventoried silk moths species in tapia (Uapaca bojeri Baill.) forests located in the central highlands of Madagascar. Inventories have been conducted during one year from August 2009 to July 2010 by sampling transects in Imamo forests. Three species of Lasiocampidae belonging to two genera were found: Borocera cajani Vinson, Borocera marginepunctata Guérin-Méneville and Europtera punctillata Guenée. These three silk moth species are endemic to Madagascar but only one (B. cajani) is commercially exploited in the silk industry. The habitat, host plants, abundance, life cycle and feeding behaviour of these species in their natural habitat are described. [less ▲]