Identification d'insectes vecteurs "potentiels" du Cape Saint Paul Wilt sur le cocotier au Ghana par PCR

Le vecteur du phytoplasme responsable du jaunissement mortel du cocotier au Ghana est inconnu à ce jour. Il est cependant admis que les phytoplasmes sont transmis par des insectes piqueurs-suceurs, ces insectes étant supposés être les seuls à avoir la capacité d'injecter les phytoplasmes dans les tubes criblés du phloème. Bien que la présence de phytoplasmes dans un insecte ne prouve sa capacité à transmettre la maladie, nous avons testés une grande quantité d'insectes pour la présence de phytoplasmes par PCR (directPCR et NestedPCR), en utilisant des amorces spécifiques des phytoplasmes en général, et du phytoplasme responsable du jaunissement mortel du cocotier en particulier. En effet, la mise en évidence d'une ou plusieurs espèces d'insectes porteurs du phytoplasme pourrait orienter nos recherches pour les essais de transmission en cages par insectes spécifiques. (Résumé d'auteur

Field optimization of pheromone traps for monitoring and controlling cocoa mirids, Sahlbergella singularis

In Cameroon, pheromone traps appear interesting to monitor or even control Sahlbergella singularis populations on cocoa farms. The efficiency of traps baited with pheromones relies on a good knowledge of both visual and olfactory stimuli that attract cocoa mirids and on appropriate trap deployment in cocoa plantations. The aim of this preliminary study is first to compare the attractiveness of traps of different colors and baited with different pheromone blends. To achieve this purpose, we monitored a total of 90 traps of 3 different colors (30 red, 30 yellow and 30 white) and baited with 2 different pheromone blends, deployed in ten 1-ha plots (100 x 100m) PVC tubular traps were monitored from March on a weekly basis. Simultaneously, experiments in flight tunnel were conducted in the laboratory to confirm trends observed in the field. Secondly, to better understand how trap deployment influences mirid capture rate, we tested 3 trap densities in a total of twenty one 1-ha plots (100 x 100m) which received different treatments: 7 plots with a high trap density (16 traps ha-1), 7 plots with a medium trap density (9 traps ha-1) and 7 plots with a low trap density (4 traps ha-1). Traps were monitored on a weekly basis. Also, mirid populations and damage were assessed in each plot twice a year. Seven plantations with no trap were sprayed with insecticide according to spraying recommendations and were also monitored to evaluate the productivity gain or loss between the two control methods. Understanding the factors involved in oriented movements of mirids in the field, will help to formulate relevant recommendations to improve integrated management of S. singularis and potentially to reduce the economical cost of control strategies. (Résumé d'auteur

A review of the genus Alurnus Fabricius, 1775 (Coleoptera: Chrysomelidae: Cassidinae)

The species of the genus Alurnus Fabricius (Coleoptera: Chrysomelidae: Cassidinae) are reviewed. Twentythree species are recognized as valid. Alurnus bicolor from Colombia and A. crenatus from Bolivia are described as new species. Alurnus costalis dallieri Pic is elevated to full species status. Lectotypes are designated for A. humeralis Rosenberg, A. mutabilis Waterhouse, and A. salvini Baly. The species are redescribed and illustrated, and a key to the species is presented

A catalogue of West Indies Anthribidae (Coleoptera)

This is a catalogue of 23 described and 6 undescribed genera, and 48 described and 157 undescribed species of West Indian Anthribidae distributed from the Bahamas to Grenada. Each described genus has author, date, page, type species and how designated, World distribution, number of World species, and synonyms. Each described species has author, date, page, original generic name if a transfer has occurred, type locality, sex and location of type(s) if known, synonyms, and island-by-island distribution. New taxa are numbered, with data on museum location and island distribution. There are brief comments on New World distributions as they relate to the Antilles, and on missing Suffrian and Wolfrum types

Waste management in the stingless bee Melipona beecheii Bennett (Hymenoptera: Apidae)

Waste management is important in insect societies because waste can be hazardous to adults, brood and food stores. The general organization of waste management and the influence of task partitioning, division of labor and age polyethism on waste processing were studied in three colonies of the tropical American stingless bee Melipona beecheii Bennett in Yucatán, Mexico. Waste generated in the colony (feces, old brood cells, cocoons, dead adults and brood) was collected by workers throughout the nest and taken to specific waste dumps within the nest. During the day, workers based at the waste dumps formed waste pellets, which they directly transferred in 93% of cases, to other workers who subsequently removed them from the nest. This is an example of task partitioning and is hypothesized to improve nest hygiene as has been found in leafcutting ants, Atta. To investigate division of labor and age polyethism we marked a cohort of 144 emerging workers. Workers forming waste pellets were on average 31.2±6.5 days old (±SD, N= 40, range of 18-45 days). The life span of M. beecheii workers was 49.0±14.0 days (N= 144). There was no difference in the life span of workers who formed (52.2±11.6 days, N= 40) or did not form (49.9±11.5 days, N= 97) waste pellets, suggesting that waste work did not increase mortality. Although waste was probably not hazardous to adults and brood, because the dumps are located outside the brood chamber, its presence inside the nests can attract phorid flies and predators, which can harm the colony

The Sequential Relationship of Body Oscillations in the Paper Wasp, \u3ci\u3ePolistes Fuscatus\u3c/i\u3e (Hymenoptera: Vespidae)

Three kinds of body oscillations by foundresses of the paper wasp, Polistes fuscatus, were analyzed from 100 h of videotapes of 17 multiple- and 16 single-foundress, preworker colonies. The three kinds of oscillations were observed to be temporally proximate only after prey returns. Their sequential occurrence was always antennal drumming (AD), abdominal wagging (AW), and lateral vibration (LV). This sequence is consistent with the hypothesized communicative meanings of ADs, AWs, and LVs. In particular, ADs may signal larvae to withold salivary secretions prior to receiving a liquid meal from an adult female; oscillations AW and LV may signal larvae to secrete and withold saliva, respectively, Additional studies are required to provide causal evidence of the communicative meanings of ADs, AWs, and LVs

Biological control in French Guiana, Guadeloupe and Martinique

Several biological control agents have been introduced successfully in Guyana, and / or Guadeloupe and Martinique: three tachinid dipterans and one hymenopteran for control of sugarcane borers, a ladybird and a hymenopteran parasitoid against the pink hibiscus mealybug, a hymenopteran parasitoid to control Asian citrus psyllid, another hymenopteran parasitoid against citrus blackfly, and a hymenopteran parasitoid for control of fruit flies. Mass rearings of a lacewing and a Trichogramma egg parasitoid are being implemented in Martinique for augmentative biocontrol. Use of native natural enemies in conservation biocontrol projects is being initiated in several crops, after a period of intensive prospecting for natural enemies. A recently started project in French Guiana aims at control of the mango mealybug by introducing two exotic parasitoids

Oviposition behavior of Plutella xylostella onto cabbages covered with nets

Plusieurs expérimentations de terrains menées en zone tropicale en Afrique et en Asie ont montré l'efficacité des filets anti-insectes pour protéger les cultures de choux contre les Lépidoptères en particulier Plutella xylostella. La taille de maille recommandée varie de 0.8 mm à 1.2 mm selon les auteurs. Le comportement de P. xylostella a été étudié au laboratoire en présence de différents types de filets protégeant des feuilles ou des plants de choux en situation de choix et de non choix. Les résultats ont montrés que les filets de 0.85, 0.93, 1.33 et 1.80 mm de maille ont laissé passer respectivement 0%, 10%, 50% et 85% d'adultes en contact forcé. Les femelles ont toujours préfèré pondre directement sur les feuilles de choux en situation de choix mais en l'absence de choix elles ont pondu à travers le filet en contact avec une feuille. Dans le cas contraire, quand le filet n'était pas en contact avec une feuille ou un plant de choux, les femelles ont pondu sur un filet multifilament à maille complexe mais pas sur un filet monofilament. Nous avons montré également que les adultes du parasitoïde Cotesia plutellae sont passés à travers le filet de 0.93 mm. Ces résultats ont permis de mieux comprendre l'efficacité des filets anti-insectes généralement utilisés sur le terrain en situation de choix dans des dispositifs expérimentaux. Les caractéristiques des filets pour la protection des cultures de choux ont été discutés selon leur mode d'utilisation au champ et le système de culture. (Texte intégral

Mating system and population genetic structure of the bulldog ant Myrmecia pavida

Understanding the evolution of the alternative mating strategies of monandry and polyandry is a fundamental problem in evolutionary biology because of the cost-benefit trade-offs associated with mating for females. The problem is particularly intriguing in the social insects because queens in most species appear to be obligately monandrous (i.e., only a single male fathers their offspring), while those in a minority of species have evolved high, and sometimes extreme, polyandry. One group which may shed particular insight is the ant subfamily Myrmeciinae (Myrmecia and Nothomyrmecia). Here we examine the population and colony genetic structure of the bulldog ant Myrmecia pavida CLARK, 1951 by genotyping offspring workers from 45 colonies. We find little evidence of geographic structuring or inbreeding in the population, indicating that the species outbreeds, most probably in mating swarms. We also find that queens of M pavida show moderately high polyandry, with 84% having mated with between two and seven males, and an overall mean observed mating frequency of 3.8. This is significantly higher than previously reported for queens of Nothomyrmecia macrops, in which most females mate singly. This was similar to that of M pyriformis, M brevinoda, and M pilosula, the three congenerics for which mating frequencies have recently been reported. The two genera in the Myrmeciinae therefore appear to show multiple transitions in mating frequency and further investigation of the subfamily may be highly informative for disentangling the forces driving the evolution of alternative mating strategies