International journal of insect science最新文献

Recently, Taylor-Wells et al published evidence that the γ-aminobutyric acid (GABA) receptor, resistance to dieldrin (RDL), from mosquitoes undergoes RNA A-to-I editing to generate an extraordinarily large range of isoforms. This editing was found to affect GABA receptor pharmacology, as it influenced the potency of GABA and ivermectin. This highlights RNA editing as a species-specific mechanism to fine-tune receptor function as well as possibly increase tolerance of mosquitoes to certain insecticides. This commentary also considers novel findings from analysis of Rdl transcripts from individual mosquitoes taken from different geographical areas.

Alpha-amylases are major digestive enzymes that act in the first step of maltopolysaccharide digestion. In insects, these enzymes have long been studied for applied as well as purely scientific purposes. In many species, amylases are produced by multiple gene copies. Rare species are devoid of Amy gene. They are predominantly secreted in the midgut but salivary expression is also frequent, with extraoral activity. Enzymological parameters are quite variable among insects, with visible trends according to phylogeny: Coleopteran amylases have acidic optimum activity, whereas dipteran amylases have neutral preference and lepidopteran ones have clear alkaline preference. The enzyme structure shows interesting variations shaped by evolutionary convergences, such as the recurrent loss of a loop involved in substrate handling. Many works have focused on the action of plant amylase inhibitors on pest insect amylases, in the frame of crop protection by transgenesis. It appears that sensitivity or resistance to inhibitors is finely tuned and very specific and that amylases and their inhibitors have coevolved. The multicopy feature of insect amylases appears to allow tissue-specific or stage-specific regulation, but also to broaden enzymological abilities, such as pH range, and to overcome plant inhibitory defenses.

Chemical traits of Terminalia catappa L. leaves were determined on the island of Guam to understand the changes caused by beetle leaf herbivory. Green leaf chemistry indicated nitrogen was the most limiting nutrient in the climate and soils of Guam. The changes in leaf chemistry following beetle damage were extensive. Senesced leaf chemistry indicated beetle damage decreased some traits that predict lower leaf litter quality, such as lignin, but also decreased some traits that predict higher leaf litter quality, such as nitrogen. The stoichiometric traits based on carbon:macronutrient and lignin:macronutrient generally predicted higher quality leaf litter following beetle herbivory. The beetles that produce this form of T. catappa leaf damage on Guam are non-native, and overall, the results indicate these pests will increase the rate of litter decomposition and nutrient turnover in habitats where T. catappa is prevalent.

Compensational recovery from the damage created by stressors is important for all animals. However, how organisms recover from stress-induced negative impacts has been poorly understood. An 1-hour exposure to heat stress at 35°C led to reduced feeding activity of Drosophila melanogaster larvae, which caused reduction in body weight 2 hours after the stress, but not at other times. Such weight losses seem to be rescued by following enhanced feeding activities. We investigated the mechanisms underlying the accelerated feeding activity after the stress-induced reduction in feeding behavior. Our data showed increased expression of sweet taste gustatory receptor genes (Grs) and concomitant decreased expression of bitter taste Grs in the mouth parts 2 to 4 hours after the heat treatment for 1 hour. However, nontypical taste Gr expression was not changed. Furthermore, integration of both messenger RNA and protein expression analysis revealed that expression levels of tropomyosin and ATP (adenosine triphosphate) synthase β subunit were significantly increased in their mouths 3 to 5 hours after the heat stress. The increased expression of these genes would contribute to accelerated muscular movement of the mouth hooks. This study indicated that Drosophila larvae possess an efficient systemic mechanism that enables them to recover from growth delay caused by stress conditions.

Cowpea is an essential food legume in the tropics and particularly for sub-Saharan African populations. Postharvest grain storage, however, is a major constraint for crop expansion and year-round availability due to the cowpea weevil, Callosobruchus maculatus F., the main storage pest of cowpeas in West Africa. The use of chemicals for cowpea storage is a common practice which represents, however, a risk for consumers, environment, and could also exacerbate pest control. In Burkina Faso, since the early 2000s, several scientific investigations have focused on the control of C maculatus using botanicals considered as promising and safe alternatives to chemicals. The aim of this review is to take stock of the research conducted and to identify the potential candidates on which future studies in this field will focus. The set of data analyzed show that several plants materials, including powders, crushed plants and essential oils (EO), were active against eggs, larvae, and adults of C maculatus, through dose-dependent mortality responses. However, EO extracted from native aromatic plants have yielded the most promising results, specifically EO from Ocimum canum appeared as the best candidate control agent. Other potentially interested EO tested included Hyptis suaveolens, Hyptis spicigera, and Lippia multiflora. Based on these results, attempts to optimize the use of EO for cowpea storage were conducted in laboratory and field conditions. Side effects of botanicals toward the main biological control agent, the ectoparasitoid Dinarmus basalis have also been highlighted. The results are discussed in a view of practical use of botanicals and EO as safe alternatives for Integrated Pest Management in stored cowpeas in Africa and developing countries.

AIMS AND SCOPE: The aim of this special collection is to highlight the importance of reproduction (ie, oviposition) in the life history, population dynamics, survival, and fitness of beneficial insects, broadly defined. Specific areas of interest include the (1) identification of natural products to boost oviposition; (2) importance of chemical cues in oviposition site selection; (3) influence of host plant defenses on oviposition success; (4) reproductive physiology and the frequency of egg laying; (5) trade-offs between maternal size and egg size; (6) foraging behavior, host selection, and oviposition in parasitoids; and (7) oviposition decisions in the face of intraguild predators.

A new neotropical genus and species of soft scale insect from Cuba, Hamonicoccus Mestre and Kondo gen. nov. is described and Hamonicoccus alayoi Mestre and Kondo sp. nov. (Hemiptera: Coccomorpha: Coccidae) is described and illustrated based on the adult female. The species was collected in Cayos de las Cinco Leguas, Matanzas Province, on Capparis cynophallophora (Capparaceae), and in Surgidero de Batabanó, Mayabeque Province, on Rhizophora mangle (Rhizophoraceae). The affinities of H alayoi sp. nov. with closely related species is discussed based on published literature. An updated list of soft scale insects (Hemiptera: Coccidae) known from Cuba is provided.

This study investigated the effects of varying photoperiodic conditions on critical life stages' parameters of Culex quinquefasciatus. To this end, first larval stage was reared under different constant photoperiodic regimens: 0, 6 (short), 12 (equal), 13 (prevailing condition), and 18 and 24 (long) hours of light (hL). Duration of development, survivorship, emergence successes, adult longevity, caloric indices (CIs), and utilisation of teneral reserves for metamorphosis at each regimen were monitored. Analyses revealed significant negative effects of increasing photoperiod on all entomological variables measured. Short photo-phases elicited faster development times, increased life stages' survivorship and number at emergence, adult longevity, and CI for all life stages while increasing teneral components for adult life traits. The information generated in this study is important in understanding the role played by photoperiod in disease transmission and for development of integrated vector control strategies based on environmental manipulation.

Oviposition strategies and mechanisms of host selection in parasitoids may be crucial for the success of parasitization and parasitoid production. These aspects are far less known in tachinid parasitoids than in hymenopteran parasitoids. Depending on the species, parasitoid flies may adopt direct or indirect oviposition strategies. The 'direct type' females lay eggs on or, in relatively a few species, inside the host body. This review describes cues involved in host selection by tachinid parasitoids and their oviposition strategies and presents 2 case studies in more detail, focusing on Exorista larvarum and Exorista japonica. These 2 polyphagous parasitoids of Lepidoptera lay macrotype eggs directly on the host cuticle. Both species have been used as biological control agents in inoculative release against the gypsy moth Lymantria dispar in the Northern United States. Improved knowledge of the mechanisms involved in host selection and oviposition strategies may increase the possibility of eliciting oviposition by these tachinids on target lepidopterous hosts (and even artificial substrates), thus facilitating their rearing and ultimately making their exploitation as regulators of target insect pests more feasible and efficient.

Maximizing the reproductive potential of ladybird beetles fed factitious foods or artificial diets, in lieu of natural prey, is a major challenge to cost-effective mass rearing for augmentative biological control. In this study, we tested the hypothesis that compounds in redcedar, Juniperus virginiana, stimulate oviposition in the ladybird Coleomegilla maculata. We also tested the prediction that several bioflavonoids, identified in heartwood fractions, elicited this behavioral response. Phenolic compounds were extracted from J. virginiana heartwood sawdust, separated into several fractions, then presented to adult beetles, in a powdered, pure form, in the laboratory. Females preferentially oviposited within 1 to 2 cm of fractions B, C, D, and E, but not A or the unfractionated extract, at the base of test cages. Chemical analysis identified bioflavonoids in heartwood fractions and subsequent bioassays using several identified in fractions C, D, and E confirmed that quercetin, taxifolin, and naringenin (to a lesser extent) stimulated oviposition. All tested fractions and bioflavonoids readily adhered to the chorion of freshly laid eggs but did not reduce egg hatch. This study demonstrates that several bioflavonoids stimulate oviposition by C. maculata and could be useful for mass rearing programs.