Diachasmimorpha longicaudata is a hymenopteran fruit fly endoparasitoid. Females of this species find their hosts for oviposition by using complex sensorial mechanisms in response to physical and ...chemical stimuli associated with the host and host habitat. Ecological and behavioral aspects related to host-seeking behavior for oviposition have been extensively studied in D. longicaudata, including the identification of volatile organic compounds acting as attractants to females. In this sense, molecular mechanisms of chemoreception have been explored in this species, including a preliminary characterization of odorant-binding proteins (OBPs), chemosensory proteins (CSPs) and odorant receptors (ORs), among other proteins. Functional assays on OBP and CSP have been conducted as a first approach to identify molecular mechanisms associated with the female host-seeking behavior for oviposition. The aims of the present study were to identify the D. longicaudata sensory gene repertoire expressed in the antenna of sexually mature and mated individuals of both sexes, and subsequently, characterize transcripts differentially expressed in the antennae of females to identify candidate genes associated with the female host-seeking behavior for oviposition.
A total of 33,745 predicted protein-coding sequences were obtained from a de novo antennal transcriptome assembly. Ten sensory-related gene families were annotated as follows: 222 ORs, 44 ionotropic receptors (IRs), 25 gustatory receptors (GRs), 9 CSPs, 13 OBPs, 2 ammonium transporters (AMTs), 8 pickpocket (PPKs) receptors, 16 transient receptor potential (TRP) channels, 12 CD36/SNMPs and 3 Niemann-Pick type C2 like proteins (NPC2-like). The differential expression analysis revealed 237 and 151 transcripts up- and downregulated, respectively, between the female and male antennae. Ninety-seven differentially expressed transcripts corresponded to sensory-related genes including 88 transcripts being upregulated (87 ORs and one TRP) and nine downregulated (six ORs, two CSPs and one OBP) in females compared to males.
The sensory gene repertoire of D. longicaudata was similar to that of other taxonomically related parasitoid wasps. We identified a high number of ORs upregulated in the female antenna. These results may indicate that this gene family has a central role in the chemoreception of sexually mature females during the search for hosts and host habitats for reproductive purposes.
Cerambycid and buprestid woodborers are important invasive forest pests. Parasitoids play a unique role in reducing woodborer populations because of their specific adaptations regarding host ...concealment. We reviewed parasitoid guilds of cerambycid and buprestid woodborers to characterize their life-history traits and macroecological patterns of host use. The parasitoid guilds shift from more specialist endoparasitoids to more generalist ectoparasitoids following the hosts’ ontogeny and the increased concealment of host feeding niche. Larval ectoparasitoids dominate the guilds, and many of them locate hosts through substrate vibration from living hosts, rendering attacked (paralyzed) hosts undetectable by other parasitoids and consequently leading to a rarity of multiparasitism. These characteristics promote novel associations between exotic woodborers and extant larval parasitoids, leading to coexistence and synergistic regulation of host populations by different parasitoids. We provide case studies to propose a framework of optimal use of co-evolved and novel associations for complementary suppression of invasive woodborer populations. We also discuss potential non-target impacts for the use of generalist parasitoids in biological control of invasive cerambycid and buprestid woodborers.
Braconidae and Figitidae parasitoids are important agents of pest population regulation in natural and agricultural systems, with species used in applicate biological control programs of fruit flies ...(Diptera Tephritidae). However, many aspects of the interactions of parasitoids with their heterospecific and conspecific are poorly understood. Thus, the interspecific competition between the parasitoids Diachasmimorpha longicaudata (Ashmead) (DL) (Hymenoptera Braconidae) and Aganaspis pelleranoi (Brethes) (AP) (Hymenoptera Figitidae), was studied using Anastrepha fraterculus (Wiedemann) (Diptera Tephritidae) as host. Host larvae were offered to only one parasitoid on a single occasion or on two occasions, or even to two parasitoid species, alternating the offering sequence. Thus, six exposure regimes were completed: AP (host exposed for 4 hours); DL (host exposed for 40 minutes); AP-AP (host exposed to AP for 4 hours and then to a conspecific for an additional further 4 hours); DL-DL (host exposed to DL for 40 minutes and then to a conspecific for an additional 40 minutes); AP-DL (host exposed to AP for 4 hours and then to DL for 40 minutes); and DL-AP (host exposed to DL for 40 minutes and then exposed to AP for 4 hours). The mean number of parasitized pupae, emerged parasitoids, oviposition scars per host (larvae) and sex ratio of parasitoids were compared between the different exposure regimes. The mean of parasitized pupae and emerged parasitoids was higher in the DL-DL and DL-AP treatments. The mean number of oviposition scars per host was correlated positively with the mean number of parasitoid offspring and the emerged females in treatments AP, DL, AP-AP, DL-DL for both species, and DL-AP only to D. longicaudata. When the hosts were exposed only once to the parasitoids, the sex ratio was male biased (AP and DL treatments); but when exposed twice, the treatments spawned offspring female biased, except for D. longicaudata at AP-DL treatment. Irrespective of the parasitism order, D. longicaudata suppress the emergence of A. pelleranoi.
Citrus fruits are considered, in Algeria, to be a strategic crop, given their importance in food and human health. They attract a phytophagous fauna, as well, as their natural enemies, which are ...quite remarkable in ensuring natural regulation. A parasitoid inventory was conducted in three Citrus orchards at the University of Mostaganem’s experimental farm in Mazagran during the years 2018–2019, with a total of thirty Citrus trees studied. The parasitoid insects were identified in the laboratory using a binocular dissection microscope and direct inspection while processing the gathered leaves. This study enabled the identification of a group of distinct parasitoids that grow on harmful insects such as aphids and cochineal insects, and some of which have been found as adults, who belong to different families: Aphelinidae, Trichogrammatidae, Braconidae, Chalcidoidea, and Figitidae, among which we can quote: Encarsia sp., Aphytis sp., Trichogramma sp., Lysiphlebus sp., Bracon sp, Aphidius matricariae, Praon sp, Alloxysta sp, and several other parasitoids are yet to be identified. Natural enemies reflect the natural ecological integrity of ecosystems, and Elekçİoğlu, 2007 have found natural enemies such as Aphytis melinus, Chrysoperla carnea., Conwentzia sp. Chilocorus bipustulatus., Exochomus quadripustulatus., and Adonia variegata. These findings may be sufficient as an effective first step in learning about auxiliary insects, in order to establish proper breeding methods and carry out biological control.
Invasive stink bugs (Hemiptera: Pentatomidae) are responsible for high economic losses to agriculture on a global scale. The most important species, dating from recent to old invasions, include ...Bagrada hilaris (Burmeister), Halyomorpha halys (Stål), Piezodorus guildinii (Westwood), Nezara viridula (L.), and Murgantia histrionica (Hahn). Bagrada hilaris, H. halys, and N. viridula are now almost globally distributed. Biological control of these pests faces a complex set of challenges that must be addressed to maintain pest populations below the economic injury level. Several case studies of classical and conservation biological control of invasive stink bugs are reported here. The most common parasitoids in their geographical area of origin are egg parasitoids (Hymenoptera: Scelionidae, Encyrtidae, and Eupelmidae). Additionally, native parasitoids of adult stink bugs (Diptera: Tachinidae) have in some cases adapted to the novel hosts in the invaded area and native predators are known to prey on the various instars. Improving the efficacy of biocontrol agents is possible through conservation biological control techniques and exploitation of their chemical ecology. Moreover, integration of biological control with other techniques, such as behavioural manipulation of adult stink bugs and plant resistance, may be a sustainable pest control method within organic farming and integrated pest management programs. However, additional field studies are needed to verify the efficacy of these novel methods and transfer them from research to application.
We present a century of classical biological control of invasive stink bugs and review the biocontrol strategies on a global scale. These strategies include classical, augmentative, and conservation biological control, as well as innovative proactive classical biological control, all of which are described through case studies. Based on information on stink bug and parasitoid chemical ecology, we discuss semiochemical‐based approaches and other methods to increase natural enemy efficacy and to manage stink bug pests as part of sustainable control strategies.
Facultative, heritable endosymbionts are found at intermediate prevalence within most insect species, playing frequent roles in their hosts’ defence against environmental pressures. Focusing on ...Hamiltonella defensa, a common bacterial endosymbiont of aphids, we tested the hypothesis that such pressures impose seasonal balancing selection, shaping a widespread infection polymorphism. In our studied pea aphid (Acyrthosiphon pisum) population, Hamiltonella frequencies ranged from 23.2% to 68.1% across a six‐month longitudinal survey. Rapid spikes and declines were often consistent across fields, and we estimated that selection coefficients for Hamiltonella‐infected aphids changed sign within this field season. Prior laboratory research suggested antiparasitoid defence as the major Hamiltonella benefit, and costs under parasitoid absence. While a prior field study suggested these forces can sometimes act as counter‐weights in a regime of seasonal balancing selection, our present survey showed no significant relationship between parasitoid wasps and Hamiltonella prevalence. Field cage experiments provided some explanation: parasitoids drove modest ~10% boosts to Hamiltonella frequencies that would be hard to detect under less controlled conditions. They also showed that Hamiltonella was not always costly under parasitoid exclusion, contradicting another prediction. Instead, our longitudinal survey – and two overwintering studies – showed temperature to be the strongest predictor of Hamiltonella prevalence. Matching some prior lab discoveries, this suggested that thermally sensitive costs and benefits, unrelated to parasitism, can shape Hamiltonella dynamics. These results add to a growing body of evidence for rapid, seasonal adaptation in multivoltine organisms, suggesting that such adaptation can be mediated through the diverse impacts of heritable bacterial endosymbionts.
Populations of herbivorous insects are considered to be primarily regulated by natural enemies. However, little is known about the ecological role of entomopathogenic fungi. There is very little data ...on the diversity and prevalence of fungal pathogens in natural insect populations. In this study, the percentage mortality attributable to fungal pathogens for the immature stages of three noctuid moths feeding inside the stems of the herbaceous plant, Typha latifolia, were determined. The average percentage mortality caused by fungal pathogens was around 8%, with the value never exceeding 20% at any of the studied sites. As many as ten species of fungi were identified in the 52 infected larvae/pupae collected, this high diversity is consistent with the results of comparable studies. The prevalence of fungal infections did not correlate with host population density or performance of the host insects. This study contributes to the emerging generalisation that populations of insects commonly harbour diverse assemblages of pathogenic fungi, but with low overall prevalence. A significant contribution of these antagonists to regulating insect populations is unlikely.
Clistopyga kenyensis sp. n. from the Southeast of Kenya is described and illustrated. It is the second recorded species of the genus Clistopyga from the country, together with C. incitator ...(Fabricius, 1793), and the third known species from the Afrotropical Region.
Halyomorphahalys
(Stål) is a severe agricultural pest that is spreading worldwide from its original distribution in Asia. Egg parasitoids from Asia, which play a key role in the population dynamics ...of
H.halys
, are following its host along global pathways. We present the first records of
Trissolcusmitsukurii
in Europe, and of
Trissolcusjaponicus
in Italy. Both discoveries were made in northern Italy, where
H.halys
is widely present and has reached extremely high population densities in some areas. Given the availability of their host, the distributions and populations of these exotic egg parasitoids are expected to expand, even in the absence of human intervention.
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