Parasitoid Larvae Research Articles

A naturally occurring mitochondrial genome variant confers broad protection from infection in Drosophila.

The role of mitochondria in immunity is increasingly recognized, but it is unclear how variation in mitochondrial DNA (mtDNA) contributes to variable infection outcomes. To quantify the effect of mtDNA variation on humoral and cell-mediated innate immune responses, we utilized a panel of fruit fly Drosophila melanogaster cytoplasmic hybrids (cybrids), where unique mtDNAs (mitotypes) were introgressed into a controlled isogenic nuclear background. We observed substantial heterogeneity in infection outcomes within the cybrid panel upon bacterial, viral and parasitoid infections, driven by the mitotype. One of the mitotypes, mtKSA2 protected against bacterial, parasitoid, and to a lesser extent, viral infections. Enhanced survival was not a result of improved bacterial clearance, suggesting mtKSA2 confers increased disease tolerance. Transcriptome sequencing showed that the mtKSA2 mitotype had an upregulation of genes related to mitochondrial respiration and phagocytosis in uninfected flies. Upon infection, mtKSA2 flies exhibited infection type and duration specific transcriptomic changes. Furthermore, uninfected mtKSA2 larvae showed immune activation of hemocytes (immune cells), increased hemocyte numbers and ROS production, and enhanced encapsulation response against parasitoid wasp eggs and larvae. Our results show that mtDNA variation acts as an immunomodulatory factor in both humoral and cell-mediated innate immunity and that specific mitotypes can provide broad protection against infections.

Reproductive ecology and egg parasitism of the Samoan swallowtail butterfly

AbstractWe investigated the reproductive ecology and effects of egg parasitism on the Samoan swallowtail butterfly (Papilio godeffroyi), which survives only on Tutuila Island, American Samoa, after having disappeared from the much larger islands of Upolu and Savai‘i in independent Samoa. During monthly surveys of its only known host plant, Micromelum minutum, across eight sites in 2013 and 2014, we collected eggs, eggshells, larvae, pupae, and pupal exuviae. Live specimens were reared under laboratory conditions to determine reproductive outcomes, developmental rates, and sex ratios, as well as parasitoid attack frequencies, brood sizes, and sex ratios. Sixty‐six of 448 (14.7%) eggs produced larvae, 47 of which became adults. The sex ratio was approximately even overall and within each developmental stage. Eggs were slightly larger on individual host trees and in host tree stands that yielded more eggs per unit of foliage, indicating that ovipositing females responded to some features of host trees and stands. Eggs hatching female or male larvae were similar in size, and the sexes developed at similar rates. A newly described species of parasitoid wasp, Ooencyrtus pitosina (Encyrtidae), emerged from 73.6% of 382 butterfly eggs that failed to hatch in the laboratory (62.7% of 448 eggs overall). Forty‐one other eggs contained dead parasitoid larvae. An additional, unidentified Ooencyrtus wasp species emerged from a single P. godeffroyi egg. No parasitoids were reared from P. godeffroyi larvae or pupae. Of 656 P. godeffroyi eggshells collected in the field and examined in the laboratory, 62.2% showed signs of having been parasitized by O. pitosina. There was no evidence that parasitism rates were density‐dependent. O. pitosina brood sizes ranged from 1 to 5, with the sex ratio skewed toward females (2.40 F:1.00 M). Larger parasitoid broods were associated with slightly larger host eggs, indicating that female wasps may adjust brood size according to host egg size or that fewer wasp larvae are able to complete development in smaller eggs. Techniques used to rear both P. godeffroyi and O. pitosina in the laboratory could be applied to a captive‐rear, wild‐release program, which may facilitate reestablishment of the species in Samoa.

Characterization of larval gut microbiota of two endoparasitoid wasps associated with their common host, Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae).

Insect gut microbes play important roles in digestion, metabolism, development, and environmental adaptation. Parasitoid wasps are one of the most important biological control agents in pest control, while the gut microbial species compositions and the associated functions have been poorly investigated. Two endoparasitoid wasps, Cotesia vestalis and Diadromus collaris, parasitize the larval stage and pupal stage of the diamondback moth, Plutella xylostella, respectively. Using whole-genome shotgun metagenomic sequencing, we characterized the gut microbial composition, diversity, and potential functional roles associated with the two parasitoid wasp larvae. The results reveal that Proteobacteria and Firmicutes are the dominant phyla in the gut of C. vestalis and D. collaris larvae, with Rhizobium and Enterococcus being the dominant genera. The putative microbial functions associated with the two parasitoid wasps might play a virtual role in assisting in consuming the host's nutritional composition. The enriched CAZymes family genes are primarily involved in the degradation and synthesis of chitin. Despite the richness of microbial species and communities, the microbes species and the microbial community structure exhibit significant similarity between the two parasitoid wasps and between the parasitoid wasp and the host P. xylostella. Notably, the prevalence of the genus Enterococcus shared among them suggests a possible link of gut microbes between the host and their associated parasitoids. Our study offers insights into the gut microbe-based interactions between the host and parasitoid wasps for the first time, potentially paving the way for the development of an ecologically friendly biocontrol strategy against the pest P. xylostella.IMPORTANCEEndoparasitoid wasps spend the majority of their lifespan within their host and heavily rely on the host's nutrition for survival. There is limited understanding regarding the composition and physiological impacts of gut microbial communities in parasitoid wasps, particularly during the larval stage, which is directly linked to the host. Based on a thorough characterization of the gut microbe and comprehensive comparative analysis, we found the microbial species of the larval parasitoid wasp Cotesia vestalis and the pupal parasitoid wasp Diadromus collaris were similar, sharing 159 genera and 277 species, as were the microbial community structure. Certain of the dominant microbial strains of the two parasitoid wasps were similar to that of their host Plutella xylostella larvae, revealing host insect may affect the microbial community of the parasitoid wasps. The putative microbial functions associated with the parasitoid wasp larvae play an important role in dietary consumption.

Benefits of remating of a hyperparasitoid acting as a biocontrol agent

Encarsia sophia is the dominant parasitoid of invasive whitefly pest such as Bemisia tabaci. This heteronomous hyperparasitoid species lays fertilised diploid eggs in whitefly nymphs, which serve as primary hosts. Larvae develop as female progeny by consuming whitefly hosts, providing direct biocontrol benefits. However, male progeny originate from unfertilised eggs laid on secondary hosts (primary parasitoids within whitefly nymphs) and develop by consuming primary parasitoid larvae rather than whitefly hosts. Therefore, it is crucial for indoor rearing and field release of the hyperparasitoid to determine whether a female with single-mating experience can parasitise primary hosts and produce female progeny for a whole lifetime and, if not, whether it is remating events and prolong the period of female production, thereby increasing the amount of parasitism on whiteflies. Our fecundity experiments of females with single-mating experience, equally provided with primary and secondary hosts, showed that single mating was insufficient for E. sophia females to lay fertilised eggs in whitefly nymphs for their whole lifetime. In multiple mating experiments, 76.7 % of male adults completed their second mating 2 h after the first, whereas female adults accepted the second mating only if primary hosts were available thereafter. Remating was beneficial for female adults as it prolonged the ovipositional period of fertilised eggs (from 13.3 ± 0.6 days for single to 17.1 ± 0.7 days for twice mating) and increased parasitism on B. tabaci primary host (from 53.1 ± 3.8 for single to 76.4 ± 5.9 for twice mating respectively). The mating experience of males increased their copulation success, whereas that of females decreased it. In conclusion, recommendations are provided for large-scale indoor rearing and field release of E. sophia. Firstly, sufficient time for providing males can be shortened to within 2 h, and a single male can engage in 2–3 mating sessions. Following the 15-day peak oviposition period, the addition of newly emerged males is advised. Secondly, for field release of adult parasitoids, it is recommended to concentrate on releasing females after completing mating indoors. For the release of pupae cards, ensure a balanced ratio of males and females on each card to facilitate mating upon emergence. Additionally, release extra males and females 2 weeks after the initial batch of releases.

Caterpillar-parasitoid interactions: species-specific influences on host microbiome composition.

There is increasing evidence that host-parasitoid interactions can have a pronounced impact on the microbiome of host insects, but it is unclear to what extent this is caused by the host and/or parasitoid. Here, we compared the internal and external microbiome of caterpillars of Pieris brassicae and Pieris rapae parasitized by Cotesia glomerata or Cotesia rubecula with nonparasitized caterpillars. Additionally, we investigated the internal and external microbiome of the parasitoid larvae. Both internal and external bacterial densities were significantly higher for P. brassicae than P. rapae, while no differences were found between parasitized and nonparasitized caterpillars. In contrast, parasitism significantly affected the composition of the internal and external microbiome of the caterpillars and the parasitoid larvae, but the effects were dependent on the host and parasitoid species. Irrespective of host species, a Wolbachia species was exclusively found inside caterpillars parasitized by C. glomerata, as well as in the corresponding developing parasitoid larvae. Similarly, a Nosema species was abundantly present inside parasitized caterpillars and the parasitoid larvae, but this was independent of the host and the parasitoid species. We conclude that parasitism has pronounced effects on host microbiomes, but the effects depend on both the host and parasitoid species.

Effects of host size on progeny sex and survivorship of Hymenoepimecis pinheirensis

Abstract Parasitoid larvae consume their hosts to obtain the nutritional resources required for their development. Parasitoid wasps can optimally select the size of their hosts by laying unfertilized and fertilized eggs according to the amount of biomass available for consumption by the larvae. However, parasitoids may eventually experience low host availability within the optimal range of body sizes, affecting the survival of their offspring. In this study, we identified a situation in which all available hosts (Leucauge volupis) were smaller than those previously observed to be parasitized by Hymenoepimecis pinheirensis at the same study site. Therefore, we investigated how these parasitoids can bypass the scarcity of ideal hosts. Female wasps biased their oviposition toward the largest L. volupis females available. In this suboptimal scenario, they did not oviposit only unfertilized eggs, which developed into relatively small offspring (males). In this situation, they lay fertilized eggs mainly on larger spiders. Larval mortality was high, but the larvae attached to the larger spiders were more likely to complete their development. In general, H. pinheirensis females managed to target the best hosts available but could not delay the oviposition of fertilized eggs or avoid offspring mortality. Here, we discuss the potential causes of asynchronies in the life cycles of parasitoid wasps and their hosts, the availability of optimal hosts, and how these factors may affect their populations.

Reproductive Biology and Rearing Improvements of Apanteles opuntiarum, Potential Biocontrol Agent of the Argentine Cactus Moth, Cactoblastis cactorum.

The cactus moth, Cactoblastis cactorum (Berg) (Lepidoptera: Pyralidae) is native to South America and has been used as a biocontrol agent of Opuntia (Cactaceae) in Australia and South Africa. Its invasion in North America has raised concerns for the native Opuntia in the USA and Mexico. We investigated the reproductive biology and rearing procedures of a host-specific potential biocontrol agent, Apanteles opuntiarum Martínez and Berta (Hymenoptera: Braconidae). Given the gregarious nature of the parasitoid larvae, we studied the morphology of the immature stages and evaluated evidence of polyembryony and superparasitism. We also investigated the effects of host exposure arena and host density on parasitism rates and wasp production. The morphological descriptions provide a basis for comparison with other species. Early larval instars of A. opuntiarum are similar to other microgastrine immature stages. However, the mature larva exhibits placoid sensilla in the epistomal region, a unique character not previously reported. We provide evidence that A. opuntiarum eggs are not polyembryonic; females frequently superparasitize and have an oviposition preference for larvae parasitized 1-2 d previously. Exposing larvae of C. cactorum to wasps while inside the cactus resulted in lower parasitism and fewer offspring from each host than exposing larvae in the arena without the cactus. Parasitism and mortality rates were higher at lower host densities, possibly due to reduced host group defensive behavior. These results suggest that preference for superparasitism, host defensive behavior, and interactions with the cactus may play an important role in per-host wasp production under laboratory conditions.

Lipid Metabolism in Parasitoids and Parasitized Hosts.

Parasitoids have an exceptional lifestyle where juvenile development is spent on or in a single host insect, but the adults are free-living. Unlike parasites, parasitoids kill the host. How parasitoids use such a limiting resource, particularly lipids, can affect chances to survive and reproduce. In part 1, we describe the parasitoid lifestyle, including typical developmental strategies. Lipid metabolism in parasitoids has been of interest to researchers since the 1960s and continues to fascinate ecologists, evolutionists, physiologists, and entomologists alike. One reason of this interest is that the majority of parasitoids do not accumulate triacylglycerols as adults. Early research revealed that some parasitoid larvae mimic the fatty acid composition of the host, which may result from a lack of de novo triacylglycerol synthesis. More recent work has focused on the evolution of lack of adult triacylglycerol accumulation and consequences for life history traits. In part 2 of this chapter, we discuss research efforts on lipid metabolism in parasitoids from the 1960s onwards. Parasitoids are alsomaster manipulators of host physiology, including lipid metabolism, havingevolved a range of mechanisms to affect the release, synthesis, transport, and take-up of lipids from the host. We lay out the effects of parasitism on host physiology in part 3 of this chapter.

Size matters: Host‐seeking ectoparasitoid larvae prefer larger hosts, but not the largest

AbstractKoinobiont parasitoids do not prevent host development immediately after the attack, hence the quality of their resource units may vary over time. Potential advantages exist, though less clear, of choosing a host of better initial nutritional quality. We studied the effect of host nutritional quality on Mallophora ruficauda Wiedemann (Diptera: Asilidae), a solitary, koinobiont ectoparasitoid that preferentially attacks larvae of Cyclocephala signaticollis Burmeister (Coleoptera: Scarabaeidae). In the field, lighter hosts were parasitized more often than heavier hosts, but sex did not explain parasitism patterns. Our experiments showed that parasitoid larvae did not differentially attack heavier or lighter hosts in either two‐ or four‐choice selection experiments, but do show differential selection based on the size of the host. Experiments simulating a host patch showed that parasitoid larvae choose larger hosts, but at a finer scale, as the size of the hosts increased, larvae chose the smaller host in a dyad. These results suggest that M. ruficauda larvae may select hosts of higher nutritional quality (i.e., larger hosts) but that there is an upper limit where a trade‐off between nutrient acquisition and survival (related to life expectancy or host defenses) may drive the larval decisions.

Innexin hemichannel activation by Microplitis bicoloratus ecSOD monopolymer reduces ROS

The extracellular superoxide dismutases (ecSODs) secreted by Microplitis bicoloratus reduce the reactive oxygen species (ROS) stimulated by the Microplitis bicoloratus bracovirus. Here, we demonstrate that the bacterial transferase hexapeptide (hexapep) motif and bacterial-immunoglobulin-like (BIg-like) domain of ecSODs bind to the cell membrane and transiently open hemichannels, facilitating ROS reductions. RNAi-mediated ecSOD silencing invivo elevated ROS in host hemocytes, impairing parasitoid larva development. Invitro, the ecSOD-monopolymer needed to be membrane bound to open hemichannels. Furthermore, the hexapep motif in the beta-sandwich of ecSOD49 and ecSOD58, and BIg-like domain in the signal peptides of ecSOD67 were required for cell membrane binding. Hexapep motif and BIg-like domain deletions induced ecSODs loss of adhesion and ROS reduction failure. The hexapep motif and BIg-like domain mediated ecSOD binding via upregulating innexins and stabilizing the opened hemichannels. Our findings reveal a mechanism through which ecSOD reduces ROS, which may aid in developing anti-redox therapy.

Population dynamics of Palpita forficifera Munroe, 1959 (Lepidoptera: Crambidae) and associated parasitoids in olive orchards.

Palpita forficifera Munroe, 1959 (Lepidoptera: Crambidae) is the main pest of the olive tree (Olea europaea L., Oleaceae) in Brazil and its management has been difficult, as there are few products recommended for its control. This study aimed to evaluate the population dynamics of P. forficifera and the entomofauna of parasitoid eggs and larvae in three olive orchards under different cultivation systems, in Rio Grande do Sul state, Brazil. The study was carried out from October to May, in the 2017/18 and 2018/19 harvests, in olive orchards of different cultivars in the municipalities of Pelotas and Rio Grande, state of Rio Grande do Sul, Brazil. Population dynamics of P. forficifera varied according to the agricultural season, the months sampled, and the orchards (sites) evaluated. The highest infestation reached around 60% of the shoots in some months, depending on the orchard evaluated. During the pest infestation period, the occurrence of the egg parasitoid Trichogramma foersteri Takahashi, 2021 (Hymenoptera: Trichogrammatidae) was observed along with three larval parasitoids belonging to the genera Dolichogenidea Viereck, 1911, Hymenochaonia Dalla Torre, 1898 (Hymenoptera: Braconidae) and Temelucha Förster, 1869 (Hymenoptera: Ichneumonidae). Temelucha hilux Gauld, 2000 is recorded for the first time in association with a host, and its distribution in the country is extended to the southern region, from Brazil. Due to the scarcity of information on pest management, the natural occurrence of natural enemies in crops is of paramount importance in helping to manage P. forficifera in the field. The population dynamics of P. forficifera is also influenced by the parasitoid community, made up of at least four species of parasitic Hymenoptera. Therefore, strategies aimed at managing P. forficifera must be well developed in order to maintain and increase natural biological control in the field.

Simulating immunosuppressive mechanism of Microplitis bicoloratus bracovirus coordinately fights Spodoptera frugiperda.

Parasitoid wasps control pests via a precise attack leading to the death of the pest. However, parasitoid larvae exhibit self-protection strategies against bracovirus-induced reactive oxygen species impairment. This has a detrimental effect on pest control. Here, we report a strategy for simulating Microplitis bicoloratus bracovirus using Mix-T dsRNA targeting 14 genes associated with transcription, translation, cell-cell communication, and humoral signaling pathways in the host, and from wasp extracellular superoxide dismutases. We implemented either one-time feeding to the younger instar larvae or spraying once on the corn leaves, to effectively control the invading pest Spodoptera frugiperda. This highlights the conserved principle of "biological pest control," as elucidated by the triple interaction of parasitoid-bracovirus-host in a cooperation strategy of bracovirus against its pest host.

Further data on the establishment of Coptodisca lucifluella (Clemens, 1860) (Lepidoptera: Heliozelidae) in Romania

AbstractFollowing its first report in Romania in August 2022, more data regarding the walnut shield bearer Coptodisca lucifluella was collected. The leafminer moth is an invasive species of North American origin that entered Europe in 2010 (in Italy), and then spread to Hungary, Ukraine, Bulgaria and Romania. It is not an economically important pest alone but in association with other stresses affecting walnut trees, over time, it could contribute to their premature decline. In Romania, C. lucifluella was identified in 24 localities in eight counties and in Bucharest. The main host is the common walnut, Juglans regia (L.), while secondary hosts include the black walnut Juglans nigra (L.), Caucasian walnut Pterocarya fraxinifolia (Lam.) Spach and the pecan nut tree Carya illinoinensis (Wangenh & K. Koch). All walnut trees inspected in 2022 were affected by the leafminer to a greater or lesser extent. The proportion of attacked leaves per tree, evaluated in Northern Bucharest and Moara Domnească in the south of the country respectively, was 40% and 41% in August and increased to 69 and 93%, in October. Inside the mines, our team discovered a significant number of parasitoid larvae and pupae. These were kept in the laboratory until the emergence of adults which were photographed, but so far remain unidentified. The rate of parasitism was 17.4% in N. Bucharest and 31.8% in Moara Domnească.

The strategy of optimal control for managing sugarcane shoot borer larvae

Pests and plant diseases pose significant challenges to Indonesia's agricultural development of sugar cane. The fall in national sugar productivity can be attributed, in part, to the presence of sugar cane shoot borer bugs. Managing sugar cane shoot borer pests is a crucial aspect of agriculture. The objective of this scientific study is to ascertain the optimal approach for the introduction of parasitoid larvae of sugarcane shoot borer pests. This will be done by looking at the Lotka-Volterra equation's stability and finding the best way to control it. This is a mathematical model used to show how biological control systems work. Specifically, the study focuses on the biological control of sugarcane shoot borer pests using their parasitic larvae, the Diatraeophaga striatalis Towns. The researchers opted for the qualitative descriptive approach, employing analytical tools derived from Miles and Huberman's four-stage framework. The equilibrium point and optimal control analyses show that the model presents various outcomes with distinct methods. These findings will be further examined in the subsequent sections of this paper.

Immature stages of Utetes anastrephae (Hymenoptera: Braconidae) developed in Anastrepha fruit fly larvae (Diptera: Tephritidae)

The morphology of the immature stages of Utetes anastrephae (Hymenoptera: Braconidae), a native parasitoid of larvae of flies of the Neotropical genus Anastrepha (Diptera: Tephritidae), is shown. This study aimed to characterize the immature stages and morphological changes in the development of the koinobiont endoparasitoid in two species of larval hosts, Anastrepha obliqua and Anastrepha ludens. The definition of structures and morphological changes during development was made through daily microscopic observations and photographs of dissected hosts. The immature development of the parasitoid corresponds to a holometabolous insect with three well-defined stages: egg (two days), larva with three larval instars (approximately eight days), and pupa (six days). Similar development times were obtained in the two host species. Males and females completed their cycle in 17 and 18 days, respectively. During egg-first instar development, host antagonistic activity through melanization and encapsulation as mortality factors was evident and frequent only in A. obliqua. These results serve as basic knowledge for the use of this parasitoid in the biological control of fruit flies.

Indirect plant-mediated interactions between heterospecific parasitoids that develop in different caterpillar species.

Parasitoids induce physiological changes in their herbivorous hosts that affect how plants respond to herbivory. The signature of parasitoids on induced plant responses to feeding by parasitized herbivores indirectly impacts insect communities interacting with the plant. The effect may extend to parasitoids and cause indirect interaction between parasitoids that develop inside different herbivore hosts sharing the food plant. However, this type of interactions among parasitoid larvae has received very little attention. In this study, we investigated sequential and simultaneous plant-mediated interactions among two host-parasitoid systems feeding on Brassica oleracea plants: Mamestra brassicae parasitized by Microplitis mediator and Pieris rapae parasitized by Cotesia rubecula. We measured the mortality, development time, and weight of unparasitized herbivores and performance of parasitoids that had developed inside the two herbivore species when sharing the food plant either simultaneously or sequentially. Plant induction by parasitized or unparasitized hosts had no significant effect on the performance of the two herbivore host species. In contrast, the two parasitoid species had asymmetrical indirect plant-mediated effects on each other's performance. Cotesia rubecula weight was 15% higher on plants induced by M. mediator-parasitized hosts, compared to control plants. In addition, M. mediator development time was reduced by 30% on plants induced by conspecific but not heterospecific parasitoids, compared to plants induced by its unparasitized host. Contrary to sequential feeding, parasitoids had no effect on each other's performance when feeding simultaneously. These results reveal that indirect plant-mediated interactions among parasitoid larvae could involve any parasitoid species whose hosts share a food plant.

Oviposition fluids from adult wasps mediate interspecific competition between parasitoid larvae

Abstract Parasitoid wasp larvae engage in intense interspecific competition when sharing a host insect, with lethal consequences for the losers. Larval parasitoid competition is generally thought to be resolved by physical traits, such as enlarged mandibles. Although solitary parasitoid larvae are typically superior competitors against gregarious larvae, such physical traits are unlikely to be effective against large numbers of competitors. Larval competition may instead be mediated by maternal factors that increase the survival of offspring facing interspecific competition, thus increasing parental fitness. When laying eggs inside a host, many female parasitoids also inject oviposition fluids that are known to suppress host immune responses, permitting successful offspring development. We explored whether the oviposition fluids of two wasp species in the genus Cotesia (Cotesia rubecula, a strong competitor that almost always wins interspecific competition against a weaker competitor, Cotesia glomerata) might also represent maternal factors that improve the interspecific competitive ability of their offspring. We demonstrate that injections of both venom and calyx fluid from C. rubecula can inhibit egg hatching and larval development of C. glomerata. Venom from C. rubecula decreased C. glomerata egg development by 2.7 times, and calyx fluid injections caused deformities in 23% of developing C. glomerata. In contrast, reciprocal injections of the oviposition fluids from C. glomerata did not inhibit the development of C. rubecula. Our results show that maternal factors can improve the interspecific competitive ability of parasitoid larvae, challenging the previous assumptions that larval competition was resolved primarily through physical combat or larval secretions.

Intraguild predation of Phenacoccus manihoti parasitoid Anagyrus lopezi by two mealybug predators, Cryptolaemus montrouzieri and Plesiochrysa ramburi

Anagyrus lopezi is a specialist parasitoid was introduced to Indonesia in 2014 to control cassava mealybug, Phenacoccus manihoti. Plesiochrysa ramburi and Cryptolaemus montrouzieri are generalist predator insects associated with the mealybug. Intraguild predation is a crucial competition in an insect community. The study objective was to investigate interference of both predators on healthy mealybug (unparasitized) or parasitized mealybug by A. lopezi (mealybug which containing parasitoid larvae 1-, 3-, 8-, and 14-day old). Experiments were carried out in a non-choice test (served only one unparasitized or parasitized mealybug of a specific parasitoid age) and choice test (unparasitized and parasitized mealybug of a specific parasitoid age together) in laboratory under controlled environmental conditions. Both of predators species able to fed on both unparasitized and parasitized mealybugs of three different age (1-, 3-, and 8- day-old), but both predators discriminated against mealybug were parasitized 14-day old (hardened mummies). Interaction between parasitoid of A. lopezi and both predators showed antagonistic interaction type. We recommended A. lopezi should be released in field at the beginning of the time when the population of the mealybug is still low and could be continued with the predators release when the mealybug population is high.

Early destruction of cockroach respiratory system and heart by emerald jewel wasp larvae

In the 1880s, Henri Fabre was captivated by the "special art of eating", whereby a parasitoid wasp larva fed selectively on host internal organs, avoiding the heart (dorsal vessel) and tracheal system (respiratory system) to preserve life. In Fabre's words: "The ruling feature in this scientific method of eating, which proceeds from parts less to the parts more necessary to preserve a remnant of life, is none the less obvious"1. Subsequent investigators have reported the same for many parasitoid wasps2,3, including for the emerald jewel wasp (Ampulex compressa)4. Here it is reported that larval jewel wasps destroy the dorsal vessel and tracheae (respiratory system) in the thorax of their cockroach host (Periplaneta americana) at their earliest opportunity. Moreover, the broken tracheae release air into the host, which the larval jewel wasp inspires. An increase in larval chewing rate, cotemporaneous with the sudden release of air from the host's broken tracheae, suggests the larva taps into the host respiratory system to support its metabolism while rapidly consuming the host. VIDEO ABSTRACT.

Dietary Challenges for Parasitoid Wasps (Hymenoptera: Ichneumonoidea); Coping with Toxic Hosts, or Not?

Many insects defend themselves against predation by being distasteful or toxic. The chemicals involved may be sequestered from their diet or synthesized de novo in the insects' body tissues. Parasitoid wasps are a diverse group of insects that play a critical role in regulating their host insect populations such as lepidopteran caterpillars. The successful parasitization of caterpillars by parasitoid wasps is contingent upon their aptitude for locating and selecting suitable hosts, thereby determining their efficacy in parasitism. However, some hosts can be toxic to parasitoid wasps, which can pose challenges to their survival and reproduction. Caterpillars employ a varied array of defensive mechanisms to safeguard themselves against natural predators, particularly parasitoid wasps. These defenses are deployed pre-emptively, concurrently, or subsequently during encounters with such natural enemies. Caterpillars utilize a range of strategies to evade detection or deter and evade attackers. These tactics encompass both measures to prevent being noticed and mechanisms aimed at repelling or eluding potential threats. Post-attack strategies aim to eliminate or incapacitate the eggs or larvae of parasitoids. In this review, we investigate the dietary challenges faced by parasitoid wasps when encountering toxic hosts. We first summarize the known mechanisms through which insect hosts can be toxic to parasitoids and which protect caterpillars from parasitization. We then discuss the dietary adaptations and physiological mechanisms that parasitoid wasps have evolved to overcome these challenges, such as changes in feeding behavior, detoxification enzymes, and immune responses. We present new analyses of all published parasitoid-host records for the Ichneumonoidea that attack Lepidoptera caterpillars and show that classically toxic host groups are indeed hosts to significantly fewer species of parasitoid than most other lepidopteran groups.