Parasitism Rates Research Articles

Previously introduced braconid parasitoids target recent olive fruit fly (Bactrocera oleae) invaders in Hawai’i

The olive fruit fly Bactrocera oleae (Diptera: Tephritidae) was detected on Maui and Hawai’i Islands in 2019, affecting yields and quality of the state’s emerging olive oil industry. Given previous parasitoid releases to control other invasive frugivorous tephritids in Hawai’i, we were interested in determining whether these parasitoids were naturally targeting recent olive fly invaders in field, if local olive cultivar differences affected parasitization rates, and if there was a seasonal pattern of parasitization that could inform future management decisions. To address these questions, we collected data from olive growing in Hawai’i during 2021 and 2022. During the fruiting season we collected monthly samples and reared out B. oleae in the lab. We detected two previously introduced braconid wasps: first Diachasmimorpha tryoni during 2021 and 2022 and later Fopius arisanus during the 2022 collection. Cultivar effects were limited to a single site in our study, where more D. tryoni were reared from ‘Arbequina’ olives. Seasonality of olive fruit fly and parasitoid activity was earlier in lower elevation sites, as expected based on tree phenology and temperature-dependent insect development. This represents the first report of D. tryoni parasitism activity against B. oleae and may reflect elevational effects combined with the ecological complexity in interactions between multiple invasive arthropod pests, their invasive and cultivated plant hosts, and introduced braconid parasitoids.

Landscape complexity effects on Brassicogethes aeneus abundance and larval parasitism rate: a two-year field study

Global biodiversity has suffered a decline primarily attributed to landscape simplification and intensified agricultural practices. Agricultural environments, characterized by homogeneity and frequent disturbances, are often suboptimal habitats for various insect species. While agricultural fields do favour pests, they generally fail to provide suitable habitats for natural enemies. The inclusion of diverse supporting habitats, such as semi-natural habitats, grassy and woody field margins etc. surrounding agricultural fields, play a crucial role in fostering effective biodiversity conservation. Moreover, determining the influence of different adjacent habitat types is essential in elucidating their influence on pest abundance and parasitism rates. Our two-year field study focused on assessing the abundance of Brassicogethes aeneus and its parasitism rate. The findings revealed that the adjacent habitat type did not significantly increase pest abundance and the parasitism rate of B. aeneus larvae consistently stayed over the threshold for effective biological control throughout the fields. This was attributed to the high proportion (35 and 38% in the 2 study years) of semi-natural habitats within most of the 1 km radius study areas. While our study did not identify any specific adjacent habitat type or habitat within a 1 km radius that directly impacted B. aeneus abundance, it emphasises the intricate interplay between the pests, parasitism and the surrounding environment because the interactive effect of distance from the crop edge and habitat type had a significant influence on B. aeneus infestation levels but not on parasitism. Decision tree analysis suggests that > 18% semi-natural habitat is needed to ensure sufficient levels of parasitism for effective biological control. A comprehensive understanding of habitats that influence not only B. aeneus but also other pests is critical for the successful implementation of IPM strategies and conservation initiatives within the agricultural sector.

Estimation of the infestation rate and parasitism rate of the citrus leafminer Phyllocnistis citrella in a Thomson orchard near a greenhouse where beneficials are reared in Boufarik-Blida (Algeria)

The citrus leafminer Phyllocnistis citrella causes severe damage to young citrus shoots in Algeria. It therefore indirectly delays fruit set and consequently production and crop profitability. The endophytic lifestyle of the insect's larvae has made chemical control difficult, making the use of other control agents essential.
 To this end, a study on the population dynamics of Phyllocnistis citrella and the incidence of the parasite was carried out for 08 months in 2021 (from January to August 2021) in the Boufarik-Blida region (Algeria) on the Thomson variety.
 The main results gathered from the sampling show that the parasitism rate reached 68% and the infection rate 39%, due to the intervention of auxiliaries (Semielacher petiolatus, Cirostichus phyllocnistoides) from the greenhouse where these species are reared near the Thomson orchard. The citrus leafminer population is declining. Parasite brokering has a positive effect on the defense against Phyllocnistis citrella and represents an effective method of reinforcing biological control of this pest. In addition, the installation of mini greenhouses for the rearing of beneficials in orchards infested by citrus leafminer can be proposed as a means of reinforcing biological control. Moreover, regional containment is a healthy alternative in the context of integrated pest management, helping the ecosystem to reduce pollution. For this reason, it is worthwhile scheduling containment periods in agricultural regions.

Infection pattern of Echinorhynchus salobrensis (Acanthocephala) in congeneric species of piranha from a Neotropical floodplain region.

Acanthocephalans are obligate endoparasites characterised by the presence of a proboscis with hooks, which are used to adhere and perforate the intestinal wall of their hosts. Individuals of Echinorhynchus salobrensis Machado Filho, 1948 have been reported parasitising the piranhas Serrasalmus maculatus Kner and Serrasalmus marginatus Valenciennes in the upper Paraná River floodplain. Serrasalmus marginatus is considered non-native at this site, and its establishment occurred after the closure of the Itaipu Hydroelectric, which flooded a natural geographic barrier that separated two ecoregions in the Paraná River. Since they are phylogenetically close and have similar biological and ecological characteristics competition for resources caused the non-native species to become dominant over the native one. Considering the specificity of species of Echinorhynchus Zoega, 1776 in serrasalmids, we evaluated the distribution of E. salobrensis along the gastrointestinal tract of S. maculatus and S. marginatus from the upper Paraná River floodplain. All parasites indices of E. salobrensis were higher in the invasive host S. marginatus when compared to the native S. maculatus. There were no significant interaction effects between host species and sex, and host species and/or sex in the presence of the parasite. When we evaluated the effect of E. salobrensis parasitism on the different gut regions and accessory organs, total abundance was significant in the stomach and caecum organs, and in the first and second regions of the intestine. None of the analytical approaches tested showed an effect of the sex of the host or the sex of the parasite on the presence and abundance of the parasite in the gastrointestinal tract. Studies on acanthocephalan parasitism in fish in Brazil focus on fish farm. The fact that two species of selvage carnivorous fish present high rates of acanthocephalan parasitism, added to the fact that most studies with this group are on farmed fish fed with feed, only emphasise the need for continuity in studies of acanthocephalans in the parasitology of aquatic organisms.

Prevalence of the endoparasitoid Verrallia aucta in Central Scotland: A potential biocontrol for Philaenus spumarius (Hemiptera, Aphrophoridae), an important vector of Xylella fastidiosa

AbstractXylella fastidiosa is a bacterial plant pathogen transmitted by xylem‐feeding insect vectors such as the meadow spittlebug, Philaenus spumarius (Hemiptera, suborder Auchenorrhyncha, family Aphrophoridae). Although X. fastidiosa is not currently found in the UK, methods for reducing vector populations will play an important role in controlling the spread of disease in the event X. fastidiosa is introduced. The endoparasitoid big‐headed fly, Verrallia aucta Fallén 1817 (Diptera, Pipunculidae), is a parasite specific to Aphrophoridae and has the potential to be used as a biological control agent; however, there is limited information available on its current presence and prevalence in Scotland. This study used Sanger sequencing and morphology to identify V. aucta within Central Scotland. Additionally, four species of adult Auchenorrhyncha collected during Summer 2021 from sites across Central Scotland were molecularly screened for presence of V. aucta parasitism. Sex and habitat prevalence in V. aucta parasitism in P. spumarius was also examined. Findings from this study demonstrate V. aucta is present in Scotland and specifically parasitizes Aphrophoridae. Parasitism rates of P. spumarius ranged between 17% and 57%, with both male and female adult P. spumarius parasitized equally and rates differing according to habitat. Together, this study improved our knowledge and understanding of the parasitism rate, distribution and nature of V. aucta parasitism in Scotland. Further work is required to strengthen our understanding of the host–parasite relationship and take the first steps towards using V. aucta as a natural biocontrol agent to protect plants against transmission of X. fastidiosa.

Species diversity and abundance of parasitoids of fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae) from South Sumatra, Indonesia

Abstract. Herlinda S, Suwandi S, Irsan C, Adrian R, Fawwazi F, Akbar F. 2023. Species diversity and abundance of parasitoids of fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae) from South Sumatra, Indonesia. Biodiversitas 24: 6184-6190. The parasitoid species attacking Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) have never been reported from South Sumatra. The objectives of this research were to identify and analyze the species diversity of egg and larval parasitoids of S. frugiperda and to determine their abundance in corn fields from South Sumatra. Surveys were carried out in Ogan Komering Ilir District, Ogan Ilir District, Muara Enim District, and Palembang City. The results showed that fourteen species of parasitoids were found attacking eggs and larvae of S. frugiperda in South Sumatra. Two species were egg parasitoids (Telenomus remus (Nixon) and Trichogramma sp.), and 12 species of larval parasitoids (Chelonus formosanus Sonan, Chelonus oculator F., Chelonus annulipes Wesm., Chelonus cautus (Cresson), Microplitis manilae Ashmead, Microplitis marshallii Kokujev, Euplectrus corriemoreauae Hansson, Compsilura concinnata (Meigen), Sarcophaga sp., Macrocentrus sp., Exorista sp., and Megaselia sp.). The most abundant species of the parasitoids found was T. remus. The highest species diversity was found in Muara Enim District. The number of parasitoid species was greater in the dry season compared to the rainy season. Egg parasitism rates were significantly higher at the corn vegetative stage (59.03%) compared to the generative stage (53.56%).

Transgenerational hormesis and sublethal effects of five key insecticides for controlling Spodoptera frugiperda on its endoparasitoid Cotesia marginiventris.

The endoparasitoid Cotesia marginiventris (Cresson) is a promising biological control agent of the fall armyworm (FAW) Spodoptera frugiperda (Smith). Because the application of insecticides is one of the prime choices in pest management, we evaluated the sublethal and transgenerational effects of the five key insecticides-chlorantraniliprole, emamectin benzoate, spinetoram, Bacillus thuringiensis (Bt), and Mamestra brassicae nucleopolyhedrovirus (MbNPV)-on the parasitoid. Exposure to five insecticides at a concentration causing 10% mortality (LC10 ) caused hormetic effects in the parent generation (F0 ) by increasing the parasitism and reducing the immature duration. Interestingly, the hormetic response was also observed in the offspring generation indirectly exposed to the insecticides. Furthermore, insecticides increased the parasitism rate by 6.32-14.73% in the F1 generation, which was similar to that of the F0 generation (3.96-11.81%) compared with the control. No significant adverse effect was observed on the number of emerged parasitoids of the F1 and F2 generations. However, insecticides had a detrimental impact on body size and fecundity in the F1 and F2 generations, which showed a small body size with shorter hind tibiae and a significant reduction in the female ratio compared with the control; the exception was that chlorantraniliprole significantly improved the female ratio in the F2 generation. Five insecticides at LC10 induced transgenerational hormetic and sublethal effects on C. marginiventris. Our results provide a scientific basis for a better understanding of the long-term impacts of insecticides at sublethal doses on parasitoids, facilitating the development of improved integrated pest management programs for FAW control. © 2023 Society of Chemical Industry.

Reproductive Parameters and Host Specificity of Eurytoma erythrinae (Hymenoptera: Eurytomidae), a Biological Control Agent of the Erythrina Gall Wasp, Quadrastichus erythrinae (Hymenoptera: Eulophidae).

Eurytoma erythrinae Gates & Delvare (Hymenoptera: Eurytomidae) is an important biological control agent of the erythrina gall wasp (EGW), Quadrastichus erythrinae Kim (Hymenoptera: Eulophidae), an invasive species likely originating in eastern Africa that is a threat to Erythrina trees in Hawaii and worldwide. Thousands of Erythrina trees in Hawaii have succumbed to EGW since 2005 and died within a few years of infestation. The endemic wiliwili tree, Erythrina sandwicensis, an important component of Hawaii's dry forests and one of few deciduous native trees, were severely impacted by this wasp. Early during the invasion by EGW it became evident that the endemic species may be driven to extinction, and exploration programs for natural enemies of the EGW started in December 2005. East Africa was selected as the starting point for natural enemy exploration owing to high native Erythina species richness. Several gall formers were found in Tanzania and a putative color variant type of Q. erythrinae was detected in association with three ectoparasitoids. During January 2006, the dominant parasitoid of this gall former was introduced to Hawaii and described as the new species, E. erythrinae. It was found in Ghana and South Africa attacking other gall wasp species on Erythrina. Eurytoma erythrinae was a voracious ectoparasitoid feeding as a predator on 1-5 adjacent EGW immatures to complete its development. Host specificity studies that included seven nontarget gall-forming species showed no evidence of attraction or parasitism by this parasitoid. Mean ± SEM longevity of host-deprived females (40.4 ± 2.2 days) was significantly higher than males (20.5 ± 1.1 days). Host feeding enhanced longevity of ovipositing females (51.3 ± 1.5 days). Female E. erythrinae is synovigenic, with high egg-maturation rate. Peak fecundity (105-239 offspring/female), host feeding biology, short life cycle (18.4 ± 0.1 days), and synchronization with the host were additional desirable attributes of this species. The parasitoid was approved for field release in Hawaii in November 2008. A total of 3998 wasps were distributed on six Hawaiian Islands, with establishment in less than a year. Impacts on high density infestations of EGW were sufficient to prevent tree deaths. Limited rates of parasitism on low-density galled leaves, flowers, and seedpods necessitated the consideration for releasing a second parasitoid, Aprostocetus nitens Prinsloo & Kelly (Hymenoptera: Eulophidae). We report on the reproductive characteristics and host specificity of E. erythinae that could be of importance for classical biocontrol programs in areas with an EGW problem.

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.

Waterborne parasites in Uganda: A survey in Queen Elizabeth Protected Area

AbstractBackgroundPathogenic waterborne protozoa and helminths have the potential to cause infections in vulnerable populations such as children and immunocompromised individuals. Those residing in close proximity to wildlife‐protected areas in sub‐Saharan Africa, who are among the most economically disadvantaged, may have an increased susceptibility to these infections. This study aimed at detecting protozoan trophozoites/cysts, and helminth eggs in environmental and piped tap water (PTW) used by locals and tourists in the Queen Elizabeth Protected Area (QEPA) in western Uganda.MethodsWater samples were taken from the natural environment and domestic PTW sources. The samples were analysed for helminth eggs, free‐living amoeba (FLA) trophozoites/cysts, Cryptosporidium oocysts and Giardia cysts. The parasites were examined under the microscope, after which they were identified and counted. The data was subjected to univariate analysis to compare the prevalence rates across the different sample sites. The variables were summed using the mean and standard error of the mean.ResultsThe overall prevalence rates of the protozoan parasites, from highest to lowest, were as follows: FLA (56.6%), Cryptosporidium spp. (38.2%), Giardia spp. (36.5%), Eimeria spp. (20.3%) and Paramecium spp. (2.7%). Similarly, helminth parasite prevalence was as follows: Strongyle (38.2%), Ascaris spp. (33.3%), Trematodes (25%), Strongyloides (10.5%), Toxocara spp. (8.3%) and Capillaria spp. (3.2%).ConclusionThe presence of parasites in natural water sources inside QEPA presents a significant hazard for the contamination of domestic water. It is imperative to implement established procedures for enhancing water quality.

INTENSITAS DAN PREVALENSI EKTOPARASIT PADA IKAN LELE DI BALAI BENIH IKAN LOKAL (BBIL) AIR MAWAR KOTA PANGKALPINANG

The research entitled "Intensity and Prevalence of Ectoparasites in Catfish at the Air Mawar Local Fish Seed Center (BBIL) Pangklapinang City" aims to determine the level of intensity, prevalence and types of ectoparasites that infect catfish in that location. Samples of 30 fish were taken randomly. In identifying ectoparasites, observations were made on the outside of the catfish's body, including mucus, fins and gills. Analysis of research data is descriptive and also presented in the form of pictures and tables. Data from the research results show that the types of ectoparasites that infect the external organs of the sampled fish include Dactylogyrus sp, Gyrodactylus sp, Argulus sp, Ichhtyobodo sp, Trichodina sp, and Cichlidogyrus sp. The prevalence rate of parasites that infect catfish is 90% with the category almost always and severe infection. The highest intensity of ectoparasites that attack catfish is by the parasite Dactylogyrus sp with an intensity value of 6.48 individuals per fish in the medium category, and the lowest intensity value is by the parasite Trichodina sp with an intensity value of 1 individual per fish. It is also known that the water conditions in the catfish pond This is not good for the survival of catfish, because the oxygen levels are low and the ammonia levels are high

Prevalence and risk factors associated with gastrointestinal parasites in goats (Capra hircus) and sheep (Ovis aries) from three provinces of China

Gastrointestinal (GI) parasites in small ruminants, especially goats and sheep, have caused significant socio-economic and public health challenges worldwide. The aim of the present study was to investigate the diversity and prevalence of GI parasites in goats and sheep in Jiangsu, Shaanxi and Hunan provinces of China, and to assess whether the age of animals, sampling season and feeding mode influence the distribution and infection of GI parasites. A total of 1,081 fecal samples collected from goats (n = 835) and sheep (n = 246) were detected by saturated saline flotation technique and nylon sifter elutriation and sieving method for eggs/oocysts, respectively. Based on the morphological observation of eggs and oocysts, one tapeworm, five nematodes, three trematodes and nineteen coccidia were identified, of which seven helminths belong to zoonotic parasites. The infection rate of parasites was 83.4% (902/1081) in total samples, 91.6% (765/835) in goats, and 55.7% (137/246) in sheep. The infection rate of coccidia was 71.0% (767/1081), and that of helminths was 56.2% (607/1081). The dominant species was E. alijeri (67.3%, 562/835) in goats, E. parva (30.1%, 74/246) in sheep. The highest prevalent helminths were Trichostrongylidae spp. in goats (58.3%, 487/835), and Moniezia spp. in sheep (22.76%, 56/246). Of 902 positive samples, 825 (91.5%, 825/902) contained multiple (2–10) parasites. The feeding mode, sampling season and regions were relevant risk factors which have significant influence on the occurrence of GI parasites in goats and sheep. The risk coefficient of parasite infection in autumn was 2.49 times higher than spring (Odds ratio = 2.49, 95% CI = 1.51–4.09, p < 0.001). Compared to raising on the high beds, the goats and sheep raising on the ground had the higher risk of parasite infection (OR = 3.91, 95% CI = 2.07–7.40, p < 0.001). The risk coefficient of parasite infection in Shaanxi and Hunan was 3.78 and 1.25 times higher than that in Jiangsu (OR = 3.78, 95% CI = 2.01–7.12, p < 0.001; OR = 1.25, 95% CI = 1.21–1.29, p < 0.001). These data are significant for the development of prevention strategies to minimise economic losses from small ruminant production and to reduce the risk of water and food infecting humans as vectors of zoonotic parasitic diseases.

Parasitism rate differs between herbivore generations in the univoltine, but not bivoltine, range.

With climate change, plant-feeding insects increase their number of annual generations (voltinism). However, to what degree the emergence of a new herbivore generation affects the parasitism rate has not been explored. We performed a field experiment to test whether the parasitism rate differs between the first and the second generations of a specialist leaf miner (Tischeria ekebladella), both in the naturally univoltine and bivoltine parts of the leaf miner's distribution. We found an interactive effect between herbivore generation and geographical range on the parasitism rate. The parasitism rate was higher in the first compared to the second host generation in the part of the range that is naturally univoltine, whereas it did not differ between generations in the bivoltine range. Our experiment highlights that shifts in herbivore voltinism might release top-down control, with potential consequences for natural and applied systems.

Automatic classification of parasitized fruit fly pupae from X-ray images by convolutional neural networks

The parasitoid wasp Diachasmimorpha longicaudata (Hymenoptera: Braconidae) has been used for the biological control of fruit fly larvae in many countries. Due to the large scale of production, quality control systems must be utilized to assess insect quality to optimize prerelease activities. However, the parasitism rate, and the unparasitized puparia, which become waste pupae, can only be known after waiting for the emergence of the adults from sampled pupae (ca. 16 days at 25 °C). This waiting time can result in resources being wasted. A way to speed up the quality control of pupal batches and increase the accuracy of the production process would be to combine digital radiography of the parasitized pupae and deep learning methods for the automatic classification of images. Therefore, the purpose of this work was to discriminate parasitized from waste pupae through X-ray images and to test the suitability of 7 Convolutional Neural Networks to classify the pupal images. Radiographic images from 11-day-old pupae allowed the in vivo identification of immature stages of the parasitoid, preserving the viability of the wasp. A positive correlation was found between the number of emerged parasitoids and the ones identified in the X-ray images. In terms of performance metrics, the accuracies achieved by all CNN-based neural architectures were higher than 97%, indicating a high predictive classification power. At least three of the CNNs tested showed great potential as classifiers of X-ray images of parasitized pupae and can be indicated for practical applications in quality control programs.

Acalypha ostryifolia: a natural refuge for Chloridea virescens and Helicoverpa zea (Lepidoptera: Noctuidae) in the Southern United States

Abstract The tobacco budworm, Chloridea virescens (F.), and corn earworm, Helicoverpa zea (Boddie) (heliothines), have had a long-intertwined relationship with respect to their importance as pests in agricultural production systems. Previous studies have examined the impacts of early-season wild host plants on local population density and distribution of these 2 insects on cultivated crops such as cotton, Gossypium hirsutum L., and soybean, Glycine max L. Additional studies have examined the importance of wild host plants, which act as a refuge of nonexposed populations of C. virescens and H. zea to insecticidal toxins from the soil bacterium, Bacillus thuringiensis (Bt) Berliner. The current study examined hophornbeam copperleaf, Acalypha ostryifolia Riddell, as a host plant for mid-late season populations of C. virescens and H. zea. Patches of A. ostryifolia were sampled along roadsides and the edges of fields from 2014 to 2020 in Mississippi, USA, to examine larval density, species composition, and parasitism of heliothines on this wild host plant. Insects were collected from the end of June through October. The largest densities (based on the number of caterpillars per sweep) of heliothines were over one larva per sweep. Overall, 49.5% of the collected caterpillars were determined to be tobacco budworms, while 50.5% were corn earworms. Parasitism rates ranged from approximately 1–30%, increasing throughout the season. In general, densities of heliothines encountered on A. ostryifolia were greater than densities reported for other wild host plants. Hophornbeam copperleaf is an important natural refuge for both heliothines from Bt toxins and synthetic insecticide applications.

Complex Effects of a Land-Use Gradient on Pollinators and Natural Enemies: Natural Habitats Mitigate the Effects of Aphid Infestation on Pollination Services.

Pollinators and natural enemies are essential ecosystem service providers influenced by land-use and by interactions between them. However, the understanding of the combined impacts of these factors on pollinator and natural enemy activities and their ultimate effects on plant productivity remains limited. We investigated the effects of local and landscape vegetation characteristics and the presence of herbivorous pests on pollination and biological control services and their combined influence on phytometer seed set. The study was conducted in a Mediterranean agro-ecosystem, encompassing ten shrubland plots spanning a land-use gradient. Within each plot, we placed caged and uncaged potted phytometer plants that were either aphid-infested or aphid-free. We quantified insect flower visitation, aphid predation and parasitism rates, and fruit and seed set. We found scale-dependent responses of pollinators and natural enemies to land-use characteristics. Flower species richness had a positive impact on aphid parasitism rates but a negative effect on pollinator activity. Notably, we found a more pronounced positive effect of natural areas on pollinator activity in aphid-infested compared to aphid-free plants, indicating a potentially critical role of natural habitats in mitigating the adverse effects of aphid infestation on pollination services. These results highlight the complex and interactive effects of land-use on pollinators and natural enemies, with significant implications for plant productivity.

Pilot Testing of an Area-Wide Biological Control Strategy against the Coffee Berry Borer in Colombia Using African Parasitoids.

The coffee berry borer (CBB), Hypothenemus hampei (Ferrari, 1867) (Coleoptera: Curculionidae: Scolytinae), native to Africa, is a major global insect pest of coffee. It has invaded many coffee production areas around the world that do not have natural enemies. In this study, two African parasitoids, Prorops nasuta Waterston (Hymenoptera: Bethylidae) and Phymastichus coffea Waterston (Hymenoptera: Eulophidae), were mass-reared for field release against H. hampei in Chinchiná, Colombia. More than 1.5 million wasps of each species were released on a 61-hectare coffee farm in replicated plots, resulting in parasitism rates of up to 7.7% for P. nasuta and 56.3% for P. coffea. This led to a maximum reduction in H. hampei field populations of 81% from dispersal coffee plots (old coffee crops before plant stumping) and 64.3% in colonization coffee plots (new coffee crops with active growing and fruiting plants) within the farm. As a result of this area-wide strategy, the percentage of CBB-infested coffee berries in colonization coffee plots decreased from 51.1 to 77.5% compared to coffee plots without parasitoid releases. This approach offers a promising alternative to the use of chemical insecticides and could be integrated into current pest management programs to control H. hampei.

Potential side effects of the interaction between Phthorimaea absoluta parasitoids: the exotic Dolichogenidea gelechiidivoris and the native Bracon nigricans

The coexistence and efficiency in pest control of introduced and native parasitoids can be challenging. Continuous observations of the cohabitation of parasitoid species could confirm the persistence of the introduced parasitoid in the ecosystem under co-existence scenarios. This study provides an example of such a co-existence for biocontrol of the invasive pest, Phthorimaea absoluta (Meyrick) (Lepidoptera: Gelechiidae). Two parasitoids, the introduced endoparasitoid Dolichogenidea gelechiidivoris (Marsh) (Hymenoptera: Braconidae) and the native ectoparasitoid Bracon nigricans Szépligeti (Hymenoptera: Braconidae) were released in cages containing a tomato plant infested with P. absoluta. Parasitism and killing rate of P. absoluta by both parasitoid species, and the parasitoid and P. absoluta population were monitored weekly. The parasitoid species coexisted for seven weeks in the experimental units. Parasitism by D. gelechiidivoris was significantly affected by the presence of B. nigricans, with 73% and 22% parasitism in the absence and presence of B. nigricans, respectively. Parasitism by B. nigricans was not affected by its co-existence with D. gelechiidivoris. The number of D. gelechiidivoris adults increased eight-fold in five weeks in the absence of B. nigricans, while less than the initial number of adults were present in co-existence with B. nigricans. The P. absoluta infestation declined from the fifth week to 98% lesser than the control in all the treatments, either D. gelechiidivoris or B. nigricans as standalone treatments, as well as in combination. Since B. nigricans negatively affected D. gelechiidivoris population growth, releases of this introduced parasitoid should be considered with caution in areas where B. nigricans occurs.

A Survey in Hawaii for Parasitoids of Citrus Whiteflies (Hemiptera: Aleyrodidae), for Introduction into Greece.

Whitefly species of Aleurocanthus spiniferus (Quaintance) and A. woglumi Ashby (Hemiptera: Aleyrodidae) are serious pests of citrus and other important fruit crops. The problem of citrus has initiated the successful introduction of several natural enemies for biocontrol programs in Hawaii and many other countries. Here, we summarized the history of infestation and biocontrol efforts of the two whiteflies in Hawaii for possible parasitoid importation into Greece. Two Platygasteridae (Amitus hesperidum Silvestri, A. spiniferus (Brethes), and three Aphelinidae (Encarsia clypealis (Silvestri), E. smithi (Silvestri), E. perplexa Huang, and Polaszek) were released in Hawaii for biocontrol of the citrus whiteflies during the period 1974-1999. The aphelinid Cales noacki Howard, purposely released for Aleurothrixus flococcus (Maskell) in 1982, was also reported to attack other whiteflies, including Aleurocanthus species, on citrus. An additional aphelinid parasitoid, Encarsia nipponica Silvestri, native to Japan and China, was accidentally introduced and found to attack both citrus whiteflies on the islands. Since the colonization of introduced parasitoids in infested fields on four Hawaiian Islands, no survey has been conducted to evaluate their potential impact. We conducted two short surveys during September-November 2022 on the islands of Kauai, Hawaii, and Oahu to introduce the dominant parasitoids to Greece for the biocontrol of A. spiniferus. Results showed that the infestation level was very low on Kauai, Hawaii, and Oahu Islands, with a mean infestation level range of 1.4-3.1 on Hawaii and Oahu Islands, mostly on pummelo and sweet orange, with no detection on the island of Kauai. The dominant parasitoid was characterized as Encarsia perplexa, using molecular analysis. Its parasitism rates ranged from 0 to 28% on the island of Hawaii and 11 to 65% on the island of Oahu. Emerged parasitoids have been reared in Greece for evaluation. This was the first field survey of Hawaii since the introduction and release of citrus whitefly natural enemies.

Evaluation of Telenomusremus (Hymenoptera: Platygastridae) as a biocontrol agent of Spodopteralitura (Lepidoptera: Noctuidae) based on two-sex life table and functional response analyses

BackgroundTelenomusremus Nixon is an important egg parasitoid of Spodoptera spp. pests and, as such, has potential as a biological control agent. Spodopteralitura (Fabricius) is a significant pest of many economically important crops worldwide. This study was conducted to evaluate the demographic parameters and functional response of T.remus on the S.litura eggs.ResultsT.remus can lay 186.90 eggs/female in the lifetime, adult preoviposition period was 0 days, total preoviposition period was 10.03 days, and the ratio of female and male offspring was 0.495 and 0.421, respectively. In addition, most females emerged from 24 h-old eggs, whereas most males emerged from 48 h-old eggs. The intrinsic rate of increase, finite rate of increase, net reproductive rate, mean generation time, and population doubling time were 0.3506 d–1 1.4199 d–1 92.45 offspring/individua, 12.91 days and 1.98 days, respectively. The net killing rate of T.remus on S.litura was 101.49 eggs/female, indicating the high capacity of T.remus to parasitize S.litura eggs. Moreover, the higher the egg density, the higher the parasitism rate by female T.remus, although there was a trend of parasitism stabilization at an egg density of 100, indicating a type II functional response curve for this parasitoid.ConclusionOverall, these findings suggest that T.remus can be efficiently reared on S.litura eggs and shows potential as biocontrol agent for this economically important pest species.