Buffalobur (Solanum rostratum Dunal) () is an invasive weed in China, identifying its pathogens is crucial for developing effective biological control measures. In this study, leaf samples from S. rostratum showing typical disease symptoms were collected in Liaoning and Jilin provinces, China. The isolated fungal pathogens were identified based on their morphological characteristics and by using molecular biology techniques. Pathogenicity was assessed by artificially inoculating spore suspensions from the fungal pathogen onto the seeds, isolated leaves, and plants of S. rostratum. The safety of the fungal pathogens for eight plant species was also evaluated. We then identified the following five fungal pathogens causing disease in S. rostratum in Liaoning and Jilin provinces: Alternaria alternata, Epicoccum sorghinum, Fusarium equiseti, Curvularia hawaiiensis, and Nigrospora oryzae. These fungal pathogens exhibited pathogenicity, with N. oryzae exhibiting the strongest pathogenicity and highest safety. N. oryzae demonstrated the highest inhibition rate against the radicle germination length of S. rostratum and showed robust pathogenicity towards both isolated leaves and plants. Notably, despite inducing mild reactions in corn, sorghum, rice, and tomatoes, N. oryzae did not impose any detrimental effects on the growth of these plants.

The egg parasitoid Anastatus japonicus is a key natural enemy in the biological control of various agricultural and forestry pests. It is particularly used against the brown marmorated stink bug Halyomorpha halys and the emerging defoliator pest Caligula japonica in East Asia. It has been proved that the eggs of Antheraea pernyi can be used as a factitious host for the mass production of A. japonicus. This study systematically documented the parasitic behaviour and developmental morphology exhibited by A. japonicus on the eggs of A. pernyi. The parasitic behaviour of A. japonicus encompassed ten steps including searching, antennation, locating, digging, probing, detecting, oviposition, host-feeding, grooming, and resting. Oviposition, in particular, was observed to occur in three stages, with the parasitoids releasing eggs during the second stage when the body remained relatively static. Among all the steps of parasitic behaviour, probing accounted for the longest time, constituting 33.1% of the whole time. It was followed by digging (19.3%), oviposition (18.5%), antennation (9.6%), detecting (7.4%), and the remaining steps, each occupying less than 5.0% of the total event time. The pre-emergence of adult A. japonicus involves four stages: egg (0 to 2nd day), larva (3rd to 9th day), pre-pupa (10th to 13th day), pupa (14th to 22nd day), and subsequent development into an adult. Typically, it takes 25.60 ± 0.30 days to develop from an egg to an adult at 25℃. This information increases the understanding of the biology of A. japonicus and may provide a reference for optimising reproductive devices.

Many parasitoids alter their reproductive behaviour in response to the quality of encountered hosts. They make adaptive decisions concerning whether to parasitise a potential host, the number of eggs laid on an accepted host, and the allocation of sex to their offspring. Here we present evidence that Goniozus jacintae Farrugia (Hymenoptera: Bethylidae), a gregarious ectoparasitoid of larval tortricids, adjusts its reproductive response to the size and developmental stage of larvae of the light brown apple moth (LBAM), Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae). Goniozus jacintae parasitises instars 3–6 of LBAM, but most readily parasitises the later, larger, instars. Brood sizes were bigger on larger hosts and brood sex ratios were female biased (proportion of males = 0.23) with extremely low variance (never >1 male in a brood at emergence), perhaps the most precise of all studied bethylids. Host size did not influence brood development time, which averaged 19.64 days, or the body size of male offspring. However, the size of females was positively correlated with host size and negatively correlated with brood size. The sizes of individual males and females were positively related to the average amount of host resource available to individuals within each brood, suggesting that adult body size is affected by scramble competition among feeding larvae. Average brood sizes were: 3rd instar host, 1.3 (SE ± 0.075); 4th instar, 2.8 (SE ± 0.18); 5th instar, 4.7 (SE ± 0.23); 6th instar, 5.4 (SE ± 0.28). The largest brood size observed was 8 individuals (7 females, 1 male) on the 6th instar of LBAM. These results suggest that later instars would give the highest yield to optimise mass-rearing of G. jacintae if used for augmentative biological pest control.

The symbiosis between microorganisms and host arthropods can cause biological, physiological, and reproductive changes in the host population. The present study aimed to survey facultative symbionts of the genera Wolbachia, Arsenophonus, Cardinium, Rickettsia, and Nosema in Cotesia flavipes (Cameron) (Hymenoptera: Braconidae) and Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae) in the laboratory and evaluate the influence of infection on the fitness of these hosts. For this purpose, 16S rDNA primers were used to detect these facultative symbionts in the host species, and the hosts' biological and morphological features were evaluated for changes resulting from the infection caused by these microorganisms. The bacterial symbionts studied herein were not detected in the D. saccharalis samples analysed, but the endosymbiont Wolbachia was detected in C. flavipes and altered the biological and morphological aspects of this parasitoid insect. The results of this study may help to elucidate the role of Wolbachia in maintaining the quality of populations/lineages of C. flavipes.

Entomopathogenic nematodes (EPNs) are closely associated with Popillia japonica and potentially used as their biological control agents, although field results proved inconsistent and evoked a continual pursuit of native EPNs more adapted to the environment. Therefore, we surveyed the Azorean Archipelago to isolate new strains of Heterorhabditis bacteriophora and to evaluate their virulence against the model organism Galleria mellonella under laboratory conditions. Six strains were obtained from pasture and coastal environments and both nematode and symbiont bacteria were molecularly identified. The bioassays revealed that Az172, Az186, and Az171 presented high virulence across the determination of a lethal dose (LD50) and short exposure time experiments with a comparable performance to Az29. After 72 hours, these virulent strains presented a mean determination of a lethal dose of 11 infective juveniles cm-2, a lethal time (LT50) of 34 hours, and achieved 40% mortality after an initial exposure time of only 60 minutes. Az170 exhibited an intermediate performance, whereas Az179 and Az180 were classified as low virulent strains. However, both strains presented the highest reproductive potential with means of 1700 infective juveniles/mg of larvae. The bioassays of the native EPNs obtained revealed that these strains hold the potential to be used in biological control initiatives targeting P. japonica because of their high virulence and locally adapted to environmental conditions.

Aphidius colemani is an important biological control agent, used in greenhouses and open fields against aphid pests. Despite this economical importance, A. colemani, along with A. transcaspicus and A. platensis, has gone through a complex taxonomical history. The three species have only recently gained status as separate species again, comprising the morphologically defined Aphidius colemani species group. Other than sporadic records probably as a consequence of escape from greenhouses, the A. colemani species group members prefer warmer regions and there are numerous records from South America, Southern Europe and Asia. Based on slide-mounted material collected in the period 1964–2001 in Africa, we describe five new species belonging to this group, and report A. colemani, A. transcaspicus and A. platensis from several African countries. This data opens questions about the origin of the group and presents potential for the diversification of biological control agents against aphid pests.

Cactoblastis cactorum (Berg) (Lepidoptera: Pyralidae), the cactus moth, is native to South America with a widespread distribution in Argentina. The larvae consume the interior of Opuntia spp. (Cactaceae) plants. The moth was used as a biocontrol agent against invasive non-native Opuntia spp. in many countries around the world. The cactus moth arrived unintentionally in Florida, USA, expanded its range and threatened Opuntia-based agriculture and natural ecosystems in southern North America. The insect is also a pest of cultivated O. ficus-indica L. in Argentina. An endemic South American parasitoid, Goniozus legneri Gordth (Hymenoptera: Bethylidae), is used in inundative biological control programmes against lepidopteran pests. The goal of this work was to evaluate G. legneri as a biocontrol agent to be used in inundative releases against C. cactorum. Mortality of C. cactorum by G. legneri was assessed at different spatial scales, as well as the interactions with Apanteles opuntiarum Martínez & Berta (Hymenoptera: Braconidae), a common Argentine natural enemy of C. cactorum. The ability of G. legneri to paralyse, parasitise and kill C. cactorum was confirmed. The paralysis inflicted on C. cactorum larvae reduced larval damage to the plants by 85%. Using two parasitoid species increased the mortality of C. cactorum larvae, but it was highly dependent on the order of their arrival. The combined mortality caused by both parasitoids was higher than a single one, in particular when G. legneri arrived first (56 ± 1%), suggesting asymmetric competition due to the preference of G. legneri attacking previously parasitised larvae. Goniozus legneri has potential as an inundative biocontrol agent of C. cactorum, but its interaction with the classical biocontrol agent A. opuntiarum needs to be considered.

The U.S. Department of Agriculture–Agricultural Research Service (USDA-ARS) has been a leader in weed science research covering topics ranging from the development and use of integrated weed management (IWM) tactics to basic mechanistic studies, including biotic resistance of desirable plant communities and herbicide resistance. ARS weed scientists have worked in agricultural and natural ecosystems, including agronomic and horticultural crops, pastures, forests, wild lands, aquatic habitats, wetlands, and riparian areas. Through strong partnerships with academia, state agencies, private industry, and numerous federal programs, ARS weed scientists have made contributions to discoveries in the newest fields of robotics and genetics, as well as the traditional and fundamental subjects of weed–crop competition and physiology and integration of weed control tactics and practices. Weed science at ARS is often overshadowed by other research topics; thus, few are aware of the long history of ARS weed science and its important contributions. This review is the result of a symposium held at the Weed Science Society of America’s 62nd Annual Meeting in 2022 that included 10 separate presentations in a virtual Weed Science Webinar Series. The overarching themes of management tactics (IWM, biological control, and automation), basic mechanisms (competition, invasive plant genetics, and herbicide resistance), and ecosystem impacts (invasive plant spread, climate change, conservation, and restoration) represent core ARS weed science research that is dynamic and efficacious and has been a significant component of the agency’s national and international efforts. This review highlights current studies and future directions that exemplify the science and collaborative relationships both within and outside ARS. Given the constraints of weeds and invasive plants on all aspects of food, feed, and fiber systems, there is an acknowledged need to face new challenges, including agriculture and natural resources sustainability, economic resilience and reliability, and societal health and well-being.

Arthropod species diversity enhances ecosystem productivity and sustainability by increasing pollination and biological control services. Although, it is declining rapidly due to conventional agricultural intensification, organic agriculture with reduced reliance on agronomic inputs can regenerate ecosystems' resilience and restore them. Here, we report whether hexapod communities differ on both types of farming systems in small-scale field plot experiments, wherein Maize variety AG-589 was grown organically and conventionally in the 2020 and 2021 seasons. Livestock manure was applied in organic fields, whereas nitrogen and phosphorous were used as synthetic fertilizers in conventional fields. Hexapods were sampled three weeks after sowing once a week from the middle rows of subplots from both organically and conventionally grown maize. Twelve species of herbivores and four species of predators were recorded. Hexapod abundance overall and that of herbivores only was higher in conventionally cultivated maize, while predator abundance was higher in organic maize. Herbivores species diversity and evenness were significantly higher in conventional maize. Predator species diversity and evenness were significantly higher in organic maize fields. We noted predator abundance, diversity, and evenness as strong predictors to lower herbivore populations. These findings suggest that organic farming conserves natural enemies’ biodiversity and regulates herbivores with increased provision of suitable habitats and prey resources for natural enemies, leading to enhanced relative abundance in their specialized niches. Thus, organic agriculture can potentially mediate better ecosystem services.

The present study evaluated the reproductive compatibility of Trichogramma pretiosum Riley, 1879, through an integrative approach using biological data and morphometry of three isofemale lines (isolines) collected from two geographical areas. These isolines differed in sequences of mitochondrial DNA and reproductive performance in the laboratory. The wasps used to initiate the isolines were collected in different environments: two lines from a Mediterranean climate in Irvine, California, USA, and one line from a tropical climate in Piracicaba, São Paulo, Brazil. Reproductive compatibility was studied by evaluating the sex ratio and number of adult offspring produced of all mating combinations between adults from these isolines. Morphometry was studied by measuring 26 taxonomically useful characters, followed by a multivariate analysis. For the allopatric matings among Brazilian and North American isolines, a low level of crossing incompatibility was recorded, in only one direction of the crosses; whereas the sympatric North American isolines were incompatible in both directions. Multivariate analysis of the morphometric data indicated no distinct groups, suggesting that despite the genetic and biological differences, the isofemale lines are morphologically similar.

Three polyphagous pest Liriomyza spp. (Diptera: Agromyzidae) have recently invaded Australia and are damaging horticultural crops. Parasitic wasps are recognized as effective natural enemies of leafmining species globally and are expected to become important biocontrol agents in Australia. However, the hymenopteran parasitoid complex of agromyzids in Australia is poorly known and its use hindered due to taxonomic challenges when based on morphological characters. Here, we identified 14 parasitoid species of leafminers based on molecular and morphological data. We linked DNA barcodes (5′ end cytochrome c oxidase subunit I (COI) sequences) to five adventive eulophid wasp species (Chrysocharis pubicornis (Zetterstedt), Diglyphus isaea (Walker), Hemiptarsenus varicornis (Girault), Neochrysocharis formosa (Westwood), and Neochrysocharis okazakii Kamijo) and two braconid species (Dacnusa areolaris (Nees) and Opius cinerariae Fischer). We also provide the first DNA barcodes (5′ end COI sequences) with linked morphological characters for seven wasp species, with three identified to species level (Closterocerus mirabilis Edwards & La Salle, Trigonogastrella parasitica (Girault), and Zagrammosoma latilineatum Ubaidillah) and four identified to genus (Aprostocetus sp., Asecodes sp., Opius sp. 1, and Opius sp. 2). Phylogenetic analyses suggest C. pubicornis, D. isaea, H. varicornis, and O. cinerariae are likely cryptic species complexes. Neochrysocharis formosa and Aprostocetus sp. specimens were infected with Rickettsia. Five other species (Cl. mirabilis, D. isaea, H. varicornis, Opius sp. 1, and Opius sp. 2) were infected with Wolbachia, while two endosymbionts (Rickettsia and Wolbachia) co-infected N. okazakii. These findings provide background information about the parasitoid fauna expected to help control the leafminers.

We tested the effectiveness of predation by the cyclopoid copepod Mesocyclops longisetus (Thiébaud, 1912) in Culicidae and Chironomidae larvae, aiming to test if (i) the introduction of copepods effectively controls mosquito larvae and (ii) the density of copepods is important for ensuring control. We conducted two semi-field experiments: the first involved 14 experimental runs over 75 consecutive days, compared in a randomized block design, four repetitions per treatment in each experimental run (block); and the second experiment involved a total of five experimental runs, lasting 25 and 33 days each. In the first experiment, culicid larvae were preyed on by copepods, especially at high copepod densities (15 copepods per litre), which reduced culicid densities by approximately 61% and 64% for different containers, considering that the environmental temperature declined linearly by about 10ºC from February (summer) to May (autumn) (32ºC to 22ºC). Even the lowest copepod density (5 per liter) produced a substantial reduction in the abundance of culicid larvae when chironomid larvae were abundant. On the other hand, there was no effective control of chironomid larvae. In the second experiment, increases in Culicidae and Chironomidae were concomitant with decreases in copepods. Thus, when the copepods were in high densities, there was no increase in insects, although the larvae of culicids were not eliminated from the experimental units. We conclude that the introduction of copepods in small containers and ponds can be useful for the control of culicid larvae without harming chironomid populations, and densities up to 15 per litre are recommended, although even low densities cause substantial reduction.

Native Cirsium species play an important role in landscapes across North America. Hadroplontus litura (F.) (formerly Ceutorhynchus litura), the stem-mining weevil and biological control agent of Canada thistle [Cirsium arvense (L.) Scop.] can complete its life cycle on five Cirsium species native to the upper Midwest. Although these five Cirsium species are within the fundamental host range of H. litura, as determined by host-range tests, we wanted to explore whether phenological differences among Cirsium species help define the field ecological host range of H. litura. The objective of this study was to determine the phenology of Cirsium species native to the upper Midwest in relation to C. arvense and H. litura. Our goal was to explore whether shoots of native Cirsium species could escape H. litura shoot oviposition in spring due to delayed shoot emergence relative to C. arvense. Soil cumulative growing degree days (GDD) were a superior predictor of shoot emergence for perennial Cirsium species or initiation of leaves in biennial Cirsium species, with a 2.4 times larger effect on time to emergence relative to air GDD. All native Cirsium species initiated new leaves or shoots before C. arvense shoot emergence, even when native Cirsium species growth was delayed in the spring. In turn, C. arvense shoots emerged approximately 1 to 3 wk before female H. litura began to lay eggs. As such, all native Cirsium plants had shoots available for H. litura oviposition. There was no phenological separation between native Cirsium and C. arvense shoot emergence or initiation that would render native Cirsium species safe from H. litura attack. Based on the phenology of shoot emergence or initiation in the spring, all tested Cirsium species native to the upper Midwest would be within the ecological host range of H. litura.

Non-cultivated areas are resting, overwintering, feeding, and/or reproducing habitats for insects, and also places from where crop areas are colonized; thus, they are essential for understanding the biological control programs in agroecosystems. We developed a simulation model for a non-cultivated area of Buenos Aires province (Argentina), and we analyzed the control of Nezara viridula achieved by the action of two parasitoids: the oophagous Trissolcus basalis and the tachinid Trichopoda giacomellii, which attack older nymphs and adults. The model is a discrete time, deterministic, phenomenological, spatially homogeneous with a 1-week time interval simulation model, based on the age-structure and/or stage-structure of N. viridula and its two parasitoids. The host–parasitoid interactions were combined with a degree-day model affecting development times of T. giacomellii pupae and T. basalis pre-imaginal stages. The simultaneous attack of both parasitoid species enables the persistence of the system at low host densities, mediated by the functional response of the parasitoids, identified as population regulation factors. However, if only one parasitoid exists (i.e., only T. basalis or only T. giacomellii) the interaction N. viridula–parasitoid persisted but at higher density of N. viridula. These results explain the successful biological control of N. viridula after the introduction of T. basalis in the 1980s, when T. giacomellii was the only parasitoid present, unable to control N. viridula. Our model shows an indirect competition when both parasitoids are present: the attack of one of them diminished the potential number of hosts available to the other parasitoid species. In the field this interaction is obscured by the hibernation period which acted as a reset mechanism affecting the density and age/stage structure of all three populations. Our model was supported by field observations, and never exhibited the extinction of any of the parasitoids from the interaction.

The likelihood of parasitoids establishing in new geographic regions depends upon the availability of suitable host species. Identifying these hosts and the degree of their suitability is particularly important when they include species that are economically important as pests. In laboratory studies, we examined the suitability of 47 species of Lepidoptera as potential hosts of a parthenogenetic strain of the gregarious parasitoid Cotesia vanessae (Hymenoptera: Braconidae). Previously known from Eurasia and northern Africa, the first known recovery of C. vanessae in North America was in 2009. C. vanessae completed development in 34 species, of which three were known hosts (Noctuidae) and 31 (30 Noctuidae, 1 Nymphalidae) were not. Many of these noctuid species are economic pests. Parasitoid fitness was generally highest on species of Plusiinae (Noctuidae), measured as either percentage of successful parasitism, developmental time, or number and mass of F1 progeny. Closely related species were generally similar in their suitability as hosts. In some cases, parasitoid eggs or larvae were killed by the immune system of the parasitized host, but the host eventually failed to excrete food waste, did not pupate, and ultimately died. Such cases reached up to 100% mortality depending upon the lepidopteran species. The suitability of many species of noctuid pests as hosts for C. vanessae suggests that this parasitoid will become established widely throughout North America and may help to suppress populations of some pest species.

A steady supply of hosts at the susceptible stage for parasitism is a major component of mass rearing parasitoids for biological control programs. Here we describe the effects of storing 5th instar Plodia interpunctella larvae in dormancy on subsequent host development in the context of host colony maintenance and effects of the duration of host dormancy on the development of Habrobracon hebetor parasitoids reared from dormant hosts. We induced dormancy with a combination of short daylength (12L:12D) and lower temperature (15°C), conditions known to induce diapause in this species, and held 5th instar larvae of P. interpunctella for a series of dormancy durations ranging from 15 to 105 days. Extended storage of dormant 5th instar larvae had no significant impacts on survival, development, or reproductive potential of P. interpunctella, reinforcing that dormant hosts have a substantial shelf life. This ability to store hosts in dormancy for more than 3 months at a time without strong negative consequences reinforces the promise of using dormancy to maintain host colonies. The proportion of hosts parasitized by H. hebetor did not vary significantly between non-dormant host larvae and dormant host larvae stored for periods as long as 105 days. Concordant with a prior study, H. hebetor adult progeny production from dormant host larvae was higher than the number of progeny produced on non-dormant host larvae. There were no differences in size, sex ratio, or reproductive output of parasitoids reared on dormant hosts compared to non-dormant hosts stored for up to 105 days. Larval development times of H. hebetor were however longer when reared on dormant hosts compared to non-dormant hosts. Our results agree with other studies showing using dormant hosts can improve parasitoid mass rearing, and we show benefits for parasitoid rearing even after 3 months of host dormancy.

Megathyrsus maximus is nonnative in the neotropics, with a tall form that is commonly used as a forage grass and a smaller-statured form that is considered invasive in south Texas, USA. Biological control researchers are challenged to find an agent that will attack the short form, but not the desirable tall form in other parts of the neotropics. We conducted molecular analyses on 155 Megathyrsus maximus samples from its native range in Africa and compared them with U.S. short-form samples to help determine the geographic origins of its invasion. We found eight distinct genotypes in 34 short-form samples from Texas and Florida, USA. The highest genetic similarity of invasive samples was with plants from South Africa, while highest matches for the desirable tall form were from Kenya, Uganda, Ivory Coast, and Zambia. Ongoing biological control agent exploration and research has found agents from Kenya that are associated with an M. maximus genotype not well matched to the invasive short form, thus leading to a lack of rearing success. Two eriophyoid mite agents from the genetic match locality in South Africa have been evaluated but are not sufficiently host specific, as they develop on both the short and tall forms. Additional exploration is needed at the genetic match populations in South Africa to discover and evaluate potential biological control agents for the invasive form of M. maximus.

Insects are mass-reared for release for biocontrol including the sterile insect technique. Insects are usually reared at temperatures that maximize the number of animals produced, are chilled for handling and transport, and released into the field, where temperatures may be considerably different to those experienced previously. Insect thermal biology is phenotypically plastic (i.e. flexible), which means that there may exist opportunities to increase the performance of these programmes by modifying the temperature regimes during rearing, handling, and release. Here we synthesize the literature on thermal plasticity in relation to the opportunities to reduce temperature-related damage and increase the performance of released insects. We summarize how and why temperature affects insect biology, and the types of plasticity shown by insects. We specifically identify aspects of the production chain that might lead to mismatches between the thermal acclimation of the insect and the temperatures it is exposed to, and identify ways to harness physiological plasticity to reduce that potential mismatch. We address some of the practical (especially engineering) challenges to implementing some of the best-supported thermal regimes to maximize performance (e.g. fluctuating thermal regimes), and acknowledge that a focus only on thermal performance may lead to unwanted trade-offs with other traits that contribute to the success of the programme. Together, it appears that thermal physiological plasticity is well-enough understood to allow its implementation in release programmes.

The objective of this study was to evaluate the predatory activity of the nematophagous fungus Duddingtonia flagrans on infective larvae of gastrointestinal nematodes from dairy heifers in different conditions (shaded and sunny) of a silvopastoral system (SPS) on an agroecological farm. Ten Jersey heifers were divided into two groups: treated (received pellets containing fungus); and control (received pellets without fungus). Twelve hours after fungus administration, faeces samples were collected for in vitro efficacy tests. The animals then remained for 8 h in the experimental pasture area. At the end of this period, 20 faecal pads (10 treated and 10 control) were selected. Pasture, faecal pad and soil collections occurred at intervals of seven days (d), totalling four assessments over 28 d. To evaluate the influence of the conditions shaded and sunny, we registered the condition of the location of each faecal pad per hour. After 12 h of gastrointestinal transit in dairy heifers, a reduction of 65% was obtained through the in vitro test. The treated group presented a lower number of infective larvae (L3) in the faecal pad and upper pasture. Differences in numbers of L3 were observed between the conditions (sunny and shaded) in the faecal pad of the control group; while in the treated group there were no differences between the conditions. The predatory activity of the fungus was efficient over time in the shaded and sunny conditions of an SPS, decreasing the parasite contamination during the pasture recovery time in a subtropical climate.