Sublethal effects of a spiromesifen and abamectin combination on Tetranychus urticae (Acari: Tetranychidae) and its predators Phytoseiulus persimilis and Amblyseius swirskii (Acari: Phytoseiiidae).

The two-spotted spider mite, Tetranychus urticae Koch (TSSM), is an important cosmopolitan pest of agricultural crops that is often managed in greenhouses by augmentation of predatory mites in combination with acaricides. Here we examined the transgenerational effects of low lethal concentrations of a widely-used acaricide, Oberon Speed® (a combination of spiromesifen and abamectin), on the life history traits and population growth of T. urticae and two of its predators, Phytoseiulus persimilis Athias-Henriot and Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae). The concentrations employed corresponded to the LC10, LC20 and LC30 values estimated for TSSM protonymphs 48 h post-exposure in a topical bioassay, which yielded an LC50 value of 207.2 ppm. Parental exposure of TSSM to all three low concentrations increased the total developmental time of progeny; both the LC20 and LC30 treatments reduced adult longevity and number of oviposition days, but only the LC30 treatment increased the preoviposition period. Similarly, both the LC20 and LC30 treatments significantly reduced life table parameters (r, R0, λ, and GRR), and increased generation time (T) and population doubling time (DT). Although maternal exposure to the acaricide had various impacts on progeny life history, A. swirskii was less affected than P. persimilis, suggesting the former species would be more compatible for integration with Oberon Speed® for control of T. urticae in greenhouse vegetable production.

Metabolic reprogramming of Helicoverpa armigera larvae by HearNPV facilitates viral replication and host immune suppression.

Baculoviruses are highly evolved parasites that genetically reprogram the developing phenotype of their host insect to produce a vessel for virus replication and dispersal. Here we show that larvae of Helicoverpa armigera infected with HearNPV accumulate glucose in the midgut, which reduces food consumption and alters the dynamics of pathways governing metabolism and immunity. We used transcriptomics to demonstrate the role of the insulin signalling pathway in regulating the HearNPV infection process. Dietary restriction decreased mortality of infected larvae and reduced viral replication prior to death, whereas dietary supplementation with glucose produced the opposite effects. The expression of most tricarboxylic acid cycle (TCA) and energy metabolism-related genes was reduced in infected larvae, whereas the expression of immunity-, glycolysis- and insulin-related genes was enhanced. Treatment of infected larvae with insulin increased their survival, reduced viral replication and inhibited climbing behaviour compared to a control treatment with DMSO, whereas RNAi suppression of the insulin receptor gene produced the opposite effects. Inhibition of glycolysis with dichloroacetate (DCA) promoted viral replication and accelerated larval death, but inhibition of the TCA cycle with 2-deoxyglucose (2-DG) did not, although both diminished climbing behaviour. This work demonstrates that successful baculovirus infections hinge on metabolic reprogramming of the host and concurrent suppression of immune responses in the larval midgut, with the insulin signalling pathway mediating a trade-off between glucose metabolism and virus resistance.

A roadmap for ladybird conservation and recovery.

Ladybirds (Coleoptera: Coccinellidae) provide services that are critical to food production, and they fulfill an ecological role as a food source for predators. The richness, abundance, and distribution of ladybirds, however, are compromised by many anthropogenic threats. Meanwhile, a lack of knowledge of the conservation status of most species and the factors driving their population dynamics hinders the development and implementation of conservation strategies for ladybirds. We conducted a review of the literature on the ecology, diversity, and conservation of ladybirds to identify their key ecological threats. Ladybird populations are most affected by climate factors, landscape composition, and biological invasions. We suggest mitigating actions for ladybird conservation and recovery. Short-term actions include citizen science programs and education, protective measures for habitat recovery and threatened species, prevention of the introduction of non-native species, and the maintenance and restoration of natural areas and landscape heterogeneity. Mid-term actions involve the analysis of data from monitoring programs and insect collections to disentangle the effect of different threats to ladybird populations, understand habitat use by taxa on which there is limited knowledge, and quantify temporal trends of abundance, diversity, and biomass along a management-intensity gradient. Long-term actions include the development of a worldwide monitoring program based on standardized sampling to fill data gaps, increase explanatory power, streamline analyses, and facilitate global collaborations.

Las catarinas (Coleoptera: Coccinellidae) proporcionan servicios que son críticos para la producción de alimento, y juegan un papel ecológico como fuente de alimento para depredadores. Sin embargo, la riqueza, abundancia y distribución de catarinas están en peligro debido a muchas amenazas antropogénicas. La carencia de conocimiento sobre el estatus de conservación de la mayoría de las especies y los factores que inciden en su dinámica poblacional dificulta el desarrollo e implementación de estrategias de conservación para las catarinas. Realizamos una revisión de la literatura sobre la ecología, diversidad y conservación de catarinas para identificar sus amenazas ecológicas clave. Las poblaciones de catarinas fueron afectadas mayormente por factores climáticos, composición del paisaje e invasiones biológicas. Proponemos acciones de mitigación para la conservación y recuperación de catarinas. Acciones a corto plazo incluyen programas de ciencia y educación ciudadana, medidas de protección para la recuperación de hábitat y de especies amenazadas, prevención de la introducción de especies no nativas y el mantenimiento y restauración de áreas naturales y la heterogeneidad del paisaje. Acciones a mediano plazo implican el análisis de datos obtenidos de programas de monitoreo y colecciones de insectos para desenmarañar el efecto de las diferentes amenazas a las poblaciones de catarinas, comprender el uso del hábitat por taxa de los que se tiene conocimiento limitado y cuantifica las tendencias temporales de la abundancia, diversidad y biomasa a lo largo de un gradiente de intensidad de manejo. Acciones a largo plazo incluyen el desarrollo de un programa de monitoreo a nivel mundial basado en muestreos estandarizados para subsanar la falta de datos, incrementar el poder explicativo, optimizar los análisis y facilitar colaboraciones globales.

The Ecological Significance of Aphid Cornicles and Their Secretions.

Aphid cornicles are abdominal appendages that secrete an array of volatile and nonvolatile compounds with diverse ecological functions. The emission of alarm pheromones yields altruistic benefits for clone-mates in the aphid colony, which is essentially a superorganism with a collective fate. Secreted droplets also contain unsaturated triglycerides, fast-drying adhesives that can be lethal when smeared on natural enemies but more often impede their foraging efficiency. The longest cornicles have evolved in aphids that feed in exposed locations and are likely used to scent-mark colony intruders. Reduced cornicles are associated with reliance on alternative defenses, such as the secretion of protective waxes or myrmecophily. Root-feeding and gall-forming lifestyles provide protected feeding sites and are associated with an absence of cornicles. In some eusocial gall-formers, soldier morphs become repositories of cornicle secretion used to defend the gall, either as menopausal apterae that defend dispersing alatae or as sterile first instars that dispatch predators with their stylets and use cornicle secretions as a construction material for gall repair. Collectively, the evidence is consistent with an adaptive radiation of derived cornicle functions molded by the ecological lifestyle of the aphid lineage.

Baculoviruses hijack the visual perception of their caterpillar hosts to induce climbing behaviour thus promoting virus dispersal.

Baculoviruses can induce climbing behaviour in their caterpillar hosts to ensure they die at elevated positions to enhance virus transmission, providing an excellent model to study parasitic manipulation of host behaviour. Here, we demonstrate that climbing behaviour occurred mostly during daylight hours, and that the height at death of Helicoverpa armigera single nucleopolyhedrovirus (HearNPV)-infected larvae increases with the height of the light source. Phototaxic and electroretinogram (ERG) responses were enhanced after HearNPV-infection in host larvae, and ablation of stemmata in infected larvae prevented both phototaxis and climbing behaviour. Through transcriptome and quantitative PCR, we confirmed that two opsin genes (a blue light-sensitive gene, HaBL; and a long wave-sensitive gene, HaLW) as well as the TRPL (transient receptor potential-like channel protein) gene, all integral to the host's visual perception pathway, were significantly upregulated after HearNPV infection. Knockout of HaBL, HaLW, or TRPL genes using the CRISPR/Cas9 system resulted in significantly reduced ERG responses, phototaxis, and climbing behaviour in HearNPV-infected larvae. These results reveal that HearNPV alters the expression of specific genes to hijack host visual perception at fundamental levels-photoreception and phototransduction-in order to induce climbing behaviour in host larvae.

Molecular characterization of insulin receptor (IR) in oriental fruit moth, Grapholita molesta (Lepidoptera: Tortricidae), and elucidation of its regulatory roles in glucolipid homeostasis and metamorphosis through interaction with miR-982490.

As an intermediate molecule in the Insulin/Insulin-like growth factor signalling pathway (IIS), the insulin receptor (IR) plays vital roles linking nutritional signals to the downstream regulation of metabolic homeostasis, development, metamorphosis, reproduction and stress responses. In the present study, we describe the molecular characteristics of IR in the cosmopolitan fruit boring pest, Grapholita molesta, and its predicted posttranscription regulator miR-982490, and elucidate its regulatory roles in glucolipid homeostasis and metamorphosis. Phylogenetic and domain analyses indicate that lepidopteran IRs normally cluster within families, and that four main domains are conserved in GmIR and those of other Lepidoptera. Bio-informatic prediction, synchronic expression profile evaluation and dual luciferase reporter assays indicated negative regulation of GmIR by miR-982490. Injection of miR-982490 agomir into fifth instar larvae yielded effects similar to dsGmIR injection, resulting in enhanced levels of trehalose and triglyceride in haemolymph, and reduced pupation success and pupal weight, both of which could be rescued by co-injection of dsGmIR and miR-982490 antagomir. We infer that GmIR regulates glucolipid homeostasis and affects G. molesta metamorphosis via interactions with its posttranscriptional regulator miR-982490. This study expands our understanding of the regulatory network of IIS in insect nutritional homeostasis and development.

Optimization of silver nanoparticle biosynthesis by entomopathogenic fungi and assays of their antimicrobial and antifungal properties.

Entomopathogenic fungi produce extracellular enzymes to facilitate host infection, and these can also reduce metal ions to produce nanoparticles. In the present study, three isolates of Beauveria bassiana (JS1, JS2 and KA75) and one isolate of Metarhizium anisopliae (TT1) were evaluated for their ability to biosynthesize silver nanoparticles (AgNPs). In general, the best yields and smallest NP sizes were obtained at 60 °C and pH 7.0. Nanoparticle properties were studied using UV-visible spectroscopy, Fourier transform infrared spectroscopy, and scanning electron microscopy. Biosynthesized AgNPs ranged from 23 to 101 nm across, the smallest being produced by KA75, and the largest by TT1. UV-visible spectroscopy confirmed peak absorption of AgNPs in the range of 420-454 nm. AgNP antibacterial activity was highest against the gram-negative bacteria Pectobacterium carotovorum and Erwinia amylovora, and lower against the gram-positive Bacillus sp. AF1. JS1-AgNPs caused the greatest growth restriction of P. carotovorum at a concentration of 75 µL/mL at lower OD600 (0.25). Smaller AgNPs generally had better antifungal activities against B. bassiana, M. anisopliae, and the plant-pathogenic Rhizoctonia solani. Complete inhibition of vegetative growth of the JS2 fungus was obtained with TT1-synthesized AgNPs at 15 µL/mL, a control level similar to half the field rate of benomyl. Generally, fungal sporulation was more inhibited than vegetative growth, and all AgNPs showed good compatibility with the fungi at low concentrations. We conclude that AgNPs mycosynthesized by these entomopathogens have promising antibacterial and antifungal properties with potential for various applications.

The transgenerational consequences of maternal parasitism for aphid life history and suitability for subsequent parasitism.

Aphids parasitized in later instars can give birth to several nymphs before their reproduction is curtailed by the developing parasitoid. We examined the life histories of Aphis fabae Scopoli born to mothers parasitized by Lysiphlebus fabarum Marshall, and their suitability as subsequent hosts, to test the 'fecundity compensation' hypothesis. Maternal parasitism negatively impacted life history parameters, resulting in reduced estimates of population increase (rm, R0, and λ), and increased generation time (GT) and doubling time (DT). These impacts were greater when the larva developing in the mother turned out to be female rather than male, and greater still when mothers were superparasitized. Maternal parasitism produced aphids with shorter hind tibia (HTL), at birth and at maturity, but their developmental time was unaffected. Although female L. fabarum readily accepted such aphids for oviposition, rates of mummification and wasp emergence were lower, and more so when the maternal parasitoid was female. The resulting parasitoids took longer to develop than progeny from control wasps, had shorter HTLs, lower egg loads, smaller eggs, and produced fewer mummies with lower rates of adult emergence, all differences that were more pronounced when the maternal parasitoid was female. The progeny of these wasps exhibited similar impairments to these biological parameters as their parents, demonstrating that the negative impacts of development in maternally parasitized hosts extended for at least two generations. Thus, our results do not support fecundity compensation, but suggest that any benefits of post-parasitism reproduction will be offset by reduced fitness in both aphid progeny and the parasitoids that develop in them.

FoxO-promoted peroxiredoxin1 expression induced by Helicoverpa armigera single nucleopolyhedrovirus infection mediates host development and defensive responses.

Helicoverpa armigera single nucleopolyhedrovirus (HearNPV) has a long coevolutionary history with its host, exerting profound effects on larval development, physiology and immune responses, although the mechanisms mediating these effects remain unclear. We demonstrate that HearNPV infection constrains the growth and development of larvae by inducing high levels of reactive oxygen species (ROS), which increase the expression of forkhead box O transcription factor (FoxO). FoxO upregulates the expression of peroxiredoxin 1 (Prx1) which serves to regulate larval development and immune responses following HearNPV infection. Collectively, our results provide novel insights into the role of Prx1 in larval development and immunity subsequent to HearNPV infection. Further investigation of the oxidative stress induced by HearNPV in H. armigera and its interactions with host immunity could yield novel insights useful in agricultural pest control.

Comparative Transcriptome Analysis Reveals Genetic Mechanisms of Sugarcane Aphid Resistance in Grain Sorghum.

The sugarcane aphid, Melanaphis sacchari (Zehntner) (Hemiptera: Aphididae) (SCA), has become a major pest of grain sorghum since its appearance in the USA. Several grain sorghum parental lines are moderately resistant to the SCA. However, the molecular and genetic mechanisms underlying this resistance are poorly understood, which has constrained breeding for improved resistance. RNA-Seq was used to conduct transcriptomics analysis on a moderately resistant genotype (TAM428) and a susceptible genotype (Tx2737) to elucidate the molecular mechanisms underlying resistance. Differential expression analysis revealed differences in transcriptomic profile between the two genotypes at multiple time points after infestation by SCA. Six gene clusters had differential expression during SCA infestation. Gene ontology enrichment and cluster analysis of genes differentially expressed after SCA infestation revealed consistent upregulation of genes controlling protein and lipid binding, cellular catabolic processes, transcription initiation, and autophagy in the resistant genotype. Genes regulating responses to external stimuli and stress, cell communication, and transferase activities, were all upregulated in later stages of infestation. On the other hand, expression of genes controlling cell cycle and nuclear division were reduced after SCA infestation in the resistant genotype. These results indicate that different classes of genes, including stress response genes and transcription factors, are responsible for countering the physiological effects of SCA infestation in resistant sorghum plants.

The parental effects of body size on developmental phenotype in Harmonia axyridis.

Body size is a trait with many potential impacts on fitness. Adult body size can affect the strength of condition-dependent parental effects that determine offspring phenotypes, with potentially important transgenerational consequences. In a preliminary experiment, larval food deprivation (30 min daily access) created Harmonia axyridis Pallas (Coleoptera: Coccinellidae) females that weighed <50% of controls reared on ad libitum food (eggs of Ephestia kuehniella Zeller). Although only 1/3 of larvae survived to adulthood in the 30 min treatment, adult pairs produced eggs that were not significantly different in size from those of pairs fed ad libitum as larvae. Less extreme larval food deprivation (4 h daily access) was used to create a cohort of H. axyridis that weighed <60% of controls reared on ad libitum food. Small couples had lower 20-day fecundities and reduced egg fertility relative to large couples. Both egg and pupal periods were shortest when both parents were small, and longest when both parents were large, with reciprocal crosses intermediate. There were no consistent effects of parental body size on larval development time, but the progeny of small females mated to large males pupated later than other treatments. Progeny of large pairs had the heaviest adult weights at emergence, and progeny of small pairs, the lightest, with the progeny of reciprocal crosses intermediate. Small females produced the lightest female offspring, whereas small males sired the lightest male offspring, suggesting stronger responses to epigenetic signals from parents of the same sex. These results indicate that H. axyridis cohorts maturing with abundant food will produce progeny with larger potential body size and fitness, whereas those experiencing food limitation will confer size and fitness limitations to the subsequent generation, with potentially important implications for short-term population dynamics.

Behavioral and Developmental Responses of Habrobracon hebetor (Hymenoptera: Braconidae) to Larvae of Helicoverpa armigera (Lepidoptera: Noctuidae) Inoculated With Various Concentrations of Bacillus thuringiensis var. kurstaki (Bacillales: Bacillacae).

Bacillus thuringiensis Berliner subsp. kurstaki (Btk) and Habrobracon hebetor Say are both biological control agents of Helicoverpa armigera Hubner. The present study evaluated their compatibility for combined application against this pest by examining the acceptability of Btk-inoculated hosts for H. hebetor females and testing for negative life-history impacts on developing progeny. Second-instar H. armigera larvae fed for 72 h on potted chickpea plants treated with three concentrations of Btk (LC15, LC35, and LC70) and were then used in bioassays of parasitoid development and parasitism behavior. Survival of parasitoids was significantly reduced, and immature development prolonged, on hosts fed chickpea plants treated with LC35 and LC70  Btk, but not on plants treated with LC15  Btk. Parasitoids failed to discriminate against hosts treated with LC15 or LC35  Btk in choice tests, but attacked fewer hosts treated with LC70  Btk, paralyzing and parasitizing more healthy hosts, and laying more eggs on them. In contrast, a no-choice test revealed that more hosts treated with LC35 and LC70  Btk were paralyzed compared with control or LC15-treated hosts, but the numbers of hosts parasitized and eggs laid did not vary among Btk treatments. Thus, females required an experience with healthy hosts, as they had in the choice test, to discriminate against diseased ones. We conclude that H. hebetor and Btk are compatible for joint application against H. armigera, which could potentially improve biological control of this pest.

Physiological responses of plants and mites to salicylic acid improve the efficacy of spirodiclofen for controlling Tetranychus urticae (Acari: Tetranychidae) on greenhouse tomatoes.

Salicylic acid (SA) is a signaling molecule that can induce plant resistance to certain herbivores. Although the role of jasmonic acid in mediating mite-tomato plant interactions has been well studied, the role of salicylic acid has not. This study examined how the application of exogenous SA, via its effects on tomato plant physiology, alters the activity of mite digestive enzymes, mite energy reserves, and mite susceptibility to spirodiclofen. Enzymatic activity-including superoxide dismutase, ascorbate peroxidase, guaiacol peroxidase, polyphenol oxidase, and phenylalanine ammonia-lyase-along with contents of total phenolic, hydrogen peroxide, and total chlorophyll significantly increased in plants 24 h after treatment with 2 mM of SA. In contrast, catalase activity significantly decreased in treated plants, and malondialdehyde content was unaffected. Mites fed on tomato plants treated with SA had significantly lower glutathione S-transferase, esterase, α-amylase, and aminopeptidase activities than those fed on control plants. Energy reserve analyses demonstrated a significant decrease in contents of lipid, protein, and glycogen in mites fed on SA-treated plants, whereas carbohydrate content significantly increased. The LC50 of spirodiclofen was decreased 1.8-fold for Tetranychus urticae fed on SA-treated tomato plants compared to controls. Treatment of adult mites with 2 mM SA on leaf discs did not cause any direct mortality after 24 h. Finally, a greenhouse bioassay confirmed that spider mite mortality following exposure to spirodiclofen was significantly higher on SA plants than on control plants. Mortality of mites exposed to half of the recommended rate of spirodiclofen was similar to those exposed to the recommended rate when they were held on treated plants. These results have valuable implications for T. urticae management programs in tomato production.

Cornicle secretions by Aphis fabae (Hemiptera: Aphididae) result in age-dependent costs and improved host suitability for Lysiphlebus fabarum (Marshall) (Hymenoptera: Braconidae).

We examined the life history consequences of cornicle secretion by Aphis fabae Scopoli in second and fourth instars, and its effects on host suitability for its parasitoid, Lysiphlebus fabarum (Marshall). Cornicle secretion did not affect aphid fecundity, but secretion in the second instar enhanced life table parameters, whereas secretion in the fourth instar affected them negatively, suggesting a higher cost of secretion in later instars. Secretion in either instar improved host suitability for L. fabarum. Although control and treated aphids were parasitized at similar rates, and with similar success, wasps developed faster and emerged as larger adults in aphids that had secreted, regardless of instar. Transgenerational effects were also evident. Progeny emergence was higher when parental wasps developed in fourth instars than in seconds, whether aphids secreted or not, and progeny were larger when parental hosts secreted in the second instar, but not in the fourth. Secreting fourth instars were preferred to controls by L. fabarum females in choice tests, but not secreting second instars, and fourth-instar secretion improved wasp emergence. When control aphids were attacked, second instars were more likely to secrete than fourth instars, whereas the latter were more likely to kick the parasitoid. Cornicle secretion reduced the probability of subsequent secretion events and the frequency of other aphid defensive behaviors, indicating energetic tradeoffs among defensive tactics. Overall, our results revealed that cornicle secretion by immature A. fabae exacts both physiological and behavioral costs and results in improved host suitability for its parasitoid.

No nutritional benefits of egg cannibalism for Coleomegilla maculata (Coleoptera: Coccinellidae) on a high-quality diet.

Egg cannibalism serves various functions in the Coccinellidae. Here we examined the fitness consequences of egg cannibalism by neonates, fourth instar larvae, and prereproductive adults of Coleomegilla maculata DeGeer, with beetles fed a diet of Ephestia kuehniella Zeller eggs. Cannibalism of two eggs by neonates had no effect on development, and cannibalism of five eggs by fourth instars did not benefit any aspect of reproduction, but delayed pupation slightly. Cannibalism of eggs by pre-reproductive adults had no effect on reproductive success in any combination of reciprocal crosses of cannibals and non-cannibals. Females did not recognize, nor avoid consuming, their own clutches, and cannibalism propensity did not change following mating and onset of oviposition in either sex. These results contrast with those for more strictly aphidophagous species in which larvae gain developmental benefits, and females may recognize and avoid filial egg clusters while using cannibalism to interfere with conspecific females, whereas males reduce egg cannibalism after mating because they cannot recognize filial clusters. Egg cannibalism may confer developmental benefits to C. maculata when diet is suboptimal, as previously shown, but no such benefits were evident on the high-quality E. kuehniella egg diet. Female C. maculata do not require aphids to reproduce and distribute their eggs broadly in the environment, given that larvae can develop on pollen and non-aphid prey. Thus, C. maculata is not subject to the intraspecific competition that selects for cannibalism in more aphidophagous species, and also lacks many secondary adaptations associated with the behaviour.

Differential impacts of six insecticides on a mealybug and its coccinellid predator.

Broad-spectrum insecticides may disrupt biological control and cause pest resurgence due to their negative impacts on natural enemies. The preservation of sustainable pest control in agroecosystems requires parallel assessments of insecticide toxicity to target pests and their key natural enemies. In the present study, the leaf dipping method was used to evaluate the relative toxicity of six insecticides to the striped mealybug, Ferrisia dasylirii (Cockerell) (Hemiptera: Pseudococcidae) and its predator, Tenuisvalvae notata (Mulsant) (Coleoptera: Coccinellidae). Three neurotoxic insecticides, lambda-cyhalothrin, methidathion and thiamethoxam, caused complete mortality of both pest and predator when applied at their highest field rates. In contrast, lufenuron, pymetrozine and pyriproxyfen caused moderate mortality of third-instar mealybug nymphs, and exhibited low or no toxicity to either larvae or adults of the lady beetle. At field rates, lufenuron and pymetrozine had negligible effects on prey consumption, development or reproduction of T. notata, but adults failed to emerge from pupae when fourth instar larvae were exposed to pyriproxyfen. In addition, pyriproxyfen caused temporary sterility; T. notata females laid non-viable eggs for three days after exposure, but recovered egg fertility thereafter. Our results indicate that the three neurotoxic insecticides can potentially control F. dasylirii, but are hazardous to its natural predator. In contrast, lufenuron and pymetrozine appear compatible with T. notata, although they appear less effective against the mealybug. Although the acute toxicity of pyriproxyfen to T. notata was low, some pupal mortality and reduced egg fertility suggest that this material could impede the predator's numerical response to mealybug populations.

Toxicity of three aphicides to the generalist predators Chrysoperla carnea (Neuroptera: Chrysopidae) and Orius insidiosus (Hemiptera: Anthocoridae).

Recent widespread infestations of the invasive sugarcane aphid, Melanaphis sacchari (Zehntner) (Hemiptera: Aphididae), in sorghum fields in the southern USA have created demand for insecticides that will provide effective control of sugarcane aphid, while conserving those beneficial species that contribute to biological control of the pest. We tested the susceptibility of both adult and immature stages of two aphid predators, the green lacewing, Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae), and the insidious flower bug, Orius insidiosus (Say) (Hemiptera: Anthocoridae), to three aphicides, flonicamid, sulfoxaflor and flupyradifurone. Flonicamid was innocuous to both species regardless of life stage or route of exposure. Lacewing adults were more susceptible to sulfoxaflor and flupyradifurone than were larvae, and had higher mortality when fed contaminated honey solution than when contacting residues on an inert surface. When laid in sunflower stems treated with these two materials, eggs of O. insidiosus hatched successfully, but nymphs experienced significant mortality when exposed to treated stems, likely due to phytophagous behavior that resulted in some insecticide ingestion. Despite these impacts, we conclude that both sulfoxaflor and flupyradifurone are likely to be relatively innocuous in comparison to more broad-spectrum insecticides and are thus potentially compatible with biological control and overall management of M. sacchari in grain sorghum.

Comparative Life Histories of Greenbugs and Sugarcane Aphids (Hemiptera: Aphididae) Coinfesting Susceptible and Resistant Sorghums.

Host-plant resistance has been a fundamental component of aphid management in cereal crops. Over decades, various sources of resistance to greenbug, Schizaphis graminum (Rondani), were bred into cultivars of sorghum, Sorghum bicolor (L.) Moench, to counter recurring virulent greenbug biotypes. The recent invasion of sugarcane aphid, Melanaphis sacchari (Zehntner), raised questions about plant-mediated interactions between the two aphids and the possibility of using greenbug antibiosis against sugarcane aphid. The present work was undertaken to characterize the impact of PI 550610 resistance to 'biotype I' greenbug, expressed in seed parental line KS 116B, on aphid life histories and to observe plant-mediated interactions between aphid species in its presence and absence. At 23°C, sugarcane aphid nymphs matured 1.5 d faster than greenbug nymphs on susceptible hybrid P8500, but at similar rates on the resistant line, which delayed maturity by 1-1.5 d in both species and increased juvenile mortality by three- to fourfold. Sugarcane aphid reproductive rate was double that of greenbug on susceptible sorghum (4.45 vs. 2.30 nymphs per female per day), but not significantly different on the resistant one (3.09 vs. 2.27). Thus, PI 550610 expresses antibiosis, not tolerance, to these aphids. Coinfestation of P8500 had a positive effect on greenbug intrinsic rate of increase (rm), which changed to negative on KS 116B, whereas the rm of sugarcane aphid was unaffected by coinfestation with greenbug on either cultivar. The results indicate that KS 116B will be useful for producing sugarcane aphid-resistant hybrids, and that PI 550610 antibiosis changes the sugarcane aphid-greenbug interspecific relationship from commensalism to amensalism.

Reciprocal crosses between two populations of Trissolcus vassilievi (Mayr) (Hymenoptera: Scelionidae) reveal maternal effects on thermal phenotypes.

The egg parasitoid Trissolcus vassilievi (Mayr) (Hymenoptera: Scelionidae) is a significant natural enemy of the sunn pest, Eurygaster integriceps Puton (Hemiptera: Scutelleridae), the most important pest of wheat in Iran. This study examined the developmental time and egg-to-adult survival of two geographically separate populations of T. vassilievi on two corresponding host populations at five constant temperatures ranging from 15.0 to 35.0 ± 1°C. No wasps of either population emerged at 15.0°C and the temperature threshold for development was similar between populations, ranging from 13.1 ± 0.3 to 13.8 ± 0.4°C for males and 12.2 ± 0.1 to 12.6 ± 0.1°C for females, but the thermal constant varied with gender and parasitoid population. Development of wasps from the colder Tabriz location was slower, with thermal constants for males and females of 172.6 ± 3.1 and 204.1 ± 1.2 degree-days, respectively, compared to Varamin wasps with 164.7 ± 3.0 and 195.6 ± 1.3 degree-days, respectively. Based on genetic inheritance patterns, reciprocal crosses between the two populations were expected to result in females with thermal phenotypes intermediate to their parental populations, and males that resembled their mothers. However, female progeny of crosses more closely resembled their maternal population, indicating a maternal effect on thermal phenotype. Furthermore, the magnitude of the maternal effect on the thermal constant was asymmetric and was more strongly expressed by Varmin than Tabriz females. These results suggest the possibility of using selective crosses between wasp populations, in combination with artificial selection in the laboratory, to tune the thermal phenotype of parasitoids to specific regions prior to augmentative releases.

Sexual selection drives the evolution of limb regeneration in Harmonia axyridis (Coleoptera: Coccinellidae).

When Harmonia axyridis larvae were subjected to amputation of a foreleg in the fourth instar, 83% survived and, of these, 75% regenerated the leg during pupation. Regenerators pupated at heavier weights than controls (unoperated) or non-regenerators, and spent longer in pupation. Regenerated males were preferred by females in choice tests and produced more viable progeny than control males. Unregenerated males were less preferred by females, copulated for shorter periods than control males, and reduced female fecundity. Amputation diminished beneficial paternal effects, whether males regenerated or not, resulting in progeny with slower development and smaller adult body mass relative to control paternity. Progeny of unregenerated males had lower survival and body mass, whether male or female, confirming that regeneration was an honest signal of mate quality. When offspring had a foreleg amputated, a regenerated paternity yielded higher survival than control paternity, but similar rates of regeneration, whereas an unregenerated paternity yielded lower rates of survival and leg regeneration than control paternity. Regenerating beetles were twice as likely to be melanic as non-regenerating or control beetles, suggesting pleiotropic effects of melanism on processes involved in regeneration. This is the first report of complete limb regeneration by a holometabolous insect in the pupal stage, and the first example of sexual selection for regenerative capacity.