Pupal Mass Research Articles

Differential temperature responses between Plutella xylostella and its specialist endo-larval parasitoid Diadegma semiclausum-Implications for biological control.

Understanding the thermal dynamics of host-parasitoid interactions is crucial to predicting how biological control of pest insects by parasitoids might be affected by geographic location and climate change. We compared performance traits of Plutella xylostella (Lepidoptera: Plutellidae) and its solitary endo-larval parasitoid Diadegma semiclausum (Hymenoptera: Ichneumonidae), over a wide range of constant rearing temperatures (10-30°C). Parasitoids reared at 30°C experienced reductions in pupation rate, pupal mass, egg load, and adult life span when compared with those reared at lower temperatures. Our analyses of the fate of parasitoids and their hosts and intergenerational population growth at different rearing temperatures show that D. semiclausum and P. xylostella respond differently to temperature, leading to divergent outcomes under different temperature conditions. Some parasitoid larvae could not complete development at 30°C, the temperature at which the host biomass was least and the metabolic demands of the parasitoid could be high, suggesting that parasitoid development might be constrained by lack of host resources at higher temperatures. We discuss the potential mechanisms of parasitoid susceptibility to elevated temperatures, which likely explain the pronounced seasonal dynamics of D. semiclausum in subtropical regions and its failure to establish in lowland tropical regions, where P. xylostella is a serious pest. Similar interactions in other host-parasitoid associations would constrain the efficacy of parasitoids as biological control agents as global temperatures increase.

Combined influences of transgenerational effects, temperature and insecticide on the moth Spodoptera littoralis

Climate warming is expected to impact the response of species to insecticides. Recent studies show that this interaction between insecticides and temperature can depend on other factors. Here, we tested for the influence of transgenerational effects on the Insecticide × Temperature interaction in the crop pest moth Spodoptera littoralis. Specifically, we analysed reaction norms among experimental clutches based on a split-plot design crossing the factors temperature, insecticide and clutch. The study was performed on 2280 larvae reared at four temperatures (23, 25, 27 and 29 °C), and their response to the insecticide deltamethrin (three concentrations and a control group) was tested. Temperature had a global influence with effects on larval survival, duration of development, pupal body mass, and significant reaction norms of the clutches for temperature variations of only 2 °C. In addition to the expected effect of deltamethrin on mortality, the insecticide slightly delayed the development of S. littoralis, and the effects on mortality and development differed among the clutches. Projection models integrating all the observed responses illustrated the additive effects of deltamethrin and temperature on the population multiplication rate. Variation in the response of the clutches showed that transgenerational effects influenced the impact of insecticide and temperature. Although no evidence indicated that the Insecticide × Temperature interaction depended on transgenerational effects, the studies on the dependence of the Insecticide × Temperature interaction on other factors continue to be crucial to confidently predict the combined effects of insecticides and climate warming.

The Galleria mellonella-Enteropathogenic Escherichia coli Model System: Characterization of Pathogen Virulence and Insect Immune Responses.

The use of Galleria mellonella (Linnaeus) (Lepidoptera: Pyralidae), an economical insect model, for the study of enteropathogenic Escherichia coli (Migula) (EPEC), a diarrheagenic human pathogen, has been demonstrated previously but remains poorly understood. The present study characterizes the Galleria-EPEC system extensively for future studies using this system. We found that EPEC causes disease in G. mellonella larvae when injected intrahemocoelically but not orally. Disease manifests as increased mortality, decreased survival time, delayed pupation, decreased pupal mass, increased pupal duration, and hemocytopenia. Disease symptoms are dose-dependent and can be used as metrics for measuring EPEC virulence in future studies. The type III secretion system was only partially responsible for EPEC virulence in G. mellonella while the majority of the virulence remains unknown in origin. EPEC elicits insect anti-bacterial immune responses including melanization, hemolymph coagulation, nodulation, and phagocytosis. The immune responses were unable to control EPEC replication in the early stage of infection (≤3 h post-injection). EPEC clearance from the hemocoel does not guarantee insect survival. Overall, this study provided insights into EPEC virulence and pathogenesis in G. mellonella and identified areas of future research using this system.

Improved performance of the eastern spruce budworm on black spruce as warming temperatures disrupt phenological defences

Phenological shifts, induced by global warming, can lead to mismatch between closely interacting species. The eastern spruce budworm, Choristoneura fumiferana, an important outbreaking insect defoliator in North America, mainly feeds on balsam fir, Abies balsamea, which has historically been well synchronized with the insect. But as climate change pushes the northern range limit of the budworm further north into the boreal forest, the highly valuable black spruce, Picea mariana, historically protected against the budworm by its late budburst phenology, is suffering increased defoliation during the current outbreak. We tested the hypothesis that rising temperatures can lead, not to a mismatch, but to an improved match between the budworm and black spruce through differential phenological advancement. For 3years, eastern spruce budworm larvae were reared from instar 2 to pupae, on both black spruce and balsam fir, in a temperature free-air controlled enhancement experiment (T-FACE) consisting in 24 field plots, half of which were heated at +2°C from March to October. Our results show that every year, larval development was faster on heated trees and pupation was earlier than on unheated trees. Bud development was also accelerated in heated trees of both species. However, there was no difference in mass between pupae that developed at +2°C and controls at the end of the season. Finally, we found no difference either in development rate or pupal mass between larvae reared on black spruce and those reared on balsam fir. This suggests that under higher temperature regimes, eastern spruce budworm will be as successful on black spruce as on balsam fir, as black spruce budburst becomes better synchronized with the insect's emergence from diapause. This could lead to critical changes in outbreak dynamics and severity with important ecological state shifts at the landscape level.

Responses of Manduca sexta larvae to heat waves.

Climate change is increasing the frequency of heat waves and other extreme weather events experienced by organisms. How does the number and developmental timing of heat waves affect survival, growth and development of insects? Do heat waves early in development alter performance later in development? We addressed these questions using experimental heat waves with larvae of the tobacco hornworm, Manduca sexta. The experiments used diurnally fluctuating temperature treatments differing in the number (0-3) and developmental timing (early, middle and/or late in larval development) of heat waves, in which a single heat wave involved three consecutive days with a daily maximum temperature of 42°C. Survival to pupation declined with increasing number of heat waves. Multiple (but not single) heat waves significantly reduced development time and pupal mass; the best models for the data indicated that both the number and developmental timing of heat waves affected performance. In addition, heat waves earlier in development significantly reduced growth and development rates later in larval development. Our results illustrate how the frequency and developmental timing of sublethal heat waves can have important consequences for life history traits in insects.

Ambient Humidity Affects Development, Survival, and Reproduction of the Invasive Fall Armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), in China.

Ambient humidity can directly affect the water balance in insects. The migratory fall armyworm, Spodoptera frugiperda Smith, has spread to more than 60 countries and regions in Africa, Asia, and Oceania that have a great difference in average ambient humidity. Understanding the effects of ambient humidity changes on its development, survival, and reproduction can help to predict its population dynamics in different habitats. Therefore, we evaluated the effects of atmospheric relative humidity (RH) on the development, survival, and reproduction and soil moisture on the pupation and emergence of fall armyworm. As a result, survival and pupal mass increased significantly with increasing RH. Among the five RHs tested, 80% RH was the most suitable for fall armyworm with the highest intrinsic rate of increase (r), finite rate of increase (λ), and net reproduction rate (R0). The population growth at the different RHs in decreasing order was 80 > 100 > 60 > 40 > 20%. A relative moisture (RM) of soil from 6.80 to 47.59% was suitable for fall armyworm pupation, survival, and eclosion, but fall armyworm could not pupate normally in soil with 88.39 and 95.19% RM. The survival and emergence rate of fall armyworm pupae were reduced by irrigation that increased the RM after the mature larvae entered the soil. These findings may be helpful for refining laboratory rearing protocols, population forecasting, and management of fall armyworm.

Contact toxicity of a new acaricide, SYP-9625, to the natural predator, Chrysopa pallens

• We first evaluated the contact toxicity of an acaricide, SYP-9625, on C. pallens . • SYP-9625 only had mild detrimental impacts on insect growth and metamorphosis. • SYP-9625 had significant adverse effects on adult survival and Vg expression. • The paper will strengthen the compatibility of acaricide and natural predators. SYP-9625 is a novel acaricide synthesized by using cyenopyrafen as lead compound. It is characterized by high acaricidal activity and low toxicity to mammals and has been widely used in Chinese farming areas. However, to date, the toxicity of SYP-9625 to natural enemy insects remained unclear. Here, we evaluated the effects of SYP-9625 on survival, growth, metamorphosis and reproduction of a common natural predator, Chrysopa pallens . Contact toxicity bioassay revealed that SYP-9625 had no significant detrimental impacts on egg hatchability, larval survival and duration, pupation rate, pupal mass, emergence rate, digestive enzyme activity, reproductive output and offspring quality, but drastically reduced adult survival rate, adult lifespan, secondary follicle size and vitellogenin (Vg) transcripts by 27.8%, 15.4%, 33.4% and 59.4%, respectively, suggesting a low contact toxicity of SYP-9625 to C. pallens . This study will strengthen the compatibility of chemical acaricide and natural enemy insects in integrated pest management.

Molecular characterization of diverse defensins (γ-thionins) from Capsicum annuum flowers and their effects on the insect pest Helicoverpa armigera

Plant defensins (γ-thionins) are antimicrobial peptides (AMPs) constituting the host defense system. They are known to interact with the cell membranes to exhibit antifungal and antibacterial activity. Though defensin genes are inducible under biotic and abiotic stress, their involvement in insect herbivore defense is not well studied. In this work we studied the phylogeny, structural diversity, biochemical and functional properties of defensins from Capsicum annuum L with particular emphasis on their interaction with insect and fungal pathogens. Phylogenetic analysis of defensin peptides from Solanaceae, Pinaceae, Fabaceae, Asteraceae, Brassicaceae and similar peptides from invertebrates divided them into ten groups and Capsicum peptides were represented in most of them. Three thionin (CanThio-1, −2, −3) and two defensin (CanDef-20, −21) genes isolated from the flowers of Capsicum annuum were cloned and recombinant proteins were expressed. The mature peptide amino acid sequences of CanThio and CanDef were 54–75 aa with 21.82 to 73.81% similarity. They contained the conserved features of defensin peptides like the gamma core region and the presence of eight cysteine residues. Predicted structural alignment indicated that CanThio and CanDef had structural diversity and structurally unaligned loop regions.The recombinant CanThio and CanDef inhibited 5% - 65% Aspergillus oryzae amylase activity at 20 μM and ~ 20% of Helicoverpa armigera gut amylase activity at 50 μM peptide concentrations. CanThio-2 displayed bovine trypsin inhibition (~14%) while all the CanThio and CanDef inhibited ~20% of H. armigera gut proteinase activity at 20 μM. H. armigera larvae fed on an artificial diet incorporated with recombinant CanThio-2 and CanDef-20 (125 μg/ml) exhibited a 15% reduction in larval mass and 13% reduction in pupal mass. The CanThio and CanDef peptides also exhibited antifungal properties against pathogenic fungus Fusarium oxysporum at 5 μg/ml, where CanThio-2 and CanDef-20 showed the strongest activity, which may be attributed to the positively charged amino acids in the γ-core region.We conclude that despite having relatively similar conserved three-dimensional structures CanThio and CanDef display functional variability, which can be utilized for enhancing insect and fungal resistance in plants.

Ontogenetic Basis of Among-Generation Differences in Size-Related Traits in a Polyphenic Butterfly

Seasonal polyphenisms are cases in which individuals representing generations occurring in different times of the year systematically differ in their morphological, physiological, and/or behavioral traits. Such differences are often assumed to constitute adaptive responses to seasonally varying environments, but the evidence for this is still scarce. The adaptive character of the response would be corroborated by the pattern in which the decision about choosing a particular seasonal phenotype is made before the onset of respective environmental conditions (anticipatory plasticity). Alternatively, the between-generation differences can be caused by immediate effects of seasonally varying environments (responsive plasticity). Here we reared the larvae of the seasonally polymorphic map butterfly Araschnia levana under two different photoperiodic regimes, which provided different seasonal cues. These two treatments induced direct development and diapause pathways, respectively. Replicating the experiment at different temperatures and levels of host plant quality allowed us to evaluate both the anticipatory and the responsive components of the associated plastic changes in life-history traits. Larvae representing the direct development pathway invariably had higher growth rates and shorter development periods, although the difference between the developmental pathways was smaller at inferior host quality. Body size differences between the developmental pathways turned out to be less consistent, as the natural pattern of higher pupal mass of the directly developing individuals could only be reproduced at lower rearing temperature. Though being considerably modified by immediate environmental effects, the between-generation differences in size, growth rates, and larval are largely based on anticipatory plasticity (= responses to photoperiodic cues) and should be treated as seasonal adaptations in A. levana. In a more general context, we show how investigating the proximate basis of size differences can serve the purpose of identifying the limits of phenotypic plasticity in juvenile growth schedules.

Population life tables for the invasive fall armyworm, Spodoptera frugiperda fed on major oil crops planted in China

The fall armyworm (FAW), Spodoptera frugiperda, is a newly invasive, widespread agricultural pest in China. Understanding the suitability of the main field crops in Chinese agricultural system as host for this polyphagous herbivore is especially important for making control strategy. Here, after FAWs were fed three important oil-bearing crops (oilseed rape, soybean and sunflower) planted in China and resultant population parameters were compared using the age-stage, two-sex life table method, survival of larvae on soybean was significantly lower than that on oilseed rape and sunflower. Developmental duration of larvae on soybean was also the longest (23.3 days). The highest pupation rate was recorded on sunflower. The highest pupal mass (0.19 g) was attained on oilseed rape, significantly higher than on the other host plants; the lowest mass was on soybean (0.15 g). On soybean, oilseed rape and sunflower, respectively, the average generation period was 42.21, 39.10 and 40.44 d; the intrinsic rate of increase (r) was 0.0844, 0.1041 and 0.1134; the finite rate of increase (λ) was 1.0881, 1.1098 and 1.1202. While the most suitable host plant overall was sunflower, S. frugiperda completed development and increased its population on all three host plants. Thus, soybean, oilseed rape and sunflower were all suitable for FAW, and population monitoring and management of FAW in these crops should be increased.

Invasive grass negatively affects growth and survival of an imperiled butterfly

With only ~1% of native prairie remaining in North America, populations of many prairie-obligate species, including the imperiled Dakota skipper butterfly, have drastically declined in recent decades. Unfortunately, population recovery is impeded by an insufficient understanding of Dakota skipper biology. Because larvae have never been naturally observed in the wild, even basic life history elements including preferred host plant(s) are not well understood, and potential hosts have been inferred from grasses inhabiting remnant sites rather than direct observations. To improve our understanding of Dakota skipper biology and habitat needs and inform recovery efforts, we conducted a no-choice performance experiment offering larvae 1 of 5 commonly occurring native grasses and 2 pervasive invasive grass species found across their historic range. We monitored larvae during key life history intervals and evaluated host plant quality by measuring larval and pupal mass, time to pupation, and survivorship. Larvae fed on all offered host grasses, but mass, phenology, and survivorship varied among treatments. Larvae reared on prairie dropseed and porcupine grass had the highest survival, the shortest time to adulthood, and the greatest mass, whereas larvae provided smooth brome and Kentucky bluegrass fared poorly for all observed metrics. All other grasses offered during the study were deemed ‘medium’ quality. Our results suggest that although larvae can feed on a variety of potential host plants, these hosts vary in quality. Invasive grasses across prairies in North America may pose an ecological trap to the conservation of Dakota skipper and other prairie-obligate Lepidoptera.

EFFECTS OF ARTIFICIAL DIETS ON THE BIOLOGICAL CYCLE OF Condylorrhiza vestigialis

The objective of this work was to determine the influence of different artificial diets on biological parameters related to the life cycle of C Condylorrhiza vestigialis aiming to determine the most suitable diet for the rearing of a population of this insect. Four diet formulations were tested. Ten repetitions were used, with 30 caterpillars per repetition. All stages of C. vestigialis life cycle were followed to evaluate biological parameters: viability of larvae, pre pupa, pupa and adults, as well as the sex ratio. The number of larval instars, the pupal mass and the total number of eggs per day and per female day were also calculated. The four diets tested allowed the development of C. vestigialis caterpillars. All diets were considered adequate for the purpose of the work, which is the production of baculovirus used in the control program of this pest. It was the diet 2 that provided the best results, the largest pupal mass, and the quantity and viability of the eggs produced by C. vestigialis females fed in this larval phase.

Growth, stress, and acclimation responses to fluctuating temperatures in field and domesticated populations of Manduca sexta.

Diurnal fluctuations in temperature are ubiquitous in terrestrial environments, and insects and other ectotherms have evolved to tolerate or acclimate to such fluctuations. Few studies have examined whether ectotherms acclimate to diurnal temperature fluctuations, or how natural and domesticated populations differ in their responses to diurnal fluctuations. We examine how diurnally fluctuating temperatures during development affect growth, acclimation, and stress responses for two populations of Manduca sexta: a field population that typically experiences wide variation in mean and fluctuations in temperature, and a laboratory population that has been domesticated in nearly constant temperatures for more than 300 generations. Laboratory experiments showed that diurnal fluctuations throughout larval development reduced pupal mass for the laboratory but not the field population. The differing effects of diurnal fluctuations were greatest at higher mean temperature (30°C): Here diurnal fluctuations reduced pupal mass and increased pupal development time for the laboratory population, but had little effect for the field population. We also evaluated how mean and fluctuations in temperature during early larval development affected growth rate during the final larval instar as a function of test temperature. At an intermediate (25°C) mean temperature, both the laboratory and field population showed a positive acclimation response to diurnal fluctuations, in which subsequent growth rate was significantly higher at most test temperatures. In contrast at higher mean temperature (30°C), diurnal fluctuations significantly reduced subsequent growth rate at most test temperatures for the laboratory population, but not for the field population. These results suggest that during domestication in constant temperatures, the laboratory population has lost the capacity to tolerate or acclimate to high and fluctuating temperatures. Population differences in acclimation capacity in response to temperature fluctuations have not been previously demonstrated, but they may be important for understanding the evolution of reaction norms and performance curves.

Climate‐related geographical variation in performance traits across the invasion front of a widespread non‐native insect

AbstractAimInvasive species are ideal systems for testing geographical differences in performance traits and measuring evolutionary responses as a species spreads across divergent climates and habitats. The European gypsy moth, Lymantria dispar dispar L. (Lepidoptera: Erebidae), is a generalist forest defoliator introduced to Medford, Massachusetts, USA in 1869. The invasion front extends from Minnesota to North Carolina and the ability of this species to adapt to local climate may contribute to its continuing spread. We evaluated the performance of populations along the climatic gradient of the invasion front to test for a relationship between climate and ecologically important performance traits.LocationEastern United States of AmericaTaxonLymantria dispar dispar L. (Lepidoptera: Erebidae)MethodsInsects from 14 populations across the US invasion front and interior of the invasive range were reared from hatch to adult emergence in six constant temperature treatments. The responses of survival, pupal mass and larval development time were analysed as a function of source climate (annual mean normal temperature), rearing temperature and their interaction using multiple polynomial regression.ResultsWith the exception of female development time, there were no significant interactions between source climate and rearing temperature, indicating little divergence in the shape of thermal reaction norms among populations. Source population and rearing temperature were significant predictors of survival and pupal mass. Independent of rearing temperature, populations from warmer climates had lower survival than those from colder climates, but attained larger body size despite similar development times. Larval development time was dependent on rearing temperature, but there were not consistent relationships with source climate.Main ConclusionsThermal adaptation can be an important factor shaping the spread of invasive species, particularly in the context of climate change. Our results suggest that L. d. dispar is highly plastic, but has undergone climate‐related adaptation in thermal performance and life‐history traits as it spread across North America.

Daily temperature variation lowers the lethal and sublethal impact of a pesticide pulse due to a higher degradation rate

Daily temperature variation (DTV) is an important warming-related stressor that may magnify pesticide toxicity. Yet, it is unknown whether the pesticide impact under DTV is partly ameliorated by a faster pesticide degradation caused by cyclically higher temperatures under DTV. As synergisms may be more likely under energy-limiting conditions, the impact of the pesticide chlorpyrifos was tested under DTV on the mosquito Culex pipiens in the absence and presence of interspecific competition with the water flea Daphnia magna. Chlorpyrifos exposure at a constant temperature without interspecific competition caused considerable mortality, decreased development time, and increased pupal mass of C. pipiens. Competition with D. magna had negative sublethal effects, but it did not affect the toxicity of chlorpyrifos. In contrast, the presence of C. pipiens decreased the impact of chlorpyrifos on D. magna probably due to corporal absorption of chlorpyrifos by C. pipiens. A key finding was that chlorpyrifos no longer caused lethal effects on C. pipiens under DTV, despite DTV on its own being mildly lethal. Additionally, chlorpyrifos exposure under DTV decreased development time less and had no effect anymore on pupal mass compared to chlorpyrifos exposure at a constant temperature. Similarly, the negative chlorpyrifos impact on adult survival of D. magna was less under DTV than at the constant temperature. This could be explained by a faster chlorpyrifos degradation under DTV. This antagonism between pesticide exposure and DTV is likely widespread because organisms experience DTV, many pesticides are applied in pulses, and pesticide degradation is faster at higher temperatures.

Maternal and larval niche construction interact to shape development, survival, and population divergence in the dung beetle Onthophagus taurus.

Through niche construction, organisms modify their environments in ways that can alter how selection acts on themselves and their offspring. However, the role of niche construction in shaping developmental and evolutionary trajectories, and its importance for population divergences and local adaptation, remains largely unclear. In this study, we manipulated both maternal and larval niche construction and measured the effects on fitness-relevant traits in two rapidly diverging populations of the bull-headed dung beetle, Onthophagus taurus. We find that both types of niche construction enhance adult size, peak larval mass, and pupal mass, which when compromised lead to a synergistic decrease in survival. Furthermore, for one measure, duration of larval development, we find that the two populations have diverged in their reliance on niche construction: larval niche construction appears to buffer against compromised maternal niche construction only in beetles from Western Australia, but not in beetles from the Eastern United States. We discuss our results in the context of rapid adaptation to novel conditions and the role of niche construction therein.

Frequency and consequences of the collection of already parasitized caterpillars by a potter wasp

Maladaptive behaviors reflecting a “bad” choice of habitat or resource have been widely documented; however, their persistence is often difficult to interpret. The potter wasp Delta dimidiatipenne constructs mud cells, in each of which it lays a single egg and places several caterpillars to feed its offspring. Preliminary observations indicated that a portion of these caterpillars were already parasitized and contained the offspring of the gregarious parasitoid Copidosoma primulum. As a result, the offspring of the potter wasp often failed to develop. To characterize the distribution, frequency and consequences of this intriguing phenomenon, we surveyed potter wasp nests throughout the Negev Desert. Evidence for parasitized caterpillars (mummies) was found in ~85% of the sampled sites, in ~20% of previous years’ nest cells and in ~70–80% of the same year’s cells. The survival and pupal mass of the potter wasp offspring were negatively associated with the presence and number of parasitized caterpillars inside the cells. We concluded that the collection of parasitized caterpillars by D. dimidiantipenne is frequent and costly. The persistence of this behavior may result from limited discrimination ability against parasitized prey by female potter wasps, or by their limited ability to exhibit choosiness under field conditions.

Yeasts Influence Host Selection and Larval Fitness in Two Frugivorous Carpophilus Beetle Species.

We explored how gut-associated yeasts influence olfactory behaviour and resource use in two pest species of Carpophilus beetle that co-exist in Australian stone fruits. Molecular analysis of yeasts isolated from the gut of C. davidsoni (prefers ripe fruits) and C. hemipterus (prefers overripe and rotting fruits) revealed that the predominant species were Pichia kluyveri and Hanseniaspora guilliermondii. In olfactory attraction and oviposition trials, adult beetles preferred H. guilliermondii over P. kluyveri, and follow up GC-MS analysis revealed unambiguous differences between the odour profiles of these yeasts. In contrast to behavioural trials, larval feeding assays showed that fruit substrates inoculated with P. kluyveri yielded significantly faster development times, higher pupal mass, and a greater number of adult beetles, compared to H. guilliermondii-in other words, the lesser preferred yeast (by foraging adults) was more suitable for larval survival. Moreover, whilst larvae of both species survived to adulthood when fed solely on P. kluyveri (i.e. without a fruit substrate), only larvae of C. davidsoni could develop on H. guilliermondii; and only C. davidsoni reached adulthood feeding on a yeast-free fruit substrate. We discuss how these findings may relate to adaptations towards early colonising of fruits by C. davidsoni, enabling differences in resource use and potentially resource partitioning in the two beetles. More broadly, consideration of microbial interactions might help develop host selection theory. Our results could pave the way to more powerful attractants to mass-trap and monitor Carpophilus pests in fruit orchards.

Diet-mediated modulation on the development and phenoloxidase activity in the Alder leaf beetle larvae, Agelastica alni (L., 1758) (Coleoptera: Chrysomelidae)

Food-induced changes in the phenoloxidase activity and development of Agelastica alni (L.,1758) (Coleoptera: Chrysomelidae) larvae reared on unbalanced artificial diets were examined. The study was conducted between 2015- 2016. Food quality had an impact on the phenoloxidase activity and growth performance of alder leaf beetle. The maximum pupal mass was recorded in the 0.5:1 P:C (protein:carbohydrate) diet and the minimum pupal mass was recorded from the larvae fed on the 3:1 P:C diet. The amount of carbohydrate consumed affected the pupal mass positively, whereas the amount of protein consumed negatively affected the pupal mass. The highest amount of pupal lipid was found in the 0.5:1 P:C diet and the lowest pupal lipid amount in the 1:3 P:C diet. Also, imbalance diets affected phenoloxidase activity. There was a positive relationship between P ratio of the diet and phenoloxidase activity. Phenoloxidase activity decreases as the amount of carbohydrate consumed by larvae increases. As a result, unbalanced diet affects the immune system of larvae. Carbohydrate also has a significant effect on immune defenses as much as protein. In addition, larvae increase their body size with excessive consumption of carbohydrate.

Where you come from matters: temperature influences host-parasitoid interaction through parental effects.

Temperature alters host suitability for parasitoid development through direct and indirect pathways. Direct effects depend on ambient temperatures experienced by a single host individual during its lifetime. Indirect effects (or parental effects) occur when thermal conditions met by a host parental generation affect the way its offspring will interact with parasitoids. Using the complex involving eggs of the moth Lobesia botrana as hosts for the parasitoid Trichogramma cacoeciae, we developed an experimental design to disentangle the effects of (1) host parental temperature (temperature at which the host parental generation developed and laid host eggs) and (2) host offspring temperature (temperature at which host eggs were incubated following parasitism, i.e. direct thermal effects) on this interaction. The host parental generation was impacted by temperature experienced during its development: L. botrana females exposed to warmer conditions displayed a lower pupal mass but laid more host eggs over a 12-h period. Host parental temperature also affected the outcomes of the interaction. Trichogramma cacoeciae exhibited lower emergence rates but higher hind tibia length on emergence from eggs laid under warm conditions, even if they were themselves exposed to cooler temperatures. Such indirect thermal effects might arise from a low nutritional quality and/or a high immunity of host eggs laid in warm conditions. By contrast with host parental temperature, offspring temperature (direct thermal effects) did not significantly affect the outcomes of the interaction. This work emphasises the importance of accounting for parental thermal effects to predict the future of trophic dynamics under global warming scenarios.