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.

Ancestral and offspring nutrition interact to affect life-history traits in Drosophila melanogaster

Ancestral environmental conditions can impact descendant phenotypes through a variety of epigenetic mechanisms. Previous studies on transgenerational effects in Drosophila melanogaster suggest that parental nutrition may affect the body size, developmental duration and egg size of the next generation. However, it is unknown whether these effects on phenotype remain stable across generations, or if specific generations have general responses to ancestral diet. In the current study, we examined the effect on multiple life-history phenotypes of changing diet quality across three generations. Our analysis revealed unforeseen patterns in how phenotypes respond to dietary restriction. Our generalized linear model showed that when considering only two generations, offspring phenotypes were primarily affected by their own diet, and to a lesser extent by the diet of their parents or the interaction between the two generations. Surprisingly, however, when considering three generations, offspring phenotypes were primarily impacted by their grandparents' diet and their own diet. Interactions among different generations’ diets affected development time, egg volume and pupal mass more than ovariole number or wing length. Furthermore, pairwise comparisons of diet groups from the same generation revealed commonalities in strong responses to rich versus poor diet: ovariole number, pupal mass and wing length responded more strongly to poor diet than to rich diet, while development time responded strongly to both rich and poor diets. To improve investigations into the mechanisms and consequences of transgenerational, epigenetic inheritance, future studies should closely examine how phenotypes change across a higher number of generations, and consider responses to broader variability in diet treatments.

Oviposition preference and biological performance of Ceratitis capitata in Anacardiaceae, Cactaceae and Vitaceae fruit

ABSTRACT: The objective of this study was to compare the use of fruits of great economic and social importance for the northeast of Brazil by Ceratitis capitata Wied. (Diptera: Tephritidae) for oviposition, larval development, size and longevity of adults. Fruits of mango (Mangifera indica L.), quiabento (Pereskia bahiensis Gürke), forage palm [Opuntia fícus indica (L.) Mill] and grape (Vitis vinifera L.) were used, as well as flies from a hybrid laboratory population. Initially, four treatments (fruits) and six replications were used; the fruits were offered to 10 C. capitata couples, with later (96 hours) egg count. The second was conducted with six treatments and 10 replicates, offering two types of fruits simultaneously, combined two to two, to 10 C. capitata couples. The last bioassay comprised four treatments and six replicates, where 20 g of fruit were offered to 20 first-instar C. capitata larvae. After six days, the larvae were placed in plastic pots containing vermiculite until pupation, quantifying larval and pupal periods, viability and pupal mass, besides longevity and adult size. The data were submitted to ANOVA using the R Core Team software. Ceratitis capitata oviposits and completes its biological cycle in the four hosts studied, exhibiting no preference for oviposition and low biological performance in quiabento fruits. It yielded smaller adults and lower grape survival. Cactaceae palm and quiabento allow the survival of C. capitata in the laboratory, and this knowledge has been reported for the first time, proving that they can act as alternative hosts in the field.

Ancestral and offspring nutrition interact to affect life history traits in Drosophila melanogaster

ABSTRACTAncestral environmental conditions can impact descendant phenotypes through a variety of epigenetic mechanisms. Previous studies on transgenerational effects in Drosophila melanogaster suggest that parental nutrition may affect the body size, developmental duration, and egg size of the next generation. However, it is unknown whether these effects on phenotype remain stable across generations, or if specific generations have general responses to ancestral diet. In the current study, we examined the effect on multiple life history phenotypes of changing diet quality across three generations. Our analysis revealed unforeseen patterns in how phenotypes respond to dietary restriction. Our generalized linear model showed that when considering only two generations, offspring phenotypes were primarily affected by their own diet, and to a lesser extent by the diet of their parents or the interaction between the two generations. Surprisingly, however, when considering three generations, offspring phenotypes were primarily impacted by their grandparents’ diet and their own diet. Interactions amongst different generations’ diets affected development time, egg volume, and pupal mass more than ovariole number or wing length. Further, pairwise comparisons of diet groups from the same generation revealed commonalities in strong responses to rich vs. poor diet: ovariole number, pupal mass, and wing length responded more strongly to poor diet than to rich diet, while development time responded strongly to both rich and poor diets. To improve investigations into the mechanisms and consequences of transgenerational, epigenetic inheritance, future studies should closely examine how phenotypes change across a higher number of generations, and consider responses to broader variability in diet treatments.

Alternative to formaldehyde in artificial diet for sugarcane borer and its effects on the parasitoid

The formaldehyde used as anti-contaminant agent in artificial diets of insects can cause serious risks to human health. However, there are products with the same purpose, but with less toxicity to humans. In this sense, the aim of this study was to evaluate the biological parameters of Diatraea saccharalis (Fabricius, 1794) (Lepidoptera: Crambidae) fed on an artificial diet containing different anti-infective agents to replace the formaldehyde, as well as analyze the effects on its parasitoid Cotesia flavipes (Cameron, 1891) (Hymenoptera: Braconidae). The experiment was conducted under a completely randomized design, studying the anti-contaminant agents: sodium benzoate, potassium sorbate, 2-phenylphenol, and formaldehyde (standard diet), with deionized water as control. The larvae of sugarcane borer were fed on diets with the cited agents, and were daily observed for: larval and pupal periods, larval and pupal viabilities, number of unviable larvae, longevity, pupae weight, sex ratio and the adults fecundity. To analyze the effects of the anti-contaminant agents on the C. flavipes parasitoid, 50 larvae of sugarcane borer were parasitized and daily observed until the parasitoid pupae formation, being evaluated: number of adults emerged per pupal mass, longevity and sex ratio. D. saccharalis larvae are positively influenced by replacing formaldehyde to 2-phenylphenol in their diet, not causing significant deleterious effects to C. flavipes.

Increased water salinity applied to tomato plants accelerates the development of the leaf miner Tuta absoluta through bottom-up effects

Variation in resource inputs to plants may trigger bottom-up effects on herbivorous insects. We examined the effects of water input: optimal water vs. limited water; water salinity: with vs. without addition of 100 mM NaCl; and their interactions on tomato plants (Solanum lycopersicum), and consequently, the bottom-up effects on the tomato leaf miner, Tuta absoluta (Meytick) (Lepidoptera: Gelechiidae). Plant growth was significantly impeded by limited water input and NaCl addition. In terms of leaf chemical defense, the production of tomatidine significantly increased with limited water and NaCl addition, and a similar but non-significant trend was observed for the other glycoalkaloids. Tuta absoluta survival did not vary with the water and salinity treatments, but the treatment “optimal water-high salinity” increased the development rate without lowering pupal mass. Our results suggest that caution should be used in the IPM program against T. absoluta when irrigating tomato crops with saline water.

Effects ofin situclimate warming on monarch caterpillar (Danaus plexippus) development

Climate warming will fundamentally alter basic life history strategies of many ectothermic insects. In the lab, rising temperatures increase growth rates of lepidopteran larvae but also reduce final pupal mass and increase mortality. Usingin situfield warming experiments on their natural host plants, we assessed the impact of climate warming on development of monarch (Danaus plexippus) larvae. Monarchs were reared onAsclepias tuberosagrown under ‘Ambient’ and ‘Warmed’ conditions. We quantified time to pupation, final pupal mass, and survivorship. Warming significantly decreased time to pupation, such that an increase of 1 °C corresponded to a 0.5 day decrease in pupation time. In contrast, survivorship and pupal mass were not affected by warming. Our results indicate that climate warming will speed the developmental rate of monarchs, influencing their ecological and evolutionary dynamics. However, the effects of climate warming on larval development in other monarch populations and at different times of year should be investigated.

Infection by Nosema fumiferanae (Microsporidia: Nosematidae) and feeding on previous-year’s foliage do not interact in affecting late instars of the spruce budworm (Lepidoptera: Tortricidae)

Infection by Nosema fumiferanae (Thomson) (Microsporidia: Nosematidae) and feeding by late-instars on previous year’s foliage due to depletion of current year’s growth (also known as back-feeding) are likely to co-occur in high-density outbreak populations of the spruce budworm (Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae)). We tested the hypothesis that effects of the two factors on larval fitness are exacerbated by their interaction. Twigs of balsam fir (Abies balsamea Linnaeus; Pinaceae) with or without new-growth shoots were fed to sixth-instar offspring from uninfected, moderately infected, or highly infected females in two laboratory experiments. Pupal mass and time to reach the pupal stage were significantly affected by infection and back-feeding but not by their interaction. Pupal mass decreased and development time increased with increasing spore burden in a linear fashion. Back-feeding had a significant effect on survival to the pupal stage, but infection did not, nor did their interaction. The relatively small changes in survival, pupal mass, and development time caused by infection and back-feeding were additive. The results thus refute our hypothesis that infection by N. fumiferanae and forced feeding on last year’s foliage by late instars are likely to interact in affecting spruce budworm recruitment in older outbreak populations.

Effects of in situ climate warming on monarch caterpillar (Danaus plexippus) development

Climate warming will fundamentally alter basic life history strategies of many ectothermic insects. In the lab, rising temperatures increase growth rates of lepidopteran larvae, but also reduce final pupal mass and increase mortality. Using in situ field warming experiments on their natural host plants, we assessed the impact of climate warming on development of monarch (Danaus plexippus) larvae. Monarchs were reared on Asclepias tuberosa grown under ‘Ambient’ and ‘Warmed’ conditions. We quantified time to pupation, final pupal mass, and survivorship. Warming significantly decreased time to pupation, such that an increase of 1˚ C corresponded to a 0.5 day decrease in pupation time. In contrast, survivorship and pupal mass were not affected by warming. Our results indicate that climate warming will speed the developmental rate of monarchs, influencing their ecological and evolutionary dynamics. However, the effects of climate warming on larval development in other monarch populations and at different times of year should be investigated.

Effects of in situ climate warming on monarch caterpillar (Danaus plexippus) development

Climate warming will fundamentally alter basic life history strategies of many ectothermic insects. In the lab, rising temperatures increase growth rates of lepidopteran larvae, but also reduce final pupal mass and increase mortality. Using in situ field warming experiments on their natural host plants, we assessed the impact of climate warming on development of monarch (Danaus plexippus) larvae. Monarchs were reared on Asclepias tuberosa grown under ‘Ambient’ and ‘Warmed’ conditions. We quantified time to pupation, final pupal mass, and survivorship. Warming significantly decreased time to pupation, such that an increase of 1˚ C corresponded to a 0.5 day decrease in pupation time. In contrast, survivorship and pupal mass were not affected by warming. Our results indicate that climate warming will speed the developmental rate of monarchs, influencing their ecological and evolutionary dynamics. However, the effects of climate warming on larval development in other monarch populations and at different times of year should be investigated.