Journal of Insect Physiology

Ongoing climate change has increased temperatures and the frequency of droughts in many parts of the world, potentially intensifying the desiccation risk for insects. Because resisting desiccation becomes more difficult at higher temperatures and lower humidity, avoiding water loss is a key challenge facing terrestrial insects. However, few studies have examined the interactive effects of temperature and environmental humidity on desiccation resistance in insects. Such studies on bees (Hymenoptera: Apoidea: Anthophila) are especially rare, despite their ecological and economic importance...

Cotesia typhae is an eastern African endoparasitoid braconid wasp that targets the larval stage of the lepidopteran stem borer, Sesamia nonagrioides, a maize crop pest in Europe. The French host population is partially resistant to the Makindu strain of the wasp, allowing its development in only 40% of the cases. Resistant larvae can encapsulate the parasitoid and survive the infection. This interaction provides a very interesting frame for investigating the impact of parasitism on host cellular resistance...

Photic entrainment is an essential function of the circadian clock, which enables organisms to set the appropriate timing of daily behavioral and physiological events. Recent studies have shown that the mechanisms of the circadian clock and photic entrainment vary among insect species. This study aimed to elucidate the circadian photoreceptors necessary for photic entrainment in firebrats Thermobia domestica, one of the most primitive apterygote insects. A homology search of publicly available RNA sequence (RNA-seq) data from T...

Honey bees are globally important pollinators, key to many aspects of ecosystem function and agricultural production. However they are facing an increasing array of stress factors. These stressors include exposure to pathogens and pesticides, agricultural intensification, and changes in climate, and likely contribute to colony dysfunction and colony losses. Here we use temperature-controlled glasshouse experiments to investigate the impact of a field-realistic temperature-range on honey bee colonies, including temperatures based on projections for near-future local conditions...

Mormon cricket eggs can remain diapausing in soil for multiple years without forming an embryo. I investigated whether embryonic development was dependent on the number of annual cycles since the egg was laid, duration of the summer period (forcing), or duration of the winter period (chilling). Male and female Mormon crickets collected in Arizona and Wyoming were paired in the lab. For each mating pair, sibling eggs were incubated 12 weeks, eggs with fully developed embryos removed, and the remaining eggs were split evenly among three treatments: a long cold period and a long warm period; a short cold period and a long warm period; and a short cold period and a short warm period, which respectively completed 2 annual cycles, 3 cycles, and 4 cycles in 60 calendar weeks...

In many katydids, the male feeds his mate with a large gelatinous spermatophore. While providing large spermatophores can increase female fecundity and lifespan, it may also decrease their sexual receptivity, benefiting male fitness. Allocating resources to these edible gifts may entail a lower apportionment of them to other functions, generating a trade-off between somatic and reproductive functions. Despite their effect on male and female fitness, little is known of the compounds associated with katydid spermatophores...

The maxillary palp is an auxiliary olfactory organ in insects, which, different from the antennae, is equipped with only a few olfactory sensory neuron (OSN) types. We postulated that these derived mouthpart structures, positioned at the base of the proboscis, may be particularly important in mediating feeding behaviors. As feeding is spatio-temporally segregated from oviposition in most Tephritidae, this taxonomic group appears quite suitable to parse out sensory breadth and potential functional divergence of palps and antennae...

About half of the serosal cells (Scs) of Cotesia kariyai (Ck) eggs are released as teratocytes into the host body cavity after hatching, and another half remain attached to the larval epidermis until the 1st instar larvae of Ck ecdysis to 2nd instars. To investigate the role of the serosal cells surrounding Ck 1st instar larvae (1st Scs) in immune avoidance, Ck 1st instar larvae with and without Scs removed using dispase were transplanted into Mythimna separata host larvae, respectively. As a result, Ck 1st instar larvae surrounded by Scs were less susceptible to host encapsulation than Ck 1st instar larvae without the Scs, suggesting that the Scs are involved in suppressing the encapsulation of the host...

Beetle elytra act as natural protective covers and effectively shield their flexible abdomens and fragile hindwings from damage. The existing studies have attributed this contribution of the elytra to its honeycomb structures. In this combined experimental and theoretical study, we used the seven-spotted ladybird beetle to demonstrate that both biological morphology and the hollow structure of the dome-like elytra combined to reduce damage during falling. The falling ladybird beetles had a high probability (59...

Workers of social hymenopterans (ants, bees and wasps) display specific tasks depending on whether they are younger or older. The relative importance of behavior and age in modulating immune function has seldom been addressed. We compared the strength of encapsulation-melanization immune response (hereafter melanotic encapsulation) in paper wasps displaying age polyethism or experimentally prevented from behavioral specialization. Foragers of Polybia paulista had higher melanotic encapsulation than guards, regardless of their age...

Herbivorous insects can identify their host plants by sensing plant secondary metabolites as chemical cues. We previously reported the two-factor host acceptance system of the silkworm Bombyx mori larvae. The chemosensory neurons in the maxillary palp (MP) of the larvae detect mulberry secondary metabolites, chlorogenic acid (CGA), and isoquercetin (ISQ), with ultrahigh sensitivity, for host plant recognition and feeding initiation. Nevertheless, the molecular basis for the ultrasensitive sensing of these compounds remains unknown...

Farnesol, a sesquiterpene found in all eukaryotes, precursor of juvenile hormone (JH) in insects, is involved in signalling, communication, and antimicrobial defence. Farnesol is a compound of floral volatiles, suggesting its importance in pollination and foraging behaviour. Farnesol is found in the resin of Baccharis dracunculifolia, from which honeybees elaborate the most worldwide marketable propolis. Bees use propolis to seal cracks in the walls, reinforce the wax combs, and as protection against bacteria and fungi...

In nectivorous pollinators, timing and pattern of allocation of consumed nectar affects fitness traits and foraging behavior. Differences in male and female behaviors can influence these allocation strategies. These physiological patterns are not well studied in Lepidoptera, despite they being important pollinators. In this study we investigate crop-emptying rate and nectar allocation in Manduca sexta (Sphingidae), and how sex and flight influence these physiological patterns. After a single feeding event, moths were dissected at fixed time intervals to measure crop volume and analyze sugar allocation to flight muscle and fat body...

Extreme temperatures threaten species under climate change and can limit range expansions. Many species cope with changing environments through plastic changes. This study tested phenotypic changes in heat and cold tolerance under hardening and acclimation in the melon thrips, Thrips palmi Karny (Thysanoptera: Thripidae), an agricultural pest of many vegetables. We first measured the critical thermal maximum (CTmax ) of the species by the knockdown time under static temperatures and found support for an injury accumulation model of heat stress...

With increasing soil depth, the amplitude and phase of the daily temperature cycle decreases and is delayed, respectively. The onion fly, Delia antiqua, which pupates at a soil depth of 2-20 cm, advances the eclosion phase of its circadian clock as the temperature amplitude decreases. This "temperature-amplitude response" compensates for the depth-dependent phase delay of the temperature change and ensures eclosion in the early morning. To clarify the physiological mechanisms that induce a temperature-amplitude response, we performed phase-resetting experiments using a 12-h high- or low-temperature pulse with an amplitude of 1 °C or 4 °C...

The environment is changing faster than anticipated due to climate change, making species more vulnerable to its impacts. The level of vulnerability of species is influenced by factors such as the degree and duration of exposure, as well as the physiological sensitivity of organisms to changes in their environments, which has been shown to vary among species, populations, and individuals. Here, we compared physiological changes in fecundity, critical thermalmaximum (CTmax ), respiratory quotient (RQ), and DNA damage in ovaries in response to temperature stress in two species of fruit fly, Drosophila melanogaster (25 vs...

Parasitoids have utilized a variety of strategies to counteract host defense. They are in different taxonomic status and exhibit phenotypic and genetic diversity, and thus are thought to evolve distinct anti-defense mechanisms. In this study, we investigated the performance of two closely related parasitoids, Exorista japonica and Exorista sorbillans (Diptera: Tachinidae) that are biological control agents in agriculture and major insect pests in sericulture, on the host Bombyx mori. We show that the host is more susceptible to E...

Many insects living in seasonal environments sense seasonal changes from photoperiod and appropriately regulate their development and physiological activities. Genetic researches have indicated the importance of a circadian clock system in photoperiodic time-measurement for photoperiodic regulations. However, most previous studies have focused on the effects on a single photoperiodic phenotype, without elucidating whether the circadian clock is involved in the core photoperiodic mechanism or only in the production of one target phenotype, such as diapause...

Little is known about the energetic costs to insects of raising young. Honey bees collectively raise young, or brood, through a series of complex behaviors that appear to accelerate and synchronize the timing of brood maturation. These include maintaining the brood nest at warmer and consistent temperatures (33-36°C) and the exceptional activity of heater bees. Heater bees are a part of the larger group of nurse bees that care for brood by rapidly contracting thoracic muscles to generate high body temperatures, from 42 to 47 °C...

The larvae of the black headed cardinal beetle Pyrochroa coccinea, overwinters under the bark of dead logs in northern European dioecious forests, and are thus exposed to temperatures below the melting point of their bodily fluids. Here we explore the mechanisms behind their seasonal cold hardening by characterising field samples collected monthly throughout the year. Both the lower lethal temperature and supercooling point dropped as much as 10℃ in the second half of November, reaching values around -15℃ by the beginning of December...