Phytochemical screening and insecticidal activities of some medicinal plants against the maize weevil, Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae).

This study emphasizes the phytochemical study of some locally available botanicals against maize weevils. Nine plant parts were collected from six plant species. The test plant powder (200 g) was suspended sequentially in 600 ml of petroleum ether, chloroform, acetone, methanol, and distilled water for 72 h with frequent agitation. Different concentrations of the crude extracts were applied to maize seeds at rates of 10 ml, 15 ml and 20 ml per 100 g. All treatments with different extracts at different rates of application showed significant differences (p < 0.05) in the cumulative mean percentage mortality of the maize weevil. The seed extract of Maesa lanceolata and Croton macrostachyus and the leaf extract of Clausena anisata showed cumulative percent mortality ranged 95.32-98.02% in 28 days after treatment application. There was no significant difference (p > 0.05) among all treatments for the prevention of F1 progeny emergence. In all extracts, Clausena anisata showed 100% inhibition of F1 progeny emergence. All treatments significantly reduced seed weight loss and damage. The treated maize seeds were germinated with an acceptable germination quality. In conclusion, an increased dosage of the extract resulted in significant mortality in maize weevils. The seed extracts of Maesa lanceolata and Croton macrostachyus and Clausena anisata leaf extract were observed to be the most promising botanical in protecting stored maize against maize weevil.

Diel flight activity in response to attractants in the predatory beetle, Cathartus quadricollis (Coleoptera: Silvanidae) in macadamia nut in Hawaii.

The diel flight activity in Cathartus quadricollis (Guerin-Meneville) (Coleoptera: Silvanidae), a predator of two important pests in Hawaii, coffee berry borer, Hypothenemus hampei (Ferrari) and tropical nut borer, Hypothenemus obscurus (F.) (Coleoptera: Curculionidae: Scolytinae) was studied in a macadamia nut orchard using yellow sticky traps baited with pheromone and fungal volatile attractants. The study was conducted at different months throughout the year and at different times during the lunar cycle (new moon and full moon). Flight activity peaked in the late hours of the photophase into the early hours of the scotophase, between 1830 and 2000 h; flight activity also occurred but to a lesser extent in the early morning hours between 0700 and 1030 h. Numbers of captured C. quadricollis during periods of flight activity were negatively correlated with wind speed. The implications of these findings for the development of optimal pest management strategies including biological control are discussed.

Evolution, types, and distribution of flight control devices on wings and elytra in bark beetles.

Gaining the ability to fly actively was a ground-breaking moment in insect evolution, providing an unprecedented advantage over other arthropods. Nevertheless, active flight was a costly innovation, requiring the development of wings and flight muscles, the provision of sufficient energetic resources, and a complex flight control system. Although wings, flight muscles, and the energetic budget of insects have been intensively studied in the last decades, almost nothing is known regarding the flight-control devices of many crucial insect groups, especially beetles (Coleoptera). Here, we conducted a phylogenetic-informed analysis of flight-related mechanosensors in 28 species of bark beetles (Curculionidae: Scolytinae, Platypodinae), an economically and ecologically important group of insects characterized by striking differences in dispersal abilities. The results indicated that beetle flight apparatus is equipped with different functional types of mechanosensors, including strain- and flow-encoding sensilla. We found a strong effect of allometry on the number of mechanosensors, while no effect of relative wing size (a proxy of flight investment) was identified. Our study constitutes the first step to understanding the drivers and constraints of the evolution of flight-control devices in Coleoptera, including bark beetles. More research, including a quantitative neuroanatomical analysis of beetle wings, should be conducted in the future.

G-Protein Coupled Receptor Gpr-1 Is Important for the Growth and Nutritional Metabolism of an Invasive Bark Beetle Symbiont Fungi Leptographium procerum.

Leptographium procerum has been demonstrated to play important roles in the invasive success of red turpentine beetle (RTB), one of the most destructive invasive pests in China. Our previous studies found that bacterial volatile ammonia plays an important role in the maintenance of the RTB-L. procerum invasive complex. In this study, we found a GPCR gene Gpr-1 that was a response to ammonia but not involved in the ammonia-induced carbohydrate metabolism. Deletion of Gpr-1 significantly inhibited the growth and pathogenicity but thickened the cell wall of L. procerum, resulting in more resistance to cell wall-perturbing agents. Further analyses suggested that Gpr-1 deletion caused growth defects that might be due to the dysregulation of the amino acid and lipid metabolisms. The thicker cell wall in the ΔGpr-1 mutant was induced through the cell wall remodeling process. Our results indicated that Gpr-1 is essential for the growth of L. procerum by regulating the nutritional metabolism, which can be further explored for potential applications in the management of RTB.

Acibenzolar-S-methyl induces resistance against ambrosia beetle attacks in dogwoods exposed to simulated flood stress.

Xylosandrus spp. ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) are important wood-boring pests of nursery trees weakened by abiotic and biotic stressors. Acibenzolar-S-methyl (ASM), a plant defense elicitor, was tested for inhibiting Xylosandrus spp. tunneling (i.e., attacks) into flood-stressed flowering dogwoods (Cornus florida L. (Cornales: Cornaceae)). Container-grown dogwoods were treated with ASM substrate drench + flooding, ASM foliar spray + flooding, ASM drench + no flooding, ASM foliar + no flooding, no ASM + flooding, or no ASM + no flooding at 3 days before flood stress in a completely randomized design under field conditions. Trees were flooded for 14 days and then drained and watered as needed. Attacks were counted every 2 days for 28 days. Plant tissue samples were collected at 7 and 14 days after flooding to determine ethanol content using solid-phase microextraction-gas chromatography-mass spectrometry. Trees were dissected to determine gallery formation and depth, fungal colonization, and the presence of eggs, larvae, and adults. The highest number of Xylosandrus beetle species attacks were recorded from plants exposed to no ASM + flooding, but attacks were reduced in ASM treated trees (drench or foliar) + flooding. Trees treated with drenches had fewer attacks than foliar sprays. Plants assigned to no flood had the fewest beetle attacks. Moreover, ASM reduced Xylosandrus spp. gallery formation and depth, fungal colonization, and presence of eggs, larvae, and adults. All flooded trees produced ethanol. In conclusion, ASM induced a plant defense response to Xylosandrus spp. tunneling in dogwoods under flood stress conditions.

Positive Chemotaxis of the Entomopathogenic Nematode Steinernema australe (Panagrolaimorpha: Steinenematidae) towards High-Bush Blueberry (Vaccinium corymbosum) Root Volatiles.

The foraging behavior of the infective juveniles (IJs) of entomopathogenic nematodes (EPNs) relies on host-derived compounds, but in a tri-trophic context, herbivore-induced root volatiles act as signals enhancing the biological control of insect pests by recruiting EPNs. In southern Chile, the EPN Steinernema australe exhibits the potential to control the raspberry weevil, Aegorhinus superciliosus, a key pest of blueberry Vaccinium corymbosum. However, there is no information on the quality of the blueberry root volatile plume or the S. australe response to these chemicals as putative attractants. Here, we describe the root volatile profile of blueberries and the chemotaxis behavior of S. australe towards the volatiles identified from Vaccinium corymbosum roots, infested or uninfested with A. superciliosus larvae. Among others, we found linalool, α-terpineol, limonene, eucalyptol, 2-carene, 1-nonine, 10-undecyn-1-ol, and methyl salicylate in root volatiles and, depending on the level of the emissions, they were selected for bioassays. In the dose-response tests, S. australe was attracted to all five tested concentrations of methyl salicylate, 1-nonine, α-terpineol, and 2-carene, as well as to 100 µg mL-1 of 10-undecyn-1-ol, 0.1 and 100 µg mL-1 of linalool, and 100 µg mL-1 of limonene, whereas eucalyptol elicited no attraction or repellency. These results suggest that some volatiles released from damaged roots attract S. australe and may have implications for the biocontrol of subterranean pests.

Piperitone (p-Menth-1-En-3-One): A New Repellent for Tea Shot Hole Borer (Coleoptera: Curculionidae) in Florida Avocado Groves.

The tea shot hole borer, Euwallacea perbrevis, has been recently established in Florida, USA, where it vectors fungal pathogens that cause Fusarium dieback in avocado. Pest monitoring uses a two-component lure containing quercivorol and α-copaene. Incorporation of a repellent into IPM programs may reduce the incidence of dieback in avocado groves, particularly if combined with lures in a push-pull system. This study evaluated piperitone and α-farnesene as potential repellents for E. perbrevis, comparing their efficacy to that of verbenone. Replicate 12-week field tests were conducted in commercial avocado groves. Each test compared beetle captures in traps baited with two-component lures versus captures in traps containing lures plus repellent. To complement field trials, Super-Q collections followed by GC analyses were performed to quantify emissions from repellent dispensers field-aged for 12 weeks. Electroantennography (EAG) was also used to measure beetle olfactory response to each repellent. Results indicated that α-farnesene was ineffective; however, piperitone and verbenone were comparable in repellency, achieving 50-70% reduction in captures, with longevity of 10-12 weeks. EAG responses to piperitone and verbenone were equivalent, and significantly greater than response to α-farnesene. Since piperitone is less expensive than verbenone, this study identifies a potential new E. perbrevis repellent.

Naïve Pine Terpene Response to the Mountain Pine Beetle (Dendroctonus ponderosae) through the Seasons.

Insect herbivores must contend with constitutive and induced plant defenses. The mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae, Scolytinae) has expanded its range east of the Rocky Mountains into the western boreal forest and is encountering evolutionarily naïve lodgepole pines (Pinus contorta) and jack pines (Pinus banksiana). Pinus contorta and P. banksiana in the expanded range have different constitutive and induced defenses in response to wounding and inoculation with fungal associates of D. ponderosae. In the historic range, previous studies have examined phloem terpene content prior to and just after D. ponderosae mass attack, but the terpene profile of attacked trees post-overwintering is unknown. We examined the response of mature P. contorta and P. banksiana trees to experimentally-applied mass attack by D. ponderosae and quantified phloem terpenes at three time points, pre-attack, post-attack (same season), and the following spring, post-overwintering. Phloem content of total terpenes as well as many individual terpenes increased after D. ponderosae attack but were only significantly higher than pre-attack levels at the post-overwintering time point in both P. contorta and P. banksiana. The absence of a significant increase in phloem terpenes in the month following attack in naïve pines is a potential cause for increased D. ponderosae offspring production reported in naïve P. contorta. Beetle attack density did not influence the phloem terpene profiles of either species and there was no significant interaction between attack density and sampling time on terpene content. High phloem terpenes in trees that are attacked at low densities could prime these trees for defense against attacks in the following season but it could also make these trees more apparent to early-foraging beetles and facilitate efficient mass attack at low D. ponderosae population densities in the expanded range.

Frequent and efficient harvesting as an economically viable strategy to regulate coffee berry borer on commercial farms in Hawaii.

Coffee is the second most economically important agricultural crop in Hawaii, valued at around $175M for green and roasted coffee in the 2021-2022 season. With the introduction of coffee berry borer (CBB, Hypothenemus hampei Ferrari) to Hawaii in 2010, growers have faced a significant challenge in producing the specialty coffee that the region is known for. This tiny beetle infests the coffee seed and reduces the yield and quality of coffee products. While field sanitation, frequent harvesting and strip-picking are known to be essential for controlling CBB, the associated costs and benefits of these cultural control practices have not been estimated for Hawaii. In the present study, we examined two CBB management strategies across 10 commercial coffee farms on Hawaii Island: (i) conventional management including frequent sprays of pesticides and few rounds of sanitation and harvesting, and (ii) cultural control-focused management consisting of few sprays of pesticides and frequent sanitation and harvesting. Cultural management resulted in significantly lower mean CBB infestation (4.6% vs. 9.0%), total defects (5.5% vs. 9.1%), and CBB damage to processed coffee (1.6% vs. 5.7%) compared to conventional management. Additionally, yields were higher (mean increase of 3,024 lbs of cherry/acre) and harvested more efficiently (4.8 vs. 7.9 raisins/tree) on culturally managed vs. conventional farms. Lastly, the cost of chemical controls was 55% lower and the net benefit of frequent harvesting was 48% higher on cultural vs. conventional farms. Our findings demonstrate that frequent and efficient harvesting is an effective and economically viable alternative to frequent pesticide applications.

Differential response to the South American rice water weevil (Coleoptera: Curculionidae) damage of rice cultivars with contrasting levels of resistance: implications for field management.

BACKGROUND: Oryzophagus oryzae (Costa Lima) (Coleoptera: Curculionidae) is a major pest of flooded rice paddies throughout South America, and species with very similar life histories are present in many rice-producing regions of the world (collectively rice water weevils, RWWs). The damage caused by RWW larvae on rice cultivars with contrasting levels of resistance ('BRS Pampa CL'= 'Pamp': susceptible, 'BRS Atalanta' = 'Atal': resistant-antibiosis) was evaluated in two consecutive years in the field under seven infestation levels: 0, 2, 4, 6, 8, 10 and 20 adult couples per cage with plants. RESULTS: Higher densities of adults increased the number of leaf-feeding scars and larvae on roots, respectively, at the rate ≤2.14 and 2.75 in Pamp and 2.23 and 2.48 in Atal, with the total number of larvae generated being lower in Atal. Grain yield was negatively impacted with increasing larval density on the roots, mainly by decreasing root volume and the number of grains per panicle. Root injury intensity and yield loss showed a nonlinear relationship. It was found that significant yield losses occurred with 8.37 larvae per plant in Pamp and 9.80 larvae per plant in Atal CONCLUSION: The results provided the first evidence of a tolerance limit for RWW larval damage that, even though similar between cultivars of contrasting resistance, corresponds to twice the current conventional level for larval control in Brazil. We also discuss here the potential of applying tolerance limits to manage the RWW adult population in rice fields. © 2022 Society of Chemical Industry.

Alfalfa Weevil (Coleoptera: Curculionidae) Resistance to Lambda-cyhalothrin in the Western United States.

Forage alfalfa (Medicago sativa L. [Fabales: Fabaceae]) is a key agricultural commodity of the western region of the United States. The key insect pest of alfalfa, Hypera postica Gyllenhal (Coleoptera: Curculionidae), has developed resistance to the most common class of insecticide used to manage its damage. Alfalfa weevil samples from 71 commercial alfalfa fields located in Arizona, California, Montana, Oregon, Washington, and Wyoming were assayed for susceptibility to lambda-cyhalothrin during 2020-2022 using a laboratory concentration-response assay. Seventeen field sites representing all six states were highly resistant to lambda-cyhalothrin (resistance ratios > 79.6) and bioassay mortality often did not exceed 50% even at the highest concentration tested (3.30 µg/cm2 in 2020 and 10.00 µg/cm2 in 2021-2022). Field sites assayed with more than one pyrethroid active ingredient indicated likely cross-resistance between lambda-cyhalothrin and zeta-cypermethrin (type II pyrethroids) and variable and/or limited potential cross-resistance to permethrin (type I pyrethroid). Thirty-two field sites representing five states were susceptible to lambda-cyhalothrin (resistance ratios ranging from 1 to 20). While resistance is widespread, integrated resistance management strategies including rotating mode of action groups, applying chemical control tactics only when economic thresholds have been met, and utilizing cultural control tactics can be employed to slow the further development of resistance.

Caught on camera: Field imagery reveals the unexpected importance of vertebrates for biological control of the banana weevil (Cosmopolites sordidus Col. Curculionidae).

Understanding of ecological interactions is necessary for the application of biological control. Banana is the second most produced fruit worldwide and the banana weevil (Cosmopolites sordidus) is the most important pest of banana and plantain. Its biological control remains challenging because of the robustness and cryptic behaviour of the adult and the hidden development of larval stages. Researchers therefore tend to favour conservation biological control of this pest. The commonly used methods for measuring the effects of natural enemies on the regulation of this pest focus on invertebrates and may underestimate the role of vertebrates on biological control. Using cameras, we recorded the predation of sentinel adult weevils in banana plots in La Réunion island that differed in weevil infestation levels and in animal biodiversity. To facilitate image analysis, we used background subtraction to isolate moving parts of image sequences and thus detect predators and predation events. Our cameras recorded only vertebrates as predators of adult banana weevils. The most important predator appeared to be the Asian shrew (Suncus murinus), which was responsible for 67% of the predation events. Other predators included the house mouse (Mus musculus), the oriental garden lizard (Calotes versicolor), and the guttural toad (Sclerophrys gutturalis). The exact time of predation events were determined from the images metadata. It was thus possible to identify predator foraging periods that coincided with activity of adult weevils. Our results confirm that images provide useful information for biological and ecological studies. Along with other recent studies, our results suggest that the role of vertebrates in biological control may be underestimated. Based on these results, we advocate for several management implications such as the installation of hedges, grasslands, and ponds to favour these vertebrate predators of the banana weevil, possibly also favouring other vertebrate and invertebrate natural enemies.

The female Euscepes postfasciatus refractory period is induced by the male but length is determined by the female.

Females of many animals mate multiple times during their lives (i.e., polyandry). The period between matings (mating interval) is called the refractory period (RP). In the West Indian sweet potato weevil (Euscepes postfasciatus), males use the ejaculate to induce the RP in females to prevent re-mating. By measuring the RP, a large variation of 1-49 days was observed. This variation may be due to the males (ejaculate quantity and quality) and females (ejaculate sensitivity/degradation ability and body size) and their interactions, but the exact mechanisms are currently unclear. Here, we investigated a tendency towards a particular female RP duration and the associated traits of males and females to test the following three factors responsible for variation in the length of the RP: male manipulation of ejaculate volume, individual differences in male ejaculation substances, and ejaculate sensitivity/degradation ability in females. We prepared virgin males and females to create mating pairs. The following day, another mate was introduced to the females, and the first RP was measured. The same procedure was used for measuring the second RP. The males were also provided with another female (second female), mated, and then the RP of the second female was measured. In addition, the relationship between the length of the RP and female fitness was investigated. The results showed that there was a significant positive correlation between the first and second RP in the focal females, while no significant correlation was observed between the RP of the first and second females induced by the same male. It was also found that the length of the RP did not affect female fitness. This indicated that the males did not adaptively manipulate ejaculation volume depending on the quality of the females, and variance in the length of the RP may be explained by variation in the female physiological ability against ejaculate.

Feeding preference of Rhynchophorus ferrugineus (Oliver) (Coleoptera: Curculionidae) on different date palm cultivars and host biochemical responses to its infestation.

To counter the insect infestation, plants respond with wide-ranging and highly dynamic biochemical reactions. Of these, the anti-oxidative activity is poorly understood. The red palm weevil (RPW) Rhynchophorus ferrugineus (Oliver), one of the most widespread pests in Pakistan, prefers to infest date palm Phoenix dactylifera. Our present study investigated the feeding preference of RPW to 11 different date palm cultivars and the results suggested that the Hillawi cultivar was most preferred. Greater infestation rate, fecundity and hatching rate were also recorded from Hillawi and Mozawati than other cultivars. No significant decreases were observed in chlorophyll a, chlorophyll b, total chlorophylls and carotenoids of RPW-infested Hillawi cultivar over un-infested control. In contrast, the contents of enzymatic antioxidants including phenols, proline, hydrogen peroxide, anthocyanin, malondialdehyde, ascorbic acid and glycine betaine showed a drastic increase after RPW infestation, and there was enhanced superoxide dismutase, peroxidase and catalase activities. Furthermore, we recorded the increase of total protein and sugar contents in RPW-infested date palms. These findings offer valuable insight into the antioxidative molecular mechanism of date palms under RPW attack and may contribute to the breeding of insect-resistant crops.

The Role of Wind and Semiochemicals in Mediating Switching Behavior in the Southern Pine Beetle (Coleoptera: Curculionidae: Scolytinae).

Aggressive bark beetles colonize and kill healthy conifers through pheromone-mediated mass aggregation. In several species, the focal point of aggregation moves progressively from mass-attacked 'focus trees' to adjacent, unattacked 'recipient trees', resulting in infestation growth. This process, termed 'switching', is hypothesized to be mediated in whole or in part by antiaggregation pheromones released by beetles as colonization intensifies on a focus tree. We tested this hypothesis with the southern pine beetle, Dendroctonus frontalis Zimmermann (Coleoptera: Curculionidae: Scolytinae), by using a windvane apparatus that maintained an unbaited, black, cylindrical trap (surrogate for a recipient tree) continuously 4 m downwind from an identical trap baited with synthetic aggregation attractant (surrogate for a focus tree). In two of three replicated trials, addition of pheromone components with antiaggregation activity, endo-brevicomin or verbenone, to the upwind trap caused a significant but small (<15%) increase in the proportion of beetles caught in the downwind trap. In one of two trials with endo-brevicomin, this shift was associated with a significant reduction in catches in the downwind trap and an overall reduction in catches of beetles by the trap pair. This suggests that an inhibitor-induced increase in landings on the recipient relative to the focus tree may be countered by the radial effects of the inhibitor, which at sufficiently high release may reduce responses to both the focus and recipient tree. We discuss spatial factors that might govern the role of antiaggregation pheromones in stimulating infestation growth as well as additional factors that likely govern switching behavior.

Metabolomics and transcriptomics of pheromone biosynthesis in an aggressive forest pest Ips typographus.

Eurasian spruce bark beetle, Ips typographus, is a destructive pest in spruce forests. The ability of I. typographus to colonise host trees depends on its massive aggregation behaviour mediated by aggregation pheromones, consisting of 2-methyl-3-buten-2-ol and cis-verbenol. Other biologically active compounds such as ipsdienol and verbenone have also been detected in the beetle. Biosynthesis of 2-methyl-3-buten-2-ol and ipsdienol de novo from mevalonate and that of cis-verbenol from α-pinene sequestrated from the host have been reported in preliminary studies. However, knowledge on the molecular mechanisms underlying pheromone biosynthesis in this pest is currently limited. In this study, we performed metabolomic and differential gene expression (DGE) analysis for the pheromone-producing life stages of I. typographus. The highest amounts of 2-methyl-3-buten-2-ol (238 ng/gut) and cis-verbenol (23 ng/gut) were found in the fed male gut (colonisation stage) and the immature male gut (early stage), respectively. We also determined the amount of verbenyl oleate (the possible storage form of cis-verbenol), a monoterpenyl fatty acid ester, to be approximately 1604 ng/mg in the immature stage in the beetle body. DGE analysis revealed possible candidate genes involved in the biosynthesis of the quantified pheromones and related compounds. A novel hemiterpene-synthesising candidate isoprenyl-di-phosphate synthase Ityp09271 gene proposed for 2-methyl-3-buten-2-ol synthesis was found to be highly expressed only in the fed male beetle gut. Putative cytochrome P450 genes involved in cis/trans-verbenol synthesis and an esterase gene Ityp11977, which could regulate verbenyl oleate synthesis, were identified in the immature male gut. Our findings from the molecular analysis of pheromone-producing gene families are the first such results reported for I. typographus. With further characterisation of the identified genes, we can develop novel strategies to disrupt the aggregation behaviour of I. typographus and thereby prevent vegetation loss.

Conditions to Terminate Reproductive Diapause of a Univoltine Insect: Ceratapion basicorne (Coleoptera: Apionidae), a Biological Control Agent of Yellow Starthistle.

Ceratapion basicorne (Illiger) is a recently approved univoltine biological control agent that develops inside the rosette of yellow starthistle (Centaurea solstitialis L.), an invasive annual plant. Adult weevils normally emerge in early summer, and females are thought to be in reproductive diapause until the following spring, when they oviposit in rosettes. The long period of reproductive diapause constrains mass-rearing this weevil because only one generation per year can be produced. Determining the environmental conditions that regulate diapause termination may enable shortening diapause under laboratory conditions to increase production of adults to release. We tested three hibernating conditions (greenhouse [ambient temperature and photoperiod], glass door refrigerator [5°C and ambient photoperiod], and growth chamber [5°C and 24 h dark]) for three durations (4, 8, 11 wk). The highest proportion of females laying eggs came from the growth chamber, with 40% terminating diapause after 4 wk, 80% after 8 wk, and 95% after 11 wk of exposure. Our study demonstrates that duration of cold temperature is an important stimulus to terminate reproductive diapause of C. basicorne, and that exposure to ambient light had no effect at 5°C. However, 47% of females held at ambient greenhouse conditions, without any chilling period, completed diapause within 11 wk. Thus, a cold period can accelerate diapause development, but it is not necessary for its completion. Reducing the winter diapause period from about 6 mo to 11 wk should enable the production of multiple generations per year to increase the number of insects available to release.

Demography and perturbation analyses of the coffee berry borer Hypothenemus hampei (Coleoptera: Curculionidae): Implications for management.

The coffee berry borer (CBB) Hypothenemus hampei Ferrari is the most serious pest of coffee worldwide. Management of the CBB is extremely difficult because its entire life cycle occurs inside the fruit, where it is well protected. Knowing which life stages contribute most to population growth, would shed light on the population dynamics of this pest and help to improve CBB management programs. Two staged-classified matrices were constructed for CBB populations reared in the lab on artificial diets and CBB populations from artificial infestations in the field. Matrices were used to determine demographic parameters, to conduct elasticity analyses, and to perform prospective perturbation analysis. Higher values of the intrinsic rate of natural increase (rm) and population growth rate (λ): were observed for CBB populations growing in the lab than in the field (rm: 0.058, λ: 1.74 lab; rm: 0.053, λ: 1.32 field). Sensitivity values for both CBB populations were highest for the transitions from larva to pupa (G2: 0.316 lab, 0.352 field), transition from pupa to juvenile (G3: 0.345 lab, 0.515 field) and survival of adult females (P5: 0.324 lab, 0.389 field); these three vital rates can be important targets for CBB management. Prospective perturbation analyses indicated that an effective management for the CBB should consider multiple developmental stages; perturbations of >90% for each transition are necessary to reduce λ to <1. However, when the three vital rates with highest sensitivity are impacted at the same time, the percentage of perturbation is reduced to 25% for each transition; with these reductions in survival of larvae, pupae and adult females the value of λ was reduced from 1.32 to 0.96. Management programs for CBB should be focused on the use of biological and cultural measures that are known to affect these three important targets.

Combined drought and bark beetle attacks deplete non-structural carbohydrates and promote death of mature pine trees.

How carbohydrate reserves in conifers respond to drought and bark beetle attacks are poorly understood. We investigated changes in carbohydrate reserves and carbon-dependent diterpene defences in ponderosa pine trees that were experimentally subjected to two levels of drought stress (via root trenching) and two types of biotic challenge treatments (pheromone-induced bark beetle attacks or inoculations with crushed beetles that include beetle-associated fungi) for two consecutive years. Our results showed that trenching did not influence carbohydrates, whereas both biotic challenges reduced amounts of starch and sugars of trees. However, only the combined trenched-bark beetle attacked trees depleted carbohydrates and died during the first year of attacks. While live trees contained higher carbohydrates than dying trees, amounts of constitutive and induced diterpenes produced did not vary between live and beetle-attacked dying trees, respectively. Based on these results we propose that reallocation of carbohydrates to diterpenes during the early stages of beetle attacks is limited in drought-stricken trees, and that the combination of biotic and abiotic stress leads to tree death. The process of tree death is subsequently aggravated by beetle girdling of phloem, occlusion of vascular tissue by bark beetle-vectored fungi, and potential exploitation of host carbohydrates by bark beetle symbionts as nutrients.

High-temperature shock consequences on the red flour beetle (Tribolium castaneum) and the rice weevil (Sitophilus oryzae).

Temperature shocks have profound effects on biological and physiological functions at all levels of organization. However, the recovery periods from these shocks and their subsequent impacts remain unknown. Herein, our study investigated the effect of short temperature stress on survival, dormancy recovery time, nutritional indices, life traits and development rate for T. castaneum (larvae and adults) and S. oryzae adults. The results showed significant effects on survival rates of T. castaneum (larvae and adults) and S. oryzae adults. When both insects had been exposed to high-temperature shock, survival rates decreased with higher temperatures and longer periods of exposure. Furthermore, recovery times varied between and within the insect species, as prolonged exposure to thermal shocks increased recovery periods. Moreover, dormancy time resulting from the high-temperature shocks significantly affected food deterrence and food intake, regardless of the stage of development, species, exposure periods and temperature-exposure conditions. Subsequently, differences in body growth rates and food consumption rates are an appropriate indicator of differences in food conversion rates under high-temperature shocks, regardless of the species and developmental stages. On the other hand, our results indicated that as high-temperature shocks increased, the total development period increased of T. castaneum. Likewise, the pupal stage increased with increasing high-temperature shocks, and the larval stage decreased with increasing thermal shocks and increasing the periods of exposure. In summary, our study showed the importance of dormancy recovery time and its subsequent effects for improving disinfestation effectiveness of heat treatment, and understanding insect response to high temperatures.