Number Of Instars Research Articles

Dynamic Energy Budget approach for modeling growth and reproduction of Neotropical stink bugs

Global warming and other climate change drivers have a significant impact on the life cycle of insects which in turn affect their population dynamics and geographic distribution. Among these insects are stink bugs (Hemiptera: Pentatomidae), which are hemimetabolous agricultural pests that cause major damage on crops in many countries. Their life cycle consists of three stages: egg, nymph, and adult. The nymph grows and molts through a small number of instars until reaching emergence, at which point growth ceases. The Dynamic Energy Budget (DEB) theory provides the framework for modeling the life cycle of stink bugs. Nevertheless, determining the most accurate model for nymphal growth and energy allocation during the adult stage remains a challenge, as the best model is not always evident. For two species of the Pentatomidae family, we parameterized and evaluated four DEB models that differ in nymphal growth and the energy allocation rules in adults: isomorphic or V1-morphic nymphal growth combined with the energy allocation scheme in adults that follows the κ-rule or the scheme that the κ-rule is not operational in adults. Overall, all models fit the data, but those with isomorphic nymphal growth reproduce the growth trajectories and instar duration better. However, with the available data we cannot conclude which rule is most likely the energy allocation in adults. Using these models, we further studied the effects of temperature and food availability on individual dynamics and its life cycle. Simulations show that temperature has a higher impact on the duration of life stages and survival, while food availability affects egg production. When simulating a variable environment in terms of temperature for both a summer and a fall generation, the results reveal that the summer generation has higher feeding and egg production rates in comparison to the fall generation. DEB models are valuable tools for simulating individual under various environmental conditions and when combined with appropriate modeling approaches, they can predict population traits and even the potential distribution of a species.

Development and reproductive biology of Dermaptera: a comparative study of thirteen species from eight families

Abstract We examine and describe the embryonic development of 13 species from eight families of Dermaptera, i.e., all families excluding Karschiellidae, Hemimeridae, and Arixeniidae: Diplatys flavicollis (Diplatyidae), Cranopygia sp., Echinosoma sp., and Parapsalis infernalis (Pygidicranidae), Apachyus chartaceus (Apachyidae), Anisolabis maritima and Euborellia pallipes (Anisolabididae), Labidura riparia (Labiduridae), Forficula scudderi and Anechura harmandi (Forficulidae), Paralabella curvicauda (Spongiphoridae), and Proreus simulans and chelisochid gen. sp. (Chelisochidae). We also provide new findings on the reproductive biology of the Pygidicranidae and the postembryonic development of the Apachyidae. Based on information from the present and previous studies, we reconstruct the developmental and reproductive-biological groundplan for Dermaptera and discuss phylogenetic issues related to this order. We confirmed that Dermaptera possesses the embryological features (related to mode of embryonic formation and manner of blastokinesis) that are regarded as autapomorphies of Polyneoptera. Eudermaptera is characterized by the extraordinarily great length of the embryo which attains its maximum length in anatrepsis period, the positioning of its posterior end at the egg’s anterior ventral side, the type of egg tooth, and four larval instars. Anisolabididae, Labiduridae, and Eudermaptera share an elongation ratio of embryos in the anatrepsis period (ERE) of 160% or less and a larval instar number of five or less, whereas Protodermaptera is characterized by an ERE of 210% or more, a ratio of embryonic primordium relative to the egg’s longitudinal circumference (IL) of 40% or less, and a larval instar number of six or more. Notably, the ERE, IL, and larval instar number of Apachyidae are within the ranges observed in Protodermaptera.

Does the Neotropical‐native parasitoid Ganaspis pelleranoi successfully attack the worldwide invasive pest Drosophila suzukii?

AbstractThe Asian Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) is a harmful invasive pest widespread throughout Argentinian fruit‐producing regions. It coexists with both pests, the sub‐Saharan African Ceratitis capitata (Wiedemann) and the Neotropical‐native Anastrepha fraterculus (Wiedemann) (both Diptera: Tephritidae), in northwestern Argentina. The Neotropical‐native parasitoid Ganaspis pelleranoi (Brèthes) (Hymenoptera: Figitidae) is frequently found in non‐crop fruit infested by those frugivorous dipterans. The northwestern Argentinian region is known for producing and exporting berries and citrus, which are affected by those pests. Thus, eco‐friendly control strategies are under assessment. This study mainly assessed the potential of the G. pelleranoi population lineage from Tucumán (GpTuc) as a D. suzukii biocontrol agent. First, both the host‐killing effectiveness and the reproductive success of GpTuc on larvae of D. suzukii, C. capitata, A. fraterculus, and Drosophila melanogaster Meigen were compared in no‐choice tests under laboratory conditions. Then, the GpTuc host preference was evaluated in dual‐choice tests (D. suzukii vs. C. capitata or A. fraterculus) under laboratory and field conditions. Naive parasitoid females were allowed to forage for 8 h on screen‐covered Petri dishes filled with host larvae under laboratory conditions and for 48 h on peaches inoculated with host larvae under field conditions. Host puparia dissections were performed to determine the number and condition of parasitoid eggs, first and second instars, such as alive/dead, without/with melanization process, and proportions of parasitized, superparasitized, and dead puparia. Drosophila suzukii was not a suitable host for the successful development of GpTuc immature stages as they did not overcome the host's immune system. However, GpTuc performed efficiently regarding D. suzukii mortality, but parasitoid specificity was restricted to both tephritid species as only thriving offspring were achieved from them. Interestingly, the effectiveness of GpTuc on D. suzukii increased when it co‐occurred with C. capitata instead of A. fraterculus, the preferred host.

Morphometric analysis for determination of larval instars in Dermestes frischii Kugelann and Dermestes undulatus Brahm (Coleoptera: Dermestidae).

Dermestes frischii Kugelann, 1792 and Dermestes undulatus Brahm, 1790 are the most abundant species worldwide at outdoor or indoor crime scenes during the dry and skeletal stages of decomposition. The attribution of larval age in these beetles is problematic due to the variable number of instars, which is influenced by environmental factors. In this study, a morphometric approach was used to look for potential morphological features as evidence of larval stages. Breeding and monitoring were performed for both species in an incubator with a preset temperature of 28°C ± 0.5 without a photoperiod. Morphometric measurements were made on 10 larvae per instar for each species using length, width, and thickness parameters. Linear discriminant analysis was then used to generate decision boundaries that clearly separated larval stages. The cross-validation procedure demonstrated that the morphometric approach successfully discriminated adjacent larval stages in both species with high values of sensitivity and specificity. This less-invasive approach could improve the ability to estimate minPMI in forensic studies of Dermestidae beetles. Future studies may extend this approach to other species and establish good practices for collecting and storing specimens for morphometric analysis.

Investigating the effect of host plant identity on instar number in fall webworm, a common generalist herbivore.

For herbivorous insects with a broad diet breadth, host plant identity can influence larval development by either accelerating or delaying growth. For some species of Lepidoptera, the number of larval instars varies depending on the host plant's identity. Fall webworm (Hyphantria cunea, Drury) is a polyphagous herbivore that feeds on over 450 host plants worldwide. Of the 2 morphotypes (red- and black-head) of fall webworm, the number of instars for the red-head fall webworms has not been characterized. Given its broad diet breadth, fall webworm developmental stages may vary with plant identity. We investigated whether host plant identity affected the number of instars observed during red-head fall webworm development. We measured the head capsules of over 6,000 fall webworm larvae reared on 6 different plants commonly eaten by fall webworms in Colorado. We modeled head capsule widths as Gaussian mixture models, with a Gaussian distribution that corresponded to each instar. We show that our red-head fall webworms varied in number of instars depending on the identity of their host plant upon which they fed. We found that red-head fall webworm exhibited 7 instars on 5 of the host plants and 8 instars on 1 host plant that we studied. Our results for the number of instars for red-head fall webworm are consistent with reports of the number of instars for black-head fall webworm. Our research provides insight into the influence of host plant identity on fall webworm development, which can be used to advance lab and field research of this species.

Larval instars determination for the twig borer weevil (Coleoptera: Curculionidae) of Falcataria moluccana (Miq.) Barneby & Grimes in Moluccas, Indonesia

In establishing an integrated pest control strategy, it is important first to discover the life history of a potential agent, including the number of larval instars. The snout-weevil of the tribe Ithyporini Genus species (Coleoptera: Curculionidae) is a holometabolous insect that attacks Falcataria moluccana, a native tree of the Moluccas (Maluku), Indonesia. Preliminary observations show that their larvae feed and develop as a twig borer, making direct observation of their development complicated. This study aimed to determine the number of larval instars by measuring the head capsule width (HCW) and the growth pattern of larvae. As many as 940 larvae of all sizes were collected from three islands in Maluku Province: Ambon, Seram, and Haruku. Kernel density estimation (KDE) and Gaussian mixture model (GMM) were used for data analysis. The growth instars were verified using Brooks-Dyar’s rule. The results indicated four peaks in the frequency distribution from KDE, and cluster four showed the best-fit model from GMM. The growth ratio of HCW was 1.47, which also agrees with Brooks-Dyar’s rule that the growth ratio was consistent and followed a constant geometric. Thus, this research concluded that there were four instars for Ithyporini Gen. sp. larvae.

Immature stages of Phloeosinus tacubayae (Curculionidae: Scolytinae): morphology and chaetotaxy of larva and pupa, sexual dimorphism of adults, and developmental time.

The current knowledge of morphology and chaetotaxy of the different developmental stages within the subfamily Scolytinae presents an information deficit that needs to be addressed. Thus, the objective of the present study was to describe, the chaetotaxy and morphology of larvae and pupae, and determine the number of larval instars, the sexual dimorphism in adults, and the development time in Phloeosinus tacubayae. The number of larval instars was determined using traditional morphometry of cephalic capsule and multivariate analysis; description of morphology and chaetotaxy of larvae and pupae, and sexual dimorphism in adults was based on light microscopy and scanning electron microscopy photographs; finally, we quantified development time by mean reviews of 10 gallery systems selected randomly in infested logs, in the laboratory. Morphometric analysis of the cephalic capsule allowed the recognition of 3 different instars. Our results showed that the larvae of P. tacubayae have unique attributes in the body that differentiate them from other genera of the subfamily for example the epicranial suture is not marked, and differentiated from Phloeosinus canadensis, such as a smaller number of setae in the maxillae and without a tergal plate. The pupa had a smaller number of setae on the whole body. The most useful morphological characters to identify a sexual dimorphism in adults were found in the shape and relative position of the seventh and eighth tergites; development time lasted 40 days in total, being the pupal stage the one that took the longest to complete.

Unraveling the effect of temperature and humidity on the life cycle of Diatraea saccharalis (Lepidoptera: Crambidae) and the impact on pest outbreaks.

Temperature and humidity are considered the main abiotic factors that affect both the development and survival of ectothermic organisms. In this study, we estimated the development time as well as the thermal requirements of the sugarcane borer, Diatraea saccharalis (Fabricius, 1794; Lepidoptera: Crambidae), a key insect pest of sugarcane and discussed the influence of temperature and relative humidity and its infestation intensity in a scenario of climate change. The models Brière-1 and Ikemoto-Takai provided the best fit to the data of development rate versus temperature. The average life cycle (from egg to adult) ranged from 39.21 ± 4.84 at 32 °C to 137.10 ± 7.47 at 18 °C days. The thermal constant and average base temperature were 547.69 degree-days and 13.64 °C, respectively. The number of larval instars varied from 4 to 7 depending on the temperature, being higher at lower temperatures. The thermal range comprised the interval from 16.7 °C to 33.9 °C and the optimum temperature was estimated as 27.4 °C. Locations with elevated temperature (≥25 °C) and high relative humidity (≥70%) presented larger populations of D. saccharalis. Our findings show that the infestation pressure of this species is highly influenced by both temperature and humidity, and the studied models allow to forecast pest outbreaks. In the context of climate change, information about the thermal range and the optimum temperature contributes to predicting the spatial-temporal distribution of D. saccharalis and, consequently, aids decision making in pest management.

Sub-optimal host plants have developmental and thermal fitness costs to the invasive fall armyworm.

The fall armyworm (FAW) Spodoptera frugiperda (J.E. Smith) is a global invasive pest of cereals. Although this pest uses maize and sorghum as its main hosts, it is associated with a wide range of host plants due to its polyphagous nature. Despite the FAW's polyphagy being widely reported in literature, few studies have investigated the effects of the non-preferred conditions or forms (e.g., drought-stressed forms) of this pest's hosts on its physiological and ecological fitness. Thus, the interactive effects of biotic and abiotic stresses on FAW fitness costs or benefits have not been specifically investigated. We therefore assessed the effects of host plant quality on the developmental rates and thermal tolerance of the FAW. Specifically, we reared FAW neonates on three hosts (maize, cowpeas, and pearl millet) under two treatments per host plant [unstressed (well watered) and stressed (water deprived)] until the adult stage. Larval growth rates and pupal weights were determined. Thermal tolerance traits viz critical thermal maxima (CTmax), critical thermal minima (CTmin), heat knockdown time (HKDT), chill-coma recovery time (CCRT), and supercooling points (SCPs) were measured for the emerging adults from each treatment. The results showed that suboptimal diets significantly prolonged the developmental time of FAW larvae and reduced their growth rates and ultimate body weights, but did not impair their full development. Suboptimal diets (comprising non-cereal plants and drought-stressed cereal plants) increased the number of larval instars to eight compared to six for optimal natural diets (unstressed maize and pearl millet). Apart from direct effects, in all cases, suboptimal diets significantly reduced the heat tolerance of FAWs, but their effect on cold tolerance was recorded only in select cases (e.g., SCP). These results suggest host plant effects on the physical and thermal fitness of FAW, indicating a considerable degree of resilience against multiple stressors. This pest's resilience can present major drawbacks to its cultural management using suboptimal hosts (in crop rotations or intercrops) through its ability to survive on most host plants despite their water stress condition and gains in thermal fitness. The fate of FAW population persistence under multivariate environmental stresses is therefore not entirely subject to prior environmental host plant history or quality.

The number of larval instars in the flax weevil (Anagotus fairburni) (Coleoptera: Curculionidae)

ABSTRACT The flax weevil Anagotus fairburni is a large flightless beetle, that is one of the members of the endemic insect ‘megafauna’ of New Zealand. It is a protected species that currently persists only on predator-free islands or in remote and difficult to access alpine areas. Little is documented about the ecology of the flax weevil. In this study we estimated the number of instars in the A. fairburni life cycle by measuring the head capsule widths of larvae collected in the field on Mana Island Scientific Reserve. We used kernel density function estimates to predict average head-capsule widths and the number of larval instars. We then used Brooks-Dyar’s law on the head capsule width data and analysed Brooks and Crosby indexes to refine the estimated number of instars based on imperfect data. Results from sampling of 86 larvae suggested four instar groupings, but further analysis based on Brooks-Dyar’s law found that A. fairburni likely passes through 6 or 7 larval stages prior to pupation, with some uncertainty for smaller instars. Our method provides new data on ecology of an endemic species and provides a framework for further work on similar endangered species where data is imperfect or difficult to gather.

Developmental models and morphological characteristics of the hide beetle, Dermestes frischii, under different constant temperatures

Many species of hide, larder, and carpet beetles (Coleoptera, Dermestidae) are economically important pests of stored products of animal and plant origin, and also have high forensic application value. This study investigated the developmental duration of the immature stage of Dermestes frischii (Kugelann, 1792) under six constant temperatures (19, 22, 25, 28, 31, and 34 °C) and found that development was longest at 19 °C, taking 97.4 ± 7.9 days, and was shortest at 31 °C, taking 31.3 ± 7.2 days. The isomorphen diagram was established based on the developmental events under the different constant temperatures, and the thermobiological parameters of D. frischii were evaluated using linear thermal summation and curvilinear Optim SSI models. The thermal summation constant was 559.89, while the intrinsic optimum temperature and lower and upper lethal developmental thresholds were 24.65, 13.37, and 34.98 °C, respectively. The mortality rate and the mean number of larval instars increased under higher or lower temperatures. The mean instar duration of the first to the fifth instar was generally similar, while the instar duration was the shortest under high temperatures with the fastest developmental rate. We conclude that temperature has a separate effect on the number and duration of the larval instar of D. frischii. In addition, the larval morphological parameters were measured, and the ultrastructures of the antennae, mouthparts, and urogomphi were characterized. This work provides important basic data for storage pest control and minimum postmortem interval estimation of D. frischii in forensic entomology research and application.

The Life History and Ecology of the Lesser Wasp Moth, Pseudocharis minima, (Lepidoptera, Erebidae, Euchromiina) in the Pine Rocklands of South Florida

The Arctiinae species Pseudocharis minima (Lesser Wasp Moth) is considered imperiled according to Florida Natural Areas Inventory but little had been published on its life history. We describe the life history of the Lesser Wasp Moth descriptively and quantitatively while providing images of eggs, larval instars, pupae, and adults. We describe a variance in the number of larval instars from 6 to 8. We also report the first field observations of Lesser Wasp Moths utilizing Crossopetalum rhcoma (Maidenberry) for egg laying and larval consumption. The mean life-cycle duration is ∼61 days and can provide about 6 generations in a single year. We anticipate that our research will aid in the management of native pine rockland habitats for the Lesser Wasp Moth as well as laying the groundwork for conservation efforts in the event of possible further population declines.

Biodegradation of Expanded and Extruded Polystyrene with Different Diets by Using Zophobas atratus Larvae (Coleoptera: Tenebrionidae)

Polystyrene waste pollutes the environment and poses a significant health risk to humans, animals, and marine ecology. This study aims to evaluate the effectiveness of degradation on expanded (EPS) and extruded (XPS) polystyrene with different diets using superworms (Zophobas atratus larvae) obtained in Malaysia. The growth and development of the larvae after consumption of EPS and XPS and the gut microbial community changes in response to high polystyrene consumption diets were also identified. The oatmeal, wheat bran, and cornmeal were used as supplement diets and showed significantly enhanced EPS and XPS consumption and degradation compared to sole diet treatment. Gel permeation chromatography was carried out using egested frass of Z. atratus larvae to characterize depolymerization of EPS and XPS, indicating a significant reduction in the average molecular weight and average molecular weight. The highest reduction occurred in the presence of oatmeal. Proton nuclear magnetic resonance and Fourier transform infrared spectroscopy analyses indicated functional group changes and chemical modification occurred with depolymerization and partial oxidation of EPS and XPS. The larvae length increased, while the number of instars and duration of larvae became shorter with the addition of supplement diets. Oatmeal is predominantly effective among other supplements in assisting Z. atratus larvae with EPS and XPS degradation. The results of this study support the ubiquity of polystyrene biodegradation in Z. atratus and the next-generation sequencing studies. Kluyvera sp., Klebsiella sp., and Enterobacter sp. were found to be strongly associated with degrading EPS and XPS polystyrene with oatmeal as a supplemental diet.

"Biology of the invasive shell lerp psyllid, Spondyliaspis cf. plicatuloides (Froggatt) (Hemiptera: Aphalaridae)"

Spondyliaspis cf. plicatuloides (Froggatt) (Hemiptera: Aphalaridae) is native to Australia but was first detected outside its native range in 2014, in South Africa. It feeds on eucalypt species and thus has the potential to become a pest in commercial Eucalyptus plantations. Information on the basic biology of this insect, which is important for the development of surveillance and management strategies, is lacking. To investigate the life cycle and general biology of S. plicatuloides, the psyllid was reared under controlled glasshouse conditions on potted red-flowering gum, Corymbia ficifolia. The egg incubation period, number of nymphal instars and their developmental time, adult fecundity, adult longevity and duration of the life cycle were determined. The major diagnostic features used to differentiate the five nymphal instars were the number of antennal segments, wing pad development and body length. Females reached reproductive maturity 2.3 ± 0.47 (mean ± SD) days after eclosion and laid 16.2 ± 3.9 (mean ± SD) eggs on average. Reproduction was sexual. The first nymphal instar took 10.7 ± 1.2 (mean ± SD) days to hatch from the egg. The nymphal instars completed their development in 22.6 ± 1.4 (mean ± SD) days under the brown scalloped shelters they secrete. The insect's total life cycle lasted 37.37 ± 1.17 (mean ± SD) days from egg to adult death. Males and females lifespan is also reported. The study provides the first information on the basic biology of S. cf. plicatuloides that will be useful for future studies on surveillance and management strategies.

A Review on the Biology, Ecology, and Management Tactics of Helicoverpa armigera (Lepidoptera: Noctuidae)

In the agronomical field, different internal and external factors are responsible for substantially diminished crop harvest. A hindrance that can be listed in those factors is insect pests. African bollworm (Helicoverpa armigera) is a significant polyphagous, rapacious feeder, and the serious pest of agricultural cosmos. This pest can infest a wide array of species (almost 180 plant species) and a diverse range of families regarding it to be the most versatile and economically important nuisances for crops. H. armigera is widely far-reaching throughout the globe mostly in the Asian domain. Likewise, the subsequent number of instars makes it more detrimental and positively influences its existence pattern. The biological parameters like high fecundity, reproducibility, and comparatively long-life period support in the incitement of damage threshold (DT). Thusly, this article depicts the presentation and control tactics against H. armigera, and further incorporates science and damage to acquaint this pest and access raise in production.

Notes on the lifecycle and distribution of Sphodromantis gastrica (Stål, 1858) (Mantodea: Mantidae) in South Africa

Sphodromantis gastrica (Stål) (Mantodea: Mantidae), also known as the African mantis, is suggested to be common and widespread in southern Africa. Limited information is available regarding the distribution of this species in South Africa and no information is available on its biology. The aim of this study was to determine the distribution of S. gastrica in South Africa based on historic insect collection records as well as to study its basic biology and developmental parameters under captive breeding conditions. A total of 153 South African museum records of Sphodromantis spp. were recorded during this study. These records indicated that S. gastrica occurred in all but two provinces of South Africa. The incubation time of the S. gastrica oothecae were approximately 10 weeks and each ootheca contained an average of 84 egg chambers. The mean fertility rate was 54.6% while the survival rate until adulthood was 41.8%. The numbers of nymphal instars until adulthood ranged between four and nine. The mean lifespan of S. gastrica individuals were approximately 332 days and females lived longer than males.

Temperature-mediated developmental plasticity in winter and summer larvae of Palaemon serratus

In a seasonal environment, variation in larval phenotype and developmental plasticity allow crustacean larvae to maximise survival by lengthening or shortening their development. The aim of this study is to investigate the effects of temperature, laying season and their interaction on larval developmental pathways (larval instars and larval stages). We monitored the different larval stages and calculated the number of larval instars reached during the development of winter and summer larvae of Palaemon serratus incubated at 12, 16 or 20 °C. We observed a great variability in the larval development (6–13 larval instars and 6 to 11 larval stages). A higher temperature decreases the development time and the number of larval instars. At a given temperature, the development time of winter and summer larvae was not different. Two larval stages were considered supernumerary (zoea 4 and 6), as they were more frequent at low temperatures. At higher temperatures, some larvae started to develop pleopods as early as the third instar, larval stage which had never been described (named here zoea 3′). This phenomenon was more common in winter larvae than in summer larvae. These results provide new insights into the expression of developmental plasticity in decapod larvae.

Instar Determination for the Tomato Leafminer Tuta absoluta (Lepidoptera: Gelechiidae) Using the Density-Based OPTICS Clustering Algorithm.

The tomato leafminer Tuta absoluta (Meyrick) is one of the most harmful pests of solanaceous crops. Its larval morphological characteristics are similar, making the distinguishing between different larval instars difficult. Accurate identification of T. absoluta instars is necessary either for population outbreak forecasting, or developing successful control programs. Although a clustering algorithm can be used to determine the number of larval instars, little is known regarding the use of density-based ordering points to identify the clustering structure (OPTICS) and determine the number of larvae. In this study, larval instars of 240 T. absoluta individuals were determined by the density-based OPTICS clustering method, based on mandible width, and head capsule width and length. To verify the feasibility of the OPTICS clustering method, we compared it with the density-based spatial clustering of applications with noise (DBSCAN) clustering algorithm, Gaussian mixture models, and k-means. Additionally, the instars determined by the clustering methods were verified using the Brooks–Dyar rule, Crosby rule, and linear regression model. The instars determined by the OPTICS clustering method were equal to those determined by the other types of clustering algorithms, and the instar results were consistent with the Brooks–Dyar rule, Crosby rule, frequency analysis, and logarithmic regression model. These results indicated that the OPTICS clustering method is robust for determining insect larva instar phase. Moreover, it was found that three morphological indices of T. absoluta can be used for determining instars of this pest in the field, which may provide important information for the management of T. absoluta populations.

Acoustic detection of stem and root borer Neoplocaederus ferrugineus (Coleoptera: Cerambycidae) in cashew

Block diagram of the proposed system. • Characterised the acoustic sounds of Neoplocaederus ferrugineus (Linnaeus) (Coleoptera: Cerambycidae). • There were no significant differences between the number of bursts and various larval instars. • Predicted the likelihood of infestation of N . ferrugineus and field evaluated the detection performance of the acoustic device. • This is the first work on the acoustic behaviour of cashew stem and root borer. Stem and root borer Neoplocaederus ferrugineus (Linnaeus) (Coleoptera: Cerambycidae) is a severe pest of cashew ( Anacardium occidentale L), which affects the cashew tree heavily. The larvae are tissue borers that remain concealed inside the tree and are very difficult to detect at the initial stage of infestation. Adult attractants are not identified, and manual checking of each tree in a plantation is not feasible and laborious. Acoustic technologies have been developed for the non-invasive and early detection of wood borers. The present study was conducted to characterize the acoustic sounds of various larval instars, tissues and field evaluation of the commercially available acoustic device. Burst analysis of different larval instars in cashew logs shows that there are no significant differences between the number of bursts and various larval instars. A relatively less number of bursts are found when the larvae are in the sapwood region than the cambium region. The empty cashew log and healthy trees do not produce any significant noise. The number of burst counts and impulses are used to predict the likelihood of infestation. The detection performance of the acoustic device under field conditions shows that infested trees are correctly detected with 91% accuracy. The possibility of not detecting healthy trees is 85%. This is the first report on the acoustic behaviour of cashew stem and root borer. The results of the study will help in better understanding the acoustic behaviour of the hidden pest and also be useful in the timely identification of stem and root borer-affected trees in cashew plantations.

Nonreproductive effects are more important than reproductive effects in a host feeding parasitoid

When female host feeding parasitoids encounter a potential host, they face a complicated trade-off between either laying an egg for investing in current reproduction or feeding on or killing the host for future reproduction. Few studies have measured these behavioral shift patterns in a given host-parasitoid association thus far. We systematically assessed the behavioral shifts and life history traits of a host feeding parasitoid, Necremnus tutae, on different instars of its host Tuta absoluta. N. tutae females, as idiobiont host feeding parasitoids, can act on the 1st–4th instar larvae of T. absoluta by either host feeding, parasitizing or host killing. Moreover, a significant behavioral shift was observed on different instar hosts. N. tutae preferred to feed on the young hosts (1st and 2nd instars), lay eggs on middle-aged hosts (3rd instars) and kill old hosts (4th instars) by ovipositor-mediated stinging. The offspring of N. tutae showed a significant female-biased sex ratio, with the number of instars of T. absoluta larvae that were parasitized increasing. Specifically, nonreproductive host mortality induced by host feeding and host killing accounted for high percentages of the total mortality (ranging from 70% on 3rd instar hosts to 88% on 1st instar and 4th instar hosts). We hypothesize that N. tutae could be not merely a parasitoid but also a predator. Our results shed light on the nonreproductive abilities of a host feeding parasitoid that should be given further attention, especially when evaluating the efficacy of parasitoids.