Female Oviposition Research Articles

In vitro acaricidal activity of green synthesized nickel oxide nanoparticles against the camel tick, Hyalomma dromedarii (Ixodidae), and its toxicity on Swiss albino mice

The green synthesized nanoparticles have been determined as a novel pesticide against arthropod pests. This study was designed to evaluate the in vitro acaricidal activity of green synthesized nickel oxide nanoparticles (NiO NPs) using aqueous extract of Melia azedarach ripened fruits against different developmental stages of the camel tick Hyalomma dromedarii in addition to their toxic effect on laboratory animals. The synthesized NiO NPs were characterized by UV-visible (UV-Vis) spectroscopy, Fourier transforms infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). The UV-Vis spectra of the NiO NPs showed an absorption peak at 307nm. FTIR analysis showed the possible functional groups used for capping and stabilization of NiO NPs with strong bands at 3416.2 and 1626.6cm-1. The SEM images of the NiO NPs exhibited a size ranging from 21 to 35nm. The immersion test was used for the in vitro application of the synthesized NiO NPs on the various tick stages (egg, nymph, larva, and adult). Mortality percentages and LC50 values of each tick stage were calculated. The oviposition and hatchability of the engorged females were monitored for the survived tick after treatment. The LC50 values for NiO NPs on embryonated eggs, larvae, and engorged nymphs were 5.00, 7.15, and 1.90mg/mL, respectively. The egg productive index (EPI), egg number, and hatchability (%) were lower in females treated with the NiO NPs than in control ticks. The toxicity of the NiO NPs on laboratory animals was also investigated using Swiss albino mice by oral dose of 500mg/kg/day administration for five consecutive days. The hematological, biochemical, and histopathological changes were evaluated. The hematological analysis showed significant increase in the level of white blood cells (WBC) and hemoglobin (Hb). Biochemical analysis showed non-significant decrease in alkaline phosphatase (ALP) and alanine amino transferase (ALT). We concluded that NiO NPs have a significant acaricidal activity as demonstrated on eggs, larvae, engorged nymphs, and fully fed females of H. dromedarii. From a toxicological point of view further in vivo investigations are needed to determine the mechanism of toxic effect of NiO NPs.

Trap Cropping Harlequin Bug: Distance of Separation Influences Female Movement and Oviposition.

To evaluate perimeter trap crops for management of harlequin bug, Murgantia histrionica (Hahn), we undertook greenhouse and field experiments with mustard greens as trap crop for a collard cash crop. We confirmed that harlequin bugs prefer to immigrate to and reside on mustard. Females, however, in greenhouse cage experiments, 'commuted' to collards to lay their eggs. In separate spring and fall field plantings, using replicated 12 m by 12 m collard plots in 1-ha fields, we tested mustard planted as an adjacent perimeter trap crop, or a perimeter trap crop separated by 2 unplanted rows (2.3 m), or with no trap crop. Adults accumulated on the spring mustard crop but overall numbers remained low, with all collards sustaining <1% leaves damaged. In the fall, the separation of 2.3 m reduced oviposition on collards fourfold, and feeding damage approximately 2.5-fold, compared to collards with an adjacent trap crop. Fall control plots with no border trap crop showed even lower foliar damage; likely result of preferential immigration of harlequin bugs to mustard at the field scale, resulting in fewer bugs near the control treatment plots. Thus, the spatial arrangement of the mustard trap crop, and its separation from the cash crop, influences pest abundance and damage. A separated mustard border can reduce bug movement including female commuting and egg-laying, thus better protecting the collard cash crop. Future research should address reduction in area of trap crops, deployment of semiochemicals, and possible changes in timing, to promote trap cropping that is practical for grower implementation.

Biological activity of plant extracts on the small tomato borer Neoleucinodes elegantalis, an important pest in the Neotropical region

The small tomato borer Neoleucinodes elegantalis (Guenée) (Lepidoptera: Crambidae), is the most harmful tomato pest in the Neotropical region. Control of this insect is a complex task that relies heavily on the use of chemical products and the correct timing to target the initial developmental stages (eggs and larvae) before they penetrate the tomato fruits. Given the potential of plant-derived compounds for controlling pests, the first step of this study was to assess the insecticide activity of the aqueous extracts of Capsicum annuum L. (bell pepper), Allium sativum L. (garlic), Nicotiana tabacum L. (commercial rope tobacco), and the crude oil of Ricinus communis L. (castor bean) against N. elegantalis larvae. Here, it was reported that the commercial rope tobacco extract was promising against N. elegantalis larvae (up to 100% control), and the extracts of C. annuum, A. sativum, and R. communis presented very low insecticide activity (< 50% mortality). The rope tobacco extract was then selected to assess its effectiveness not only on eggs and the prepupal stage, but also on female oviposition behavior. Finally, the components of rope tobacco were assessed through phytochemical analysis. Our toxicological bioassays revealed ovicidal (LC50 = 2.69 g/L) and larvicidal (LC50 = 1.64 g/L) activity of tobacco extract. Furthermore, exposure to low tobacco extract concentrations (0.2 g/L) caused significantly decreased survival abilities of the prepupal stage, similar to indoxacarb insecticide (positive control). Tomato fruits previously treated with low concentrations (0.2 and 3.1 g/L) reduced the egg-laying performance of N. elegantalis in short-and long-term exposure. Chemical analysis of the tobacco rope extract revealed not only nicotine as the major component, but also the presence of phenolics, terpenoids, steroids, and other alkaloids. Collectively, our findings indicate that aqueous extract of rope tobacco shows biological activities in different developmental stages, including deterrent effects on N. elegantalis oviposition, which may position it as a promising tool to prevent pest attacks on tomato fruits.

Behavioural and antennal responses of Aedes aegypti (l.) (Diptera: Culicidae) gravid females to chemical cues from conspecific larvae.

Mass trapping of gravid females represents one promising strategy for the development of sustainable tools against Aedes aegypti. However, this technique requires the development of effective odorant lures that can compete with natural breeding sites. The presence of conspecific larvae has been shown to stimulate oviposition. Hence, we evaluated the role of four major molecules previously identified from Ae. aegypti larvae (isovaleric, myristoleic, myristic [i.e. tetradecanoic], and pentadecanoic acids) on the oviposition of conspecific females, as well as their olfactory perception to evaluate their range of detection. Using flight cage assays, the preference of gravid females to oviposit in water that previously contained larvae (LHW) or containing the four larval compounds was evaluated. Then, compounds and doses inducing the highest stimulation were challenged for their efficacy against LHW. Only isovaleric acid elicited antennal response, suggesting that the other compounds may act as taste cues. Pentadecanoic acid induced significant oviposition stimulation, especially when dosed at 10 ppm. Myristoleic acid and isovaleric acid deterred oviposition at 10 and 100 ppm, while no effect on oviposition was observed with myristic acid irrespectively of the dose tested. When the four compounds were pooled to mimic larvae's chemical signature, they favored oviposition at 1 ppm but negatively affected egg-laying at higher concentrations. When properly dosed, pentadecanoic acid and the blend of compounds may be promising lures for ovitraps as they could compete with LHW. Due to their low volatility, their effect should be further evaluated under field conditions, in addition with long-range attractants for developing effective tools against gravid females.

Host plant water deficit stress impairs reproduction and development of the galling fly (Parafreutreta regalis), a biological control agent of Cape-ivy (Delairea odorata)

Drought leading to water deficit stress is known to reduce performance of galling insects. The shoot tip-galling fly Parafreutreta regalis has been released for biological control of Cape-ivy (Delairea odorata) in California. Lack of moisture during the dry season causes wilting of Cape-ivy shoots, and subsequent reduced host quantity and quality could influence the fly’s ability to multiply and establish. We imposed water deficit stress on potted Cape-ivy plants, then measured the plant’s and insect’s response to water deficit compared to fully-watered plants. Water deficit stress was imposed during female oviposition (short-term), gall development (long-term), or full insect life cycle (long-term). Plants subjected to long-term water deficit showed declines in shoot growth, leaf area, and total biomass. In choice tests, 72% fewer galls were found on water deficit stressed plants, but there was no difference in the numbers of insects per gall. In no-choice tests, long-term water deficit reduced the number and size of galls by up to 51% and 39%, respectively, and puparia inside the galls were up to 35% smaller. Long-term water deficit also increased the time required for the insect to complete its life cycle (egg to adult) by about 10 days, and up to 80% fewer adults emerged, decreasing the fly’s rate of increase by up to five-fold. Our study shows that P. regalis will oviposit and develop successfully on water deficit-stressed plants, but declines in female preference, insect development and abundance could inhibit fly field establishment and/or population growth under climatic drought conditions.

Overwintering biology of the predatory bug, Orius vicinus (ribaut) (Hemiptera: Anthocoridae) under outdoor conditions in the eastern mediterranean region of Turkey

Overwintering biology of Orius vicinus (Ribaut) (Hemiptera: Anthocoridae) was investigated between November 2017 and April 2018 in the Balcali location of Adana Province, Turkey under outdoor conditions. The duration of egg and nymphal development time, pre-oviposition, oviposition and post-oviposition periods of females, the number of eggs laid and adults longevity were determined by the experiments performed in the first day of each experimental month under the outdoor conditions at the Department of Plant Protection, Faculty of Agriculture, University of Cukurova. The duration of egg hatching lasted between 5 and 10 days in all months of experiment and the tested eggs were hatched even at low temperature and under short day length conditions. More than half of the nymphs obtained from the tested eggs became adults in the winter months. Despite the nymph’s survival was affected negatively by the sudden changes in temperature, they were tolerant to the low temperatures and short-day lengths during the winter period. All females in the trials oviposited for about 30 days even in the coldest periods (approximately 15 °C). The females were not affected by the environmental conditions particularly in winter season, and they did not undergo reproductive diapause. The obtained data shed light on the overwintering biology of O. vicinus which may be helpful for their potential role in controlling the non-diapaused pest species such as pest thrips in the early spring season.

A sex-specific switch between visual and olfactory inputs underlies adaptive sex differences in behavior

SummaryAlthough males and females largely share the same genome and nervous system, they differ profoundly in reproductive investments and require distinct behavioral, morphological, and physiological adaptations. How can the nervous system, while bound by both developmental and biophysical constraints, produce these sex differences in behavior? Here, we uncover a novel dimorphism in Drosophila melanogaster that allows deployment of completely different behavioral repertoires in males and females with minimum changes to circuit architecture. Sexual differentiation of only a small number of higher order neurons in the brain leads to a change in connectivity related to the primary reproductive needs of both sexes—courtship pursuit in males and communal oviposition in females. This study explains how an apparently similar brain generates distinct behavioral repertoires in the two sexes and presents a fundamental principle of neural circuit organization that may be extended to other species.

Fijian swallowtail butterfly Papilio schmeltzi (Papilionidae: Lepidoptera) shows clear preference–performance relationships on both native and exotic host plants

AbstractThe swallowtail butterfly Papilio schmeltzi is endemic to the Fiji Islands. To date, P. schmeltzi larvae and eggs have been found exclusively on a native Fijian shrub, Micromelum minutum, even though numerous other seemingly suitable native and exotic species of Rutaceae now occur in its Fijian forest habitat. This study used outdoor cages and laboratory studies to examine oviposition preferences and larval development of P. schmeltzi on four species of Rutaceae: the native species Micromelum minutum and Euodia hortensis and the introduced species Murraya koenigii and Citrus reticulata. The female oviposition preference sequence was the same as that for larval feeding preference, which ran, from most preferred, as Micromelum minutum &gt; C. reticulata &gt; Murraya koenigii &gt; E. hortensis. The survival of the first and fifth instar larvae was highest (≥80%) when maintained on leaves of M. minutum and C. reticulata and lowest when reared on Murraya koenigii (≤20%) and E. hortensis (≤4%). Of the two preferred host plants, P. schmeltzi larvae gained weight more quickly, consumed a larger area of leaf and pupated earlier when reared on the natural host Micromelum minutum compared with the exotic C. reticulata. In quantitative nutritional studies, the consumption rate of leaf material, and the relative growth rate of the P. schmeltzi larvae, was highest when reared on Micromelum minutum compared with C. reticulata, although the efficiency of converting leaf biomass into larval biomass was highest when reared on C. reticulata, especially in the later instars. Overall, the results of our study indicate the plants on which P. schmeltzi females choose to lay eggs are not restricted to native Fijian plant species but are appropriate when viewed in terms of subsequent larval preferences, survival and growth rate.

Does the Presence of Other Egg Rafts and Conspecific Larvae Encourage Oviposition by the Mosquito, Culex sitiens (Diptera: Culicidae)?

Mosquitoes include many major disease vectors and are often controlled in their aquatic larval stage, since they are living in defined habitats. However, non-chemical methods of control are influenced by the female oviposition behavior, and this is affected by many factors. Many mosquito species choose to oviposit on water containing egg raft pheromones (which have thus been used in control), showing another female has selected that pool as being best. However, Culex sitiens did not respond chemically to water previously containing egg rafts, but unlike most species, did strongly respond visually to artificial black egg rafts floating on the surface. Oviposition increased as the number of artificial egg rafts increased up to six, but more rafts gave no further increase. However, even nine egg rafts had no repellent effect, despite the high probability of larval overcrowding and thus starvation. Altering the pattern with which five rafts were interconnected and also altering the size of individual rafts seemed to show that the mosquitoes were responding more to total raft area rather than number. The presence of either 2nd instar or 4th (final) instar conspecific larvae in the water can be detected chemically but did not influence oviposition, either positively or negatively. Conspecific larvae show the water is suitable for oviposition, but they are competitors for the available food and so many studies have shown especially older larvae to be repellent to oviposition. Culex sitiens was thus not responding chemically to either eggs or larvae but unusually had a visual response.

Oviposition Behavior of Culex quinquefasciatus and Anopheles coluzzii Females According to the Ovitrap Color and Presence of Fertilizer in Breeding Sites

Malaria and lymphatic filariasis are still important public health problems in Cameroon and in most part of sub-Saharan Africa. However there is still not enough informations on the bionomic and oviposition behaviour of their respectives vectors. The present study assesses the influence of color and organics pollutants presence on Culex and Anopheles coluzzii females oviposition behaviour. Laboratory experiments using Culex quinquefasciatus and Anopheles coluzzii laboratory colonies were conducted. Gravid females were offered cups of different colors (red, green, yellow, black, purple and white) with water for oviposition. Experiments were also conducted with cups containing different concentration of NPK fertilizers (1%, 0.75%, 0.5% and 0%). The influence of NPK fertilizer on the larval development time was also assessed. Cx quinquefasciatus and Anopheles coluzzii gravids females were found to be attracted by dark colors over 50% of eggs were laid in cups of black, red or green colors. The experiment was conducted with the mother and the F1 and F2 generations and similar oviposition preference were registered. When mosquitoes were offered cups containing different concentration of NPK for oviposition it appeared that females of the two species prefer laying their eggs in low concentration of NPK. Rearing of larvae in water containing NPK fertilizers was found to accelerate the larval development time of Culex quinquefasciaus but not of Anopheles coluzzii. The study indicated that several factors could be influencing vector bionomic and need further understanding to improve the fight against vector populations.

Specific Determination and Evaluation of the Damage of the Tamarind Fruit Borer (&amp;lt;i&amp;gt;Tamarindus indica&amp;lt;/i&amp;gt; L.) in Villaflores, Chiapas, Mexico

The cultivation of tamarind in the producing regions of Mexico and in backyard trees is affected by insects that feed on the fruit, causing losses in yield and quality; Among the insects is the tamarind fruit and seed borer. The objective of this work was to specifically determine and evaluate the damage caused by the fruit borer. Samples were carried out in 10 tamarind trees, five trees in a backyard and five trees in a plantation established in the Álvaro Obregon community of the municipality of Villaflores, Chiapas. The collections were made directly and through the fruits with signs of the presence of the borer. For the evaluation of the damage, the total fruits of 10 trees were collected where the total number of fruits and the number of fruits infested by the borer were quantified and in this way the percentage of damaged fruits was calculated. The tamarind fruit borer was determined as the Caryedon gonagra (Coleoptera: Bruchidae) species, originally from the old world Africa, of the monophyletic group, because which is reported for the states of Colima and Morelos, this report is considered the first record for the State of Chiapas. Adults are 4 to 6 mm in length, and are characterized by presenting the prothorax in a subrectangular shape, the body slightly elongated, with golden pubescence with black or light brown spots, sometimes with small dark brown spots scattered throughout the body. differing especially in the elytra and hind legs. In the field, the initial infestation of the tamarind fruit borer in the state of Chiapas occurs at the beginning of November when the female oviposits the eggs in the middle of the tree on the tamarind pods, regardless of size. and fruit development. The damage begins when the larva penetrates the pod reaching the seed of the fruit, until reaching the adult stage, affecting 7,108 fruits, which is equivalent to 26,400 g, which represents 35.76% of the total production per tree. Regarding the weight of the tamarind fruit by C. gonagra, there is a reduction in weight of 9.341 g tree-1, that is, it affects 11.24% the production of tamarind per tree.

Evaluation of large volume yeast interfering RNA lure-and-kill ovitraps for attraction and control of Aedes mosquitoes.

Aedes mosquitoes (Diptera: Culicidae), principle vectors of several arboviruses, typically lay eggs in man-made water-filled containers located near human dwellings. Given the widespread emergence of insecticide resistance, stable and biofriendly alternatives for mosquito larviciding are needed. Laboratory studies have demonstrated that inactivated yeast interfering RNA tablets targeting key larval developmental genes can be used to facilitate effective larvicidal activity while also promoting selective gravid female oviposition behaviour. Here we examined the efficacy of transferring this technology toward development of lure-and-kill ovitraps targeting Aedes aegypti (L.) and Aedes albopictus (Skuse) female mosquitoes. Insectary, simulated field and semi-field experiments demonstrated that two mosquito-specific yeast interfering RNA pesticides induce high levels of mortality among larvae of both species in treated large volume containers. Small-scale field trials conducted in Trinidad, West Indies demonstrated that large volume ovitrap containers baited with inactivated yeast tablets lure significantly more gravid females than traps containing only water and were highly attractive to both A. aegypti and A. albopictus females. These studies indicate that development of biorational yeast interfering RNA-baited ovitraps may represent a new tool for control of Aedes mosquitoes, including deployment in existing lure-and-kill ovitrap technologies or traditional container larviciding programs.

A gustatory receptor tuned to the steroid plant hormone brassinolide in Plutella xylostella (Lepidoptera: Plutellidae).

Feeding and oviposition deterrents help phytophagous insects to identify host plants. The taste organs of phytophagous insects contain bitter gustatory receptors (GRs). To explore their function, the GRs in Plutella xylostella were analyzed. Through RNA sequencing and qPCR, we detected abundant PxylGr34 transcripts in the larval head and adult antennae. Functional analyses using the Xenopus oocyte expression system and 24 diverse phytochemicals showed that PxylGr34 is tuned to the canonical plant hormones brassinolide (BL) and 24-epibrassinolide (EBL). Electrophysiological analyses revealed that the medial sensilla styloconica of 4th instar larvae are responsive to BL and EBL. Dual-choice bioassays demonstrated that BL inhibits larval feeding and female oviposition. Knock-down of PxylGr34 by RNAi attenuates the taste responses to BL, and abolishes BL-induced feeding inhibition. These results increase our understanding of how herbivorous insects detect compounds that deter feeding and oviposition, and may be useful for designing plant hormone-based pest management strategies.

Innate preference hierarchies coupled with adult experience, rather than larval imprinting or transgenerational acclimation, determine host plant use in Pieris rapae.

The evolution of host range drives diversification in phytophagous insects, and understanding the female oviposition choices is pivotal for understanding host specialization. One controversial mechanism for female host choice is Hopkins’ host selection principle, where females are predicted to increase their preference for the host species they were feeding upon as larvae. A recent hypothesis posits that such larval imprinting is especially adaptive in combination with anticipatory transgenerational acclimation, so that females both allocate and adapt their offspring to their future host. We study the butterfly Pieris rapae, for which previous evidence suggests that females prefer to oviposit on host individuals of similar nitrogen content as the plant they were feeding upon as larvae, and where the offspring show higher performance on the mother's host type. We test the hypothesis that larval experience and anticipatory transgenerational effects influence female host plant acceptance (no‐choice) and preference (choice) of two host plant species (Barbarea vulgaris and Berteroa incana) of varying nitrogen content. We then test the offspring performance on these hosts. We found no evidence of larval imprinting affecting female decision‐making during oviposition, but that an adult female experience of egg laying in no‐choice trials on the less‐preferred host Be. incana slightly increased the P. rapae propensity to oviposit on Be. incana in subsequent choice trials. We found no transgenerational effects on female host acceptance or preference, but negative transgenerational effects on larval performance, because the offspring of P. rapae females that had developed on Be. incana as larvae grew slower on both hosts, and especially on Be. incana. Our results suggest that among host species, preferences are guided by hard‐wired preference hierarchies linked to species‐specific host traits and less affected by larval experience or transgenerational effects, which may be more important for females evaluating different host individuals of the same species.

Methoxyfenozide, a Molting Hormone Agonist, Affects Autogeny Capacity, Oviposition, Fecundity, and Fertility in Culex pipiens (Diptera: Culicidae).

The current study aimed to evaluate the effects of methoxyfenozide (RH-2485), an insect growth disrupter (IGD) belonging to molting hormone agonist class, against female adults of Culex pipiens L. under laboratory conditions. Lethal concentrations (LC50 = 24.54 µg/liter and LC90 = 70.79 µg/liter), previously determined against fourth instar larvae, were tested for adult female fertility, fecundity and oviposition after tarsal contact before mating and any bloodmeal. Methoxyfenozide was found to alter negatively their autogeny capacity and oviposition. A strong reduction of 56% and 72% (P < 0.001) in females' autogeny capacity was observed in both treated series, respectively. Alteration in oviposition were found to be higher with LC90 (OAI-LC90 = -0.62) than with the LC50 (OAI-LC50 = -0.42). Also fecundity and hatching rate (fertility) were significantly reduced in treated series as compared to controls. A significant reduction of 37.65 and 28.23% in fecundity and decrease of 56.85 and 71.87% in fertility were found, respectively in LC50 and LC90 treated series. Obtained data clearly demonstrated that methoxyfenozide have significant depressive effect on reproductive potential against medically important vector with minimizing ecotoxicological risks in mosquitoes management.

Transgenic Cry1Ac/CpTI cotton assessment finds no detrimental effects on the insect predator Chrysoperla sinica

The widespread commercialization of genetically modified (GM) cotton makes it important to assess the potential impact of this recombinant crop on non-target organisms. As important natural enemies of cotton field predators, green lacewing Chrysoperla sinica larvae are exposed to Bt insecticidal proteins expressed by GM cotton by feeding on herbivorous pests, and adults are directly exposed to Bt proteins by cotton pollen consumption. However, potential impacts of transgenic Bt cotton on C. sinica remain unclear. In this study, we evaluated the effects of two transgenic cotton varieties, CCRI41 and CCRI45, which express Cry1Ac (Bt toxin) and CpTI (Cowpea Trypsin Inhibitor), on C. sinica larvae and adults. After being fed with cotton aphids Aphis gossypii reared on transgenic cotton, the survival rate, developmental duration, pupation rate, and emergence rate of larvae were not adversely affected. After being fed two types of transgenic cotton pollen, the 7-day weight of adults and the preoviposition period and the cumulative oviposition of females were not significantly different from control specimen. Taken together, these results indicate that the potential risks of the two tested GM cotton varieties for the predator C. sinica are negligible. CapsuleOur study indicated that GM cotton varieties CCRI41 and CCRI45 have no adverse effects on insect predator C. sinica.

Invasive Agricultural Pest Drosophila suzukii (Diptera, Drosophilidae) Appeared in the Russian Caucasus.

Simple SummarySpotted-wing drosophila, Drosophila suzukii, is one of the most important invasive pests of fruit and wine production worldwide. This species feeds on cherry, raspberry, blackberry, blueberry, strawberry, peach, plums, grape, and other soft fruits. It causes significant damage because, unlike most other Drosophila species, it oviposits and feeds on healthy fruits. Drosophila suzukii is native to East Asia and has been rapidly spreading through Europe, where it is considered a quarantine pest, since 2008. Herein, we report the first records of spotted wing drosophila in European Russia. In 2017 and 2020, we placed baited traps in different districts of the resort city of Sochi (Black sea Coast of the Caucasus, Krasnodar Territory, Russia) and collected 49 adults of this species. They were identified by the typical female ovipositor, spotted wings of the males, and other characters. Krasnodar Territory is one of the main fruit-producing regions of Russia. Therefore, populations of this pest should be monitored and measures to minimize economic damage should be taken.Spotted-wing drosophila Drosophila suzukii (Matsumura) is one of the most important invasive pests of fruit and wine production worldwide. This species feeds on Prunus spp., Rubus spp., Fragaria spp. (Rosaceae), Vaccinium spp. (Ericaceae), Vitis spp. (Vitaceae), and other soft fruits. It causes significant damage because, unlike most other Drosophila species, it oviposits and feeds on healthy fruits. Drosophila suzukii is a quarantine pest that is included on the European and Mediterranean Plant Protection Organization (EPPO) A2 List. This species is native to East Asia and has been rapidly spreading through Europe since 2008. Herein, we report the first records of D. suzukii in European Russia. In 2017 and 2020, we placed baited traps in different districts of the resort city of Sochi (Black sea Coast of the Caucasus, Krasnodar Territory, Russia). Three specimens of D. suzukii were collected in June 2017, two specimens in September 2017, and 44 specimens in September 2020. Specimens were identified by the typical female ovipositor, spotted wings of the males, and other morphological characters. Krasnodar Territory is one of the main fruit-producing regions of Russia. Therefore, populations of this pest should be monitored and measures to minimize economic damage should be taken.

A chemical basis for different oviposition rates of Helicoverpa assulta across two Nicotiana species

The tobacco Nicotiana rustica is widely used as a trap crop in the fields of Nicotiana tabacum in China, by attracting oviposition of Helicoverpa assulta females, thus preventing damage to N. tabacum. The mechanism underlying the differential oviposition rates of H. assulta across these two tobacco species, however, is largely unknown. We investigated the mechanism of host plant acceptance of H. assulta with respect to these two tobaccos by using a two-choice behavioral bioassay and GC–MS. Our results indicate that both the leaves and inflorescences of N. rustica attracted significantly more eggs than the corresponding parts of N. tabacum. Extracts of leaves and inflorescences of N. rustica with two different solvents elicited similar oviposition patterns to the corresponding parts of the plants. Chemical analysis by GC–MS revealed that the volatiles of N. rustica contain larger amounts of nicotine than those of N. tabacum at the flowering stage. In addition, γ-terpinolene and β-elemene are found only in extracts of N. rustica. A two-choice bioassay on the individual compounds showed that γ-terpinolene, which is specific to the vegetative stage of N. rustica, and nicotine attracted oviposition by H. assulta. The volatile β-elemene, which is present only in N. rustica, was also attractive. We conclude that the larger amount of nicotine, and the species-specific γ-terpinolene and β-elemene may mediate the different oviposition rates of H. assulta females across N. rustica and N. tabacum.

Fatty Acid Profile as an Indicator of Larval Host for Adult Drosophila suzukii.

Simple SummarySpotted-wing drosophila, Drosophila suzukii, is an invasive pest of soft-skinned fruits. Adult female flies oviposit, or lay eggs, into fruits where the larvae develop, making infested fruit unmarketable. The flies rely on alternative hosts, both cultivated and wild, to survive and maintain populations throughout the year. Better understanding of how the flies migrate between different hosts could be beneficial to improving management of the pest in crops. This study demonstrates potential to discriminate larval host of adult flies by analysis of fatty acids carried from the larvae to the adult stage in the body using a machine learning algorithm as an alternative to linear discriminant methods. Our study shows that fatty acids in adult flies can be used to determine larval host and that the machine learning algorithm can perform the discriminant analysis without making any assumptions about the data.Drosophila suzukii is a severe economic invasive pest of soft-skinned fruit crops. Management typically requires killing gravid adult female flies with insecticides to prevent damage resulting from oviposition and larval development. Fruits from cultivated and uncultivated host plants are used by the flies for reproduction at different times of the year, and knowledge of D. suzukii seasonal host plant use and movement patterns could be better exploited to protect vulnerable crops. Rearing and various marking methodologies for tracking movement patterns of D. suzukii across different landscapes have been used to better understand host use and movement of the pest. In this study, we report on potential to determine larval host for adult D. suzukii using their fatty acid profile or signature, and to use larval diet as an internal marker for adult flies in release-recapture experiments. Fatty acids can pass efficiently through trophic levels unmodified, and insects are constrained in the ability to synthesize fatty acids and may acquire them through diet. In many holometabolous insects, lipids acquired in the larval stage carry over to the adult stage. We tested the ability of a machine learning algorithm to discriminate adult D. suzukii reared from susceptible small fruit crops (blueberry, strawberry, blackberry and raspberry) and laboratory diet based on the fatty acid profile of adult flies. We found that fatty acid components in adult flies were significantly different when flies were reared on different hosts, and the machine learning algorithm was highly successful in correctly classifying flies according to their larval host based on fatty acid profile.

Biotic and abiotic effects on density, body size, sex ratio, and survival in immature stages of the European woodwasp, Sirex noctilio.

Resource quality can have direct or indirect effects on female oviposition choice, offspring growth and survival, and ultimately on body size and sex ratio. We examined these patterns in Sirex noctilio Fabricus, the globally invasive European pine woodwasp, in South African Pinus patula plantations. We studied how tree position as well as natural variation in biotic and abiotic factors influenced sex‐specific density, larval size, tunnel length, male proportion, and survival across development. Twenty infested trees divided into top, middle, and bottom sections were sampled at three time points during larval development. We measured moisture content, bluestain fungal colonization, and co‐occurring insect density and counted, measured, and sexed all immature wasps. A subset of larval tunnels was measured to assess tunnel length and resource use efficiency (tunnel length as a function of immature wasp size). Wasp density increased from the bottoms to the tops of trees for both males and females. However, the largest individuals and the longest tunnels were found in bottom sections. Male bias was strong (~10:1) and likewise differed among sections, with the highest proportion in the middle and top sections. Sex ratios became more strongly male biased due to high female mortality, especially in top and middle sections. Biotic and abiotic factors such as colonization by Diplodia sapinea, weevil (Pissodes sp.) density, and wood moisture explained modest residual variation in our primary mixed effects models (0%–22%). These findings contribute to a more comprehensive understanding of sex‐specific resource quality for S. noctilio and of how variation in key biotic and abiotic factors can influence body size, sex ratio, and survival in this economically important woodwasp.