Overwintering stages of Callosobruchus chinensis (L.) in the field

Adzuki bean beetle, Callosobruchus chinensis, is a worldwide oligophagous and a field‐to‐storage pest of legumes including adzuki beans (Vigna angularis). Its over‐wintering stage is yet to be confirmed. A series of experiments was carried out at Jinju, in the southern part of the Republic of Korea, to elucidate the overwintering stages. Top‐ and sub‐soil samplings followed by pod and seed samplings from left over plants from adzuki bean fields in the winter of 2015, and an outdoor overwintering test (during Nov 2018 to Jun 2019) by exposing bean seeds harboring different stages (eggs, larvae, pupae, pharates and adults) of laboratory reared C. chinensis to the winter environment were carried out. None of the C. chinensis stages was detected from the top‐ and sub‐soil samples. When the pods and seeds from left over plants were sampled, only a few live pupae were obtained. In the outdoor test with laboratory reared C. chinensis, all the stages (larvae, pupae, and adults), except eggs, were detected on every other weekly samples of infested adzuki bean seeds throughout the winter. These results showed that the overwintering stages of C. chinensis in Jinju, southern Korea, are larvae, pupae, pharates and adults.     

Comparative toxicity of phosphine to developmental stages of three Callosobruchus species infesting stored pulses

Bruchids pose serious threat to stored pulses, and their successful management largely depends on phosphine fumigation. For the first time, the comparative assessment of phosphine toxicity to all the developmental stages of three bruchid species in India was attempted at varied concentrations and exposure times. Based on probit estimates, the egg stages found to be least sensitive to phosphine followed by pupae and larvae, whereas adults were highly sensitive. Among the age groups of eggs, the early age groups (0–2 days old) were less sensitive than later stages (3–6 days old). The bruchid species viz., Callosobruchus maculatus (F.), C. analis (F.), and C. chinensis L. exhibited a variable degree of susceptibility irrespective of life stages and exposure periods tested. However, the collective probit estimates indicated C. maculatus being slightly less sensitive followed by C. analis and C. chinensis. Except in 0–2 day old eggs, the mortality response in 3–6 day old eggs, larvae, pupae, and adults was increased with increasing phospine concentrations and exposure period. The mortality response got even steeper at 48 and 72 h exposures as evident by decreasing LC50 and LC90 values. The information generated on phospine sensitivity in different life stages would serve as baseline data to design insecticide resistance studies in future and also to ascertain stage-specific Concentration vs. time (Ct) products for the recommendation of phosphine doses for successful management of bruchids during any of their life stages under storage conditions.     

Rapid Development of Microsatellite Markers for Callosobruchus chinensis Using Illumina Paired-End Sequencing

Background

The adzuki bean weevil, Callosobruchus chinensis L., is one of the most destructive pests of stored legume seeds such as mungbean, cowpea, and adzuki bean, which usually cause considerable loss in the quantity and quality of stored seeds during transportation and storage. However, a lack of genetic information of this pest results in a series of genetic questions remain largely unknown, including population genetic structure, kinship, biotype abundance, and so on. Co-dominant microsatellite markers offer a great resolving power to determine these events. Here, we report rapid microsatellite isolation from C. chinensis via high-throughput sequencing.

Principal Findings

In this study, 94,560,852 quality-filtered and trimmed reads were obtained for the assembly of genome using Illumina paired-end sequencing technology. In total, the genome with total length of 497,124,785 bp, comprising 403,113 high quality contigs was generated with de novo assembly. More than 6800 SSR loci were detected and a suit of 6303 primer pair sequences were designed and 500 of them were randomly selected for validation. Of these, 196 pair of primers, i.e. 39.2%, produced reproducible amplicons that were polymorphic among 8 C. chinensis genotypes collected from different geographical regions. Twenty out of 196 polymorphic SSR markers were used to analyze the genetic diversity of 18 C. chinensis populations. The results showed the twenty SSR loci were highly polymorphic among these populations.

Conclusions

This study presents a first report of genome sequencing and de novo assembly for C. chinensis and demonstrates the feasibility of generating a large scale of sequence information and SSR loci isolation by Illumina paired-end sequencing. Our results provide a valuable resource for C. chinensis research. These novel markers are valuable for future genetic mapping, trait association, genetic structure and kinship among C. chinensis.     

Fumigant toxicity of Lavandula spica essential oil and linalool on different life stages of Tribolium confusum (Coleoptera: Tenebrionidae)

The confused flour beetle, Tribolium confusum, is a common and severe pest of stored products. Here, using fumigation tests during four different exposure times, we evaluated the toxicity of different doses of essential oil of spike lavender, Lavandula spica and one of its major constituents, linalool, on different life stages of T. confusum under laboratory conditions. The toxicity of the L. spica oil and linalool varied as a function of the developmental stage and treatment duration. Young larvae (L1) were the most susceptible to toxic effects, with LC₅₀ = 19.535 μl/L of air for L. spica oil and LC₅₀ = 14.198 μl/L of air for linalool after 24 h of exposure, whereas older larvae (L8) were affected only very little by fumigation. Linalool caused higher egg mortality than L. spica oil at equivalent doses, but lower mortality in pupae and adults. Emergence of intact adult insects from surviving eggs, larvae and pupae was further reduced as a function of dose and exposure time to both L. spica oil and linalool compared to control-treated insects. Our results show that L. spica oil and linalool might be suitable for biological control of T. confusum, but tests at a larger scale are necessary to confirm our results.     

Ethyl formate fumigation and ethyl formate plus cold treatment combination as potential phytosanitary quarantine treatments of Drosophila suzukii in blueberries

Spotted wing drosophila, Drosophila suzukii (Diptera: Drosophilidae), is a serious invasive pest of berries and cherries in the U.S. and Europe and has become a major phytosanitary trade barrier. In this pilot study, we explored the potential of using stand-alone ethyl formate (EF) treatment and a combinatory treatment of EF and cold temperature as postharvest control options for D. suzukii in imported blueberries. Stand-alone EF fumigations were effective against D. suzukii with LCt_99% of 207.7 and 168.5 g·h·m^?3 for eggs, the most tolerant life stage, at 5 and 21 °C, respectively. In a scale-up (10 m³) trial conducted at 5 °C, complete control of D. suzukii eggs placed inside and outside of blueberry boxes was achieved using 70 g·m^?3 EF for 4 h with 5% blueberry loading ratio without deleterious impact on blueberry appearance such as soft spot or berry shrivel. In small scale pilot studies, 9-d stand-alone cold treatment at 5 °C was sufficient for complete control of D. suzukii eggs and larvae tested, but not pupae. The efficacy of this cold treatment appeared to be improved when D. suzukii eggs were first treated with low-dose EF (LCt_50% level) prior to the cold treatment. The combination treatment resulted in complete mortality of D. suzukii eggs, larvae, and pupae tested after 7, 5, and 9 d of cold treatment, respectively. Together, these results suggest that stand-alone EF treatment, or the combination treatment of low-dose EF and cold as a systems approach may have a potential as postharvest treatments for D. suzukii in blueberries.     

Effects of gamma radiation on different developmental stages of the oriental tobacco budworm,Helicoverpa assulta (Lepidoptera: Noctuidae)

Ionizing radiation is increasingly used as an alternative to post‐harvest crop fumigation by methyl bromide. We studied the effects of gamma irradiation on Helicoverpa assulta (Lepidoptera: Noctuidae) at different stages of development to determine the minimal dose for the prevention of normal emergence of adults. We selected five doses of gamma rays (100, 200, 300, 400 and 500 Gy) based on preliminary experiments and irradiated eggs, larvae, pupae and adults. A dose of 100 Gy to eggs allowed 21.83% of larvae to pupate, but these all died during the pupal stage. A dose of 100 Gy to last‐instar larvae caused larval or pupal death, or the emergence of abnormal adults; no normal adults developed. Irradiation of pupae with doses of 300 Gy and above resulted either in their death or emergence of abnormal adults; however, after 100 or 200 Gy, normal adults emerged and F₁ eggs were produced, but no eggs hatched. Following irradiation of adults, eggs were produced at all doses, although the numbers were significantly decreased compared to untreated controls (P < 0.05; 69.45–125.50 vs. 475.05 eggs per female); however, none of the eggs hatched. As prevention of normal emergence is a key outcome for measuring the effectiveness of radiation, then the 100 Gy dose was effective for irradiation of eggs and larvae, and 300 Gy for pupae.     

Development of a combined cold storage and methyl bromide fumigation treatment to control the American serpentine leaf miner Liriomyza trifolii (Diptera:Agromyzidae) in imported chrysanthemum cuttings

Individual chrysanthemum cuttings and leaves infested with eggs and larvae of the alien leaf miner Liriomyza trifolii, and batches of pupae, were treated in the laboratory to find an effective quarantine treatment to control the pest in imported cuttings. The laboratory tests were based on a statutory quarantine treatment of 2 days' cold storage at 1–2°C followed by methyl bromide fumigation at 15°C with a concentration time product (CTP) of 54 g h/m³, which is used to control Spodoptera littoralis on imported chrysanthemum cuttings. Treatments of 2 days' storage at 1–2°C followed by methyl bromide fumigation at 15°C with a range of CTPs were used to obtain accurate dose-response lines and estimate the LD99 and LD99 9 for each stage of L. trifolii. The largest estimates of the LD99 for eggs, larvae and pupae up to 3 days old were 40·04, 34·49 and 42·64g h/m³ respectively. These results indicate that the Spodoptera treatment should give high levels of kill of most stages of L. trifolii. However, the LD99 values for pupae more than 3 days old were greater than those for eggs, larvae and young pupae. Therefore if this treatment were adopted as a quarantine measure against L. trifolii, good prophylactic treatments and rigorous pre-packing inspections in exporting countries would need to be maintained, to minimise any risk of importing pupae. It would also be necessary to ensure that the temperature of the imported cuttings was raised uniformly to 15°C after cold storage and prior to fumigation. The practicality of the technique as a commercial treatment will depend on whether it is possible to achieve this without causing unacceptable phytotoxicity.     

Regulation of Progeny Sex by Anisopteromalus calandrae (Hymenoptera: Pteromalidae) in Relation to Host Preference,Host Vulnerability and Host Size

Regulation of progeny sex by Anisopteromalus calandrae (Howard) in relation to host preference, host vulnerability and host size was studied with two host species, Sitophilus oryzae (L.) and Callosobruchus chinensis L. A. calandrae preferred S. oryzae to C. chinensis (preference index = 0.87). The progeny sex ratio (females/total) was significantly higher on C. chinensis, the less preferred host, than on S. oryzae regardless of the instar age of the two host species. A. calandrae could locate only a few young larvae of C. chinensis (≤third instar), which could be apparently due to the low vulnerability of the young larvae locating deeper in the adzuki bean kernels. The larval instar age of Sitophilus oryzae affect the progeny sex ratio of A. calandrae, but that of Callosobruchus chinensis did not except invulnerable ones. The progeny sex ratio of A. calandrae produced from C. chinensis, ranged from 0.66±0.05 to 0.82±0.02. The invulnerability of the young larval instar of C. chinensis and regulation of the progeny sex ratio by A. calandrae based on host size in a manner of absolute rule could explain the higher sex ratio on the young larval instar of C. chinensis, less preferred and less vulnerable host, than the old larval instar of S. oryzae, highly preferred host. The differences in host vulnerability could be another factor for A. calandrae assigning progeny sex ratio.     

Experimental evolution of competing bean beetle species reveals long‐term reversals of short‐term evolution,but no consistent character displacement

Interspecific competition for shared resources should select for evolutionary divergence in resource use between competing species, termed character displacement. Many purported examples of character displacement exist, but few completely rule out alternative explanations. We reared genetically diverse populations of two species of bean beetles, Callosobruchus maculatus and Callosobruchus chinensis, in allopatry and sympatry on a mixture of adzuki beans and lentils, and assayed oviposition preference and other phenotypic traits after four, eight, and twelve generations of (co)evolution. C. maculatus specializes on adzuki beans; the generalist C. chinensis uses both beans. C. chinensis growing in allopatry emerged equally from both bean species. In sympatry, the two species competing strongly and coexisted via strong realized resource partitioning, with C. chinensis emerging almost exclusively from lentils and C. maculatus emerging almost exclusively from adzuki beans. However, oviposition preferences, larval survival traits, and larval development rates in both beetle species did not vary consistently between allopatric versus sympatric treatments. Rather, traits evolved in treatment‐independent fashion, with several traits exhibiting reversals in their evolutionary trajectories. For example, C. chinensis initially evolved a slower egg‐to‐adult development rate on adzuki beans in both allopatry and sympatry, then subsequently evolved back toward the faster ancestral development rate. Lack of character displacement is consistent with a previous similar experiment in bean beetles and may reflect lack of evolutionary trade‐offs in resource use. However, evolutionary reversals were unexpected and remain unexplained. Together with other empirical and theoretical work, our results illustrate the stringency of the conditions for character displacement.     

Mung bean (<Emphasis Type="Italic">Vigna radiata</Emphasis>) cultivars mediated oviposition preference and development of <Emphasis Type="Italic">Callosobruchus chinensis</Emphasis> (Coleoptera: Chrysomelidae: Bruchinae)

The Azuki bean weevil, Callosobruchus chinensis (L.), is a destructive pest of stored mung bean [Vigna radiata (L.) Wilczek] as well as other leguminous seeds. The development of resistant seeds to manage this pest is of current great interest to plant breeders. In this study, we investigated the oviposition preference and development of C. chinensis on two susceptible mung bean cultivars (Seonhwa and Gyeongseon) and one previously reported resistant cultivar (Jangan), compared to the susceptible cowpea (Vigna unguiculata L.), cultivar (Yeonbun) using both multiple-choice and no-choice tests. In addition, the development of C. chinensis was also examined at four constant temperatures (20, 25, 30, and 35 °C). Both tests found cowpea to be the most suitable seed for oviposition. Total developmental time from oviposition to adult emergence ranged from 27.01 to 38.2 days, being shortest on cowpea and longest on the mung bean, cv. Jangan. However, no successful development of C. chinensis larvae on mung bean, cv. Jangan, occurred at any temperature. The highest rate of adult emergence and the longest adult longevity both occurred on cowpea and certain mung bean cultivars (Seonhwa and Gyeongseon), with the dramatic exception of cv. Jangan. These results suggest that the higher preference and performance of C. chinensis on cowpea (3.3 egg/seed) and least on mung bean, cv. Jangan (0.4 egg/seed). This information may facilitate the exploration of resistant genetic materials and chemicals associated with seeds for successful breeding. Further studies should examine the chemicals associated with mung bean cultivars and its resistant mechanism to develop a control method against bruchines.     

Nitric oxide fumigation for control of navel orangeworm,Amyelois transitella,on walnut

The navel orangeworm (NOW), Amyelois transitella (Walker), is a major post-harvest pest of tree nuts including walnut, almonds and pistachios. Nitric oxide (NO) was recently discovered to be a potential fumigant under ultralow oxygen conditions for post-harvest pest control. In this study, NO fumigation was evaluated for efficacy against eggs, larvae and pupae of NOW. NO fumigation was found to be similarly effective against NOW on artificial diet and in infested walnuts. Fumigations of 4, 8 and 16 hr with 2.0, 1.0 and 0.5% NO, respectively, achieved complete control of small and large larvae in artificial diet. Complete control of pupae on artificial diet was achieved in 8, 16 and 24 hr fumigations with 2.0, 1.0 and 0.5% NO, respectively. For NOW in infested walnuts, complete control was achieved in 6, 8 and 16 hr fumigations with 1.5, 1.0 and 0.5% NO, respectively, for small larvae; in 4-, 8- and 24-hr fumigations with 2.0, 1.0 and 0.5% NO, respectively, for large larvae; and in 8-, 16- and 24-hr fumigations with 2.0, 1.0 and 0.5% NO, respectively, for pupae. Eggs were more tolerant to NO fumigation than larvae and pupae, and complete control of NOW eggs was achieved in 8- and 16-hr fumigation with 3.0 and 2.0% NO, respectively. This study demonstrated the efficacy of NO fumigation against NOW on walnut and its potential as an alternative post-harvest treatment for the pest.     

Juvenile hormone in Drosophila melanogaster: Identification and titer determination during development

Juvenile hormone (JH) III was identified in whole-body extracts of eggs, larvae, pupae, pharate adults and adults of Drosophila melanogaster. Titers of the hormone varied according to stage of development. Highest levels were found in post-feeding (wandering) larvae and adults; only low levels were found in feeding last-stadium larvae and in pupae. None of the other known JHs were detected (limit of detection ≈0.01 ng/g). These results are discussed in the light of the known physiological roles of JH in the development of Drosophila and other insects.     

Prediction of survival ratios of Cadra cautella (Lepidoptera: Pyralidae) different life stages after treated with ultraviolet radiation in dates

Date palm, is a tree of economic importance which is grown around the world, including Saudi Arabia. Its fruit is nutritious and possesses medicinal benefits. Almond moth, is a serious date fruits pest in the field as well as in the storage and causes severe economic losses. In the given research, ultraviolet radiation type B (UV-B, 315 nm) harmful effects were evaluated against all developmental stages of C. cautella. One and 3-d-old eggs, 12 and 18-d-old larvae, 1-d and 6-d-old pupae, and 1-d-old adults, were exposed to UV-B for different intervals. Eggs were exposed for 0–30 min and 0% hatchability was achieved both for 1-d and 3-d-old eggs after 30 min. The larvae were exposed for 6–24 h, and after 24 h, mortality was 100 and 97% for 12 and 18-d-old larvae, respectively. Similarly, the pupae were exposed for 0–30 h, and 100% mortality was achieved after 30 h for 1-d-old pupae. Furthermore, none of the 6-d-old pupae emerged as an adult after 12 h of exposure. When adults were exposed for 1–4 d, no mortality was observed; however, UV-B reduced fecundity and hatchability in the treated adults. The susceptibility order was as follows: eggs > larvae > pupae > adults. Several uncharacteristic behaviors of C. cautella were noted, such as females depositing eggs openly on food items and containers, mature larvae exiting from food, larvae starting to wander for pupation, and pupation occurring typically outside the food. The application of UV-B could be an effective management strategy because all developmental stages of C. cautella were susceptible to UV-B that might be helpful to protect the dates from C. cautella infestation.     

Low Temperature Storage of <Emphasis Type="Italic">Telenomus remus</Emphasis> (Nixon) (Hymenoptera: Platygastridae) and its Factitious Host <Emphasis Type="Italic">Corcyra cephalonica</Emphasis> (Stainton) (Lepidoptera: Pyralidae)

We conducted three bioassays to evaluate the effect of low-temperature storage of eggs (host) and pupae and adults (parasitoid) on the biology and parasitism capacity of the egg parasitoid Telenomus remus (Nixon) (Hymenoptera: Platygastridae). Viable stored Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae) eggs were parasitized to the same degree or even higher than fresh eggs when stored until 14 days at 5°C or until 21 days at 10°C. In contrast, the percentage of parasitized sterilized eggs was equal to the control only when stored for 7 and 14 days. Survival of T. remus pupae declined with storage time at both studied temperatures (5 and 10°C). However, after 7 days of storage, survival of pupae was still 86.3 and 64.9% at 10 and 5°C, respectively. The number of adult male survivors remained similar until the fourth storage day at both 5 and 10°C. In contrast, female survival did not differ until day 8 at 10°C or day 6 at 5°C. Parasitism capacity of stored adults was not altered by storage compared with the control. Therefore, we conclude that the maximal storage time at 10°C is 21 days for viable C. cephalonica eggs and 7 days for T. remus pupae, while parasitoid adults should not be stored for more than 4 days at either 5 or 10°C.     

Effect of electron beam irradiation on developmental stages of Plutella xylostella (Lepidoptera: Plutellidae)

The effect of electron beam irradiation on each developmental stage of diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae), was examined. Eggs, larvae, pupae, and adults were irradiated at target doses of 30, 50, or 100 Gy or they were left untreated as controls in replicated experiments. When eggs and pupae were irradiated with 100 Gy, emergence rates greatly decreased and, although some adults laid eggs, they did not hatch. Egg hatching of irradiated larvae and adult decreased with increasing irradiation doses. However, electron beam irradiation did not kill P. xylostella directly. Adult longevity was not affected. Reciprocal crosses between irradiated and unirradiated moths demonstrated that females were more radiosensitive than males in hatchability; however, the difference was not significant. In addition, electron beam-irradiated larvae showed typical DNA fragmentation in a dose-dependent manner compared with cells from unirradiated larvae. Our findings suggest that electron beam irradiation induces abnormal development and reproduction of P. xylostella; therefore, it may contribute to effective disinfestation and quarantine treatments of P. xylostella.     

Factors affecting the efficacy of methyl bromide fumigation to control Liriomyza trifolii in imported chrysanthemum cuttings

Laboratory investigations were made into the effect of cultivar type, prior cold storage, fumigation temperature and methyl bromide concentration, on the efficacy of a fumigation treatment to control Liriomyza trifolii in chrysanthemum cuttings. The tests related to the standard quarantine treatment used in the UK to control Spodoptera littoralis on imported chrysanthemum cuttings: cold storage for 2 days at 1 – 2°C followed by methyl bromide fumigation at 15°C with a concentration time product (CTP) of 54 g h/m³. L. trifolii larvae, within detached leaves, and 1 – 2 and 2 – 3 day old pupae, were treated. Methyl bromide concentrations of 6·75 or 13·5 g/m³ were used to achieve a range of CTPs and thus obtain accurate dose-response lines and estimates of the LD99 and LD99·9 for each insect stage. Fumigation temperatures were 8, 11 or 15°C. Efficacy of the standard treatments differed between the three cultivars tested, but the LD99 for larvae remained below 54 g h/m³. Decreasing fumigation temperature to 11°C or less increased LD99 values for larvae and pupae and substantially increased variability. There is therefore little scope for using fumigation temperatures of less than 15°C for quarantine purposes. Omitting the cold storage treatment prior to fumigation did not significantly affect efficacy of fumigation. Reducing the methyl bromide concentration from 13·5 to 6·75 g/m³ did not significantly affect the LD99 for larvae but significantly reduced LD99s for pupae.     

Intra-specific Variation in the Effect of Male Seminal Substances on Female Oviposition and Longevity in Callosobruchus chinensis

Male seminal substances have been shown to induce oviposition and reduce female longevity in a number of species including the adzuki bean beetle Callosobruchus chinensis. Here the micro-injection of extracts of male reproductive tissues is used to determine the effect of male and female strain on female fecundity and longevity. Four strains of C. chinensis, known to differ in their propensity to remate were assayed. The results indicate that male and female strain both influence female fecundity and longevity. However, consistent patterns of response were not observed as revealed by a significant interaction between male and female strains. The evolutionary implications of these results are discussed.     

Avoidance of reproductive interference causes resource partitioning in bean beetle females

Reproductive interference is any interspecific sexual interaction that adversely affects female fitness through indiscriminate reproductive activities. It can be a driving force of resource partitioning in conjunction with resource competition. We previously showed that the bean beetle Callosobruchus maculatus is superior in larval resource competition, but vulnerable in reproductive interference, compared with its congener C. chinensis. We hypothesized that these two species might use two resources differently if one of the resources modified the intensity of reproductive interference or resource competition. We observed that C. maculatus females often enter gaps between beans to avoid mating attempts of heterospecific males, and hypothesized that removing bean gaps would strengthen reproductive interference. Therefore, we provided normal beans with gaps and split beans without gaps to females of the two species housed with conspecific or heterospecific males or no males and compared the number of eggs on each bean type among treatments. Callosobruchus maculatus females housed with heterospecific males were more likely to oviposit on normal beans than C. chinensis females. As a result, more C. chinensis adults hatched from split beans and more C. maculatus hatched from normal beans when females and males of both species were housed together. Thus, oviposition resource partitioning resulted from the combination of female avoidance of reproductive interference and resource competition.     

Acceptability of Drosophila suzukii as prey for common predators occurring in cherries and berries

The invasive cherry vinegar fly, Drosophila suzukii, has been identified in Europe as a destructive fruit pest since its arrival in 2008. In the present laboratory study, three predatory insects (Orius majusculus, Chrysoperla carnea, and Forficula auricularia) naturally occurring on fruit crops in Europe were investigated for their ability to attack and feed on D. suzukii within and outside fruits. The predators were provided with various D. suzukii life stages (eggs, larvae, pupae or adults) exposed or within infested cherries. The anthocorid bug O. majusculus fed on eggs and larvae, but was not able to attack pupae. Larvae of the lacewing C. carnea preyed upon D. suzukii eggs, larvae and pupae and also captured adult flies. The European earwig F. auricularia was the most voracious predator of these three tested species. Although the earwigs were not able to catch adult flies, they readily preyed upon every other developmental stage. Adult O. majusculus or third instar larvae of C. carnea significantly reduced the offspring of D. suzukii from infested cherries, when these contained the egg stage of the pest. None of the predators were able to attack early larval stages inside the cherries. But pupae that protruded from the fruit epicarp or that had pupated outside the fruit were accessible to lacewing larvae and earwigs and significantly reduced by them. Orius bugs, lacewing larvae and earwigs were able, under laboratory conditions, to capture and prey upon various life stages of the invasive pest, if not completely concealed inside the fruit. Our findings suggest that these generalist predators may have some control capacity on infested fruit in cultivated fruit crops and also in non‐crop habitats.     

Different female mating rates in different populations do not reflect the benefits the females gain from polyandry in the adzuki bean beetle

The question why females in many species mate with several males (polyandry) has engaged the interest of evolutionary biologists for many years, and many studies have been conducted on the nature of the benefits that the females gain from polyandry. To understand the variation of female mating rates among species and populations it is indispensable to test the prediction that females of more polyandrous populations experience larger fitness benefit than those of less polyandrous populations. We compared the fitness components of two strains of the adzuki bean beetle Callosobruchus chinensis that have genetically different female mating rates. We measured the number of hatched eggs of once-copulated females and twice-copulated females in each strain. The statistical interaction for the number of hatched eggs between the number of matings and strains was determined. The increase in the number of hatched eggs is larger for the lower mating-rate strain than for the higher mating rate strain. This means that females of the lower mating-rate strain would have larger fitness gain from polyandry than those of the higher mating-rate strain. The actual mating rates of females did not reflect female interests in adzuki bean beetles, suggesting they are affected by sexual conflict.