Attraction of the Larval Parasitoid <Emphasis Type="Italic">Spintherus dubius</Emphasis> (Hymenoptera: Pteromalidae) to Feces Volatiles from the Adult <Emphasis Type="Italic">Apion</Emphasis> Weevil Host

The behavioral response of the larval parasitoid Spintherus dubius (Hymenoptera: Pteromalidae) to volatile compounds derived from its Apion weevil hosts was investigated in two-choice bioassays. Odor source candidates were the larval and adult stages of weevils, clover flowers, and feces from adult weevils. Despite S. dubius being a larval parasitoid, the odor of weevil larvae isolated from the clover flowers was not attractive to female parasitoids. Surprisingly, S. dubius females were instead attracted by the odor from the feces of adult weevils. The female parasitoids were similarly attracted to the feces produced by the two main hosts, the red clover weevil (A. trifolii) and the white clover weevil (A. fulvipes). Chemical analysis of the volatile composition of feces produced by the two hosts revealed qualitatively similar odor profiles, correlating with the observed attraction by the parasitoid towards both odor sources. Some of the identified volatile compounds are commonly present in clover plant headspace fractions and may function as a kairomone to facilitate orientation by S. dubius to Apion-infested clover flowers. Larval and adult weevils were not attractive for parasitoid females, whereas, for the white clover weevil-plant association, infested flowers were highly attractive. These data show the use by the clover weevil parasitoid of an alternative source of olfactory information for locating its host.     

Reproductive tables of predatory phytoseiid mites (<Emphasis Type="Italic">Phytoseiulus persimilis,Galendromus occidentalis</Emphasis>, and <Emphasis Type="Italic">Neoseiulus cucumeris</Emphasis>)

Feeding of predatory mites (Phytoseiulus persimilis, Galendromus occidentalis, and Neoseiulus cucumeris) on different life stages of Tetranychus atlanticus under optimal conditions was studied. Daily and total consumption of prey by predators and selection of prey of different life stages were studied for 5 days and for the entire feeding period. Average daily food consumption [number of individuals] for the entire life period of mature mite females constituted 0.43 females + 5.0 [nymphs and males] + 3.4 eggs of Tetranychus atlanticus in P. persimilis; 0.12 females + 3.70 [nymphs and males] + 3.10 eggs in G. occidentalis; and 0.19 females + 4.10 [nymphs and males] + 3.50 eggs in N. cucumeris. During the entire period of feeding, P. persimilis preferred large individuals and at the postembryonic stages selected prey to a greater extent than G. occidentalis and N. cucumeris (61.8 and 55.1%, respectively). The use of a 5-day express-method is possible for estimation of some biological characteristics of phytoseiids that previously consumed the same food for a long period. In other cases, analysis of characteristics for the entire life period is necessary.     

Potential Reproductive Advantage of Short-over Long-Winged Adult Males of the Cricket <Emphasis Type="Italic">Velarifictorus ornatus</Emphasis>

A trade-off between flight capability and reproduction is well known in adult females of the wing-dimorphic cricket Velarifictorus ornatus, but it is not clear whether such a trade-off exists in adult males of the species. In the present study, we investigated sexual maturation time, mating frequency, and the fertilization success of spermatophores after sequential mating in long-winged (LW) and short-winged (SW) adult males of V. ornatus to evaluate the potential reproductive advantage of the SW over the LW male morph. We found that the SW males of V. ornatus attained sexual maturity earlier and produced heavier spermatophores during the early stage after adult emergence than their LW counterparts. Additionally, within a 24-h mating period, the SW males showed a higher mating frequency, greater spermatophore weight, and shorter intermating time interval compared with their LW counterparts. Although females copulated with the two male morphs produced eggs of similar size, fertilization success by SW males was significantly higher than by the LW males. These results provide support for a trade-off between dispersal capability and reproduction success in wing-dimorphic males of V. ornatus.     

Behavioral responses of <Emphasis Type="Italic">Hyalesthes obsoletus</Emphasis> to host-plant volatiles cues

The polyphagous planthopper Hyalesthes obsoletus Signoret is considered to be the principal vector of stolbur phytoplasma, which is associated with yellow diseases of grapevine. To explore the possibility of developing novel control strategies, the behavioral responses to six synthetic mixtures and nine single compounds, previously identified from the headspace of Vitex agnus-castus L. (chaste tree) and Urtica dioica L. (nettle), were investigated in Y-tube bioassays. Choice tests revealed differences in the behavioral responses of males and females to the volatiles that they were exposed to. Males were attracted to a mixture containing (E)-β-caryophyllene, 1,8-cineole, (E,E)-α-farnesene, (E)-β-farnesene, and methyl salicylate (mixture 2). The addition of methyl benzoate to this five-compound mixture (mixture 3) did not attract males but elicited positive responses in females. Furthermore, females were attracted to a mixture containing (E)-β-caryophyllene, (E,E)-α-farnesene, (Z)-3-hexenyl acetate, (Z)-3-hexen-1-ol, and benzothiazole (mixture 4), but here addition of methyl salicylate (mixture 5) did not attract females. Neither males nor females showed attractivity or repellency toward the singly tested compounds. This study enhances knowledge on the interaction of insect behaviorally effective constituents in complex plant volatile mixtures. The attractive mixtures of plant volatiles identified suggest the possibility of using them in monitoring and management of H. obsoletus.     

Detection of <Emphasis Type="Italic">Rickettsia</Emphasis> spp. in ticks parasitizing toads (<Emphasis Type="Italic">Rhinella marina</Emphasis>) in the northern Brazilian Amazon

This study evaluated rickettsial infection in ticks collected on toads from the northern Brazilian Amazon (Amapá state), where to our knowledge there are neither records of ticks from amphibians nor rickettsial infections in ticks. During 2016–2017, a total of 22 free-living toads were captured and identified as Rhinella marina. Overall, 12 (54.5%) toads were parasitized by a total of 97 ticks (6 males, 39 females, 31 nymphs, 21 larvae), giving a mean intensity of 8.1 ticks per infested toad. Two tick species were morphologically identified: Amblyomma rotundatum Koch (31 females, 14 nymphs), and Amblyomma dissimile Koch (6 males, 8 females, 17 nymphs). The 21 larvae were morphologically denoted as Amblyomma sp. Five toads were co-infested by A. rotundatum and A. dissimile. Morphological identifications were confirmed by nucleotide sequencing of fragments of the mitochondrial genes 16S rDNA, 12S rDNA and/or COX1. A total of 54 ticks were analyzed for the presence of rickettsial DNA. Eleven (9 females and 2 nymphs) out of 14 A. rotundatum ticks contained Rickettsia bellii. None of the 25 specimens of A. dissimile (6 males, 6 females, 13 nymphs) contained amplifiable rickettsial DNA. From 15 Amblyomma sp. larvae, a pool of 10 individuals contained Rickettsia sp. strain Colombianensi. Sequencing of the 16S rDNA amplicon derived from the positive pool yielded a sequence of A. dissimile. We detected Rickettsia sp. strain Colombianensi for the first time in Brazil. Prior records of this agent were restricted to Colombia and Honduras. In addition, we report the presence of A. rotundatum for the first time in the state of Amapá, where the only other record of A. dissimile was registered over 20 years ago.     

An omnivorous arthropod, <Emphasis Type="Italic">Nesidiocoris tenuis</Emphasis>, induces gender-specific plant volatiles to which conspecific males and females respond differently

Nesidiocoris tenuis Reuter (Heteroptera: Miridae) is an omnivorous mirid bug that preys on diverse generalist herbivorous arthropods. N. tenuis adults are attracted to volatiles from plants induced by their prey, such as tobacco cutworms (CCW) (Spodoptera litura larvae) and two-spotted spider mites (Tetranychus urticae). N. tenuis adults also induce volatiles when they infest plants. In this study, we focused on olfactory responses of N. tenuis males and females to volatiles from eggplants and sesame plants induced by conspecifics of the same or different gender by using a Y-tube olfactometer. Males were attracted to volatiles from plants of both species induced by either males or females. The male preference was biased to volatiles from plants of both species induced by females, probably because the biased response would facilitate their mate-finding. Females were attracted only to volatiles from plants of both species induced by females. Mating occurs multiple times in this species. Thus, the responses would indirectly affect mating of males and females. Slight but significant qualitative and quantitative differences were detected between the volatiles of plants of both species induced by N. tenuis females and those of the plants induced by conspecific males. N. tenuis might use such differences in their gender-specific responses.     

Intra-specific variation of sperm length in the malaria vector <Emphasis Type="Italic">Anopheles gambiae</Emphasis>: males with shorter sperm have higher reproductive success

Background

Intra-specific variation in sperm length influences male reproductive success in several species of insects. In males of the malaria vector Anopheles gambiae, sperm length is highly variable but the significance of this variation is unknown. Understanding what determines the reproductive success of male mosquitoes is critical for controlling malaria, and in particular for replacing natural populations with transgenic, malaria-resistant mosquitoes.

Methods

A laboratory population of A. gambiae males was tested for intra-specific variation in sperm length. A full-sib quantitative genetic design was used to test for a genetic component of sperm length in A. gambiae males and estimate its heritability. This study also tested for a relationship between sperm length and male reproductive success in A. gambiae. Male reproductive success was measured as the proportions of inseminated and ovipositing females.

Results

There was intra-specific variation of sperm length in A. gambiae. There was no significant genetic variation in sperm length and its heritability was low (h² = 0.18) compared to other insects. Sperm length was correlated with male body size (measured as wing length). Males with short sperm had significantly higher reproductive success than males with long sperm and this was independent of body size.

Conclusion

This is the first study to demonstrate intra-specific variation in sperm length in A. gambiae and that males with short sperm have higher reproductive success. That sperm length influences female oviposition is important for any strategy considering the release of transgenic males.

     

The Influence of Sire Presence on Survival and the Growth Rate of Juvenile Common Voles <Emphasis Type="Italic">Microtus arvalis</Emphasis>

Pup survival and growth rates were monitored to determine whether paternal care potentially contributes to reproductive success of male common voles Microtus arvalis Pallas, 1779. The subjects were 258 pups from 47 litters obtained from adult voles trapped in the wild. Reproducing pairs were formed and divided onto two groups in accordance with the age and parental experience of the reproducing individuals: group I included pairs with subadult males and nulliparous females; group II included pairs with adult males and multiparous females. Each of the groups was divided into two subgroups: in subgroups Iа (n = 13) and IIа (n= 11), litters were raised by females without sires; in subgroups Ib (n = 12) and IIb (n = 11), litters were raised by both parents. The litter size was recorded at parturition and again when the young were 12, 21, and 30 days old. Pups in each litter were weighed at parturition and also again when the young were 12, 21, and 30 days old. This study has shown that the presence of the sire may negatively affect both survival and growth rates of the pups, but this effect is dependent on the age of the reproducing individuals.     

Reproductive interference between two serious pests,oriental fruit flies <Emphasis Type="Italic">Bactrocera carambolae</Emphasis> and <Emphasis Type="Italic">B. dorsalis</Emphasis> (Diptera: Tephritidae), with very wide but partially overlapping host ranges

Bactrocera carambolae and B. dorsalis (Diptera: Tephritidae) are extremely destructive pests of fruits and vegetables in the Asia-Pacific region. Earlier reports have described that B. carambolae and B. dorsalis, respectively, use mainly star fruit and mango, suggesting a certain level of host partitioning which can be ascribed neither to differences in larval food qualities nor host-specific parasitoid mortality. This study specifically examined reproductive interference (antagonistic sexual interaction) between B. carambolae and B. dorsalis as a potential factor strongly affecting their host partitioning. We observed mating behaviors, especially interspecific courtships and mating, by cohabiting the conspecific and heterospecific pairs together. Consequently, we quantified their effects on the reproductive success of females. Males of both species frequently courted their own females, but they also courted females of other species. Courtship refusal by females was not selective in males of either species. This incomplete discrimination of both sexes led to frequent occurrences of interspecific sexual interactions in both species, but only B. carambolae females showed reduced reproductive success. These results suggest that B. dorsalis, superior in reproductive interference, can occupy high-quality mango, whereas B. carambolae, inferior in reproductive interference, must use low-quality star fruit.     

Nymph and Adult Biology of <Emphasis Type="Italic">Euschistus cornutus</Emphasis> Dallas: a Potential Soybean Pest in the Neotropics

Laboratory studies with Euschistus cornutus Dallas indicated that nymphs complete development when feeding on green bean, Phaseolus vulgaris L. pod, on soybean, Glycine max (L.) Merrill pod, and on raw shelled peanut, Arachis hypogaea L., but not on fruit (berry) of privet, Ligustrum lucidum Ait. Total mortality was lower on green bean pod (45%), and higher on soybean pod and peanut raw (75 and 80%, respectively). Nymph developmental time was significantly longer for females feeding on green bean pod (37.4 days) than on soybean pod (27 days); a single data was observed on peanut raw (32 days). Males showed no significant differences in total nymph developmental time among foods (31.3 to 33.0 days). At adult emergency, fresh body weight of females (52.2 to 68.5 mg) and males (61.9 to 71.3 mg) did not show statistical differences among foods tested nor between genders. Survivorship of E. cornutus adult after 50 days was greater on peanut raw than on green bean or soybean pod; on privet berry, the majority of males and females (>80%) were dead after 20 days. The reproductive performance data was, in general, greater on peanut raw than on green bean or soybean pod; on privet fruit, no female laid eggs. Fresh body weight gain occurred on all foods, except on privet berry, on which adults lost weight over time. Records of specimens from insect collections in Brazil indicated that E. cornutus occurs in the Southeast and South regions (19° to 31° S latitude). The most common host plant is soybean, suggesting a potential pest status of this stink bug on this crop in the future.     

Male origin determines satyrization potential of <Emphasis Type="Italic">Aedes aegypti</Emphasis> by invasive <Emphasis Type="Italic">Aedes albopictus</Emphasis>

Rapid displacements of resident Aedes aegypti by invasions of Aedes albopictus have been documented in the southeastern United States and Bermuda. Interspecific mating has been detected in nature between these species and proposed as a likely mechanism for these displacements by means of asymmetric reproductive interference, or satyrization. However, rapid displacements of A. aegypti have not been detected in most localities where these two invasive species are known to co-occur. Aedes albopictus invaded the United States and Brazil at approximately the same time, in the mid-1980s, but the origins of the invading strains are known to be different. Here we tested the hypothesis, in standardized cage environments, that A. albopictus males from Brazil are less capable of satyrizing A. aegypti females than A. albopictus males from the United States. Using strains of A. aegypti and A. albopictus from the United States of known susceptibility to and capacity for interspecific mating, we demonstrate that A. albopictus colonized from collections in the Brazilian cities of Rio de Janeiro and Manaus were relatively unsuccessful in inseminating virgin female A. aegypti from Key West Florida compared to A. albopictus from peninsular Florida. We suggest that the low satyrization potential of Brazilian A. albopictus males may contribute to the lack of documented competitive displacements of A. aegypti in that country.     

Spermatozoa production in male <Emphasis Type="Italic">Varroa destructor</Emphasis> and its impact on reproduction in worker brood of <Emphasis Type="Italic">Apis mellifera</Emphasis>

Reproduction in Varroa destructor exclusively takes place within the sealed honey bee brood cell and is, therefore, limited by the duration of the postcapping period. Oogenesis, ontogenetic development and mating must be optimized to ensure the production of as many mated daughter mites as possible. One adult male mite has to mate with up to five sister mites and transfer 30–40 spermatozoa to each female. We analyzed the production and transfer of male spermatozoa during a reproductive cycle by counting all spermatozoa in the genital tracts of the male and daughter mites in 80 worker brood cells at defined times after cell capping. We could show that spermatozoa production in male mites is an ongoing process throughout their adult lifetime starting after the adult molt. The spermatozoa are transferred to the females in an early non-capacitated stage and require further maturation within the female’s genital tract. Our study points out that a Varroa male has at any time in the brood cell enough spermatozoa to inseminate all daughter mites but does not waste energy in producing a big surplus. In total one male produced, on average, 125 spermatozoa during a reproductive cycle in worker brood which is sufficient for successful matings with at least three daughter mites. Spermiogenesis in Varroa males represents therefore a further adaptation to the limited time available for reproduction.     

The ontogeny of the oribatid mite <Emphasis Type="Italic">Nanhermannia coronata</Emphasis> (Acari,Oribatida, Nanhermanniidae)

The ontogeny of the oribatid mite Nanhermannia coronata (Oribatida, Nanhermanniidae) was studied in the laboratory. At a temperature of 22–23°C and air humidity 100%, the entire life cycle from egg to adult lasted for 105–124 days. N. coronata juveniles and females are described. The diagnostic characters of the chaetom of N. coronata and N. nana larvae and nymphs are given. Morphological differences between N. coronata and N. nana allow distinguishing these species at all active stages.     

Reproductive Biology of <Emphasis Type="Italic">Leptocybe invasa</Emphasis> Fisher &amp; La Salle (Hymenoptera: Eulophidae)

Leptocybe invasa Fisher & La Salle (Hymenoptera: Eulophidae) is an invasive pest in Eucalyptus plantations around the world. The successful colonization of L. invasa is possibly related to its reproductive biology. The objective of this study was to examine the reproductive biology of L. invasa. In Guangxi Province, the sex ratio (proportion of female, 0.99) of L. invasa was female-dominant throughout the year based on natural and artificial infestation. This result was similar to the ratios observed for other geographic populations in China, including those in Fujian (0.99), Guangdong (0.98), Hainan (0.95), Jiangxi (0.96), and Sichuan (0.99). The offspring sex ratio favored females. A large number of females emerged from the galls produced by females, with few males found. Galls on the petioles and midribs of Eucalyptus plants could be caused by newly emerged females with mature eggs. The lengths of the ovariole, spermatheca, common oviduct, and reproductive glands did not differ among L. invasa females, but their lateral oviducts showed differences from 0 to 42 h after emergence, indicating that this insect is proovigenic. These results could explain why L. invasa populations can rapidly increase in invaded areas.     

Evolutionary Consequences of Desiccation Resistance in the Male Ejaculate

Avoiding water loss for insects is critical for survival. Selection for reduced water loss will depend on trade-offs between resources allocated for reproduction and those allocated for resisting desiccation. However, we lack knowledge on how selection for desiccation resistance can affect the male ejaculate. Furthermore, as male ejaculate composition is complex, desiccation resistant females could evolve traits that enable them to derive longevity benefits from mating. Here, we assessed how selection for desiccation resistance impacts male testes and accessory gland size, protein content of these organs, female sperm storage and male ability to inhibit female remating behavior, in the Mexican fruit fly Anastrepha ludens. Additionally, we tested if mating increased longevity and fecundity in desiccation resistant females. Males selected for resistance to desiccation stress had smaller accessory glands and seminal vesicles and females mating with these males stored less sperm compared to control males. Females mating with resistant males had lower fecundity compared to females mating with control males. Desiccation resistant females lived longer than control females, yet this was irrespective of mating. Rapid evolutionary responses to hydric stress can have correlated effects in reproductive capabilities, which are not restricted to pre-copulatory traits. Trade-offs between resistance to desiccation stress are reflected in decreased allocation of resources to reproductive organs. Thus, production of the ejaculate may be costly for A. ludens males. Knowledge on the evolution of ejaculate traits and reproductive organ size in response to directional selection for desiccation resistance, will aid our understanding of differential sex-specific responses to environmental stress.     

Taxonomy and First Records of Two <Emphasis Type="Italic">Megaselia</Emphasis> Rondani Species (Diptera: Phoridae) Preying upon Eggs of <Emphasis Type="Italic">Phyllomedusa iheringii</Emphasis> Boulenger (Anura: Phyllomedusidae)

Non-aquatic reproductive modes have evolved among frogs possibly favored by some advantages such as the avoidance of aquatic predators. These reproductive modes, however, make the egg clutches susceptible to terrestrial predators, among which Diptera larvae are some of the most harmful. The present work reports the predation by phorid flies of 22 egg clutches of Phyllomedusa iheringii Boulenger in the South of Brazil. Phorid specimens were identified as Megaselia bruchiana (Borgmeier & Schmitz) and Megaselia necrophaga (Enderlein), species that were reported previously to be associated with ants and dead beetles, respectively. Frog-feeding in these species is hypothesized to be use of an alternative seasonal food source. We amend the diagnoses of both Megaselia species and provide new illustrations to facilitate their identification. We also describe the male of M. bruchiana for the first time and associate males with females of both species.     

Host-parasite association between <Emphasis Type="Italic">Didelphis albiventris</Emphasis> (Didelphimorphia: Didelphidae) and <Emphasis Type="Italic">Ixodes loricatus</Emphasis> (Acari: Ixodidae) in their southern ranges

The parasitism of Ixodes loricatus Neumann on white-eared opposum, Didelphis albiventris Lund, was analysed in the southern ranges of both. In central Argentina, 118 wild opossums were captured from 2005 to 2012. Adults of I. loricatus were collected (prevalence?=?66.1%, mean?=?7.03, median?=?4), but no immature stage. Tick infestation was not affected by sex (p?=?0.27) or age (p?=?0.37) of hosts. In line with previous studies about seasonality of larvae and nymphs of I. loricatus, adult tick infestation showed no seasonal trend. This lack of seasonal pattern of infestation for all parasitic stages of I. loricatus may indicate a life cycle governed by nidicolous behaviour, in such a way that this habit would contribute to minimize the influence of external environmental variables. The tick sex ratio was female biased, with two females per one male (p?=?0.002). The absence of I. loricatus immatures on D. albiventris suggests that in the study region there is clear segregation of immatures in rodents and adults in marsupials.     

Identification of active components from volatiles of Chinese bayberry, <Emphasis Type="Italic">Myrica rubra</Emphasis> attractive to <Emphasis Type="Italic">Drosophila suzukii</Emphasis>

Drosophila suzukii (Diptera: Drosophilidae) is native to Southeast Asia and now has become a severe pest of several soft fruits in Europe and the Americas. It causes considerable damage to Chinese bayberry, Myrica rubra, in China. In the present study, we employed gas chromatograph–electroantennographic detection (GC–EAD) together with behavioural bioassays and trapping experiments to identify volatile semiochemicals emitted by Chinese bayberry attracting D. suzukii. Electrophysiological experiments revealed the presence of six EAD-active compounds from ripe bayberry fruits, including methyl (E)-3-hexenoate, methyl (E)-2-hexenoate, ethyl (E)-2-hexenoate, α-ylangene, α-humulene and an unidentified compound that elicited consistent antennal response. In two-choice bioassays, bayberry fruits attracted all responding flies, and significantly more flies responded to the volatile extract of bayberry fruits. Four EAD-active compounds were attractive to mated female D. suzukii at lower doses (0.01 and 0.1 µg), but showed repellency at higher doses (10 and 100 µg). Mixtures of these four compounds at different ratios attracted D. suzukii flies at all test doses (0.1, 1 and 10 µg). Both male and female flies were trapped by a mixture of synthetic methyl (E)-3-hexenoate, methyl (E)-2-hexenoate, ethyl (E)-2-hexenoate and α-humulene in a ratio of 1:1.3:1:6.4 in the field trapping experiment. Significantly more males than females were captured in the trap baited with the synthetic blend, and the percentages of D. suzukii captured out of all flies by the traps baited with lure were higher than that baited with blank control. Our findings may provide insights into the olfactory responses of D. suzukii to specific host plant volatiles, and contribute to further development of an effective lure for monitoring D. suzukii in the field.     

Female Colour Polymorphism and Unique Reproductive Behaviour in <Emphasis Type="Italic">Polythore</Emphasis> Damselflies (Zygoptera: Polythoridae)

We studied Polythore damselflies by mark-recapture techniques in the Jatun Sacha Biological Reserve (Ecuador) for a period of 48 days in October–December 2014. Three species were found: Polythore mutata (MacLachlan) was the commonest species (111 individuals marked), Polythore derivata (MacLachlan) was rare (24 individuals) and Polythore concinna (MacLachlan) occasional (four individuals). In P. mutata, we found two phenotypes amongst females, one of them with a white band on the wings, very similar in colouration to the conspecific male (androchrome), and the other with an amber band (gynochrome). The recapture of marked females indicates that both phenotypes are maintained since emergence to maturation and are not age-related (i.e. polymorphism). Androchromes represent 40% of females observed. The colour of the wing band showed an age-dependent change in size with opposite trends between sexes, increasing in males and decreasing in females. Males and females were observed to return to the same forest locations in different days. Courtships and ovipositions involving androchrome females were not observed. No matings were observed in any morph. In contrast, we recorded two consecutive matings of one female P. derivata. We found that Polythore males grasp the mesothorax of females during mating instead of the prothorax as in other Zygoptera. We discuss the rarity of reproductive behaviour in this genus and how female morphs might be maintained.     

Attraction to Host Plant Volatiles and Feeding Performance of <Emphasis Type="Italic">Naupactus Xanthographus</Emphasis> (Coleoptera: Curculionidae) is Affected by Starvation

The grape weevil, Naupactus xanthographus Germar (Coleoptera: Curculionidae), is a polyphagous insect which is a cause of important damage to several economically relevant crops, including grape (Vitis vinifera) and avocado (Persea americana), in several countries of Latin America. The larvae cause damage to the roots and rootlets of plants, and adults feed on leaves of their host plant. Despite its economic importance, there are few reports on the behavioral and nutritional ecology of this weevil. In this context, laboratory feeding and olfactometer bioassays with N. xanthographus were performed. The feeding performance was evaluated by measuring the weight variation of the insects after 1 and 6 h of feeding on grape or avocado leaves, respectively. After 1 h of feeding, insects showed no significant differences in weight increase. However, after a period of 6 h of feeding, males had continued feeding on grape leaves, but not on avocado leaves. Bioassays using a Y-tube olfactometer showed that males are attracted to volatiles of both host plants. Furthermore, starved males and females showed no preference to volatiles of grape or avocado. However, non-starved males and females preferred grape volatiles over avocado volatiles. Based on the combined results of the assays, we conclude that grape is preferred over avocado for N. xanthographus. Furthermore, this is the first report on the effect of starvation on the attraction to host plant volatiles in Curculionidae.