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Anastrepha fraterculus sp.1 males are sexually stimulated by the aroma of fruit of its native host Psidium guajava (guava). Other hosts, which are exotic to A. fraterculus , do not enhance male sexual behavior. Here we evaluate the effects of fruit volatile exposure on male A. fraterculus sp. 1 sexual performance using other native hosts, under the hypothesis that male improvement derives from a common evolutionary history between A. fraterculus sp. 1 and its native hosts. Four species were evaluated: Eugenia myrcianthes , Juglans australis , Psidium cattleianum , and Acca sellowiana . Guava was used as a positive control. Males were exposed to fruit from 12:00 pm to 4:00 pm, from day 8 to day 11 post-emergence. On day 12, we evaluated their calling behavior and mating success. Both guava and P. cattleianum enhanced calling behavior. Mating success was enhanced only by guava and a trend was found for P. cattleianum . Interestingly, the two hosts belong to the Psidium genus. A volatile analysis is planned to identify the compounds responsible for this phenomenon. The other native fruits did not improve the sexual behavior of males. Implications of our findings in the management of A. fraterculus sp. 1 are discussed.

Insect microbiota, particularly, gut bacteria has recently gained especial attention in Tephritidae fruit flies, being Enterobacteriaceae the predominant bacterial group. This bacterial group has been postulated to contribute to the fitness of fruit flies through several life-history traits. Particularly in Anastrepha fraterculus, removal of Enterobacteria from male gut via antibiotic treatment impaired their mating behavior. Because the impact of gut bacteria on female reproduction was not yet addressed, we here analysed the effect of antibiotic treatment on female fecundity and nutritional status, and further explored the role of bacteria under different dietary regimes. The removal of culturable Enterobacteria from the gut of females was associated to a reduction in fecundity as well as in the protein and lipid reserves. However, fecundity reduction depended on the dietary regime; being more pronounced when females fed a poor diet. Our results suggest that nutrient reserves of females are determined, at least to some extent, by intestinal bacteria (particularly Enterobacteria). The effect of antibiotics on fecundity could be explained, thus, as a consequence of a poorer nutritional status in antibiotic-treated females compared to control females. Our results contribute to understand the interaction between gut bacteria and Tephritidae fruit flies. Considering the relevance of this insect as fruit pest and the widespread use of the sterile insect technique to control them, these findings may lead to practical applications, such as development of efficient mass rearing protocols of A. fraterculus that supplement the adult diet with probiotics., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The genus Anastrepha (Diptera Tephritidae) includes some of the most important fruit fly pests in the Americas. Here, we studied the gut bacterial community of 3rd instar larvae of Anastrepha fraterculus sp. 1 through Next Generation Sequencing (lllumina) of the V3-V4 hypervariable region within the 16S rRNA gene. Gut bacterial communities were compared between host species (guava and peach), and geographical origins (Concordia and Horco Molle in Argentina) representing distinct ecological scenarios. In addition, we explored the effect of spatial scale by comparing the samples collected from different trees within each geographic origin and host species. We also addressed the effect of fruit size on bacterial diversity. The gut bacterial community was affected both by host species and geographic origin. At smaller spatial scales, the gut bacterial profile differed among trees of the same species and location at least in one host-location combination. There was no effect of fruit size on the larval gut bacteriome. Operational Taxonomic Units (OTUs) assigned to Wolbachia , Tatumella and Enterobacter were identified in all samples examined, which suggest potential, non-transient symbioses. Better knowledge on the larval gut bacteriome contributes valuable information to develop sustainable control strategies against A. fraterculus targeting key symbionts as the Achilles' heel to control this important fruit fly pest., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Salgueiro, Nussenbaum, Milla, Asimakis, Goane, Ruiz, Bachmann, Vera, Stathopoulou, Bourtzis, Deutscher, Lanzavecchia, Tsiamis and Segura.)

Many parasitoid species discriminate already parasitized hosts, thus avoiding larval competition. However, females incur in superparasitism under certain circumstances. Superparasitism is commonly observed in the artificial rearing of the parasitoid Diachasmimorpha longicaudata, yet host discrimination has been previously suggested in this species. Here, we addressed host discrimination in virgin D. longicaudata females in a comprehensive way by means of direct and indirect methods, using Ceratitis capitata and Anastrepha fraterculus which are major fruit fly pests in South America. Direct methods relied on the description of the foraging behaviour of females in arenas with parasitized and non-parasitized host larvae. In the indirect methods, healthy larvae were offered to single females and the egg distributions were compared to a random distribution. We found that D. longicaudata was able to recognize parasitized host from both host species, taking 24 h since a first parasitization for A. fraterculus and 48 h for C. capitata. Indirect methods showed females with different behaviours for both host species: complete discrimination, non-random (with superparasitism), and random distributions. A larger percentage of females reared and tested on A. fraterculus incurred in superparasitism, probably associated with higher fecundity. In sum, we found strong evidence of host discrimination in D. longicaudata, detecting behavioural variability associated with the host species, the time since the first parasitization and the fecundity of the females.

Exposure to plant compounds and analogues of juvenile hormone (JH) increase male mating success in several species of tephritid fruit flies. Most of these species exhibit a lek mating system, characterized by active female choice. Although the pattern of enhanced male mating success is evident, few studies have investigated what benefits, if any, females gain via choice of exposed males in the lek mating system. In the South American fruit fly, Anastrepha fraterculus, females mate preferentially with males that were exposed to volatiles released by guava fruit or treated with methoprene (a JH analogue). Here, we tested the hypothesis that female choice confers direct fitness benefits in terms of fecundity and fertility. We first carried out mate choice experiments presenting females with males treated and non-treated with guava volatiles or, alternatively, treated and non-treated with methoprene. After we confirmed female preference for treated males, we compared the fecundity and fertility between females mated with treated males and non-treated ones. We found that A. fraterculus females that mated with males exposed to guava volatiles showed higher fecundity than females mated to non-exposed males. On the other hand, females that mated methoprene-treated males showed no evidence of direct benefits. Our findings represent the first evidence of a direct benefit associated to female preference for males that were exposed to host fruit odors in tephritid fruit flies. Differences between the two treatments are discussed in evolutionary and pest management terms., Competing Interests: The authors have declared that no competing interests exist.

The optimal use of available host by parasitoid insects should be favoured by natural selection. For solitary parasitoids, superparasitism (i.e. the egg-laying of several eggs/host) may represent a detrimental phenomenon both in a biological and an applied sense, but under certain circumstances it may be adaptive. Here, we studied the effects of increasing levels of superparasitism (LSPs, number of parasitoid larvae/host) on fitness-related parameters of the immature and adult stages of Diachasmimorpha longicaudata, a solitary endoparasitoid parasitizing Ceratitis capitata. We investigated the moment when supernumerary parasitoid larvae are eliminated and the effects produced by this process, together with its repercussion on female fecundity, parasitism rate, sex ratio, adult survival, flight ability and body size. Complete elimination of competitors occurred soon after larval hatching, before reaching the second larval stage. Elimination process took longer at higher LSPs, although a normal developmental (egg-adult) time was achieved. For LSPs 1, 2, 3 and 5 the effects on parasitoid emergence were mild, but LSP 10 led to the death of all developing parasitoids. Aside from this, to develop in superparasitized hosts did not significantly affect any of the evaluated parameters, and only a female-biased sex ratio was observed at higher LSPs. However, the effects of superparasitism on the adults may have a different outcome under more variable conditions in the field, once they are released for biological control purposes.

The juvenile hormone (JH) of insects triggers physiological changes related to reproduction in adults of both sexes. Methoprene is a sesquiterpene with some effects that are analogous to those of JH. Treatments with methoprene accelerate sexual maturation in males of the South American fruit fly Anastrepha fraterculus, giving young males a mating advantage over non-treated males of the same age. Here, we evaluated the effects of methoprene treatment on A. fraterculus males after the sexual maturation phase and tested whether this compound provides a long-term mating advantage. Moreover, we took the first step to unravel the mechanisms that underlie male sexual enhancement. We treated males 1day or 8days after adult emergence and compared mate choice between recently matured (young) females and females that had been mature for ca. 10days (aged females). We also addressed methoprene treatment effects on male sexual signalling. We found that methoprene treatment enhanced male sexual competitiveness even after the sexual maturation phase, and the effect did not decrease until males were older than 20days. However, when methoprene treatment was carried out close to sexual maturity, the mating enhancement was no longer observed, suggesting a non-immediate effect and excluding the possibility that methoprene acts as a pheromonal compound. Young and aged females tended to mate more frequently with treated-males. This might indicate that in a context of sexual selection, the potential benefits associated with reproductive success would be similar for females of both ages. Treated males released larger amounts of pheromonal compounds than non-treated males, but their courtship behaviour was not altered to the same extent, suggesting that methoprene treatment may accelerate differently the components of male courtship. We discuss potential benefits of using methoprene to increase the efficiency of the sterile insect technique, which is an environmentally safe method to control this important South American fruit pest., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Parasitoids searching for polyphagous herbivores can find their hosts in a variety of habitats. Under this scenario, chemical cues from the host habitat (not related to the host) represent poor indicators of host location. Hence, it is unlikely that naïve females show a strong response to host habitat cues, which would become important only if the parasitoids learn to associate such cues to the host presence. This concept does not consider that habitats can vary in profitability or host nutritional quality, which according to the optimal foraging theory and the preference-performance hypothesis (respectively) could shape the way in which parasitoids make use of chemical cues from the host habitat. We assessed innate preference in the fruit fly parasitoid Diachasmimorpha longicaudata among chemical cues from four host habitats (apple, fig, orange and peach) using a Y-tube olfactometer. Contrary to what was predicted, we found a hierarchic pattern of preference. The parasitism rate realized on these fruit species and the weight of the host correlates positively, to some extent, with the preference pattern, whereas preference did not correlate with survival and fecundity of the progeny. As expected for a parasitoid foraging for generalist hosts, habitat preference changed markedly depending on their previous experience and the abundance of hosts. These findings suggest that the pattern of preference for host habitats is attributable to differences in encounter rate and host quality. Host habitat preference seems to be, however, quite plastic and easily modified according to the information obtained during foraging.

This study evaluated the quaternary ammonium compound cetyl trimethyl ammonium bromide (CTAB) as an alternative to the chemically related dodecylguanidine (dodine) for the selective isolation of entomopathogenic fungi. Oatmeal agar (OA) with chloramphenicol was used as basal medium, and three concentrations of CTAB (0.5, 0.6, 0.7 g/L) were evaluated and compared against OA + 0.46 g/L dodine. Selective isolation and growth studies were performed with the entomopathogens Beauveria bassiana, Metarhizium anisopliae s.l. and Paecilomyces lilacinus and five common non-entomopathogenic non-target species. The three entomopathogenic fungi sporulated earlier on OA + 0.6 g/L CTAB than on OA + 0.46 g/L dodine, while none of the non-target fungi sporulated on OA + 0.6 g/L CTAB. All entomopathogenic fungal isolates grew on OA + 0.6 g/L CTAB, despite some intra-species variation, whereas non-target fungi showed no growth or sporulation. OA + 0.6 g/L CTAB resulted in an efficient medium to isolate B. bassiana, M. anisopliae s. l. and P. lilacinus from soil samples. Results of our study suggest that OA + 0.6 g/L CTAB is a suitable, simple and inexpensive to prepare medium to replace OA + 0.46 g/L dodine for the selective isolation of these fungi.

The boll weevil (Anthonomus grandis) is the main pest of cotton in the Americas. The aim of this work was to evaluate isolates of the entomopathogenic fungi Beauveria bassiana sensu lato and Metarhizium anisopliae sensu lato virulent against A. grandis. Screening was performed to evaluate the pathogenicity of 28 isolates of M. anisopliae s.l. and 66 isolates of B. bassiana s.l. against boll weevil adults. To select the isolates, LC(50) values of the most virulent isolates were calculated, and compatibility between the fungi and insecticides was studied. In addition, the effects of these isolates on the feeding behavior of the adults were evaluated. Isolates Ma 50 and Ma 20 were the most virulent against A. grandis and their LC(50) values were 1.13×10(7) and 1.20×10(7) conidia/ml, respectively. In addition, these isolates were compatible with pyrethroid insecticides, but none with endosulfan. On the other hand, infected females reduced the damage caused by feeding on the cotton squares and their weight gain. This shows that entomopathogenic fungi cause mortality in the insects, but also these fungi could influence the feeding behavior of the females. In summary, these results indicate the possibility of the use of M. anisopliae s.l. as a microbiological control agent against boll weevils. Also, this species could be included in an Integrated Pest Management program., (Copyright © 2012 Elsevier Inc. All rights reserved.)