The preference-performance hypothesis (PPH) has widely been used to explain host exploitation patterns by phytophagous insects. However, this hypothesis often fails in the case of polyphagous species when compared with specialists. One explanation, validated by the information-processing hypothesis (IPH), considers that polyphagous insects are unable to process a large array of cues, which hinders females from distinguishing between high- and low- quality hosts. Here we analyzedAnastrepha ludensfemale host preference and offspring performance, and tested if neuronal limitations could possibly play a role in the incapacity of the polyphagousA. ludensto make ‘accurate decisions’ and therefore partially explain mismatches related to PPH. Results testing the PPH by correlating female preference to six naturally occurring hosts and its offspring outcomes show thatA. ludensfemales oviposited greater proportions of eggs on fruit according to hierarchical preferences. Infestation level was low in white sapote, the preferential and seemingly putative ancestral host, likely due to sapote defence mechanisms. Pupal weight and adult size were lower whenA. ludenslarvae developed in guava (conditional host that was artificially infested) and peach, a lower ranked host compared with ‘Marsh’ grapefruit, white sapote, and ‘Manila’ mango (three preferred hosts). Larvae reared in ‘Manzano’ pepper, a low-ranked host, performed better than in peach and guava. Results testing the IPH, show that polyphagousA. ludensfemales were less accurate when discerning between a non natural host (guava) when compared with a preferred, natural host (grapefruit): error rate was significantly higher, number of oviposited fruit in a 6-h period was extremely low, time searching and ovipositing took longer, and pupae recovery was extremely low. Our findings indicate that both hypotheses tested are complementary and help better understand host use byA. ludens. However, we also discuss the complexity of polyphagy considering other factors such as plant resistance/defence mechanisms which are not fully addressed in both theories tested.

Anastepha ludens(Diptera: Tephritidae) is a highly polyphagous fruit fly that is able to develop in a wide range of hosts. Understanding the limits of this pest's host range could provide valuable information for pest management and plant breeding for pest resistance. Previous studies have shown that guavas (Psidium guajava(Myrtaceae) L.), are not attacked under natural conditions byA. ludens. To understand this phenomenon, guavas were exposed to natural infestation byA. ludensand to other fruit fly species that infest guavas in nature (Anastrepha striataSchiner,Anastepha fraterculus(Wiedemann),Anastepha obliqua(Macquart)). Once the susceptible phenological stage of guavas was determined, fruit infestation levels were compared betweenA. ludensandA. striata. Choice and non-choice tests were performed under field-cage conditions. Under field conditions, guavas were susceptible toA. striataandA. fraterculusattack all the way from when fruit was undeveloped to when fruit began to ripen. No infestation byA. ludenswas recorded under natural conditions. Similar results were obtained when forced exposures were performed, indicating that unripe guavas were preferred byA. striataover ripe fruit, and that infestation rates were higher at early fruit maturity stages. Under forced oviposition conditions,A. ludenslarvae were unable to develop in unripe guavas but did so in fully ripe fruit. However,A. ludensfitness parameters were dramatically affected, exhibiting reduced survival and reduced pupal weight compared to conspecifics that developed in a natural host, grapefruit. We confirm thatP. guajavashould not be treated as a natural host of this pestiferous species, and suggest that both behavioral aspects and the fact that larvae are unable to adequately develop in this fruit, indeed represent clear limits toA. ludens's broad host range.

We describe the daily activity patterns of resting, feeding, oviposition and mating of adult Rhagoletis turpiniae Hernández (Diptera: Tephritidae), a recently described fruit fly species from Mexico that inhabits both tropical evergreen rain and temperate cloud forests. We also compare certain mating behaviors of R. turpiniae,R. pomonella (Walsh) and R. zoqui Bush. Studies were performed under natural, field-cage and laboratory conditions. In natural settings, i.e., trees of Turpinia insignis (H. B. & K.) Tul. (Staphyleaceae) significantly more males (n = 1,059) than females (n = 178) were observed, mostly on the lower part of the host fruit (because flies were not marked, these numbers likely include resightings of the same individual over time). Only a few adults (1.13%) were observed feeding in the host plant. Of the 70 ovipositions observed, 88.9% were recorded in unripe fruits, and 11.1% took place in semiripe or ripe fruits. Greatest oviposition activity (egglaying and aculeus-dragging behavior) was observed between 1000 and 1100 hours. There was a significant positive correlation between fruit size and number of larvae in a fruit. The greatest proportion of matings (n = 89) occurred between 1100 and 1600 hours and took place on the fruit. Mean copulation duration under natural conditions was 41.78 ± 1.77 min. Studies carried out in field cages and under laboratory conditions confirmed that the “resource defense polygyny” mating system characteristic of other Rhagoletis species is also present in R. turpiniae. Under highly artificial laboratory conditions R. turpiniae females mated, on average, 10.47 ± 0.4 times, whereas R. pomonella and R. zoqui females mated, on average, 4.17 ± 0.6 and 1.61 ± 0.3 times, respectively. The maximum number of matings of a single female in one observation day was 15, 14, and 5 in R. turpiniae, R. pomonella and R. zoqui, respectively.

Biological control of the Mexican fruit fly, Anastrepha ludens, is mainly carried out by releasing parasitoids, such as Diachasmimorpha longicaudata, and by applying entomopathogenic fungi (EPF), such as Metarhizium anisopliae, Beauveria bassiana, or Isaria fumosorosea, which can be applied to the soil or dispersed using infective devices. The combined use of two or more biocontrol agents could improve A. ludens control, but IGP between natural enemies, if it occurs, may have negative effects. We evaluated the effects of EPF on D. longicaudata. First, we determined the susceptibility of adults of D. longicaudata to strains of EPF (Metarhizium robertsii strain V3-160 and M. anisopliae strain MAAP1). We also evaluated the infection of these two fungi on A. ludens larvae parasitized by D. longicaudata. Finally, we determined sub-lethal effects on adults of D. longicaudata that emerged from larvae that had been exposed to low concentrations of M. robertsii. Both fungi caused moderate mortality to D. longicaudata adults. There were no adverse effects on the longevity of parasitoids that emerged from parasitized larvae exposed to M. robertsii. Based on these results, we argue that M. robertsii has the potential to be used for biocontrol of A. ludens, with limited risk to D. longicaudata adults.