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Fruit flies (Diptera: Tephritidae) are serious pests that affect fruit production and marketing. Both third instar larvae and pupae are biological stages that persist in the soil until adult emergence. Entomopathogenic nematodes (ENs) are biological control agents that are used to control agricultural pests in greenhouse or field conditions. Several studies have been carried out under laboratory and field conditions showing how ENs can be applied within an area-wide integrated pest management approach to control fruit fly species in orchards and backyard fruit trees. In this review, we analyze how soil physical characteristics and biotic factors affect the performance of these biological control agents. Of the reviewed papers, more than half evaluated the influence of soil texture, humidity, temperature, and other factors on the performance of infective juveniles (IJs). Abiotic factors that significantly influence the performance of IJs are temperature, humidity, and texture. Among the biotic factors that affect IJs are fungi, bacteria, mites, insects, and earthworms. We conclude that ENs have the potential to be applied in the drip area of fruit trees that are infested by fruit flies and contribute to their suppression. This approach, in conjunction with an area-wide pest management approach, may contribute to pest suppression and increase the sustainability of agroecosystems.

The sterile insect technique (SIT) is a key element for the integrated management of pest populations of the Mexican fruit fly, Anastrepha ludens , in Mexico. Its success depends on the survival of mass-reared sterile males and their ability to mate with wild females. However, colonization and mass-rearing conditions can adversely affect their ability to avoid predators. To test if colony management strategies could contribute to improve field survival abilities of mass-reared flies, we compared the survival of males exposed to the orb-weaver spider Argiope argentata. Males compared originated from three strains with different colonization strategies: (a) a colony started from field-collected wild flies (replacement), (b) a colony started by hybridizing wild males with mass-reared adapted females (hybrid) and (c) a colony started with mass-reared males selected on the basis of their survival ability and mating competitiveness in field cages (selected). Mass-reared males and wild males were used as controls. Males were exposed to spiders under laboratory cage conditions. Overall, wild males showed better survival ability than mass-reared males. Regarding the colonization approach, wild males survived better than a hybrid, replaced and selected males. We conclude that mass-rearing conditions have a strong negative effect on the ability of males to escape spiders. The colonization systems evaluated did not counter this effect. The lower survival of males from the selected colony suggests that the selection over one generation did not contribute to improve males' predator avoidance and escape abilities and probably needs to be modified. Possible explanations for this and implications on colonization and colony management for SIT purpose are discussed. [ABSTRACT FROM AUTHOR]

The sexual performance of Anastrepha ludens males of the Tapachula-7 genetic sexing strain, produced via selection based on mating success, was compared with that of males produced without selection in competition with wild males. Mating competition, development time, survival, mass-rearing quality parameters and pheromone production were compared. The results showed that selection based on mating competitiveness significantly improved the sexual performance of offspring. Development time, survival of larvae, pupae and adults, and weights of larvae and pupae increased with each selection cycle. Differences in the relative quantity of the pheromone compounds (Z)-3-nonenol and anastrephin were observed when comparing the parental males with the F4 and wild males. The implications of this colony management method on the sterile insect technique are discussed. [ABSTRACT FROM PUBLISHER]

Fopius arisanus is a solitary egg–pupal endoparasitoid that attacks several species of tephritid fruit flies, particularly Bactrocera spp. This species, indigenous from the Indo-Australian region, was introduced into Mexico for biological control purposes. From the standpoint of the ‘new associations’ concept this parasitoid has been evaluated against fruit flies in the Anastrepha complex. We investigated the specificity of F. arisanus responses to fruits infested with two species of Anastrepha. We examined whether fruit volatiles attractive to this parasitoid are induced as a result of fruit fly oviposition. We also investigated whether F. arisanus females are able to discriminate between the oviposition-induced volatiles from host eggs parasitised by conspecifics and volatiles from unparasitised eggs. All experiments were performed in a wind tunnel. Results showed that mango fruits infested with A. ludens eggs (2–3 days after egg deposition) were significantly more attractive to naïve F. arisanus females compared with non-infested fruits or fruits infested with larvae. In addition, guava fruits harbouring A. striata eggs were significantly more attractive to the parasitoid than non-infested fruits or fruits infested with larvae. Thus, the parasitoid was attracted to fruits with eggs, but fruit and fly species did not influence the parasitoid attraction. We also found that F. arisanus females were more attracted to fruits exposed to fertile A. ludens females (i.e. fruits with eggs inside) compared with fruits exposed to sterile females (i.e. fruits with no eggs inside) or fruits with mechanical damage. Parasitoid females were not attracted to A. ludens eggs. The results suggest that the presence of eggs induces volatiles that attract parasitoids. Finally, we found that F. arisanus was able to discriminate between fruits with unparasitised eggs vs. eggs parasitised by conspecifics, indicating that host discrimination could be mediated by olfactory cues. [ABSTRACT FROM PUBLISHER]

Field cage tests were carried out to determine the sexual competitiveness, copulation duration and sperm transfer of sterile and wild Mexican fruit fly, Anastrepha ludens (Loew), males that were treated or not treated with Beauveria bassiana (Balsamo) Vuillemin conidia immediately before mating tests. No significant differences in sexual competitiveness were found between untreated sterile males and sterile males treated with conidia, indicating that the presence of conidia did not significantly reduce mating performance. However, both types of sterile males were less competitive than wild untreated males. There were no significant differences in copulation duration and the quantity of sperm transferred between the two groups of sterile males. A positive correlation was found between copulation duration and the quantity of sperm transferred. The four treatments exhibited significant differences regarding the quantity of transferred spermatozoids stored in the spermathecae but there were no differences in the percentages of total sperm stored in each spermatheca. Our results support the idea of using sterile flies as vectors of B. bassiana conidia in controlling fruit fly populations, while, at the same time, reducing the exposure of and harmful effects on non-target organisms. [ABSTRACT FROM AUTHOR]

Water availability is recognized as one of the most important factors in the distribution and activity of terrestrial organisms. In the case of insects, hydric stress imposes a major challenge for survival because of the small surface-area-to-volume ratio they exhibit. In general, stress resistance is expected to co-vary positively with size; however, this pattern can become obscured in insects that exhibit sexual size dimorphism, as sexes differ in size and/or shape and have dissimilar resource allocations. In the present study, we use an allometric-based approach to (i) assess the desiccation and starvation stress resistance of teneral Anastrepha ludens flies, (ii) disentangle the relationships between resistance, size and sex and (iii) examine the adult fly body differences in water and lipid contents before and after exposure to stress. After controlling for sexual size dimorphism, an allometric increase of resistance with overall size was observed for all stress-based treatments. The scaling exponents that define the proportion of increase resistance varied with size traits and with type and degree of hydric stress. In this allometric relationship, and also in the relationships between mass and wing length and between size and teneral resources, the sexes maintained similar scaling exponents but differed in the intercepts. Males were more resistant to stress than females; this competitive advantage is probably linked to greater amounts of teneral lipids and more water use during stress. [ABSTRACT FROM AUTHOR]