Reproductive ecology of phorid parasitoids in relation to the head size of leaf-cutting antsAtta sexdensForel

Abstract

The leaf-cutting ant Atta sexdens Forel (Hymenoptera: Formicidae) is one of the most damaging agricultural pests in the Neotropics. Management strategies predominantly rely on the use of general insecticides. What is needed are more species-specific and environmentally friendly options. Parasitioids such as phorid flies (Diptera: Phoridae) may be one such option, but a greater understanding of the ecology of the flies and their ant hosts is essential to devise biological control strategies. Here we report parasitism rates, ant host size, parasitoid abundance per host and resultant sex ratios of two phorid species Apocephalus attophilus Borgmeier and Eibesfeldtphora tonhascai Brown parasitizing A.sexdens. The two species achieved parasitism rates of 1.48 and 1.46%, respectively and the pupal period was 14.7 ± 1.1 days and 22.1 ± 2.8 days, respectively. There was no significant difference between the head capsule width of ants parasitized by either A. attophilus or E. tonhascai. Likewise, there was no significant effect between the head capsule width of parasitized and unparasitized ants for both species. A significant positive correlation was found between the head capsule width of the parasitized ants and the number of adult parasitoids A. attophilus emerged. Ants parasitized by E. tonhascai survived significantly longer than those parasitized by A. attophilus. There was no significant effect of ant head width on the sex ratio of the offspring of either parasitoid species and no significant difference in the sex ratio (male: female) of their offspring. In summary, these data addressed here are important steps when considering natural enemies for biological control. Studying survival of the parasitized ants, parasitoid offspring sex ratio and host size preference allows for a better understanding of ant natural biological control in the field and can help in rearing of A. attophilus and E. tonhascai in laboratory.

Parasitism, sexual dimorphism and effect of host size on Apocephalus attophilus offspring, a parasitoid of the leaf-cutting ant Atta bisphaerica

“…Ants that died were removed daily, transferred to an individual glass tube (20 × 200 mm) and maintained in the same chamber. After three days, dead ants were observed under stereomicroscope to evaluate if they were parasitized by phorids [31]. Dead ants that had been parasitized could be visually determined by the presence of parasitoid pupae between the jaws, inside the head or outside the host [17,19,31].…”

“…After three days, dead ants were observed under stereomicroscope to evaluate if they were parasitized by phorids [31]. Dead ants that had been parasitized could be visually determined by the presence of parasitoid pupae between the jaws, inside the head or outside the host [17,19,31]. Ants that were still alive 15 days after collection were discarded because they had not been parasitized [31].…”

Seasonal Parasitism of the Leaf-Cutting Ant Atta sexdens Linnaeus (Hymenoptera: Formicidae) by Phorid Flies (Diptera: Phoridae) in a Brazilian Cerrado-Atlantic Forest Ecotone

“…Palavras Chave: parasitoide; pragas; temperatura; umidade; área urbana Phorid flies are small-sized, highly diverse insects, found in Neotropical regions with varying larval lifestyles (Disney 1994). Many species of this family parasitize bees (Core et al 2012), termites (Neoh & Lee 2010), and leaf-cutting ant pests of several crops (Della Lucia et al 2014;Farder-Gomes et al 2016). Leaf-cutting ants are managed principally with insecticidal baits (Zanetti et al 2003;Montoya-Lerma et al 2012).…”

“…Additionally, these parasitoids can reduce plant material transported into the nests and ant traffic on trails (Martinez et al 2014;Guillade & Folgarait 2015). Females of these insects lay an egg into the body of each ant with the larva subsequently feeding on host tissues (Bragança & Medeiros 2006;Farder-Gomes et al 2016). Phorid flies have an evolutionary relationship with host ants, and require them as the only food source for their entire development.…”

Interspecific Eavesdropping on Ant Chemical Communication

“…Phorids can often be observed hovering above disturbed ant nests (Witte et al, 2010), injured workers (Brown and Feener, 1991) and foraging trails (Tonhasca, 1996). Trail and alarm pheromones are reliable cues that likely "advertise" host presence, whereas specific ant targets are selected based on short-range chemical and visual cues (Farder-Gomes et al, 2017). In some cases, CHC profiles confirm species identification for final host acceptance by the attacking flies (Mathis and Tsutsui, 2016) ( Figure 1C, top panel).…”