A technique to artificially inseminate leafcutter ants

Abstract

Artificial insemination (AI), the instrumental transfer of semen from the male to female reproductive organs, offers excellent opportunities to study mating system adaptations as it allows paternity to be experimentally manipulated. AI techniques have been developed for many animals, but rarely for ants, where they would be particularly useful as most species do not mate under controlled lab conditions. Here, we describe an AI technique for Atta leafcutter ants involving (1) the collection of ejaculates via induction of natural ejaculation, (2) storage in glass capillaries, and (3) transfer to queens using a modified AI equip ment as used for honeybees. Queens were fixed and anesthetized in a queen holder, after which the sting chamber was opened with two steel hooks, the tip of the semen-containing glass capillary was inserted into the bursa copulatrix and the semen slowly expelled. Sperm was successfully stored in the spermatheca of queens, and some queens produced a small colony as a result. We could furthermore confirm the earlier observations that Atta semen is directly transferred to the spermatheca rather than to the bursa copulatrix as in most other eusocial insects. The technique that we present here can offer novel opportunities to study mating events such as sperm transfer, sperm competition, and cryptic female choice in ants. At present, the number of queens that produce colonies after AI remains low. However, this number will likely increase, as our results indicate that rearing conditions after AI influence colony founding success of artificially inseminated Atta queens.

Rival seminal fluid induces enhanced sperm motility in a polyandrous ant

“…1a ). Ejaculates were obtained by separating the male gasters from their mesosomas and gently increasing pressure from the anterior to the posterior side of the gaster using thumb and forefinger, in a similar way as has been used for larger males of Atta leaf-cutting ants [ 36 , 37 ]. Single 20 μl pipette tips previously loaded with 3 μl Hayes saline containing SYTO 13 (375 μM concentration) were briefly dipped either twice in one of the two individual male ejaculates or sequentially in the two different ejaculates.…”

Advances in the Study of Olfaction in Eusocial Ants

“…Indeed, this method has proven successful across a broad range of insect species [ 123 , 124 , 125 ]. Another approach might be to deliver the CRISPR-Cas9/gRNA complex using transfected sperm, a protocol for which has been successfully developed in birds using a cationic lipid-based chemical transfectant [ 126 ], by artificially inseminating virgin queens [ 127 ].…”

Long‐term sperm storage in eusocial Hymenoptera

“…(C) Schematic representation of the abdomen of a honeybee queen showing the reproductive organs. (D) Schematic representation of the abdomen of an ant queen showing the reproductive organs; the spermathecal gland is not shown (adapted from den Boer et al ., 2013).…”