Abstract
The vast majority of braconid wasps are parasitoids of other insects. Although a few cases of pure phytophagy (primary gall production and seed predation) are known, no previous entomophytophagous species (i.e. ones that display entomophagy and phytophagy sequentially), has been discovered among braconids. We describe the detailed biology and specialized larval morphology for the first confirmed entomophytophagous braconid species. Leaf galls on Garuga pinnata Roxb. (Burseraceae) in India, induced by the psyllid, Phacopteron lentiginosum Buckton (Hemiptera: Psylloidea, Phacopteronidae) were sampled throughout a period of several months and found to suffer a high level of attack by a new species Bracon garugaphagae Ranjith & Quicke which is here described and illustrated. The wasps oviposit singly into the galls without paralysing the psyllids. The larvae first attack psyllid nymphs which they seek out within the gall, kill them with a single bite and consume them. Unique dorsal abdominal tubercles, with eversible tips present on the abdominal segments of the larvae that are used to help maintain larval position while feeding, are illustrated. After consuming all available prey, the larvae continue feeding on gall tissue until mature enough to spin cocoons and pupate. The new species illustrates, for the first time, a possible intermediate stage in the evolution of pure phytophagy within the Braconidae. Interestingly, the two unrelated seed predator Bracon species are also associated with Burseraceae, perhaps indicating that this plant family is particularly suited as a food for braconine wasps.
Highlights
Braconid wasps represent one of the most diversified groups of insects comprising 46 subfamilies with nearly 1000 genera and 15,000 described species, the vast majority of which are parasitoids of other insects [1] and have been extensively used as experimental models of host– parasite associations [2,3,4,5,6,7]
Gall induction in the Doryctinae appears to be phylogenetically associated with parasitism of gall formers, but nothing is known of the transitional stages
Primary gall formation has been demonstrated in the genus Mesostoa (Mesostoinae) [13] whilst purely phytophagous seed predation is known in two Neotropical species of Bracon (Braconinae) [14, 15]
Summary
Braconid wasps represent one of the most diversified groups of insects comprising 46 subfamilies with nearly 1000 genera and 15,000 described species, the vast majority of which are parasitoids of other insects [1] and have been extensively used as experimental models of host– parasite associations [2,3,4,5,6,7]. Members of the Braconinae, which is one of the largest of the subfamilies, are mostly ectoparasitoids that develop on concealed hosts that are usually paralysed as a result of venom injected by the female at the time of oviposition [16] It is dominated by the genus Bracon which has more than 850 described species though molecular data strongly indicate that the genus is paraphyletic and possibly even polyphyletic [17]. Not surprisingly the host range of ‘Bracon’, is by far the largest in the subfamily, and includes Coleoptera, Lepidoptera, Diptera [16], Hemiptera [18] as well as phytophagous Hymenoptera [19,20,21] Almost all of these hosts share a moderate degree of concealment, usually in living plant tissues, and typically include inhabitants of tree bark, stems of annual and biennial plants, galls, seed heads or vessels, as well as leaf rollers, leaf miners and case-bearers [16]
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