Pheropsophus aequinoctialis
Creators: name: Frank, Howard
name: Erwin, Terry
name: Hemenway, Robert
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Carabidae
Pheropsophus
Pheropsophus aequinoctialis

description: <i>Pheropsophus aequinoctialis</i> (Linné) <b> <b>EGG</b> (Fig. 15). White. Rectangulate with moderately rounded apices. Surface polygonic, with numerous very close-spaced large perforations; micropore not obvious.</b> <b> <b>INSTAR</b> <b>I. Form.</b> (Fig. 16) Campodeiform planidium; head relatively small compared to prothorax, eyes absent. Frontale with three simple-tooth egg-bursters near base of head on frontale. Body setiferous dorsally, less so than in <i>Stenaptinus</i> (see above). Segment X (PY): sternite (Figs. 16, 24) medially with two widely spaced non-serrated recurved teeth and with seta PY7 normal. Urogomphi (cf. Fig. 16) absent.</b> <b>Coloration.</b> Mostly white color with creamy-colored head capsule and slightly rufescent mandibles darkened toward the tips. <b>Chaetotaxy.</b> <i>Head</i>. (Figs. 16, 17, 18) Frontale (Fig. 17) with 9 “ancestral” setae (FR1 – FR9, FR10 and 11 missing), and one auxiliary seta each side, and 2 pores (FRd <b>–</b> FRe, a, c, and f missing) left side, right side devoid of pores in specimen illustrated. Parietale (Figs. 16, 17) with 18 setae (PA1 – PA18) and 8 pores (PAa – PAl; pores d, f, g, h absent) each side. Antenna (Figs. 16, 17): antennomere 1 with 5 “ancestral” pores (ANa – ANe) and one auxillary pore (unlabeled); antennomere 2 absent or fused with 3; antennomere 3 with 3 “ancestral” setae (AN1 – AN3), one auxillary seta, and 1 pore (ANf), plus a dome-shaped hyaline sensillum; antennomere 4 with 4 setae (AN4 – AN7) and 1 auxillary seta, no pores, and 2 small apical sensilla. Mandible (Fig. 17) falciform without setae and pores. Labium (Fig. 18): prementum with 1 seta (LA3) and 1 pore (LAa) each side; palpomere 1 with 1 seta and 3 pores, none of which correspond to the “ancestral” schema; palpomere 2 with 1 apical sensillum. Maxilla (Fig. 18): cardo without setae; stipes with 5 “ancestoral” setae (MX 1 – MX 5), and 2 pores (MXa – MXb), and no variable setae (gMX) on dorsal side; lacinia (Fig. 18) with 1 seta (MX 10); galeomere 1 with 1 seta (MX 7) and no pores; galeomere 2 with 2 minute dorsal setae, no pores; maxillary palpomeres without visible sensatory features. <i>Thorax</i>. <i>Prothorax</i>: Notum (Figs. 16, 19) with 1 identifiable major “ancestral” seta (PR 9) and numerous auxiliary setae (not labeled), PR 1 absent, and no pores. Epimeron (Fig. 20) with 1 seta (EP1), and no pores. Episternum and trochantin not defined. Prosternite (Fig. 20) with 1 seta “ancestral” (Pt1) and one auxiliary seta; gPS absent. <i>Mesothorax</i> and <i>metathorax</i>: Notum (Figs. 16, 19, 20) with 1 identifiable major “ancestral” seta (PR 9) and numerous auxiliary setae (not labeled), PR 1 absent, and no pores. Mesepisternum (Fig. 20) with 2 setae (ES1, ES2) and no pores. Trochantin and epimeron not defined. Mesoprosterite (Fig. 20) with 3 setae (Pt1, Pt2, Pt3) each side; metaprosternite with 3 setae (Pt1, Pt2, Pt3). Metepisternum with 3 setae (ES1, ES2, ES4). <i>Abdomen</i>. Figs. 16, 21 -24. Tergite I (Figs. 16, 21) with possibly one “ancestral” seta (TE2) and numerous auxiliary setae (not labeled), and no pores. Tergites II – VIII as in Tergite 1. Tergite IX, X and urogomphi (Figs. 16, 23), IX with 4 setae (UR8 – UR11) and no pores. Epipleurite IX (Fig. 16) with 2 setae (EP1 – EP2) and no pores. Hypopleurite VII (Fig. 16) with 2 setae (HY1 – HY2) and no pores. Segment VII sternite (Fig. 24) with 5 setae (ST1 – ST5) each side and no pores. Segment IX sternite (Fig. 24) with 3 setae (ST1 – ST3) each side and no pores. Segment X (PY) sternite (Figs. 16, 24) with 1 seta (ST1) each side, no pores. Medially with two wide-spaced nonserrated and recurved teeth (Figs. 16, 24). <i>Legs</i>. (Fig. 25) All legs stout, similar in proportions and setation; anterior leg slightly shorter than middle and posterior ones. Coxa with 7 setae (ancestral CO10 – CO17, with CO1-9 absent, and no pores. Trochanter with 5 setae (TR2 – TR5, and TR8) and one pore. Femur with 4 setae (FE2 – FE5) and no pores FEa and FEb. Tibia with 7 setae (TI1 – TI7) and no pores. Tarsus with 1 constant seta (TA1) and no pores. Claws simple, with no setae or tooth, symmetrical in shape and size. <b> <b>INSTAR</b> <b>II. Form.</b> (generally as in Fig. 35) Hypermetamorphic stage 2 instar.</b> <b>Coloration.</b> White; head capsule creamy-white with mouthparts slightly infuscated in part; mandibles piceous at tips. <b>Chaetotaxy.</b> <i>Head</i>. (Figs. 26-27) Frontale (Fig. 26) with 7 “ancestral” setae (FR1 – FR7), and no pores. Parietale (Figs. 26, 27) with 12 setae (PA3, PA5– PA7, PA9, PA11 – PA13, PA15 and PA17) and no pores. Antenna (Figs. 26): antennomere 1 with one “ancestral” seta (AN1) and no pores. Dome-shaped hyaline sensillum absent. Mandible (Fig. 26) falciform without setae and pores. Labium (Fig. 27) without setae or pores. Maxilla (Fig. 27): cardo without setae; stipes with 3 “ancestral” setae (MX 3 – MX 5), and no pores, nor variable setae (gMX) on dorsal side; lacinia (Fig. 27) without setae; galeomere without setae; palpomere 1 and 2 without setae, palpomere 3 with 2 minute apical setae, no pores. <i>Thorax. Prothorax</i>: Figs. 28-29. Notum (Fig. 28) with 12 major “ancestral” setae (PR 2 – PR 4, PR 6 – PR 14) and numerous auxiliary setae (not labeled), and no pores on each side. Epimeron, episternum, and trochantin not defined. Prosternite (Fig. 29) with a ring of auxiliary setae, gPS absent. <i>Mesothorax</i> and <i>metathorax</i>: Figs. 28-29. Mesonotum (Fig. 28) with 9 “ancestral” setae (ME1 – ME2, ME8 – ME14), and no pores on each side. Mesepisternum (Fig. 28) with 1 seta (PL1) and no pores. Trochantin and epimeron not defined. Sternum (Fig. 29) with 9 setae (unlabeled) in a median rosette. Metanotum (Fig. 28) with 5 “ancestral” setae (MT2, MT7 – MT9, MT12), and no pores on each side. Metepisternum (Fig. 29) with 5 setae (unlabeled) and no pores. Trochantin and epimeron not defined. Sternum (Fig. 29) with 14 setae (unlabeled) in a median rosette. <i>Abdomen.</i> Figs. 30-34. Tergite I (Fig. 30) with 11 “ancestral” setae (TE1 – TE11) and 5 auxiliary setae (not labeled), and no pores each side.Tergites II – VIII as in Tergite 1 with numerous auxiliary setae. Sternum with numerous setiferous rosettes. Tergite IX, X and urogomphi (Fig. 32), all with numerous setae in raised rosettes or on raised lobes, and no pores. Epipleurites (Fig. 33) with numerous setae and no pores. Hypopleurite not defined. Segment VII sternite (Fig. 33) with numerous setae in rosettes and no pores. Segments VIII and IX with numerous setae (not in rosettes) each side and no pores. Segment X (PY) sternite (Fig. 33, 34) with numerous auxiliary setae in apical 2/3 rd, with no pores. <i>Legs.</i> As in Fig. 35; reduced size and setation compared to instar I. <b> <b>INSTAR</b> <b>III. Form.</b> (Fig. 35) Hypermetamorphic stage 3 instar.</b> <b>Coloration.</b> White; head capsule creamy-white with mouth parts slightly infuscated in part; mandibles piceous at tips. <b>Chaetotaxy.</b> <i>Head</i>. (Figs. 35 -37) Frontale (Fig. 36) with 9 “ancestral” setae (FR1 – FR5, FR7 and FR9) and and no pores each side. Parietale (Figs. 36, 37) with 5 “ancestral” setae (PA4 – PA8) and 3 pores (PAa – Pac) each side. Antenna (Figs. 36, 37): antennomere 3 with 1 seta (unlabeled); antennomere 4 with 3 in an apical ring; the dome-shaped hyaline sensillum absent. Mandible (Fig. 36) falciform without setae and pores. Labium (Fig. 37): prementum with 1 seta (LA5) and no pores each side; labial palpomeres reduced and without vestiture. Maxilla (Fig. 37): cardo with 1ventral seta (ca1); stipes with 5 “ancestral” setae (MX 1 – MX 5), and no pores and no variable setae (gMX) on dorsal side; lacinia and galeomere absent; maxillary palpomeres reduced with palpomere 1 unisetose (pa10) and without other visible sensory features. <i>Thorax</i>. <i>Prothorax</i>: Notum (Figs. 38 – 40) with numerous long setae on front margin and numerous shorter setae posteriorly (not labeled), and no pores on each side. Parietal with 6 “ancestral” setae (PR 2 – PR 4, PR 6, PR 8, PR 14) and numerous auxiliary setae (not labeled), and no pores on each side. Epimeron (Fig. 38) with 5 setae (EP3 – EP4, EP6, EP10 – EP11), and no pores on each side. Episternum and trochantin not defined. Prosternite (Fig. 40) with numerous medial auxiliary setae some in a rosette, gPS absent. <i>Mesothorax</i> and <i>metathorax</i>: Notum (Figs. 38, 39) with 2 long setae medially and 3 shorter setae nearby (not labeled), and no pores on each side. Episternum (Fig. 38) with numerous stout setae and no pores. Epimeron and trochantin not defined. Sternum with rosette of setae medially (Fig. 39). <i>Abdomen</i>. Figs. 41 – 44. Tergite I (Fig. 41) with 2 stout setae medially and numerous shorter auxiliary setae in patches (not labeled), and no pores each side. Tergites II – VIII as in Tergite 1. Tergite IX with 2 stout setae each side and numerous shorter setae nearby. Tergite X (PY) with numerous short apical setae and no pores. Epipleurite IX (Fig. 44) with numerous long and stout setae on raised knob and no pores. Hypopleurite not defined. Segment VII and VIII sternites (Fig. 44) with numerous setae on raised knobs in rosettes each side and no pores. Segment IX sternite (Fig. 44) with subapical band of short setae each side and no pores. Segment X (PY) sternite (Fig. 35, 44) with numerous scattered short setae each side, no pores. <i>Legs</i>. As in Fig. 35; reduced size and setation compared to instar I. <b> <b>PUPA</b> <b>. Form.</b> (Fig. 45) Typical of carabid species. In addition, pygidium with fine short setae and dorsal surface with an array of small tubercules.</b> <b>Notes on advancing an understanding of phylogenetic relationships.</b> Much works still needs to be done in solving to infer the relationships between the Brachininae tribes Crepidogastrini and Brachinini and the subtribes Brachinina, Pheropsophina, and Masticina (Erwin 1970). Here we have added larval traits that will, in part, add information toward a more robust phylogenetic analysis in the future. Immature stages of Crepidogastrini and Masticina are, as yet unknown, and we do not even know whether they are ectoparasitoids, or specialized predators. Likely, they are one or the other, but on what taxa? Larvae of <i>Brachinus</i> develop in 5 instars; they also have 6 eyespots (as in other carabids), whereas Pheropsophina larvae have 3 instars and at most a single eye-spot, usually none. First instar <i>Brachinus</i> have no egg burster and chew their way out of the egg (Erwin 1967); <i>Stenaptinus</i> larvae possess a single-toothed egg burster; those of <i>Pheropsopus</i> have a triple-toothed egg burster. Pheropsophina larvae have pygidial hooks that aid them in attacking mole cricket egg clutches (Habu and Sadanga 1969), whereas <i>Brachinus</i> larvae do not. Larvae of <i>Stenaptinus</i> and <i>Brachinus</i> possess urogomphi whereas those of <i>Pheropsophus</i> do not. Conclusion and discussion Adult <i>P. aequinoctialis</i> and many <i>S. jessoensis</i> burrowed in sand-filled containers in the laboratory. Many <i>S. jessoensis</i> ̴ 91.4%) but few <i>P. aequinoctialis</i> ̴ 16.7%) were active on the surface in daylight. Th is supports field observations that <i>P. aequinoctialis</i> adults are active nocturnally. Very few <i>P. aequinoctialis</i> adults (1.2%) found brown paper towel on the sand surface to be as adequate a refuge as their burrows; perhaps more solid objects (as a result of photoperception or thigmoperception) would have been more acceptable as refuges. In contrast, more <i>S. jessoensis</i> adults (78.7%) sheltered under paper towel in daylight than sheltered in burrows, but most did not shelter at all. Th ere is a clear contrast between the mainly diurnal behavior of <i>S. jessoensis</i> and the mainly nocturnal behavior of <i>P. aequinoctalis</i>. Timing of daily activity will have an effect on ability to find food. All diets presented to these adults were consumed, but we did not observe cannibalism by adults. Larvae of <i>T. ni</i> alone sustained adult <i>S. jessoensis</i> of unknown age for an average 12 months. Earlier authors showed that a broad diet of animal food is acceptable to them, and neither we nor previous authors tested acceptability of plant food alone. A diet of mealworm pupae, oatmeal and raisins was avidly fed upon by adult <i>P. aequinoctialis</i>, and sustained them well, so they will feed on plant food, supporting an observation of feeding upon palm fruits in nature (Reichardt 1971). We did not attempt to produce an optimal diet for adults of either species. Adults of the two species produced many eggs on the diets provided. Females of both species oviposited abundantly on crumpled, moist, brown paper towel under highly artificial conditions. Chemicals produced by eggs or adults of mole crickets are not necessary to stimulate abundant oviposition. However, Weed and Frank (2005) found that more eggs were laid in tunnels excavated by mole crickets than in artificial tunnels, suggesting that perhaps allomones produced by adult mole crickets are detected by female <i>P. aequinoctialis</i> and influence placement of eggs. Adult <i>P. aequinoctalis</i> oviposited in all months of the year; and adult <i>S. jessoensis</i> oviposited in most months of the year in the laboratory. Seasonality of oviposition in the field is mutable under laboratory conditions. We suspect that neonate larvae of both species suffer high mortality because they fail to detect suitable prey and thus die. Although <i>P. aequinoctialis</i> and <i>S. jessoensis</i> are highly fecund, Th iele (1977) gave examples of high fecundity among other carabids without such a specialized life cycle. Fertility of laboratory-produced <i>P. aequinoctialis</i> eggs varied for unknown reasons, at some times being very low. Th e evolutionary consideration is: Why are so many infertile eggs produced? Presence of two species of <i>Wolbachia</i> (Bacteria: Rickettsiae) in our 1992 <i>P. aequinoctialis</i> stock from Bolivia has been demonstrated. A suggested heat-treatment to eliminate the <i>Wolbachia</i> resulted in mortality of some adults, temporarily reduced oviposition, and failed to eliminate production of infertile eggs. Th e heat treatment may, of course, have killed some essential flora in the digestive system. Incubation of fertile eggs of <i>S. jessoensis</i> took 11.4 days and of <i>P. aequinoctialis</i> 13.5 days on average. Most neonate larvae of <i>S. jessoensis</i> and <i>P. aequinoctialis</i> died when presented with mole cricket eggs in Petri dishes. Th ey wandered for days until they died, almost continually in motion. Neonate larvae were presented with alternative diets including <i>A. domesticus</i> and <i>Gryllus</i> sp. eggs, eggs and pieces of larvae of <i>T. ni</i>, intact pupae of <i>T. molitor</i>, and pieces of cucumber. All neonate larvae of both species died when presented with any diet other than mole cricket eggs although imbibition of fluid was observed from pieces of cucumber. However, a few began to feed on mole cricket eggs. Th ose eggs were of <i>Scapteriscus abbreviatus</i>, <i>Sc. borellii</i>, <i>Sc. vicinus</i>, and <i>N. hexadactyla</i>; however, replication was inadequate to determine any differences in survival success between these mole cricket eggs diets. At least it can be stated that <i>S. jessoensis</i> can survive on mole cricket eggs other than those of <i>Gryllotalpa</i>, in contrast to unsupported claims by Habu and Sadanaga (1965, 1969). Once neonate larvae began to feed, their survival to the adult stage on the same diet was highly probable. Perhaps larvae will not begin to feed until they encounter enough eggs to complete their development (Habu and Sadanaga 1965, 1969), but we have no data to support this claim. Faced with the impasse that neonate larvae would seldom develop on a diet of mole cricket eggs in a Petri dish, even when that dish was enclosed totally with aluminum foil to exclude light, we adopted a variant of the rearing method proposed for <i>S. jessoensis</i> by Habu and Sadanaga (1969). Using this method, an artificial mole cricket egg chamber is made in sand in a plastic vial, stocked with 30 mole cricket eggs, covered with sand, and a neonate larva is dropped onto the sand surface. The larva burrows down to enter the chamber and begins feeding on eggs. Th is resulted in high survival of larvae and pupae to the adult stage, and became our standard rearing method. Feeding and development seldom occurred in the more artificial conditions of a small Petri dish with mole cricket eggs piled onto a disc of paper towel, even in the dark, but we ran many feeding trials under those circumstances. Unfortunately, the method of an artificial egg chamber excluded frequent observation. Much later, we found by accident that the artificial egg chamber did not need covering with sand to exclude light. Th en, we conducted more feeding trials and confirmed that <i>Acheta domesticus</i> eggs, <i>Tenebrio molitor</i> pupae, and pieces of cucumber are not acceptable diets.Adult <i>P. aequinoctialis</i> are scavengers and generalist predators. Larvae, however, so far as determined, are specialist predators on mole cricket eggs. Th ey can develop under laboratory conditions on a diet containing only eggs of <i>Scapteriscus abbreviatus</i>, <i>Sc. borellii</i>, <i>Sc. vicinus</i>, or <i>Neocurtilla hexadactyla</i> but none survived using any other diet tried. Proof of restriction of the larval diet still is inadequate. Each larva of the carabid genus <i>Brachinus</i> (<i>Neobrachinus</i>) feeds on only one water beetle pupa and is an ectoparasitoid (Erwin 1967, 1979) replacing its host in a small mud chamber constructed by the water beetle larva. In Europe, <i>Brachinus</i> s. str. larvae feed on the pupal stage of the carabid genus <i>Amara</i> (Saska and Honek 2004). However, each larva of <i>P. aequinoctialis</i> and <i>S. jessoensis</i> requires tens of mole cricket eggs as food to complete its development. Such behavior is more aptly termed predation (Van Driesche and Bellows 1996, p. 21 citing many earlier authors), so we consider <i>Pheropsophus</i> and <i>Stenaptinus</i> larvae to be specialist predators. At no time in our laboratory cultures did more than one <i>P. aequinoctialis</i> or <i>S. jessoensis</i> larva survive long on a single cache of eggs, so we believe they practice fratricide as has been noted in <i>Brachinus</i> (Juliano 1984). Erwin (1967) noted that fratricide did not occur in <i>Brachinus pallidus</i>, rather the first larva that began feeding became the “owner” of the pupa and the other larvae departed in search of another pupa. Th ese larvae, when offered a fresh pupa, developed to the adult stage. <b>Implications for biological control</b> The studies reported above were initiated because of a suspicion by T.L. Erwin that <i>Pheropsophus</i> spp. larvae might, as had been reported for <i>Stenaptinus</i>, develop only on a diet of mole cricket eggs. It was eggs of invasive species of the South American mole cricket genus <i>Scapt</i>
description: Published as part of <i>Frank, Howard, Erwin, Terry &amp; Hemenway, Robert, 2009, Economically Beneficial Ground Beetles. The specialized predators Pheropsophus aequinoctialis (L.) and Stenaptinus jessoensis (Morawitz): Their laboratory behavior and descriptions of immature stages (Coleoptera: Carabidae: Brachininae), pp. 1-36 in ZooKeys 14 (14)</i> on pages 18-34, DOI: 10.3897/zookeys.14.188, http://zenodo.org/record/576469
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