Category: Manduca_sexta

Manduca Sexta Pupa Mass Data

8/7/2017

After all of our Carolina sphinx (Manduca sexta) larvae pupated, we collected pupae mass data.

Yesterday, the last of the larvae pupated so we collected all of them in a single container and sexed them. As always with lepidoptera pupae, a simple examination of the sex mark at the ventral rear reliably distinguished the sexes. Typical of Sphingidae pupae, the female pupae's fourth and fifth abdominal segments after the wings are somewhat fused, with a long slit cutting through them, while the male's have clean, well defined fourth and fifth segments with a short slit inside of a circle on the latter segment.

After sexing the pupae, we recorded each of their masses. There are 23 in total, 14 female and 9 male. Their masses are as follows:
Female - 3.16, 4.02, 4.11, 4.19, 4.27, 4.47, 4.64, 4.81, 4.91, 4.93, 5.04, 5.08, 5.16, 5.60
Male - 3.59, 3.70, 3.73, 3.83, 3.88, 4.03, 4.12, 4.20, 5.12

The the data set is quite small, especially if examining just one sex, we still went ahead and did some basic statistics and generated a histogram stacked by sex.
Summary Statistics for Manduca sexta Pupa Mass
Mean Std Dev Median Min Max N
Male 4.022222222 0.4581969494 3.88 3.59 5.12 9
Female 4.599285714 0.615960342 4.725 3.16 5.6 14
All 4.373478261 0.6192415353 4.2 3.16 5.6 23

Like always, it comes to no surprise that the female pupae are larger than the male pupae. A quick t-test for the difference of means between male and female pupae supported this (t = 2.407, df = 21, p=0.025 ). The histogram appears to be symmetric but bimodal, with males on the left and females on the right. However, one can't help but notice the rather unusual 3.16 g female all the way on the left, far from the other female masses. Though not a outlier by statistical means, it is very strange for a female to be this small and be the minimum of the data set. The variability in the masses is simply very great which we often see with large species such as this one. It could also be possible that the 3.16 female received injuries at some point as a larva, perhaps on the legs, which reduced its size. We never kept record though.

Authors
Alan Liang

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Manduca sexta Rearing Notes (7/27/17-8/6/17)

8/6/2017

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Rearing notes for our Carolina sphinx (Manduca sexta) larvae. Stock originated as eggs, June 2017

Rearing Notes 7/27/17-8/6/17:

8/6:

See Manduca sexta Pupa Mass Data

8/5:

The final prepupa pupated and is male; there are 23 pupae in total, 14 female and 9 male

8/4:

Three more pupated, two male and one female

8/3:

Six more pupated and are surprisingly all female

8/2:

Five more pupated - three male, two female, all in good condition

8/1:

Two more pupated, a male and a female; the male had a bent proboscis and slightly flattened wings due to lying flat on its ventral side while still soft, but the female is in perfect shape and is the largest one yet

7/31:

Three more pupated, one male and two females; we observed one right after pupation and its proboscis had not yet elongated yet and thus was a small stub

7/30:

One of the prepupa pupated and is a 3.9 g male; this time it is in perfect condition, perhaps because we took it out of the soil

7/29:

Several pupae had wriggled back to the surface when we opened the tub today so it is definitely too crowded in there; we decided to pour out the soil and recollect all the prepupae in a new tub with paper towels and tissue paper to pupate in
There was only one new pupa in the soil but if was badly deformed; it was a male and would have been larger than the first one

7/28:

Unusually, three prepupae that had already burrowed crawled back near the surface and are lying immobile in shallow holes; perhaps there was no room in the deeper soil due to all the prepupae already there
Two more larvae became prepupae

7/27:

The first prepupa pupated but unfortunately has a slightly bend proboscis, and has mud fused into the legs (unwashable) most likely from lying with its ventral side in the soil; it is a male and is moderately sized at 3.9 g, though many incoming pupae will likely be much larger
The pupa has a typical sphinx appearance, with the very elongated shape, tapered and pointed abdomen, and a long, unfused proboscis; it is a shiny red-brown and is very smooth
One more larva became a prepupa

Authors
Alan Liang

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Manduca sexta Rearing Notes (7/21/17-7/26/17)

7/26/2017

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Rearing notes for our Carolina sphinx (Manduca sexta) larvae. Stock originated as eggs, June 2017

Rearing Notes 7/21/17-7/26/17:

7/26:

The dug up prepupa has become brownish and very soft, likely very close to pupation
Five more larvae became prepupae

7/25:

Seven more larvae became prepupa and burrowed; many were quite large, still in the 10 or 9 g range prior to burrowing
The prepupa we dug up looks more or less the same as before; it takes a long time for larvae of this size to pupate

7/24:

Three more larvae became prepupa, this time quite large in the 8 and 9 g range prior to burrowing
The remaining fifth instars are becoming quite large, with the largest at 11.9 g and a few others in the 10 and 11 g range
The very first prepupa that we dug up dulled in color and become a dirtier yellower

7/23:

Three more larvae became prepupae; unlike the ones before, the prepupae today turned quite brownish, one even somewhat purplish; they weighed in the 7 g range before burrowing
As it has been two days since the first prepupa burrowed, we decided to dig it up to see if it had created a chamber, and surprisingly, it had not done anything special at all, just like the ophthalmica prepupae we put in soil - it was just lying immobile and covered completely in soil; perhaps the soil was too loose for it to really work with it as it is very loose potting soil; it has become a brownish yellow color and has shrunk significantly, only weighing a mere 4.4
The rest of the fifth instar larvae are still feeding voraciously away at the last scraps we can pick from our tomato plants; being indoors definitely seems to increase the size of the larvae as with most other species we have reared; the largest is already at 11.7 and many others are in the 9 g range

7/22:

The larvae had stripped everything in their sleeves this morning and we would've resleeved them but the plants were becoming quite defoliated so it was difficult to find places to do so; instead, we resorted to taking most of the larvae back inside and placing them in a large tub; at first we went out and got some groundcherry cuttings (Physalis peruviana), another known host in Solanaceae, but they seemed reluctant to feed on it as the leaves were thick and dense in trichomes, so instead we scrapped up some tomato leaves and fruit from our own plans; we'll keep them there until they all become prepupae which should be quite soon by now
Most of the larvae are in the 8-9 g range, with one that weighed 10.8 g this morning but dropped back down to 9.8 g after producing watery tomatoe frass - a single excretion can decrease the larvae's weigh by as much as 0.3 g, so we can see why their weights keep fluctuating!
One of the larvae became a prepupae, turning slightly yellowish brown with a very visible pulse; we placed it in the tub of soil with the one from yesterday

7/21:

Well that certainly was fast - though most larvae are still feeding away at the tomatoes, one of the larvae has become a stubby, brownish prepupa, dropping to 7.2 g (probably peaked around 8-9 g as a larva which is likely not impressive for this species, though admittedly, rearing was not as good as it could've been so far as larvae constantly starved for several hours everyday in their early instars after finishing their food due to underestimation of their appetite)
To test if the pepupa was ready for soil, we placed it on the ground and sure enough it began to burrow, so we took it in, filled a tub with soil, and let it due it in there; it is a very powerful digger, burrowing very quickly presumably just with its mandibles and thoracic legs; we could have just had it pupate in a tub full of paper towels which usually works no problem with most earth pupators, but we wanted to actually see it burrow and, if we remember correctly from when we last reared this back in 2009, create a solid earthen chamber somewhat like an eggshell

Authors
Alan Liang

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Manduca sexta L5 Rearing Notes (7/13/17-7/21/17)

7/20/2017

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Rearing notes for our Carolina sphinx (Manduca sexta) fifth instar larvae. Stock originated as eggs, June 2017

Rearing Notes 7/13/17-7/20/17:

7/20:

Many of the larvae have become huge, having fed almost exclusively on tomatoes; the largest is at 9.3 g
The larva that was largest yesterday at 8.4 g has dropped to 7.9 g and we are wondering if it is going to become a prepupa or if the mass is simply fluctuating a lot due to feeding on tomato, which may have inflated the larva greatly shortly after feeding due to high water content; we notice the larvae produce frass excessively after feeding on tomato and it is very runny which could drop the larva's mass back down a bit after inflating which may explain the fluctuation?

7/19:

The larvae are extremely large now; largest at 8.4 g
Several have been feeding exclusively on fruit all day, easily biting through the tough rinds and seeds with their sharp mandibles, making loud cutting noises

7/18:

The larvae continue to feed voraciously on both leaves and fruit; the largest has reached 7.1 g

7/17:

Somewhat hectic resleeving today as many larvae were starving when we checked on them; hopefully it didn't damage their growth too much
The largest larvae are at 5.8 and 5.7 g and probably still have quite a bit to grow based on how few days they have been in the instar

7/16:

The larvae are quite massive, with the largest already at 3.8 g after just a few days in this instar; they consistently feed on tomatoes every day; their frass is yellow and moist after feeding on tomatoes

7/15:

The larvae are voracious as ever, at least two to three times the size they were when first molted; the markings and stripes are becoming larger and spread out due to the stretching of the cuticle

7/14:

The fifth instars are voracious and growing rapidly, becoming plump and smooth; there seems to be a preference for the tomato fruit when it gets very hot perhaps because larvae are dehydrated and the fruit has high water content; when a particular larva feeds on tomato, it feeds much more than it would have if had it been leaf and ends up quickly surpassing the other larvae in size
Unfortunately, we have always had a serious problem with European paper wasps (Polistes dominula) killing larvae around here and today when resleeving some larvae, an unfortunate fifth instar was quickly attacked by wasps and shredded to bits; the wasps tore chunks of the larva's flesh and rolled it into balls and carried it away in their mandibles

7/13:

Two larvae molted into fifth instar, having spent a short six days in fourth instar
The fifth instar is similar in appearance to the fourth instar, though the transverse white stripes and black markings have become more extensive and the spiracular rings are large and bright red; one of the larva is much more melanic than the other, with much more extensive black markings

Authors
Alan Liang

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Manduca sexta L4 Rearing Notes (7/7/17-7/12/17)

7/12/2017

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Rearing notes for our Carolina sphinx (Manduca sexta) fourth instar larvae. Stock originated as eggs, June 2017

Rearing Notes 7/7/17-7/12/17:

7/12:

The oldest larvae are still in apolysis; a few more joined them
Finished sleeving all larvae outside as they are now all fourths

7/11:

The first few larvae entered apolysis and have very taut cuticles; they are really quite large, at 40 mm and 1.3 g

7/10:

Larvae fed voraciously today, quickly devouring all the leaves clean off the stems enclosed by the sleeve and proceeding to eat the unripe green tomatoes; feeding on all parts of the plant (flower, fruit, etc., not just leaves) actually doesn't seem very common among Lepidoptera, but these larvae have probably adapting to doing so due to their strong specialization in the Solanaceae, which are mostly smaller plants that likely become completely defoliated often in the wild by the large, voracious larvae which have thus adapted to feeding on the fruit

7/9:

Due to the increased size and appetite of the larvae, we have begun sleeving all the fourth instars outside on live tomato plants; so far they are doing very well
As larvae become larger, it is apparent there are two color forms - one bluish green dorsally, and the other yellowish green - the same color forms commonly seen in many other Sphinginae and Smerinthinae

7/8:

The larvae have grown with incredible speed, becoming very plump and vibrantly colored once again; they are beginning to go through cuttings very quickly, stripping the leaves clean

7/7:

The first few larvae molted into fourth instar, having spent a shockingly short four days in third instar
The fourth instar's appearance resembles that of the previous instar, though the diagonal white stripes are very distinct now, and is lined with varying amounts of black and blue; also, the horn is thicker and brighter red, spiracular rings on some individuals are red, there are black stripes in the shape of triangles on the dorsal side, and the thoracic legs are striped in white and black

Authors
Alan Liang

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Manduca sexta L3 Rearing Notes (7/3/17-7/6/17)

7/6/2017

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Rearing notes for our Carolina sphinx (Manduca sexta) third instar larvae. Stock originated as eggs, June 2017.

Rearing Notes 7/3/17-7/6/17:

7/6:

Several larvae are preparing to molt to fourth instar now and measure 20 mm

7/5:

The larvae are have at least doubled in size, feeding very frequently, even on tomato flowers
These larvae seem to have a high volume of frass for how much they eat compared to other larvae we have seen, and it is very moist and appears to be well digested
The white stripes on the larvae are becoming more defined and have blue and black outlining

7/4:

Larvae are growing extremely quickly, already becoming plumper with tighter, smoother, cuticles

7/3:

Several of the larvae molted into third instar after spending a short four days in second instar
The third instar appearance is quite different from the second instar and resembles the mature larva much more, with white stripes lined with black and a thicker, red horn that is curved back; the cuticle has also become very granulated

Authors
Alan Liang

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Manduca sexta L2 Rearing Notes (6/29/17-7/2/17)

7/2/2017

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Rearing notes for our Carolina sphinx (Manduca sexta) second instar larvae. Stock originated as eggs, June 2017.

Rearing Notes 6/29/17-7/2/17:

7/2:

It's quite shocking how quickly these grew; only a few days after molting into second instar, many are already ready for third; they measure 15 mm in length, having a very elongated body shape; the transverse white stripes for the next instar can already be seen surfacing on their cuticle

7/1:

Larvae are constantly feeding and have really blown up like balloons, having very soft, elastic cuticles that just stretch and stretch as they grow
At rest, larvae are sometimes seen in typical "sphinx" pose, having their front pair(s) of prolegs loosely or unattached to the plant and their head slightly curled in

6/30:

The larvae are eating much more than the previous instar and are growing quickly, already much larger and greener than when first molted

6/29:

Several larvae have molted into second instar after spending a short four days in first instar
The second instar has a similar appearance to the last instar, but is much smoother and darker green; the head is also rounder and much larger; they superficially resembles many other young Sphingid larvae, such as first instar Smerinthus ophthalmica

Authors
Alan Liang

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Manduca sexta L1 Rearing Notes (6/25/17-6/28/17)

6/28/2017

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Rearing notes for our Carolina sphinx (Manduca sexta) first instar larvae. Stock originated as eggs, June 2017.

Rearing Notes 6/25/17-6/28/17:

6/28:

And again, a shocking gain in size - they must be several times larger than when they hatched now, measuring 10 mm which is larger than the first instar in many other species
Upon close examination, the larvae's cuticles have become granulated and there are two stripes going lengthwise down the dorsal side

6/27:

The larvae are growing incredibly quickly, much larger than they were yesterday again and greener
These larvae have very soft, thin cuticles, as it is very easy to accidentally injure or squish them unlike other larvae we have reared

6/26:

The larvae have literally doubled in size, perhaps more, since hatching yesterday; they have become green and robust, practically ready for the next instar from the looks; interesting to note, unlike many other larvae that have a habit of feeding from the tip or edges of the leaves, these larvae don't seem to care where they eat, just sticking their mouths anywhere and making holes in the center and sides of the leaves
The remainder of the eggs hatched; though terribly overcrowded, we stuffed all the larvae into two containers with tomato cuttings; hopefully they'll be find at this age

6/25:

See Manduca sexta Eggs Hatch

Authors
Alan Liang

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Manduca sexta Eggs Hatch

6/25/2017

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Our tobacco hornworn (Manduca sexta) eggs have started to hatch.

Even in our cool climate, Manduca sexta eggs must hatch incredibly fast. Today, several dozen of them hatched by the end of the day and the rest of the eggs look pale and clear -- just about ready to pop.

When the larvae first hatch they are completely white, down to the head capsule, legs, and horn. They tan quite quickly, probably in only about 10 minutes, and the horns become black. They measure a tiny 3.5 mm in length.

After they started hatching, we put them in an airtight container with a sprig of tomato (Solanum). Unlike most Saturniids, these things start feeding immediately after putting them on the host. As specialists on herbaceous plants, many of which are cultivated as in the one we used, it is no wonder they are so good at this. It is hard to find a better combination than this for host plant suitability. In fact, they started eating from the center of the leaves; it is much more typical for larvae, especially newborns, to bite from the edges to bypass the leaves' structural defenses such as trichomes. Clearly, they must have very well adapted mandibles for this specific host plant group, which can also explain their small size (larger newborns are usually an adaptation for battling tough host leaves). By the time we put in the newborns that hatched in the evening in, the ones from the morning were already green and noticeably larger. They also should be extremely efficient at converting plant matter to biomass. We expect that they'll be out of here in a few weeks.

Authors
Brian Liang

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Manduca sexta Eggs Arrive

6/23/2017

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Our tobacco hornworm (Manduca sexta) eggs have arrived.

Although they are now in mass supply for pet feeder or research purposes and are probably quick on their way to domestication, Manduca sexta is objectively still an interesting species. Certainly no less interesting than many of the Manduca or other Sphingini, a tribe that we still have not reared any representatives of yet.

We bought a lot of 50 eggs online, but they clearly were in overstock because we received well over a hundred. We have a few very large, healthy tomato plants (Solanum) but it is quite doubtful that we will be able to sustain so many larvae by the time they grow big. Not to mention, certain people would probably not be happy with the destruction of these plants. . . But I suppose we will deal with that when the time comes.

The eggs were in various stages of development when we received them. Presumably, they are a clear blue-green when first laid, but some of ours were already discolored and some had blue dots at the end that is the larvae's heads. These types of Sphingini eggs are known to hatch incredibly fast so its lucky that they survived the trip. Then again, we have consistently observed significantly longer development times in the species we have reared because the summer weather here is dreadfully cold.

For how large the caterpillars allegedly grow, the eggs are miniscule. They look smaller than most everything that we have reared.

Authors
Brian Liang

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