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locust with diarrhea ?

Hi everyone!

somewhere on the internet I read that locusts can suffer from diarrhea .. They can get it from keeping them too moist or give them too much wet food.

at the moment we have beautiful summer days here in Belgium (you know, a lot of rain....) :)) and the grass that I pick is not always dry when I have to give it to the locusts.

Now for my question: there are a few of my locusts dying and they literally fall apart when you want to take the dead locust away. it also leaves a red mess around everything (blood perhaps?)... normally when a locust die they are very hard and stiff (you throw them away in one piece) but now they are really mushy, they fall apart in pieces and you can just squeeze them empty!

Does anyone know what this can be? can it be diarrhea or is it Serratia marcescens again? ! DSC_0953


  • Hi Zazu, - Protein rich food consumption causes locust to evacuate their intestines; if you normally supplement protein in their diet please advise. Seasonal grasses have different % protein & % cellulose; if you know the name of the grassess you fed before & changed to another grass please advise.

    Dry food is more efficiently digested & the locust respiratory rate is lower. Given a choice between dry & wet food last instars (5th stadium) will eat more from the dry food & then on the last day they'll preferentially take ~97% of their food (based on it's dry matter content) from wet food.

    When they get the chance to eat like this (option to mix & match preference for dry:wet ratios) their growth is more. I don't know for sure, but suspect it may be the case, if in each instar this pattern holds true. There are some reasons, other than the bugs' preferences, laboratory reared locusts are often given grass that is dried & milled; which is related back to the 2nd sentence of this comments lead paragraph.

    At this point my thinking is you are describing 2 different things happening & the wet food itself is not causing those deaths. The red colored fluid from dead locust is not blood, but from a chemical reaction in the insect haemolymph (which is like our lymph & blood combined) that occurs down stream from a problem (elsewhere in Forum described how it turns red).

    Are you rearing migratory locusts, or some other kind?

  • edited July 2016

    When locust infectious agent(s) not involved once whatever protein in a meal capable of being assimilated has been assimilated their gut will empty. What is not well recognized is that the longer it takes for them to assimilate the meal's protein the less (repeat less) carbohydrate is assimilated from that meal.

    Eating annual grass, which is more nutritious, as opposed to perennial grass requires different amounts of time to assimilate it's protein; in general perennial grass protein assimilation takes ~ 50% longer. Perennial grass is tougher (has more cell wall), thicker (more cells/size), less internal moisture & some can have more % protein than annual grass (by dry weight).

    Locust can not digest the cell wall directly & cell wall differences (with co-factor of different % water in cells) in the actual kind of grass that is eaten works out to different nutrient extraction. So even though a grass may be higher in protein than another grass the amount of carbohydrate/unit protein that got assimilated from the meal on that kind of grass may be less than what linear calculation based on grass content leads us to assume.

    Because early instars (1-3 instars) have smaller mouth parts than when later on instars they mince up their food more & this grinds the grass cell wall; whereas eventually bigger instars can chomp a flake of leaf easier & then they ingest more intact cell walls. The early instars get relatively more available protein & carbohydrates this way (cell wall burst) when feed on even perennial grasses; so the subject discussed here is not really about early growth.

    Fed on fresh annual grass there is a slightly better rate of locust survival than on fresh perennial grass & also shorter stadium of instars on fresh annual grass. The moister food's quicker assimilation means they can go on to their next meal faster than when dealing with drier perennial grass which creates more congested (> % nutrient solids)haemolymph which necessitates osmolar gut adjustment.

    In the wild those migratory locust nymphs can move & find annuals (ideally, since annual grass can die of quicker) or perennials to suit their developmental needs. By the 5th instar locust that were feeding only on perennials have kept getting protein, but not the right amount of carbohydrate.

    An exclusive perennial grass diet means they would have to eat ~50% more, since in a half minute's worth of food ingested they will assimilate less than ~30% of the carbohydrates in that portion of leaf (see above long protein assimilation time factor) than if ate the same portion of annual grass leaf. On annual grass locusts will eat more, assimilate more of both protein & carbohydrate (even if a perennial grass contained more % carbohydrate). They grow faster & bigger on exclusively annual grass (they will have eaten more total dry matter); plus, somehow, the annual grass meal stays in 5th instars longer than perennial grass does & I assume this is adaptation for better adulthood.

    Laboratory diets that do not rely on synthetic locust diets often "grind" the grasses (& of course make water freely available); it breaks the cell wall & thus more carbohydrate assimilation occurs since it removes the factor of protein assimilation completion causing gut clearing out. Without grinding both the cell wall array & the physical characteristics of cell walls becomes a factor of how many cells can get broken open by the locust once they are past the 2nd instar (see above).

    By grinding perennial grass it potentially can lead to ~25% more weight gain than otherwise on the perennial; due in part to ~35% more getting eaten & 2.5 times more nutrients being retained. The result essentially means that once you feed them ground perennial grass the locust weight gain & time taken to move through their instars comes out the same as if they were raised on annual grass; laboratories try to standardize the locust generations that use as controls for the other experiment factors they introduce in order to draw accurate conclusions from their data.

    One can cut up fresh cut grass with scissors or in pieces by dicing/chopping/slicing & then freeze it. Once frozen shatter it in a mini-blender & then get it relatively dry without resorting to adding heat (avoid oven desiccation & dehydrators; eBay sells used laboratory style plastic desiccator domed chambers & reusable silica spheres which can put in chamber bottom absorb moisture, or can dry passively on top of filter paper); then provide the ground dried grass to the locust at room temperature (not cold) & make sure water is available.

    Serratia marcescens is fairly common bacteria & if determined as a regular problem for the grass collected then prior to cutting up the grass the loose leaves can be washed/bathed/immersed in a solution iodine (which kills gram negative bacteria); then the iodine treatment must be rinsed off. Obviously never risk an entire insect colony population to any new method without trial on a subject group of bugs to determine if method safe or needs perfecting the tactic (such as how many clean water rinses needed & whether agitating motion improves results).

    The standard iodine solution sold over the counter is 2% iodine & 0.25-0.5 ml of this tincture in a liter (quart) of water should be sufficient for immersion of the leaves for 20-30 minutes duration. Alternatively, povidone-iodine (called "PVP-I", having poly-vinyl-pyrrolidone), which has been used since the early 1950's, can be found in the commercially sold product "Betadine" which is about 10% iodine & 0.35-0.7 ml of this in a liter (quart) of water, it may be faster acting &/or need to use less. Another iodine sold for topical disinfection is Nonyl-phenoxy-poly (ethyleneoxy) ethanol-iodine complex can be bought that is 1.75% iodine; 0.6 in a liter (quart) of water is probably more than enough for surface disinfection.

  • hi gringojay!

    thanks for the response! they only get grass every day and a little bit of oatmeal with sugar. (i read somewhere online that it helps with cannibalism, i don't know if it's true or not).

    I don't really know what kind of grass it is, i must do it with the grass i find.. (maybe my coworker knows what kind it is, i'm going to ask her) sometimes it's a little bit different but i try to pick the grass i know they do well on. so maybe it's indeed because of change of grass...

    i'm rearing the locusta migratoria and the Schistocerca gregaria. the thing is the adults are staying in a terrarium and there everything is fine. but the little ones are going in plastic boxes and 1 big cage we made and there is the problem... we know that te plastic boxes aren't ideal because when they are adults they die (it's not a problem for us know because we don't need a lot of locusts, we're still in research) and we're still figuring out if the big cage we made is a good one. so i don't know if this makes any difference... but they all get the same grass...

    hmm very interesting about al the grass! i didn't know it could be so different! i definitely will cut the grass from now on. also very interesting what you can do with the grass! i didn't know you could clean it or freeze it... i thought it would kill the grass and that i couldn't feed it anymore.

    So if it's dried you need to give them fresh water as well? because everywhere i read they all say you may not give water to locusts, they need to take it from their food.

  • Hi Zazu, - Unless you are designing a scientific study you probably don't need to over-think about annual vs. perrenial grass & just use what is reliable at the time, but spin dry &/or blotter dry excess surface water. I'm assuming you are trying to see if can rear a commercial quantity in an economic way. What is your goal & have you a preference for 1 kind of locust?

    Take a look at old treatise "Feeding locusts on freeze-dried plants:a new rearing method for herbivorous insects", by Louveaux et al. in 1980 is available as free full 4 page pdf on-line in English. On their food (wheat seedlings) migratory locusts (over 37 generations) needed on average 28.7 days to develop on dry food vs. 25.6 days on fresh seedlings. Table II breaks down male & female responses; bear in mind that if use wild grasses the specific data may differ.

    As for giving locust water see Browne,et al (2008) "Regulation of water ingestion by the locust Chortoicetes terminifera: the effect of injections into the haemolymph" who suggests: neural "... mechanisms responsible for the regulation of water (in haemolymph) might limit intake (of food) when locusts have access only to fresh vegetation of high water content...."

    If you are specifically breeding S. gregaria locust check out Roessingh, et al. (2011) "Physiological factors influencing preferences for wet & dry food in Schistocerca gregaria nymph"; where report that fed exclusively wet food resulted in small meals & tardy next feeding, while fed exclusively dry food the meals were larger & ate next meal relatively quicker. Apparently exclusively wet or exclusively dry meals both influence osmotic features of their haemolymph. Another related report that might interest you is Lewis, et al. (2011) "Feeding behavior: selection of both and dry food for increased growth in Schistocerca gregaria nymphs"; among other things, authors found 5th instar preferentially will eat dry food until their last day, when seek 97% wet food.

    In regard to any "sick" locust (in general) those that are free to choose from dietary ingredients (composition, not moisture content) will alter their ratio of protein & carbohydrate ingestion; getting more carbohydrates in late stage instar makes their immune system work better against pathogens. See Grahm, et al. (2014) "Locusts increase carbohydrate consumption to protect against a fungal biopesticide" & (2015) "Body condition constrains immune function in field populations of female Australian plague locust Chortoicetes terminifera"

  • Hi Zazu, - (2010) "A simple diet for the rearing success of the Desert Locust, Schistocerca gregaria", by Aziz et al. reports on diets of corn (germinated) they take 41 days to imago stage, on lettuce they take 33 days to imago stage, on turnip they take 29 days to imago stage & on mixed together diet ingredients they take 28 days to imago stage. For cheapest economic diet it seems turnip wins; turnip roots store better, in temperate climate cost less & are grown easier (less bug problems, like aphids) than growing lettuce for making mixed diet .

    Although sprouted corn should be absolutely cheapest of these feed stocks , + dry seed stores best, the developmental time delay is considerably greater (12 days longer than on turnips). Furthermore the mortality going through instars was less on turnip (~12%) than on germinated corn (~43%); as per Fig. 2 . Available via as free full pdf; try this link =

  • Other plants that are favored eating by Schistocera gregaria are detailed below, which is not a complete list, taken from Bernays & Wilis (1986) "The effect of wilting on palatability of plants to Schistocerca gregaria, the desert locust"; originally published in journal Oecologia, Vol. 10, issue 1. Locust were reared with 12 hours light at 28-33 Celsius daytime temperature & 12 hours dark at 23-26 Celsius nighttime temperature; early instars were provided with free access to both fresh & dry food to let them develop without restriction confounding late instar data.

    Authors tested live plant eating times & then eating times of the same plant cut, after it lost some water content for 1-2 hours off the plant. They explained that when locust bite food & then are rejecting it is "... commonly but not invariably associated with sudden head raising and/or backward movement ..."; so this may be something to look for when devising locust diets. The summary here does not take into account an early instars' feeding times &/or preferences over their stadium length of time; which authors state may be different than the trends charted for 4th instars.

    Data that follows is from Table 1 for those plants S.gregaria 4th instars will readily feed the longest on both as cut vegetation & in comparison as when found growing fresh. I am not reproducing all the different plants' data, because only wish to highlight plants that may be very profitable to feed them. The number of seconds feeding on cut (called "excised" in Table 1) state is given after the named plant, followed in parenthesis for the number of seconds feeding on the same freshly growing (called "intact" in Table 1)) plant once it grew up to the height of at least 20 cm tall.

    The authors also tested plants & found their average fresh on the plant (intact & fully turgid) analysis was for 84% water content; in contrast wilted (achieved by under watering the plant to simulate arid growing conditions) water content was put at just under 82% water content. They found that cut ("excised") plants & wilted plants evoked the same kind of S. gregaria feeding response to the different plants in relation to when that plant is still "intact" & fully turgid. However, in the case of some plants the locust fed longer on simply wilted plants than when the plant feed was cut off (excised) that plant; in other cases the locust fed longer on the 1-2 hour cut off plant than the wilted plant (that had not been cut off before fed them) .

    Plants with their "excised" cut data (not still wilted on the plant) are as follows & the uncut (fully turgid intact still on the plant) feeding time by 4th instar S. gregaria is given next in parenthesis. It also should be mentioned that, although no comparative data is given in the report, these specific plant feeding time trends continue beyond the 4th instar since the authors remarked that the ".. fifth instar individuals {were} accepting the wilted plants sooner than fourth instar individuals ..."

    Achillea miIlefolium = 368 +/-44 seconds excised (vs. 355+/-50 seconds intact); Leontodon automnalis = 349+41(366+/-366); Crespis species (Asteracae family)=388+/-24(298+/-36); Cyperus species (Cyperacae family)=589 +/-55 (557+/-70); Sorghum bicolor=393+/-45 (450+/-61);Rumex obtusifolius=361+/-56(360+/-44); Vigna sinensis=340+/-44(371+/-52);Trifolium repens=321+/-24(302+/-24);Brassica oleracea=411+/-30(520+/-36); Taraxacum officinale =308+/-49 (39+/23) & Urtica urens (comment: this is the annual version of the highly nutritious stinging nettle which grows very short & it's seed is very cheap in bulk)=297+/-21 seconds excised (301+/-39 seconds intact).

  • Hi Zazu, seems like the weather is just as good in Belgium as it is in Holland (Ahum..).

    A commercial locust breeder told me that feeding grass that is too wet gives problems, as does feeding grass that is too dry. I believe he used to spread out grass that was too wet on a sheet on the ground to allow for it to dry a little bit. Also, feeding your locusts only once a day will certainly keep yields rather low. The breeder fed his locusts fresh grass 6-8 times spread out over the day for maximum yields. He harvested like 1000 adult/1500 subadult locusts from a 60x40x60 (LWH) breeding box. Even the slightest error in his feeding regime would cut down this amount by up to 40%.

    Try to use wheat bran as a dry feed :)

    The 6-8 times of feeding a day is what dettered me from looking any further into locust breeding until we have a solid dry feed formulation. A lot of (succesful) research has been done on this in the past by R. H. Dadd, but weights were still much lower on dry diets then they were on fresh grash diets. Apperantly, reporduction proved to be an issue as well.

    The series of papers by Dadd are "The nutritional requirements of locusts I - V", published in the later 50's / early 60's. His research is by far the most important on (migratory) locust nutrition available.

  • Dadd found that an ether extract of bran is a feeding stimulant (phago-stimulant) & that wheat germ oil was also a phago-stimulant; so suggested to have a similar compound. As per Dadd, et al. (1960) "Observations on the palatability and utilization of food by locusts, with particular reference to the interpretation of performances in growth trials using synthetic diets"; originally published in journal Entomologia Experimentalis et Applicata.

    Thiamin, riboflavin, nicotinic acid, pyridoxine, folic acid, meso-inositol, calcium pantothenate, biotin & choline chloride were determined essential for full locust development according to Dadd, et al (1961)" The nutritional requirements of locusts. IV. Requirements for vitamins of the B complex", originally published in Journal of Insect Physiology, 6.

    Table 1 elaborates the following artificial locust diet: cholesterol = 200 mg + cellulose powder = 15 g + linoleic acid = 0.2ml + 6 g of casein (low fat/vitamin free) + 2 g bacteriological peptone + 2 g egg albumen powder + 5 g sucrose + 5 g white dextrin (glucose) + 100 mg ascorbic acid + 1.5 g salt blend "Glaxo DL6" (this salt blend is found in vol. 1 and = 22 part sodium chloride + 130 part calcium phosphate + 125 part potassium citrate + 30 part magnesium sulfate crystals = 5 part iron citrate + 0.7 part trace mineral formulation, where use the following trace mineral formulation = 12 part potassium iodine + 10 part sodium fluoride + 2 part anhydrous magnesium sulfate + 1 cuprous iodine + 1 part anhydrous potassium alum + 1 part zinc sulfate) + the following vitamin formulation prepared in 10 ml solution of 20% ethyl alcohol in order to dispense for supplementation with: biotin = 1 microgram/g diet + choline chloride = 1,250 microgram/g diet + nicotinic acid = 100 microgram/g diet + riboflavin = 25 microgram/g diet + thiamine = 25 microgram/g diet + folic acid = 25 microgram/g diet + calcium pantothenate = 50 microgram/g diet+ inositol = 25 microgram/g diet + p-aminobenzoic acid = 25 mg/g diet+ pyridoxine = 25micogram/g diet

    It seems this synthetic diet was good for desert Schistocera gregaria locust & not good for migratory Locusta migratoria. Quote: (migratory locust) "...growth was poor from the start and few individuals survived beyond the third instar. However, comparisons of growth rates for the first three instars indicate that the same nine vitamins required by Schistocerca are also necessary for Locusta."

    (1985)"Compensation by locusts for changes in dietary nutrients: behavioural mechanisms" by Simpson, et al. has some data on how well migratory locusts at 3rd day into their 5th instar migratory locust react to the artificial diet of Dadd (note: they were reared until then on wheat seedling & not reared on the Dadd diet); the ingredients were moistened to have 4% moisture content & create 1-3 mm size food clumps. However, I want to point out that these were raised in a group & then fed solitary, while some more recent feeding experiments show behavioral variations based on whether locust are solitary or in groups (gregarious); still, this study may help those trying to design a locust diet. As per Table 2: 5th instar migratory locust on the Dadd artificial diet will eat 6.9 - 7.9 mg/3 min feeding, will go for their next meal in 65.6 -77 minutes, eat 46.4 - 53.4 mg in a 12 hour "day", absorb 10.7 mg protein (Dadd feed formula = ~27.5% protein) & absorb 13.2 mg carbohydrate (Dadd feed formula = ~ 27.5 % carbohydrate). Free full text link =

  • And please keep also in mind "The use of the Dadd synthetic diet as food for adult Schistocerca gregaria (Forsk.) and the effects of some additions and modifications to it" by G. G. Cavanagh, J. Ins. Physiol., 1963, vol. 9, pp. 759-775. He mentions that the Dadd synthetic diet gives very poor results in the amount of egg pods produced with subsequent low hatching rates.

    "A small daily supplement of fresh grass was found to eliminate the low fertility of the pods ... without improving clutch size, for which a much greater grass supplement was necessary."

  • edited August 2016

    Hi EntoJesse, - It would be good to know what kind of locust the commercial operation were feeding the grass you mentioned earlier. And, although probably not significant, the preceding 1963 locust egg study protocol of whether those adults were isolated (solitary) when studied; & if, as I presume, reared in a group (gregarious).

    While on the subject of locust eggs (at 30-32 Celsius take 11-13 days in wet sand). Eggs of S. gregaria weigh more, have more protein & use lipids more than L. migratoria; as per Fig 1 & 2 of following study. See Nemec's (2002) "Quantitative changes in protein, glycogen and fat content in the eggs of the locusts, Locusta migratoria migratorioides and Schistocerca gregaria (Orthoptera), during embryogenesis"; free full text link =

    Allow me to return to subject that groups (gregarious) and singe (solitary) locust feeding show different nuances. This may help some develop more suitable diets & also see the relevance of looking at locust diet study protocols to see if data presented is for gregarious or solitary conditions.

    S.J. Simpson has several published studies & in (2002) "A comparison of nutritional regulation in solitarious- and gregarious-phase nymphs of the desert locust Schistocerca gregaria" there is relevant data. I will summarize the report here for readers; free full text =

    Simpson observed that gregarious (group living) desert locust do not assimilate dietary protein as well a solitary living desert locust. Thus low protein diet leads to slower development & lower survival when living as a group than those living alone (solitary).

    The desert locust will search for a diet, if allowed/possible, to get a minimum of protein. Fig 4 shows grams of protein eaten/gr. locust protein growth & also grams carbohydrate eaten/gr. locust lipid ("fat") growth.

    However, even though both gregarious (group) living & solitary living desert locust will self regulate protein intake to approximately the same total over the course of development the amount of their protein weight ends up different. The newly adult gregarious living's fresh (wet) weight of protein = 0.567 mg & dry weight (mass) of protein = 0.299, vs. the newly adult solitary living's fresh (wet) weight of protein = 0.639 mg & dry weight of protein = 0.349 mg.

    Survival of 5th instars is also a factor for gregarious (group) living desert locust reared on 5 different protein:carbohydrate ratio diets is shown in Fig 5. On a diet with equal parts protein to same rate carbohydrates the solitary living desert locust moves through it's stadium faster; and a higher protein ratio is needed for the gregarious (group) living locust to get a good survival rate (14% protein diet needed for 80% survival of group living 5th instar Schistocera gregaria).

    Author goes on to make a notable observation from data that: during 5th instar stadium as long as they get 0.3 g carbohydrate throughout that period for every gram carbohydrate consumed both the 5th instar desert locust & migratory locust both gain 0.25 gr lipid (fat). Apparently migratory locust L. migratoria reared in groups ("gregarious") respond to protein:carbohydrate diet ratio that is like desert locust S. gregaria reared as solitary locusts (Note: this seeming contradiction is not a misprint & is stated in the study's concluding remarks); the difference seems to involve (in part) L. migratoria ability to achieve a higher dietary protein conversion than S. gregaria.

    In van der Zee, Behmer & Simpson's (2002)"Food mixing strategies in the desert locust: effects of phase, distance between foods and food nutrient content" S.J. Simpson reveals that, based on the above described study (unreported there) , that the "optimal" diet for desert locust S. gregaria is the ratio of 18% protein : 24% carbohydrate. The study compares this diet to low protein & high protein diets. Try free full text link = der Zee et al. (EEA-2002).pdf

    This study (29-31 Celsius, 12 hours light : 12 hours dark) finds that solitary living desert locust tolerate nutritional imbalances better than group living (gregarious) desert locust; since in natural habitat last instar group living desert locust will move/forage up to 1,000 meter/day. Data for S. gregaria locust given a choice (& under variable distance between food dishes of different protein:carbohydrate ratios) may offer clues for additional strategy if commercial producers have the option of dedicating more space to locusts than small bins.

    Fig. 2 reveals that group living ones eat more from high protein formula than from high carbohydrate formula, vs. solitary living ones eat more from high carbohydrate formula than from high protein formula. Fig. 3 reveals that group living ones switch between high protein & high carbohydrate choices ~ 3.5 times if dishes are set apart only 0.25 meter (but then again, even if both dishes set apart 0.25 meters have the same optimal 18% protein:24% carbohydrate content the group living ones still switch eating from one to the other - reconfirming that desert locust are "compulsive" about switching where the feed). Fig. 4 reveals that the % of time group living desert locust will hang out around any feed is different depending on the % ratios of protein to carbohydrate. Fig 5 reveals how much the desert locust eats of a formulated food at different distances.

  • Hi EntoJesse, - Grass feeding desert locust research has been done recently with a more contemporary diet than the old Dodd based one. It supports that commercial locust breeders information of grass being worthwhile. In what follows, the protocol was to feed "orchard" grass (Dactylis glomerata) + cabbage leaf + wheat bran; under 30-32Celsius, 40-70% relative humidity with 16 hours light:8 hours dark.

    The locust research team used "fresh" grass added to feed (cabbage & wheat bran) that had been put into water (250 ml) & changed every other day; they used "old" grass added to feed (cabbage & wheat bran) which had initially be stored in plastic bag for 2 days (30-32Celsius) & then refrigerated for 6 days (8-10Celsius) before giving to the locust. I want to point out that a diet of orchard grass + cabbage leaves + wheat bran has been used by this same team for many years of other desert locust Schistocera gregaria research & so may be a useful one for those considering commercial rearing of desert locust (although in their earlier 2004 report they used 50 - 70 % relative humidity & I am not certain of their low range being a misprint somewhere).

    Details & data given below is from Maeno & Tanaka (2011) "Phase-specific responses to different qualities of food in the desert locust, Schistocerca gregaria: Developmental, morphological and reproductive characteristics"; originally published in Journal of Insect Physiology, 57. The study was for solitary living desert locust & also for group (gregarious) living locust; however for brevity I will only describe the data for group living desert locust (since what commercial breeding would use), which in this case was 100 locust (whether adult or growing nymphs) in a container measuring 42 c x 22 cm x 42 cm.

    Approximately 70% of the group living (gregarious) desert locust fed with fresh grass survived; vs. ~ 50% of the group living ones fed with old grass. Notably, in the cohort fed old grass ~ 13.7% needed a 6th instar molt; while the females were more likely than males to have 6 molts. Authors tried to create the variation which foraging desert locust would find as the moister ("fresh") field grass of spring or would find in the drier ("old") field grass of summer.

    Fig 3 details a few differences among group living desert locust in response to fresh vs. old grass in diet that depends on whether they had 5 molts or whether they had 6 molts. Those that had 5 molts fed with fresh grass all along developed in less than or equal to ~30 days; their adult weight then = 2,100 - 2,300 mg. each. Those that had 5 molts fed with old grass all along developed in less than or equal to ~35 days; their adult weight then = 1,800 - 2,100 mg. each. Those that had 6 molts fed with old grass all along developed in less than or equal to ~45-50 days; their adult weight then = 1,800-2,000 mg each.

    Authors cite their previous discovery that 3rd nymph (& to lesser extent earlier instars) stadium programs how many more (whether 5 or 6) stadia will come along for that locust before adulthood. Fed on old grass, as opposed to fresh grass, the 3rd stadium desert locust instar is smaller; thus, the longer it takes for nymph to develop plays out down the line as a smaller adult.

    In terms of reproductive affects from grass quality (fresh vs. old) the authors have good data (again am only recording group living desert locust & not data for solo living ones). Before get to the data it may interest some to read authors comment in conclusions with regard to migratory locust, since the research data was for desert locust.

    Quote: " ... influences of ... nymphal and adult rearing densities ... in L. migratoria ... greatest reproductive performance ... when locusts reared under crowded conditions were kept in isolation after adult emergence ... (S. gregaria) locusts fed with low-quality food during the nymphal stage ... increased egg production specific to body weight, as compared to locusts fed with high-quality food ...." Which (to me) suggests that for those breeding migratory locust L. migratoria the actual breeding of that variety might be best done by taking breeding females to mate in a low population environment.

    Again, for group living (gregarious) desert locust, data reveals the following averages: number of egg pods (authors point out that it is the female body size that determines the number of eggs in a pod) when given fresh grass = 91.6+/-18.3 vs. number of egg pods when given old grass = 83.4+/-23.6; total egg weight (eggs kept at 30-32Celsius) in a pod when given fresh grass = 536.8 +/-96.1 mg vs. total egg weight in a pod when given old grass = 502.2 +/-132.7 mg; weight of an egg when given fresh grass=5.92+/-0.63 mg vs. weight of an egg when given old grass = 6.08 +/-0.6 mg (Note: authors point out that when look at total egg weight per adult body weight this feature is actually more when fed on old grass than when fed on fresh grass - references to last part of above quote about "low-quality").

  • Hi gringojay and entojesse!

    Sorry for the late response but i had too much work to read it all... Thanks a lot for the response and the information, it really can help us when we go bigger in the company. At the moment we can't do all the things (like feeding them 6-8 times a day) but it is really good information for the future to keep in mind!

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