We have found out in Portugal that a population of H. armigera collected "in the wild" and then reared under lab conditions without caring for consanguinity is turning slowly to sterile and you won't get a 4th generation. We have successfully reared H. armigera during 9 consecutive years, after that finding. 

We coupled 2 males with 3 females for one line (giving the offspring of each line letters and numbers like keeping a pedigree record), or, with lesser adults from the wild, 2 females and 1 male).  Each year we introduced new wild individuals into the rearing.

For mating we used simple plastic water bottles cut about 15 cm high and covered with half a plastic Petri dish. A filter paper disk on the bottom to absorve droppings, a small glas container with 10% sugar water covered with a plastic foil with holes made with a needle (if open, adults  will drown, and with cotton you can easily get infections) , taking care not to let the liquid level get lower than the mouthparts of the adults could reach, and, fixed with tape at the upper part of the bottle, a ring of "bill paper", for oviposition.

Change the mating container every 2 or 3 days not to loose hatching larvae (incubation time about 3 days at 25 + - 1ºC, 65% RH and 14/10 LD intensive light.

Taking 100 larvae of each line for the next generation, use semi artificial diet, and be careful not to let them mate inside the lines, but between lines. So for starters you need quite a big quantity of "wild" genoma. There is, as has been mentioned above, a time laps between hatching of females and males of the same line of at least half a day, that can go up to 3 days. (in my opinion a natural way of avoiding consanguinity, as hatching adults have a big wing activity - under field conditions they would go far away before their brothers hatch).

You can sex the pupae by observing the abdomen (drawing first published by an author from Turkey) and separate females from males before hatching, as the color differences (greenish for males and brownish for females) are not always so clear. Then there is the pre maturation period of one to two days. Once you obtain eggs, many of the above hints are very useful.

There are lots of described rearing methods, different diets (we have tried out some), and you can mechanise the process but will lose details of the insect's biology.

Our observations are contained in my PhD thesis (1991), unfortunately written in Portuguese and not yet scanned (387 pp). I'll do it soon, there are lots of illustrations, and I would translate it by chapters to English. Meanwhile feel free to ask all questions coming to your mind. 

You didn't indicate the light regime. This and some factors may affect the fertility of eggs.

How did you rear the larvae? What were the mating conditions? Cage size, number of individuals, ovipositing substrate etc. How did you keep the eggs after oviposition? Did any change occur in color of eggs?

Hi Mohammad:

I agree with Alican, we need more information about the conditions you used to rear your Helicoverpa armigera. There are three conditions that cause no larva eclosion in Lepidoptera. 1) If the eggs turn black very likely they may have been parasitized by wasps of the genus Telenomus, Trichogramma or Ooencyrtus. 2) Another reason is when the female did not mate with the male so you get infertile eggs. 3) if the eggs are maintained at low relative humidity (below 70% RH ) the eggs can be dehydrated and do not hatch.

Regards,

Luis Miguel

Comprehensive answer given by Luis Miguel Constantino

Making sure the eggs are fertile (healthy individuals of both sexes at the same time with appropriate food and without parasites :-), sugar solution as food delivered by a cotton wick to be renewed regularly, cages at 50% humidity and long day light conditions). Egg disinfection is a basic plus. Simplest is to lay face down the strips of plastic on which the eggs have been deposited on a 10% chlorine solutions for 2 minutes followed by thorough but gentle washing and paper/air drying. Egg storage at high humidity (>80%, ex. damp paper towel in a plastic bag) at around 23C, 16H:8D. Good luck and have fun.

Hi Mohammad,

We also rear armigera. Sometimes we have a problem where the males and females don't emerge consecutively or the pre-reproductive periods are out of sync. In this instance, although you may have males and females in the same cage at the same time, they do not mate. Even though they do not mate, females still lay eggs but they do not hatch. I suspect this is your problem. This can be difficult to resolve. There is a string of papers on the problem. See here for example; http://jee.oxfordjournals.org/content/87/6/1502.abstract

Hi, Mohammad,

True, mating with males could have been the problem first problem. A 1000 eggs is a big number try to revise your conditions afresh and see if there could be a problem with humidity and temp and light duration where you are mass rearing. Or some fungal attack, check the egg capsule under microscope. Repeat again with fresh eggs. Definitely you will find what went amiss.

Thank you for all. We received 2 series of larvae from tow places in Iran. Adult emerging was very well that inserted in a bucket for mating. I attached some picturers of it. For oviposition we put pieces of cotton in petridishes that was saturated with honey 20%. We had some fungal attack, too. We checked eggs under microscope but any embryo wasn't seen. After oviposition eggs was kept in 25°C and 70% humidity and LD 16:8. This conditions were for all of stages during rearing.

First and foremost the eggs should be ferile and second, temperature and relative humidity should be checked, as dry eggs will likely not hatch.

Egg must be fertile. 

My answer would agree with earlier comments. If the embryo didn't develop, most likely the eggs were infertile. And yes, equally important to look into are the conditions affecting development and hatching of the eggs. 

Hi. I agree with most of the earlier comments. First you maintain 1 female : 2 male sex ratio this will help to over come proper mating issues. 2. maintain RH 65 - 70% Temp - 25 -28. 3. Check for any protozoa infection in the colony this may be the reason for unfertile eggs, as protozoa infection effect the reproduction system.

According with the previous comments, you need to ensure the mating, so if the eggs are infertile, sure that you have a seriuos problems with the environmental conditions for mate. First you need to check the sexual maturation time and the caracters that indicate that the female and male are synronized in develop. Second, the requeriments for incubation of the eggs in artificial conditions.

We have found out in Portugal that a population of H. armigera collected "in the wild" and then reared under lab conditions without caring for consanguinity is turning slowly to sterile and you won't get a 4th generation. We have successfully reared H. armigera during 9 consecutive years, after that finding. 

We coupled 2 males with 3 females for one line (giving the offspring of each line letters and numbers like keeping a pedigree record), or, with lesser adults from the wild, 2 females and 1 male).  Each year we introduced new wild individuals into the rearing.

For mating we used simple plastic water bottles cut about 15 cm high and covered with half a plastic Petri dish. A filter paper disk on the bottom to absorve droppings, a small glas container with 10% sugar water covered with a plastic foil with holes made with a needle (if open, adults  will drown, and with cotton you can easily get infections) , taking care not to let the liquid level get lower than the mouthparts of the adults could reach, and, fixed with tape at the upper part of the bottle, a ring of "bill paper", for oviposition.

Change the mating container every 2 or 3 days not to loose hatching larvae (incubation time about 3 days at 25 + - 1ºC, 65% RH and 14/10 LD intensive light.

Taking 100 larvae of each line for the next generation, use semi artificial diet, and be careful not to let them mate inside the lines, but between lines. So for starters you need quite a big quantity of "wild" genoma. There is, as has been mentioned above, a time laps between hatching of females and males of the same line of at least half a day, that can go up to 3 days. (in my opinion a natural way of avoiding consanguinity, as hatching adults have a big wing activity - under field conditions they would go far away before their brothers hatch).

You can sex the pupae by observing the abdomen (drawing first published by an author from Turkey) and separate females from males before hatching, as the color differences (greenish for males and brownish for females) are not always so clear. Then there is the pre maturation period of one to two days. Once you obtain eggs, many of the above hints are very useful.

There are lots of described rearing methods, different diets (we have tried out some), and you can mechanise the process but will lose details of the insect's biology.

Our observations are contained in my PhD thesis (1991), unfortunately written in Portuguese and not yet scanned (387 pp). I'll do it soon, there are lots of illustrations, and I would translate it by chapters to English. Meanwhile feel free to ask all questions coming to your mind. 

Dear Carola

Thank you for your attention. Your comments is useful and complete. I will use of your suggestions in future.

H. armígera, need  80% of RH, and it´s posible the substrate affect the oviposition behaviour. 

Dear Dr. Vatanparast,

Did you find the problem of unhatched eggs belakhare?

Seyed Mohammad Tabadkani

Dear Dr. Tabadkani

Yeah, it was solved 3 years ago!

Mohammad Vatanparast Hi, Dr Mohammad.

What did you do to solve the problem? I'm having the same problem with Anticarsia gemmatalis. The females lay only infertile eggs.

When I put together individualized couples, they don't mate. Mating only ocurrs in cages with a lot of females and males (more than 20 of each sex).