Understanding the development and reproduction of insects surviving controlled atmosphere treatment may help in developing sound pest management strategies. The developmental duration, survival percentage, and oviposition of Plodia interpunctella and its F1 generation were determined after the fifth instar larvae (the last-stage larvae) were exposed to 98% N2 for different exposure times. The survival percentage of the last-stage larvae treated with 98% N2 for 6, 4, 1.5, and 0 day was 70, 80, 91, and 100%, respectively when measured 24 h after treatment. The survival percentage of the last-stage larvae that developed to pupae was 37, 55, 73, and 96%, corresponding to the different exposure times. The developmental time needed to pass from pupa to adult emergence of specimens treated as the last-stage larvae were 8, 7, 6, and 6 days corresponding respectively to high N2 treatment after 6, 4, 1.5, and 0 day of exposure. The mean number of eggs laid by the subsequent females developed from the treated last-stage larvae was 35, 66, 81, and 123, respectively. The oviposition inhibition ratio of the F1 generation decreased by more than 33% compared with that of the parental generation. When the last-stage larvae were exposed to 98% N2 for longer than 4 days, the immature developmental time of surviving individuals in the F1 generation was delayed more than 6 days due to slower egg hatching and longer development of the first and second instar larvae stages. The population trend index of the F1 generation was lower when raised from the treated last-stage larvae than those from untreated controls.

A steady supply of hosts at the susceptible stage for parasitism is a major component of mass rearing parasitoids for biological control programs. Here we describe the effects of storing 5th instar Plodia interpunctella larvae in dormancy on subsequent host development in the context of host colony maintenance and effects of the duration of host dormancy on the development of Habrobracon hebetor parasitoids reared from dormant hosts. We induced dormancy with a combination of short daylength (12L:12D) and lower temperature (15°C), conditions known to induce diapause in this species, and held 5th instar larvae of P. interpunctella for a series of dormancy durations ranging from 15 to 105 days. Extended storage of dormant 5th instar larvae had no significant impacts on survival, development, or reproductive potential of P. interpunctella, reinforcing that dormant hosts have a substantial shelf life. This ability to store hosts in dormancy for more than 3 months at a time without strong negative consequences reinforces the promise of using dormancy to maintain host colonies. The proportion of hosts parasitized by H. hebetor did not vary significantly between non-dormant host larvae and dormant host larvae stored for periods as long as 105 days. Concordant with a prior study, H. hebetor adult progeny production from dormant host larvae was higher than the number of progeny produced on non-dormant host larvae. There were no differences in size, sex ratio, or reproductive output of parasitoids reared on dormant hosts compared to non-dormant hosts stored for up to 105 days. Larval development times of H. hebetor were however longer when reared on dormant hosts compared to non-dormant hosts. Our results agree with other studies showing using dormant hosts can improve parasitoid mass rearing, and we show benefits for parasitoid rearing even after 3 months of host dormancy.

Heating the ambient air of a whole, or a portion of a food-processing facility to 50 to 60°C and maintaining these elevated temperatures for 24 to 36 h, is an old technology, referred to as heat treatment. There is renewed interest in adopting heat treatments around the world as a viable insect control alternative to fumigation with methyl bromide. There is limited published information on responses of the Indian meal moth, Plodia interpunctella (Hübner), exposed to elevated temperatures typically used during heat treatments. Time-mortality relationships were determined for eggs, fifth-instars (wandering-phase larvae), pupae, and adults of P. interpunctella exposed to five constant temperatures between 44 and 52°C. Mortality of each stage increased with increasing temperature and exposure time. In general, fifth-instars were the most heat-tolerant stage at all temperatures tested. Exposure for a minimum of 34 min at 50°C was required to kill 99% of the fifth-instars. It is proposed that heat treatments aimed at controlling fifth-instars should be able to control all other stages of P. interpunctella.

In a comparative situation, the moths Plodia interpunctella (Hubn.) and Ephestia cautella (Wlk.) caused more damage in groundnuts (41.85% for P. interpunctella; 29.21% for E. cautella) than in maize, when these commodities were stored for 1 month in plastic jars. For maize stored for 3 months in plastic and traditional storage gourds, the weight losses caused by the moths were: P. interpunctella—15.48% in jars; 4.53% in gourds; E. cautella—20.68% in jars; 4.12% in gourds. Orange peel suppressed two-thirds of the populations of P. interpunctella and E. cautella at a dosage of 20.0g/100g maize. Neem leaves caused 100% mortality of P. interpunctella at 15.0g/100g groundnut and suppressed more than half the population of E. cautella at 5g/100g groundnut. The results show that the plant materials utilised have some insecticidal properties against P. interpunctella and E. cautella over a short period.

Biochemical approaches have been used to enhance the potency of Bacillus thuringiensis against Plodia interpunctelia. Tests were made with different classes of chemical compounds, characterizedby being safe, non-toxic to man, and cheap in price. Among the tested inorganic salts, calcium carbonate, calcium oxide and zinc sulphate were found to increase the potency of B. thuringiensis δ-endotoxin by 2.5-, 1.9- and 2.7-fold, respectively. With the nitrogenous compounds, the amino acids serlne, arginine, alanine and teucine enhanced the endotoxin effect by 52-, 3.6-, 13- and 1.1-fold, respectively. Also, among the protein solubilizing agents, EDTA and sodium thloglycollate led to a 100- and 2.6-fold Increase in the potency. Formic acid was highly effective among the organic acids used in enhancing the potency, followed by malk acid, with 4.8- and 2.4-fold increase, respectively.

Competition between Plodia interpunctella (Hubn.) and Ephestia cautella (Wlk.) was studied in groundnuts and in a limited amount of standard medium (maize meal, wheat bran and glycerol at the ratio of 8:8:1) (w/w) when the species were reared separately (conditions PI and EC), when one was added before the other (conditions P+E/2 and E+P/2) and when both were introduced together (condition PI/EC). Separately, each species was well maintained on the standard medium, while E. cautella was the better competitor in groundnuts under conditions E+P/2 and PI/EC. The results offer a possible explanation for the pest status and distribution of the two moths species in groundnuts and where their ranges overlap, especially in the tropics.

The life cycles of two phycitid moths, Plodia interpunctella (Hubn.) and Ephestia cautella (Wik.) were studied under ambient laboratory conditions on groundnut, maize, sorghum, wheat and standard medium (maize/wheat/glycerol, 8:8:1, w/w). Egg hatchabilities were found to be 98.6 and 91.6% for P. interpunctella and E. cautella respectively. Five larval instars were recorded for each species based on head-capsule width measurements. The growth ratios of the larval head-capsule width ranged from 1.08–1.72 in P. interpunctella: and 1.33–1.57 in E. cautella. These ranges fall within the acceptable range in Dyar's rule. Mean fecundities ranged from 96.83 ± 0.31 on wheat to 190.87 ± 0.47 on standard medium for P. interpunctella; and 96.83 ± 0.31 on groundnut to 192 ± 1.33 on standard medium for E. cautella. Mean developmental periods of the two moths on the selected food media ranged from 25.65 days on standard medium to 46.11 days in broken wheat for P. interpunctella; and 26.95 days in broken sorghum to 40.14 days in ground maize for E. cautella.

The effect of temperature and relative humidity on mating and commencement of oviposition in Plodia interpunctella (Hubner) was studied in the laboratory. Mating was most successful at 20 and 30°C and was less so at temperatures of 15 and 35°C. Increased relative humidity appeared to have favoured mating at higher temperatures investigated which were 30 and 35°C.

The onset time for mating was higher at 30 and 35°C than at 15 and 20°C. Mating started earlier at the lower temperatures than at higher temperatures. The mean duration of mating was higher at 15 and 20°C than at 30 and 35°C at which high relative humidity favoured increase in mating time.

At 20 and 30°C oviposition started within the first 2 days of mating whereas at 15°C oviposition started about 8 days after mating. At 35°C oviposition commenced within 4 days. Low relative humidity caused early commencement of oviposition at 15 and 35°C.

Some factors affecting oviposition by Plodia interpunctella (Hubner) were studied under various controlled conditions in the laboratory. The effect of temperature, relative humidity, light and mating on oviposition were investigated.

Temperatures of 25 and 30°C were optimal for oviposition. The best condition was 30°C and 80% r.h. at which an average of 315.3 eggs were laid per female during its lifetime. The least favourable temperatures investigated were 15 and 35°C. Relative humidity did not have significant effect on the number of eggs laid at 15 and 25°C but at higher temperatures of 30 and 35°C, high r.h. increased the number of eggs laid by individual moths.

Light regimes of 12 hr light and 12hr darkness (LD) and 24 hr darkness (DD) were more favourable than 24 hr light (LL) for oviposition.

Virgin females laid fewer eggs than mated females while prolonged virginity reduced the number of eggs laid and caused resorption of immature oocytes and retention of ripe eggs in the ovaries.