Hexane extracts of 10 different varieties of tomato (Lycopersicon esculentum Mill) obtained in the vegetative and flowering periods were studied for synomonal response of the egg parasitoid Trichogramma chilonis Ishii. Gas chromatography of leaf extracts revealed the presence of saturated hydrocarbons ranging from C14 to C29 in varying numbers and concentrations. These hydrocarbons elicited varied synomonal responses from the parasitoid. The quantity of individual hydrocarbons varied from 72 to 34,940 ppm in the vegetative period and from 4 to 46,170 ppm in the flowering period. Hexane extracts obtained during the flowering period showed a greater synomonal response compared with those obtained during the vegetative period. A better response observed for certain varieties of tomato at a particular period could be due to the presence of higher concentrations of favourable hydrocarbons relative to unfavourable ones. Synomonal activity seems to be associated mainly with tricosane, heneicosane, pentacosane and hexacosane during the vegetative period and with heneicosane and hexacosane during the flowering period. In the vegetative period, the tomato variety To-Pant-T4 elicited the highest activity as well as parasitism at the lowest concentration of 25,000 ppm, which was higher than other varieties at all concentrations. Varieties To-BT-116-32, To-BT-20-2-1 and To-Pant-T3 in the vegetative period and To-Selection-15, To-Selection-32 and To-BT-22-2-1 in the flowering period elicited higher responses than the other varieties. To-BT-20-2-1 elicited a maximum response in the flowering period, which may be due to the presence of higher relative quantities of tricosane, heneicosane and hexacosane. In view of these findings, tomato varieties with favourable semiochemicals could be exploited in an integrated pest management programme to enhance the effectiveness of the egg parasitoid T. chilonis against the fruit borer Helicoverpa armigera (Hb).

The biological hypothesis that female parasitoids can adjust their fecundity schedule according to host availability, and tradeoff longevity with fecundity was tested in a thelytokous oophagous parasitoid, Trichogramma brasiliensis Ashmead (Trichogrammatidae: Hymenoptera) parasitising the rice moth, Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae). The tradeoff between early and late reproduction revealed that this wasp was able to exploit practically all available hosts during the first day or first few days of adult life. During spells of host unavailability, it was able to adjust its fecundity schedule accordingly. There was a negative relationship between survival and reproduction. Adult females survived shorter (10 days) when an unlimited supply of hosts was present, but longer (16 days) when no hosts were provided. These observations suggest the potential suitability of T. brasiliensis for inundative releases even in conditions of fluctuating host availability.

The development, life table and intrinsic rate of natural increase of the reduviid predator Rhynocoris fuscipes (Fabricius) on Spodoptera litura Fab., Earias vittella Fab. and Corcyra cephalonica Stainton under laboratory conditions were constructed. Fecundity, longevity and minimum developmental period of the predator were dependent on the prey diet and decreased in the order: S. litura, E. vittella and C. cephalonica. The mean number of female progeny produced over the entire period (the gross reproductive rate) was 43.0, 37.5 and 32.5 on S. litura, E. vittella and C. cephalonica respectively. The net reproductive rate (Ro), intrinsic rate of increase (rc) and weekly multiplication rate were also highest on S. litura followed by E. vittella and C. cephalonica.

Bioassays were carried out in Petri dishes with body washings of larvae, male and female moths and scale extract of Corcyra cephalonica St. in hexane to observe their kairomonal effect on Trichogramma brasiliensis (Ashmead) and T. japonicum Ashmead. The mean parasitoid activity index (PAI) and mean parasitisation were recorded. Trichogramma brasiliensis and T. japonicum recorded the highest mean parasitisation in the eggs treated with scale extract. Mean parasitisation recorded by T. japonicum in cards treated with female moth and male moth body washings were considerably lower than the corresponding values for T. brasiliensis. Both the parasitoids recorded significantly lower levels of parasitisation in cards treated with larval body washings. Gas chromatographs of host body washings / extract recorded a large number of similar hydrocarbons in the body washings of male and female moths and the scale extract. Pentadecane, heneicosane, eicosane, tetracosane, pentacosane and hexacosane were recorded in scale extracts. Female moth body washings recorded the presence of eicosane, tetracosane and pentacosane while heneicosane and eicosane were indicated in the male moth body washings.

The ovisite preference of Goniozus nephantidis (Hymenoptera: Bethylidae) was studied in relation to its hosts, Opisina arenosella, the coconut pest and Corcyra cephalonica, the flour pest. In both hosts, eggs were laid on all the segments except the first thoracic and the last four abdominal segments. Among the abdominal segments, the most preferred were segments 2 and 3 in the case of O. arenosella and 4 and 5 in the case of C. cephalonica. The percentages of eggs located intrasegmentally were 91.35 and 86.19; those of eggs located intersegmentally were 8.65 and 13.80 in the case of O. arenosella and C. cephalonica respectively. The left side was preferred in each host. In most of the egg clutches on O. arenosella, the head end faced the caudal end of the host; on Corcyra cephalonica, the head end faced the head end of the host.

Studies were conducted to compare adult longevity, number of host eggs parasitized and temporal pattern of oviposition of four species of Trichogramma, T. brasiliensis Ashmead, T. chilonis Ishii, T. minutum Riley and T. japonicum Ashmead. Parasitoids were reared on eggs of Corcyra cephalonica St. at 27 ± 2°C and 60 ± 5% r.h. With the exception of T. chilonis, females lived longer than males. The only thelytokous species, T. brasiliensis had the highest longevity and fecundity. However, T. chilonis was observed to lay more than 50% of its eggs on its first day of emergence. Of the four species, T. japonicum exhibited the shortest longevity and lowest fecundity.

Incorporated in this paper were the results of a study made on the quantitative variation of total carbohydrate, protein and lipid in whole body, fat body and integument of the larval and pupal developmental stages in rice moth, Corcyra cephalonica (St.) a storage grain pest. All three macromolecules referred to in case of whole body, exhibited a progressively decreasing trend from larva to pupa. In fat body total carbohydrate and protein contents were more in pupa than larva, while in integument the said nutrients were less in pupa than larva, showing the reverse results. The lowering down of the nutrients' level under stress caused by pyrethrum (a botanical insecticide) was also observed. The physiological and statistical significance of these findings was discussed.

Petroleum ether extract of Eichhornia crassipes (Mart) Solm. was evaluated for its biological activity against Tribolium castaneum (Herbst), Sitophilus oryzae (L.), Callosobruchus maculatiti (F.) and Corcyra cephalonica (Stainton). The crude extract included in the diet of insects retarded development and caused mortality in the fourth instar larvae of T. castaneum and C. cephalonica. Cuticle melanization in patches were observable in C. cephalonica larvae. High mortality of adult C. maculatus occurred in insects confined to the treated diet as well as in insects exposed to treated surfaces. The extract did not show any toxicity to adult S. oryzae.

The sensitivity of 1-day-old eggs of Corcyra cephalonica Staint., to ionizing radiation has been investigated in view of a possible future application of sterile-insect technique to the control of this species. Further, the irradiation effects on subsequent developmental stages were evaluated. A dose of 5 krad prevented hatching of eggs, while a dose of 4 krad was the highest dose that allowed an adequate percentage of the irradiated eggs (28.23) to complete development to the adult stage. While the mating percentage and mating frequency of resultant adults appeared to be unaffected, the percentage of multiple mating was variable and no clear pattern emerged. Egg production and fertility of P1 adults was decreased significantly and all effects of the treatment were more severe for pairings of both sexes resulting from irradiated eggs than pairings of either sex with unirradiated partners. However, the results show that a dose of irradiation low enough to permit adequate numbers of adults to develop from irradiated eggs (4 krad) is insufficient to induce high levels of sterility. Therefore, irradiation of eggs for mass production of either sterile or partially sterile adults was found not to be feasible.

A laboratory study of the biology of Corcyra cephalonica (Staint.) was made at 30°C and 70% r.h. on sorghum. The number of eggs laid per female, oviposition period, development time and survival from egg to adult were determined. The data were used to estimate the finite rate of increase and the intrinsic rate of natural increase of the moth. For the finite rate of increase (λ) the estimated value was 18 per lunar month, corresponding to an intrinsic rate of natural increase (r) of 2.9. The results are compared with published data and it is concluded that the pest potential of C. cephalonica has been, hitherto, underestimated.

Competition between Corcyra cephalonica (Stainton) and Ephestia cautella (Walker) was studied in broken cocoa beans using the two species alone, introduced one before the other and together. Both species of moths cannot co-exist for an extended period and in competition E. cautella becomes extinct. The results offer an explanation of recent evidence that C. cephalonica is rapidly becoming the most important pest of stored cocoa beans in Ghana today.

Eggs (1, 2 and 3-day-old), larvae (early and late) and 4-day-old pupae of the rice moth, Corcyra cephalonica (Stainton), were treated with 60Co gamma-radiation at doses from 0 to 100 krads. Evaluation of moth radiosensitivity by the survival of treated eggs, larvae and pupae led to the following sequence of stages in order of increasing radioresistance: for the eggs, 1, 2 and 3-day-old; for larvae and pupae, early larvae (5 days after hatching), late larvae (5 days before pupation) and 4-day-old pupae. Twenty five kiloradians was found to be the most likely unit for disinfestation by radiation of C. cephalonica.