Interspecific competition within larvae of the fall army worm (FAW), Spodoptera frugiperda (J. E. Smith), by the larval parasitoids, Cotesia(= Apanteles) marginiventris Cresson and Microplitis manilae Ashmead, and the egg-larval parasitoid Chelonus insularis Cresson was studied. Chelonus insularis was not able to compete successfully against Cotesia marginiventris, but was a successful competitor against Microplitis manilae. Multiple parasitization of larvae by either Cotesia marginiventris or Microplitis manilae, which as eggs were parasitized by Chelonus insularis, did not result in additional host mortality. Percentage parasitization under greenhouse conditions by Cotesia marginiventris of larvae parasitized previously by Chelonus insularis was two-fold higher in corn compared to sorghum and more than four-fold higher compared to Bermuda grass and itch grass. The host finding and behavioural sequence of oviposition of Cotesia marginiventris in FAW larvae already parasitized by Chelonus insularis consisted of nine steps. Microplitis manilae females changed their behaviour significantly by displaying a reduction of ca. fifty per cent in host examinations, 45% in ovipositor probes, and 55% in apparent ovipositions when Chelonus insularis parasitized larvae were presented. Cotesia marginiventris and Microplitis manilae exhibited no significant behavioural changes in the per cent contacts, examinations and apparent ovipositions when attacking larvae parasitized previously by either Cotesia marginiventris or Microplitis manilae.

Green marine algae (Codium sp.) was extracted sequentially with different organic solvents on cold. Lima bean leaf discs treated with the different extracts were offered to adult female T. urticae for 96 hr and the corrected percentage mortality of the females was calculated. The toxicity of the different extracts to the eggs was also recorded. Petroleum ether extract of this seaweed was highly toxic to females at 4 g/ml. At 1 g/ml ca. 48% of the individuals were killed. Chloroform and ethyl alcohol extracts were found to be poorly effective against the females even at high concentrations (4 g/ml) where less than 50% of the individuals died after 96 hr. Toxicity of crude extracts to the egg stage was less pronounced and chloroform extract was found to be more efficient than the other extracts tested.

Plant essential oils possess diversified insecticidal properties. Under screening programme of survey of bioactive agents for insect control 31 essential oils from different botanicals (2% in acetone), were studied for repellency and direct toxicity (insecticidal) against laboratory bred houseflies, Musca domestica L. The essential oils obtained from Ocimum gratissimum L., Thymus serpyllum L., Illicium verum Hooks, f., Myristica fragrans Houtt., Curcuma amada Roxb. showed 100% repellent activity, and Acorus calamus L. and Thymus serpyllum L. showed about 40% insecticidal activity. Results were compared with N, N-diethyl-meta-toluamide, dimethyl phthalate, malathion, pyrethrum extract, thymol, mineral oil and piperonylbutoxide. Biochemical studies of these promising oils may emerge new leads in developing future pesticides.