Developmental biology and field performance of Platygaster diplosisae Risbec (Hymn: Platygasteridae) an egg-larval parasitoid of african rice gall midge Orseolia oryzivora Harris and Gagné (Diptera: Cecidoymiidae)

The developmental biology and field performance of Platygaster diplosisae an endoparasitoid of African rice gall midge (AfRGM) Orseolia oryzivora were investigated. Experiments were conducted in the screen house, laboratory and fields during 2006/2007 farming seasons. The pre-oviposition period averaged 12.1 h. The mean number of eggs laid per female was 95.2 and mean oviposition period was 3.5 days. The average incubation period was 13.0 days with a hatchability of 67.3%. There were three larval instars with developmental duration averaging 2.2, 0.5 and 2.5 days for the 1st, 2nd and 3rd larval respectively. The prepupa and pupa developmental period lasted for 2.4 and 6.7 days respectively. The longevity of males and females were 3.0 and 4.1 days respectively without food, which varied when food was given. The parasitoid has total developmental period of 27.3 days. The results showed that P. diplosisae has an impact as a bio-control agent of AfRGM, but the percentage parasitism of the host was low at the beginning of the season and increased significantly later in the season with a peak in October of each season. It was recommended that mass rearing or conservation of the parasitoid be adopted to improve its efficiency in control of AfRGM.Keywords: Biology, Platygaster diplosisae, bio-control, field impact, Orseolia oryzivora

Parachuting Behavior and Predation by Ants in the Nettle Caterpillar, Scopelodes contracta

This paper documents the bizarre descending behavior from the tree crown to the ground of the larvae of the moth, Scopelodes contracta Walker (Lepidoptera: Limacodidae) and the interaction of the larva with predatory ants. S. contracta larvae infest leaves of many tree species in urban areas and orchards in Japan. Mature larvae and leaves without basal leaf parts were found under trees of four species infested with S. contracta larvae in Osaka, Japan. Individual larvae riding on leaves were observed falling from tree crowns to the ground. Many S. contracta cocoons were found in the soil below the trees two weeks after the observed parachuting. These observations indicate that S. contracta larvae parachuted to the ground where they spin their cocoons in the soil. When a larva that had just parachuted down was returned to an arboreal twig, the larva repeated the parachuting behavior. This parachuting behavior appears to be adaptive, because larvae can descend to the ground safely and with low energy cost. Worker ants of Tetramorium tsushimae Emery (Hymenoptera: Formicidae) and Pristomyrmex punctatus Mayr (Hymenoptera: Formicidae) occasionally attacked larvae on the ground before they had a chance to burrow in the soil

Laboratory Culture Technique for Cephonodes hylas Linnaeus (Lepidoptera: Sphingidae)

Cephonodes hylas (L) is a major Lepidopterous defoliator insect pest that is responsible for 50-70% yield loss of robusta coffee in Nigeria. The biology of the pest was not fully understood due to paucity of information on its rearing in captivity. In addition, on eclosion, the young adults have undeveloped gonads and they require feed before maturation of their gonads. A new laboratory culture technique for this pest is therefore, discussed in this study. Eight cages were initially screened in the laboratory for rearing the insects. Subsequently, four concentrations (5, 10, 20 and 25%) of three sources of sugar; table cane sugar, analytical sucrose and honey were tested for their suitability for raising adults C. hylas under laboratory conditions in the chosen muslin cage with a feeding platform. The moths fed actively on the diets and lived longer than when starved. It was also confirmed that the adults require food for maturation of the gonads. A mean longevity of 14days/adult was attained with the 25% sucrose as against 4 days when starved (given water only) while a mean fecundity of 957 viable eggs/ female was obtained compared to an average of 132 eggs/female in the wild population of the insect. No egg was recorded for the starved moth. The 10% commercial cane sugar solution was adjudged best diet for laboratory rearing of adult C. hylas. Keywords: Laboratory; Culture/Rearing; Diet; Cephonodes hyla

Current status of the larger grain borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) in five South-western States, Nigeria.

The study investigated the current distribution of the larger grain borer (LGB), Prostephanus truncatus, in five states of South-western Nigeria; Ogun, Oyo, Lagos, Ondo and Osun by visual observation of maize stored in cribs and using the synthetic aggregation pheromone of LGB as baits in survey traps for twenty days. The highest mean number of LGB was trapped in Ogun state, followed by catches from Lagos, Oyo, Ondo and Osun states respectively. The mean number of LGB trapped in Ogun state was significantly higher (P < 0.05) than mean catches in other states. In all the locations, the number of borers caught in the traps declined with days after the activation of the pheromone. In the crib survey, P. truncatus was not observed in any of the twenty cribs sampled across the states. However, other stored product insects were found in descending order; Sitophilus zeamais (L.) (60.0%), Oryzaephilus surinamensis (Motsch) (40.0%), Tribolium castaneum (Herbst.) (35.0%), Cryptolestes ferrugineus (Steph.) (25%) and Rhizopertha dominica F. (5.0%). Concerted efforts should be directed at preventing further spread of LGB in Nigeria, especially in Ogun and Lagos states that showed high presence of the borer.Keywords: Prostephanus Truncatus; Aggregation pheromone; Survey tra; Cribs; Distributio

Population structure of Vitelaria paradoxa Gaertn. F. and Parkia biglobosa(Jacq.) Benth.in the Agroforestry Parklands of Nigerian humid Savanna

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