Some British species of Anagrus (Hymenoptera: Mymaridae)

Five species of Anagrus , egg parasites of various leafhopper species (Delphacidae and Cicadellidae, Honioptera), were bred for 3–13 generations in laboratory conditions. Biological and niorphological characteristics as well as attempts at crossbreeding were used to recognise the species Anagrus ensijer Debauche and four new. species. A. ensifer occurred in two varieties. The four new species and the two varieties of A. ensifer are described, and a key is given to both sexes.     

Cellulose xanthate as a soil conditioner: implications for weed control with some soil-applied herbicides

Applications of cellulose xanthate equivalent to 50 kg cellulose/ha to fresh seedbeds preserved surface microtopography and prevented capping after rainfall. Numbers of weed seedlings were up to 50% greater than on untreated soil where capping occurred. The efficiency of nine soil-acting herbicides was not impaired when applied at normal rates either before or after cellulose xanthate. There was no evidence of interaction and the numbers of surviving weeds were proportional to the numbers where no herbicide had been applied. With propachlor, however, weed control was consistently less when applied shortly before or after cellulose xanthate, and analyses showed that in the presence of the soil conditioner the rate of herbicide loss was enhanced. This effect decreased the longer propachlor application was delayed, but was still evident with an interval of 96 h.     

The timing of gonadal development and moult in three raptors with different breeding seasons: effects of gender, age and body condition

Differences between species in breeding seasons are thought to be mediated through differences in their reproductive physiology. Little is known about how the timing and duration of gonadal maturation varies between raptor species, how the timing of moult relates to the gonadal cycle, whether the timing and degree of sexual maturation varies between juveniles and adults or whether body condition has a significant effect. To address these questions, data on gonadal size and moult for adults and juveniles of both sexes of three raptor species were extracted from the Predatory Bird Monitoring Scheme (based on birds found dead by members of the public). The three species, Sparrowhawk Accipiter nisus, Kestrel Falco tinnunculus and Barn Owl Tyto alba, have different ecologies – diurnal bird predator, diurnal mammal predator and nocturnal mammal predator, respectively. All are single‐brooded but have different breeding seasons. The duration of gonadal maturation was markedly different between the species. Barn Owls showed the earliest maturation and the latest gonad regression, and Sparrowhawks the latest maturation and earliest gonad regression. Kestrels were intermediate. In males of all species, the testes remained fully mature throughout their respective breeding seasons. In females, the ovaries remained partially mature throughout the breeding season. Moult started slightly earlier in Sparrowhawks than in Kestrels and coincided with gonadal regression in the two species. Although females of the two species started to moult earlier than males, moult duration was similar between the sexes. Barn Owls showed no distinct annual pattern of moult. In juveniles of all three species, the gonads were smaller than in adults throughout spring and started to mature later. Gonad size in birds that had starved tended to be smaller than in birds dying from other causes, but did not influence the difference in gonad mass between adults and juveniles and between seasons. Body condition had no effect on moult. Whilst ecology has led to the evolution of different breeding seasons, differences between species, and between adults and juveniles, are mediated through adaptive differences in their reproductive physiology.