Reconciliation, defined as a friendly reunion between former opponents shortly after an aggressive encounter, is common in the stumptail macaque (Macaca arctoides) but rare in the rhesus macaque (M. mulatta). Juveniles of the two species were cohoused for 5 months, after which they were observed with conspecifics only. Control rhesus monkeys, matched in age and sex to the experimental subjects, went through the same procedure without exposure to the other species. A threefold increase in the proportion of reconciled fights was measured in the rhesus subjects. The difference emerged gradually during cohousing with the tutor species and was sustained following removal of this species. Other behavior, such as grooming and aggression, decreased over time. It is suggested that the social attitude of the subjects was affected through contact with a species characterized by a more relaxed dominance style.
Two experiments were conducted to investigate the relationship between rearing temperatures, the presence or absence of Wolbachia endosymbionts, and non‐reciprocal reproductive incompatibility in inbred lines of the parahaploid phytoseiid mite Metaseiulus occidentalis (Nesbitt) (Acari: Phytoseiidae).
Heat‐treated females crossed with infected males reared at room temperature produced few eggs and high proportions of shriveled eggs. No female progeny were produced. The reciprocal cross was normal. A second experiment showed that the incompatible cross from the first experiment could be made compatible if the infected line was heat‐treated and those males crossed with the original heat‐treated females. Furthermore, a new incompatibility was induced in a formerly compatible cross when the newly heat‐treated females were crossed with males from their base colony. Heat‐treatment was correlated with the loss of Wolbachia in both experiments. Wolbachia may thus affect non‐reciprocal reproductive incompatibility in M. occidentalis, and may produce a unique incompatibility phenotype in this parahaploid species, including both reduced numbers of male progeny and a lack of female progeny.
Collard greens (Brassica oleracea var. acephala L.) were planted in the peripheries of cabbage (Brassica oleracea var. capitata L.) fields in the spring growing seasons of 1997 and 1998 to evaluate their effectiveness as a trap crop to manage the diamondback moth (DBM) [Plutella xylostella (L.)]. The numbers of DBM never exceeded the action threshold for application of insecticides in any of the fields that were completely surrounded by collards, but did exceed the action threshold in three of the fields without collards on four sampling dates in 1998. In both years, the numbers of DBM larvae in the collards exceeded the action threshold of 0.3 total larvae/plant in eight of nine fields. Larval counts in cabbage surrounded with collards were not significantly higher than in the conventionally planted cabbage, even though the number of pesticide applications was reduced in the former. The few pesticide applications in fields surrounded by collards probably targeted the cabbage looper [Trichoplusia ni (Hübner)], which was not impeded by the collards from infesting the interior cabbage. There was no significant reduction in marketability, and damage to cabbage was similar to that in fields where collards were planted and in fields where only conventional pesticides were used. The reduced number of pesticide sprays, as well as the high concentration of host larvae in the collards, may help maintain populations of natural enemies of DBM in the agroecosystem. Planting collards in field peripheries is a potentially effective tactic to manage DBM in cabbage.
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