The pea leafminer, Chromatomyia horticola (Goureau) (Diptera: Agromyzidae) is a polyphagous and serious pest of peas. In India, this pest is attacked by many parasitoids and among them Diglyphus horticola Khan (Hymenoptera: Eulophidae) is an important one, however, demographics and pest-kill potential of this parasitoid has not been studied so far. This study presents the first report on its demographics and pest-kill potential on C. horticola. The parasitoid showed three modes of host-killing behaviour viz. host-feeding, parasitism and host-stinging. The parasitoid females killed more number of hosts by parasitism than host-feeding or host-stinging. The pre-adult survival, net reproductive rate, intrinsic rate of increase (rm) and finite rate of increase (λ) were higher on the 5-days old host larvae than those reared on the 3-days old larvae. Demographics and pest-kill parameters of D. horticola were also better on 5-days old host larvae than on 3-days old host larvae. Based on the study, D. horticola appeared to be a promising biocontrol agent for the suppression of C. horticola in peas and could be promoted through conservation biological control. Further studies are required to standardize the mass production protocol and release rates to use the parasitoid by augmentation.

The influence of some s-triazine herbicides on acid phosphatase (acid Pase) and phosphodiesterase (PDase) from corn (Zea mays L. var. ‘Orfeo’) roots was investigated. Terbutryn [N-(1,1-dimethylethyl)-N′-ethyl-6-(methylthio)-1,3,5-triazine-2,4-diamine] stimulated both phosphatases, whereas prometryn [N,N′-bis(1-methylethyl)-6-(methylthio)-1,3,5-triazine-2,4-diamine] stimulated only the PDase. Atrazine [6-chloro-N-ethyl-N′-(1-methylethyl)-1,3,5-triazine-2,4-diamine] and desmetryn [N-methyl-N′-(1-methylethyl)-6-(methylthio)-1,3,5-triazine-2,4-diamine] inhibited both phosphatases to varying degrees. Atraton [N-ethyl-6-methoxy-N′-(1-methylethyl)-1,3,5-triazine-2,4-diamine], prometon [6-methoxy-N,N′-bis(1-methylethyl)-1,3,5-triazine-2,4-diamine], and simazine (6-chloro-N,N′-diethyl-1,3,5-triazine-2,4-diamine) inhibited acid Pase. No effect was exerted by ametryn [N-ethyl-N′-(1-methylethyl)-6-(methylthio)-1,3,5-triazine-2,4-diamine]. The enzyme assays and the kinetic parameters demonstrated that the interferences observed were due to an action on the synthesis of one or both enzymes rather than on the enzyme reactions. The types of the N-alkyl and the C1-substituent groups in the structures of the s-triazines tested appear important in determining the degree of the interference.