Female mites of the species Pyemotes tritici inject an extremely potent venom into their insect prey that causes muscle-contraction and paralysis. These mites are able to paralyse insects 150,000 times their size and their venom is effective in a broad range of insect species. A toxin (TxP-I) associated with the mite venom apparatus causes immediate muscle-contractive paralysis when injected into insects but not mice. In this report, we describe the cloning, sequencing and expression of a complementary DNA (Tox-34) encoding TxP-I. Insect cells infected with a recombinant baculovirus (vEV-Tox34) expressing Tox-34 secrete three polypeptides related to TxP-I which cause paralysis on injection. Larvae infected with vEV-Tox34 become paralysed during infection, thus reflecting the potential application of this toxin gene in insect biocontrol methods. The toxin gene expression system will also allow further exploration of the neurophysiological basis of its insect-specific effects.

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Volatile constituents produced by ant workers belonging to the speciesTapinoma melanocephalum andT. erraticum have been analyzed by gas chromatography-mass spectrometry. The pygidial (=anal) gland secretion ofT. melanocephalum is fortified with 6-methyl-5-hepten-2-one and actinidine (the mass spectrum of which is corrected in this paper). An unidentified compound was detected in cephalic extracts. The pygidial gland secretion ofT. erraticum was also dominated by 6-methyl-5-hepten-2-one, in addition to two isomers of iridodial, and iridomyrmecin. The sternal glands contained iridodial and C15-C20 hydrocarbons. Workers ofT. melanocephalum effectively utilize their pygidial gland secretions as an alarm-defense system during aggressive encounters with workers ofSolenopsis geminata. 6-Methyl-5-hepten-2-one is active as a releaser of alarm behavior, and actinidine is repellent to workers ofT. melanocephalum. Cephalic extracts possessed attractant and arrestant properties for workers of this species.

A full-length cDNA encoding for a microsomal juvenile hormone (JH)-metabolizing epoxide hydrolase (TmEH-1) was isolated from a cDNA library constructed from fat body of last stadium (wandering) cabbage loopers, Trichoplusia ni, at the exact developmental time of maximum JH epoxide hydrolase activity. TmEH-1 was 1887 base pairs in length with a 1389 base pair open reading frame encoding 463 amino acids. Amino acid sequence analysis showed that TmEH-1 was most similar to and contained the exact catalytic triad (Asp-226, Glu-403 and His-430) found in microsomal epoxide hydrolases. TmEH-1-specific message was present along with JH III epoxide hydrolase activity in fat body in feeding (days 1 and 2) and wandering (day 3) larvae with the peak in message level preceding the peak in JH epoxide hydrolase activity by 1 day. When TmEH-1 was expressed in baculovirus-infected Spodoptera frugiperda cells, a 46,000 molecular weight protein appeared on SDS-PAGE which corresponded to the predicted size coded by the TmEH-1 message and which was positively correlated with increases in JH III epoxide hydrolase activity above that of wild-type controls. In subcellular distribution studies, 58% of the juvenile hormone III epoxide hydrolase activity was in the insoluble fractions. Baculovirus expressed TmEH-1 demonstrated a higher specific activity for JH III as compared to the general EH substrates, cis- and trans-stilbene oxide. Southern blot analyses suggested that multiple epoxide hydrolase genes are present in T. ni.